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整理:SpringBoot入门教程(下)

整理:SpringBoot入门教程(下)

作者: __元昊__ | 来源:发表于2019-07-14 12:04 被阅读0次

    四、Web开发

    1、简介

    使用SpringBoot;

    1)、创建SpringBoot应用,选中我们需要的模块;

    2)、SpringBoot已经默认将这些场景配置好了,只需要在配置文件中指定少量配置就可以运行起来

    3)、自己编写业务代码;

    2、模板引擎

    JSP、Velocity、Freemarker、Thymeleaf

    template-engine.png

    SpringBoot推荐的Thymeleaf;

    语法更简单,功能更强大;

    2.1、引入thymeleaf;

    thymeleaf官网

            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-thymeleaf</artifactId>
            </dependency>
    切换thymeleaf版本
    <properties>
            <thymeleaf.version>3.0.9.RELEASE</thymeleaf.version>
            <!-- 布局功能的支持程序  thymeleaf3主程序  layout2以上版本 -->
            <!-- thymeleaf2   layout1-->
            <thymeleaf-layout-dialect.version>2.2.2</thymeleaf-layout-dialect.version>
      </properties>
    

    2.2、Thymeleaf使用

    @ConfigurationProperties(prefix = "spring.thymeleaf")
    public class ThymeleafProperties {
    
        private static final Charset DEFAULT_ENCODING = Charset.forName("UTF-8");
    
        private static final MimeType DEFAULT_CONTENT_TYPE = MimeType.valueOf("text/html");
    
        public static final String DEFAULT_PREFIX = "classpath:/templates/";
    
        public static final String DEFAULT_SUFFIX = ".html";
        //
    

    只要我们把HTML页面放在classpath:/templates/,thymeleaf就能自动渲染;

    使用:

    1、导入thymeleaf的名称空间

    <html lang="en" xmlns:th="http://www.thymeleaf.org">
    

    2、使用thymeleaf语法;

    <!DOCTYPE html>
    <html lang="en" xmlns:th="http://www.thymeleaf.org">
    <head>
        <meta charset="UTF-8">
        <title>Title</title>
    </head>
    <body>
        <h1>成功!</h1>
        <!--th:text 将div里面的文本内容设置为 -->
        <div th:text="${hello}">这是显示欢迎信息</div>
    </body>
    </html>
    

    2.3、语法规则

    1)、th:text;改变当前元素里面的文本内容;

    ​ th:任意html属性;来替换原生属性的值

    2018-02-04_123955.png

    2)、表达式?

    Simple expressions:(表达式语法)
    a. Variable Expressions: ${...}:获取变量值;OGNL;
        1)、获取对象的属性、调用方法
        2)、使用内置的基本对象:
        #ctx : the context object.
        #vars: the context variables.
        #locale : the context locale.
        #request : (only in Web Contexts) the HttpServletRequest object.
        #response : (only in Web Contexts) the HttpServletResponse object.
        #session : (only in Web Contexts) the HttpSession object.
        #servletContext : (only in Web Contexts) the ServletContext object.
        ${session.foo}
        3)、内置的一些工具对象:
            #execInfo : information about the template being processed.
            #messages : methods for obtaining externalized messages inside variables expressions,
            #          in the same way as they would be obtained using #{…} syntax.
            #uris : methods for escaping parts of URLs/URIs
            #conversions : methods for executing the configured conversion service (if any).
            #dates : methods for java.util.Date objects: formatting, component extraction, etc.
            #calendars : analogous to #dates , but for java.util.Calendar objects.
            #numbers : methods for formatting numeric objects.
            #strings : methods for String objects: contains, startsWith, prepending/appending, etc.
            #objects : methods for objects in general.
            #bools : methods for boolean evaluation.
            #arrays : methods for arrays.
            #lists : methods for lists.
            #sets : methods for sets.
            #maps : methods for maps.
            #aggregates : methods for creating aggregates on arrays or collections.
            #ids : methods for dealing with id attributes that might be repeated (for example, as a result of an iteration).
    
    b. Selection Variable Expressions: *{...}:选择表达式:和${}在功能上是一样;
            补充:配合 th:object="${session.user}:
            <div th:object="${session.user}">
            <p>Name: <span th:text="*{firstName}">Sebastian</span>.</p>
            <p>Surname: <span th:text="*{lastName}">Pepper</span>.</p>
            <p>Nationality: <span th:text="*{nationality}">Saturn</span>.</p>
            </div>
        
    c. Message Expressions: #{...}:获取国际化内容
    d. Link URL Expressions: @{...}:定义URL;
                @{/order/process(execId=${execId},execType='FAST')}
    f. Fragment Expressions: ~{...}:片段引用表达式
                <div th:insert="~{commons :: main}">...</div>
                
    Literals(字面量)
        Text literals: 'one text' , 'Another one!' ,…
        Number literals: 0 , 34 , 3.0 , 12.3 ,…
        Boolean literals: true , false
        Null literal: null
        Literal tokens: one , sometext , main ,…
    Text operations:(文本操作)
        String concatenation: +
        Literal substitutions: |The name is ${name}|
    Arithmetic operations:(数学运算)
        Binary operators: + , - , * , / , %
        Minus sign (unary operator): -
    Boolean operations:(布尔运算)
        Binary operators: and , or
        Boolean negation (unary operator): ! , not
    Comparisons and equality:(比较运算)
        Comparators: > , < , >= , <= ( gt , lt , ge , le )
        Equality operators: == , != ( eq , ne )
    Conditional operators:条件运算(三元运算符)
        If-then: (if) ? (then)
        If-then-else: (if) ? (then) : (else)
        Default: (value) ?: (defaultvalue)
    Special tokens:
        No-Operation: _ 
    

    3、SpringMVC自动配置

    https://docs.spring.io/spring-boot/docs/1.5.10.RELEASE/reference/htmlsingle/#boot-features-developing-web-applications

    1. Spring MVC auto-configuration

    Spring Boot 自动配置好了SpringMVC

    以下是SpringBoot对SpringMVC的默认配置:(WebMvcAutoConfiguration)

    • Inclusion of ContentNegotiatingViewResolver and BeanNameViewResolver beans.

      • 自动配置了ViewResolver(视图解析器:根据方法的返回值得到视图对象(View),视图对象决定如何渲染(转发?重定向?))
      • ContentNegotiatingViewResolver:组合所有的视图解析器的;
      • 如何定制:我们可以自己给容器中添加一个视图解析器;自动的将其组合进来;
    • Support for serving static resources, including support for WebJars (see below).静态资源文件夹路径,webjars

    • Static index.html support. 静态首页访问

    • Custom Favicon support (see below). favicon.ico

    • 自动注册了 of Converter, GenericConverter, Formatter beans.

      • Converter:转换器; public String hello(User user):类型转换使用Converter
      • Formatter 格式化器; 2017.12.17===Date;
    @Bean
    @ConditionalOnProperty(prefix = "spring.mvc", name = "date-format")//在文件中配置日期格式化的规则
    public Formatter<Date> dateFormatter() {
        return new DateFormatter(this.mvcProperties.getDateFormat());//日期格式化组件
    }
    

    ​ 自己添加的格式化器转换器,我们只需要放在容器中即可

    • Support for HttpMessageConverters (see below).

      • HttpMessageConverter:SpringMVC用来转换Http请求和响应的;User---Json;

      • HttpMessageConverters 是从容器中确定;获取所有的HttpMessageConverter;

        自己给容器中添加HttpMessageConverter,只需要将自己的组件注册容器中(@Bean,@Component)

    • Automatic registration of MessageCodesResolver (see below).定义错误代码生成规则

    • Automatic use of a ConfigurableWebBindingInitializer bean (see below).

      我们可以配置一个ConfigurableWebBindingInitializer来替换默认的;(添加到容器)

      初始化WebDataBinder;
      请求数据=====JavaBean;
      

    org.springframework.boot.autoconfigure.web:web的所有自动场景;

    If you want to keep Spring Boot MVC features, and you just want to add additional MVC configuration (interceptors, formatters, view controllers etc.) you can add your own @Configuration class of type WebMvcConfigurerAdapter, but without @EnableWebMvc. If you wish to provide custom instances of RequestMappingHandlerMapping, RequestMappingHandlerAdapter or ExceptionHandlerExceptionResolver you can declare a WebMvcRegistrationsAdapter instance providing such components.

    If you want to take complete control of Spring MVC, you can add your own @Configuration annotated with @EnableWebMvc.

    2、扩展SpringMVC

        <mvc:view-controller path="/hello" view-name="success"/>
        <mvc:interceptors>
            <mvc:interceptor>
                <mvc:mapping path="/hello"/>
                <bean></bean>
            </mvc:interceptor>
        </mvc:interceptors>
    

    编写一个配置类(@Configuration),是WebMvcConfigurerAdapter类型;不能标注@EnableWebMvc;

    既保留了所有的自动配置,也能用我们扩展的配置;

    /**
     * @Author: cuzz
     * @Date: 2018/9/21 14:29
     * @Description:
     */
    @Configuration
    // WebMvcConfigurerAdapter过时,使用WebMvcConfigurer接口
    public class MyMvcConfig implements WebMvcConfigurer {
        @Override
        public void addViewControllers(ViewControllerRegistry registry) {
            // 浏览器发送 /cuzz 请求来到 success
            registry.addViewController("/cuzz").setViewName("success");
        }
    }
    

    原理:

    ​ 1)、WebMvcAutoConfiguration是SpringMVC的自动配置类

    ​ 2)、在做其他自动配置时会导入;@Import(EnableWebMvcConfiguration.class)

        @Configuration
        public static class EnableWebMvcConfiguration extends DelegatingWebMvcConfiguration {
          private final WebMvcConfigurerComposite configurers = new WebMvcConfigurerComposite();
    
         //从容器中获取所有的WebMvcConfigurer
          @Autowired(required = false)
          public void setConfigurers(List<WebMvcConfigurer> configurers) {
              if (!CollectionUtils.isEmpty(configurers)) {
                  this.configurers.addWebMvcConfigurers(configurers);
                    //一个参考实现;将所有的WebMvcConfigurer相关配置都来一起调用;  
                    @Override
                    // public void addViewControllers(ViewControllerRegistry registry) {
                    //      for (WebMvcConfigurer delegate : this.delegates) {
                    //      delegate.addViewControllers(registry);
                    //   }
                  }
              }
        }
    

    ​ 3)、容器中所有的WebMvcConfigurer都会一起起作用;

    ​ 4)、我们的配置类也会被调用;

    ​ 效果:SpringMVC的自动配置和我们的扩展配置都会起作用;

    3、全面接管SpringMVC;

    SpringBoot对SpringMVC的自动配置不需要了,所有都是我们自己配置;所有的SpringMVC的自动配置都失效了

    我们需要在配置类中添加@EnableWebMvc即可;

    //使用WebMvcConfigurerAdapter可以来扩展SpringMVC的功能
    @EnableWebMvc
    @Configuration
    public class MyMvcConfig extends WebMvcConfigurerAdapter {
    
        @Override
        public void addViewControllers(ViewControllerRegistry registry) {
           // super.addViewControllers(registry);
            //浏览器发送 /atguigu 请求来到 success
            registry.addViewController("/atguigu").setViewName("success");
        }
    }
    

    原理:

    为什么@EnableWebMvc自动配置就失效了;

    1)@EnableWebMvc的核心

    @Import(DelegatingWebMvcConfiguration.class)
    public @interface EnableWebMvc {
    

    2)、

    @Configuration
    public class DelegatingWebMvcConfiguration extends WebMvcConfigurationSupport {
    

    3)、

    @Configuration
    @ConditionalOnWebApplication
    @ConditionalOnClass({ Servlet.class, DispatcherServlet.class,
            WebMvcConfigurerAdapter.class })
    // 容器中没有这个组件的时候,这个自动配置类才生效
    @ConditionalOnMissingBean(WebMvcConfigurationSupport.class)
    @AutoConfigureOrder(Ordered.HIGHEST_PRECEDENCE + 10)
    @AutoConfigureAfter({ DispatcherServletAutoConfiguration.class,
            ValidationAutoConfiguration.class })
    public class WebMvcAutoConfiguration {
    

    4)、@EnableWebMvc将WebMvcConfigurationSupport组件导入进来;

    5)、导入的WebMvcConfigurationSupport只是SpringMVC最基本的功能;

    5、如何修改SpringBoot的默认配置

    模式:

    ​ 1)、SpringBoot在自动配置很多组件的时候,先看容器中有没有用户自己配置的(@Bean、@Component)如果有就用用户配置的,如果没有,才自动配置;如果有些组件可以有多个(ViewResolver)将用户配置的和自己默认的组合起来;

    ​ 2)、在SpringBoot中会有非常多的xxxConfigurer帮助我们进行扩展配置

    ​ 3)、在SpringBoot中会有很多的xxxCustomizer帮助我们进行定制配置

    6、RestfulCRUD

    1)、默认访问首页

    /**
     * @Author: cuzz
     * @Date: 2018/9/21 14:29
     * @Description:
     */
    @Configuration
    // WebMvcConfigurerAdapter过时,使用WebMvcConfigurer接口
    public class MyMvcConfig implements WebMvcConfigurer {
        @Override
        public void addViewControllers(ViewControllerRegistry registry) {
            registry.addViewController("/cuzz").setViewName("success");
        }
        // 所有的WebMvcConfigurerAdapter组件都会一起起作用
        @Bean
        public WebMvcConfigurer webMvcConfigurer() {
            WebMvcConfigurer webMvcConfigurer = new WebMvcConfigurer() {
                @Override
                public void addViewControllers(ViewControllerRegistry registry) {
                    registry.addViewController("/").setViewName("login");
                    registry.addViewController("/index.html").setViewName("login");
                }
            };
            return webMvcConfigurer;
        }
    }
    

    2)、国际化

    1)、编写国际化配置文件;

    2)、使用ResourceBundleMessageSource管理国际化资源文件

    3)、在页面使用fmt:message取出国际化内容

    i18n = internationalization(国际化)的缩写,首位的i和末尾的n之间有18个字母,所以就简写为i18n了

    步骤:

    new -> add properties file to resource bundle 要先新建一个properties文件,xxx_en_US.properties语言和国家

    1537515512779.png

    1)、编写国际化配置文件,抽取页面需要显示的国际化消息

    1537515666575.png 搜狗截图20180211130721.png

    2)、SpringBoot自动配置好了管理国际化资源文件的组件;

    @ConfigurationProperties(prefix = "spring.messages")
    public class MessageSourceAutoConfiguration {
        
        /**
         * Comma-separated list of basenames (essentially a fully-qualified classpath
         * location), each following the ResourceBundle convention with relaxed support for
         * slash based locations. If it doesn't contain a package qualifier (such as
         * "org.mypackage"), it will be resolved from the classpath root.
         */
        private String basename = "messages";  
        //我们的配置文件可以直接放在类路径下叫messages.properties;
        
        @Bean
        public MessageSource messageSource() {
            ResourceBundleMessageSource messageSource = new ResourceBundleMessageSource();
            if (StringUtils.hasText(this.basename)) {
                //设置国际化资源文件的基础名(去掉语言国家代码的)
                messageSource.setBasenames(StringUtils.commaDelimitedListToStringArray(
                        StringUtils.trimAllWhitespace(this.basename)));
            }
            if (this.encoding != null) {
                messageSource.setDefaultEncoding(this.encoding.name());
            }
            messageSource.setFallbackToSystemLocale(this.fallbackToSystemLocale);
            messageSource.setCacheSeconds(this.cacheSeconds);
            messageSource.setAlwaysUseMessageFormat(this.alwaysUseMessageFormat);
            return messageSource;
        }
    

    3)、去页面获取国际化的值;

    搜狗截图20180211134506.png
    <!DOCTYPE html>
    <html lang="en"  xmlns:th="http://www.thymeleaf.org">
        <head>
            <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
            <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
            <meta name="description" content="">
            <meta name="author" content="">
            <title>Signin Template for Bootstrap</title>
            <!-- Bootstrap core CSS -->
            <link href="asserts/css/bootstrap.min.css" th:href="@{/webjars/bootstrap/4.0.0/css/bootstrap.css}" rel="stylesheet">
            <!-- Custom styles for this template -->
            <link href="asserts/css/signin.css" th:href="@{/asserts/css/signin.css}" rel="stylesheet">
        </head>
    
        <body class="text-center">
            <form class="form-signin" action="dashboard.html">
                <img class="mb-4" th:src="@{/asserts/img/bootstrap-solid.svg}" src="asserts/img/bootstrap-solid.svg" alt="" width="72" height="72">
                <h1 class="h3 mb-3 font-weight-normal" th:text="#{login.tip}">Please sign in</h1>
                <label class="sr-only" th:text="#{login.username}">Username</label>
                <input type="text" class="form-control" placeholder="Username" th:placeholder="#{login.username}" required="" autofocus="">
                <label class="sr-only" th:text="#{login.password}">Password</label>
                <input type="password" class="form-control" placeholder="Password" th:placeholder="#{login.password}" required="">
                <div class="checkbox mb-3">
                    <label>
                    <input type="checkbox" value="remember-me"/> [[#{login.remember}]]
            </label>
                </div>
                <button class="btn btn-lg btn-primary btn-block" type="submit" th:text="#{login.btn}">Sign in</button>
                <p class="mt-5 mb-3 text-muted">© 2017-2018</p>
                <a class="btn btn-sm">中文</a>
                <a class="btn btn-sm">English</a>
            </form>
    
        </body>
    
    </html>
    

    效果:根据浏览器语言设置的信息切换了国际化;

    原理:

    ​ 国际化Locale(区域信息对象);LocaleResolver(获取区域信息对象);

            @Bean
            @ConditionalOnMissingBean
            @ConditionalOnProperty(prefix = "spring.mvc", name = "locale")
            public LocaleResolver localeResolver() {
                if (this.mvcProperties
                        .getLocaleResolver() == WebMvcProperties.LocaleResolver.FIXED) {
                    return new FixedLocaleResolver(this.mvcProperties.getLocale());
                }
                AcceptHeaderLocaleResolver localeResolver = new AcceptHeaderLocaleResolver();
                localeResolver.setDefaultLocale(this.mvcProperties.getLocale());
                return localeResolver;
            }
    默认的就是根据请求头带来的区域信息获取Locale进行国际化
    

    4)、点击链接切换国际化

    /**
     * 可以在连接上携带区域信息
     */
    public class MyLocaleResolver implements LocaleResolver {
        
        @Override
        public Locale resolveLocale(HttpServletRequest request) {
            String l = request.getParameter("l");
            Locale locale = Locale.getDefault();
            if(!StringUtils.isEmpty(l)){
                String[] split = l.split("_");
                locale = new Locale(split[0],split[1]);
            }
            return locale;
        }
    
        @Override
        public void setLocale(HttpServletRequest request, 
                              HttpServletResponse response,
                              Locale locale) {
    
        }
    
    
        // 国际化注入
        @Bean
        public LocaleResolver localeResolver(){
            return new MyLocaleResolver();
        }
    }
    
    
    

    3)、登陆

    开发期间模板引擎页面修改以后,要实时生效

    1)、禁用模板引擎的缓存

    # 禁用缓存
    spring.thymeleaf.cache=false 
    

    2)、页面修改完成以后ctrl+f9:重新编译;

    登陆错误消息的显示

    <p style="color: red" th:text="${msg}" th:if="${not #strings.isEmpty(msg)}"></p>
    

    4)、拦截器进行登陆检查

    拦截器

    
    /**
     * 登陆检查,
     */
    public class LoginHandlerInterceptor implements HandlerInterceptor {
        //目标方法执行之前
        @Override
        public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
            Object user = request.getSession().getAttribute("loginUser");
            if(user == null){
                //未登陆,返回登陆页面
                request.setAttribute("msg","没有权限请先登陆");
                request.getRequestDispatcher("/index.html").forward(request,response);
                return false;
            }else{
                //已登陆,放行请求
                return true;
            }
    
        }
    
        @Override
        public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
    
        }
    
        @Override
        public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
    
        }
    }
    
    

    注册拦截器

    /**
     * @Author: cuzz
     * @Date: 2018/9/21 14:29
     * @Description:
     */
    @Configuration
    // WebMvcConfigurerAdapter过时,使用WebMvcConfigurer接口
    public class MyMvcConfig implements WebMvcConfigurer {
        @Override
        public void addViewControllers(ViewControllerRegistry registry) {
            registry.addViewController("/cuzz").setViewName("success");
        }
        //注册拦截器
        @Override
        public void addInterceptors(InterceptorRegistry registry) {
            //super.addInterceptors(registry);
            //静态资源;  *.css , *.js
            //SpringBoot已经做好了静态资源映射
            registry.addInterceptor(new LoginHandlerInterceptor()).addPathPatterns("/**")
                    .excludePathPatterns("/index.html","/","/user/login");
        }
    
        // 所有的WebMvcConfigurerAdapter组件都会一起起作用
        @Bean
        public WebMvcConfigurer webMvcConfigurer() {
            WebMvcConfigurer webMvcConfigurer = new WebMvcConfigurer() {
                @Override
                public void addViewControllers(ViewControllerRegistry registry) {
                    registry.addViewController("/").setViewName("login");
                    registry.addViewController("/index.html").setViewName("login");
                    registry.addViewController("/main.html").setViewName("dashboard");
                }
            };
            return webMvcConfigurer;
        }
    
        @Bean
        public LocaleResolver localeResolver() {
            return new MyLocaleResolver();
        }
    }
    

    5)、CRUD-员工列表

    实验要求:

    1)、RestfulCRUD:CRUD满足Rest风格;

    URI: /资源名称/资源标识 HTTP请求方式区分对资源CRUD操作

    普通CRUD(uri来区分操作) RestfulCRUD
    查询 getEmp emp---GET
    添加 addEmp?xxx emp---POST
    修改 updateEmp?id=xxx&xxx=xx emp/{id}---PUT
    删除 deleteEmp?id=1 emp/{id}---DELETE

    2)、实验的请求架构;

    实验功能 请求URI 请求方式
    查询所有员工 emps GET
    查询某个员工(来到修改页面) emp/1 GET
    来到添加页面 emp GET
    添加员工 emp POST
    来到修改页面(查出员工进行信息回显) emp/1 GET
    修改员工 emp PUT
    删除员工 emp/1 DELETE

    3)、员工列表:

    thymeleaf公共页面元素抽取

    1、抽取公共片段
    <div th:fragment="copy">
    &copy; 2011 The Good Thymes Virtual Grocery
    </div>
    
    2、引入公共片段
    <div th:insert="~{footer :: copy}"></div>
    ~{templatename::selector}:模板名::选择器
    ~{templatename::fragmentname}:模板名::片段名
    
    3、默认效果:
    insert的公共片段在div标签中
    如果使用th:insert等属性进行引入,可以不用写~{}:
    行内写法可以加上:[[~{}]];[(~{})];
    

    三种引入公共片段的th属性:

    th:insert:将公共片段整个插入到声明引入的元素中

    th:replace:将声明引入的元素替换为公共片段

    th:include:将被引入的片段的内容包含进这个标签中

    <footer th:fragment="copy">
    &copy; 2011 The Good Thymes Virtual Grocery
    </footer>
    
    引入方式
    <div th:insert="footer :: copy"></div>
    <div th:replace="footer :: copy"></div>
    <div th:include="footer :: copy"></div>
    
    效果
    <div>
        <footer>
        &copy; 2011 The Good Thymes Virtual Grocery
        </footer>
    </div>
    
    <footer>
    &copy; 2011 The Good Thymes Virtual Grocery
    </footer>
    
    <div>
    &copy; 2011 The Good Thymes Virtual Grocery
    </div>
    

    引入片段的时候传入参数:

    
    <nav class="col-md-2 d-none d-md-block bg-light sidebar" id="sidebar">
        <div class="sidebar-sticky">
            <ul class="nav flex-column">
                <li class="nav-item">
                    <a class="nav-link active"
                       th:class="${activeUri=='main.html'?'nav-link active':'nav-link'}"
                       href="#" th:href="@{/main.html}">
                        <svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="feather feather-home">
                            <path d="M3 9l9-7 9 7v11a2 2 0 0 1-2 2H5a2 2 0 0 1-2-2z"></path>
                            <polyline points="9 22 9 12 15 12 15 22"></polyline>
                        </svg>
                        Dashboard <span class="sr-only">(current)</span>
                    </a>
                </li>
    
    <!--引入侧边栏;传入参数-->
    <div th:replace="commons/bar::#sidebar(activeUri='emps')"></div>
    

    6)、CRUD-员工添加

    添加页面

    <form>
        <div class="form-group">
            <label>LastName</label>
            <input type="text" class="form-control" placeholder="zhangsan">
        </div>
        <div class="form-group">
            <label>Email</label>
            <input type="email" class="form-control" placeholder="zhangsan@atguigu.com">
        </div>
        <div class="form-group">
            <label>Gender</label><br/>
            <div class="form-check form-check-inline">
                <input class="form-check-input" type="radio" name="gender"  value="1">
                <label class="form-check-label">男</label>
            </div>
            <div class="form-check form-check-inline">
                <input class="form-check-input" type="radio" name="gender"  value="0">
                <label class="form-check-label">女</label>
            </div>
        </div>
        <div class="form-group">
            <label>department</label>
            <select class="form-control">
                <option>1</option>
                <option>2</option>
                <option>3</option>
                <option>4</option>
                <option>5</option>
            </select>
        </div>
        <div class="form-group">
            <label>Birth</label>
            <input type="text" class="form-control" placeholder="zhangsan">
        </div>
        <button type="submit" class="btn btn-primary">添加</button>
    </form>
    

    提交的数据格式不对:生日:日期;

    2017-12-12;2017/12/12;2017.12.12;

    日期的格式化;SpringMVC将页面提交的值需要转换为指定的类型;

    2017-12-12---Date; 类型转换,格式化;

    默认日期是按照/的方式;

    7)、CRUD-员工修改

    修改添加二合一表单

    <!--需要区分是员工修改还是添加;-->
    <form th:action="@{/emp}" method="post">
        <!--发送put请求修改员工数据-->
        <!--
    1、SpringMVC中配置HiddenHttpMethodFilter;(SpringBoot自动配置好的)
    2、页面创建一个post表单
    3、创建一个input项,name="_method";值就是我们指定的请求方式
    -->
        <input type="hidden" name="_method" value="put" th:if="${emp!=null}"/>
        <input type="hidden" name="id" th:if="${emp!=null}" th:value="${emp.id}">
        <div class="form-group">
            <label>LastName</label>
            <input name="lastName" type="text" class="form-control" placeholder="zhangsan" th:value="${emp!=null}?${emp.lastName}">
        </div>
        <div class="form-group">
            <label>Email</label>
            <input name="email" type="email" class="form-control" placeholder="zhangsan@atguigu.com" th:value="${emp!=null}?${emp.email}">
        </div>
        <div class="form-group">
            <label>Gender</label><br/>
            <div class="form-check form-check-inline">
                <input class="form-check-input" type="radio" name="gender" value="1" th:checked="${emp!=null}?${emp.gender==1}">
                <label class="form-check-label">男</label>
            </div>
            <div class="form-check form-check-inline">
                <input class="form-check-input" type="radio" name="gender" value="0" th:checked="${emp!=null}?${emp.gender==0}">
                <label class="form-check-label">女</label>
            </div>
        </div>
        <div class="form-group">
            <label>department</label>
            <!--提交的是部门的id-->
            <select class="form-control" name="department.id">
                <option th:selected="${emp!=null}?${dept.id == emp.department.id}" th:value="${dept.id}" th:each="dept:${depts}" th:text="${dept.departmentName}">1</option>
            </select>
        </div>
        <div class="form-group">
            <label>Birth</label>
            <input name="birth" type="text" class="form-control" placeholder="zhangsan" th:value="${emp!=null}?${#dates.format(emp.birth, 'yyyy-MM-dd HH:mm')}">
        </div>
        <button type="submit" class="btn btn-primary" th:text="${emp!=null}?'修改':'添加'">添加</button>
    </form>
    

    8)、CRUD-员工删除

    <tr th:each="emp:${emps}">
        <td th:text="${emp.id}"></td>
        <td>[[${emp.lastName}]]</td>
        <td th:text="${emp.email}"></td>
        <td th:text="${emp.gender}==0?'女':'男'"></td>
        <td th:text="${emp.department.departmentName}"></td>
        <td th:text="${#dates.format(emp.birth, 'yyyy-MM-dd HH:mm')}"></td>
        <td>
            <a class="btn btn-sm btn-primary" th:href="@{/emp/}+${emp.id}">编辑</a>
            <button th:attr="del_uri=@{/emp/}+${emp.id}" class="btn btn-sm btn-danger deleteBtn">删除</button>
        </td>
    </tr>
    
    
    <script>
        $(".deleteBtn").click(function(){
            //删除当前员工的
            $("#deleteEmpForm").attr("action",$(this).attr("del_uri")).submit();
            return false;
        });
    </script>
    

    7、错误处理机制

    1)、SpringBoot默认的错误处理机制

    默认效果:

    ​ 1)、浏览器,返回一个默认的错误页面

    搜狗截图20180226173408.png

    浏览器发送请求的请求头:

    搜狗截图20180226180347.png

    ​ 2)、如果是其他客户端,默认响应一个json数据


    搜狗截图20180226173527.png 搜狗截图20180226180504.png


    原理:

    ​ 可以参照ErrorMvcAutoConfiguration;错误处理的自动配置;

    给容器中添加了以下组件
    

    ​ 1、DefaultErrorAttributes:

    帮我们在页面共享信息;
    @Override
        public Map<String, Object> getErrorAttributes(RequestAttributes requestAttributes,
                boolean includeStackTrace) {
            Map<String, Object> errorAttributes = new LinkedHashMap<String, Object>();
            errorAttributes.put("timestamp", new Date());
            addStatus(errorAttributes, requestAttributes);
            addErrorDetails(errorAttributes, requestAttributes, includeStackTrace);
            addPath(errorAttributes, requestAttributes);
            return errorAttributes;
        }
    

    ​ 2、BasicErrorController:处理默认/error请求

    @Controller
    @RequestMapping("${server.error.path:${error.path:/error}}")
    public class BasicErrorController extends AbstractErrorController {
        
        @RequestMapping(produces = "text/html")//产生html类型的数据;浏览器发送的请求来到这个方法处理
        public ModelAndView errorHtml(HttpServletRequest request,
                HttpServletResponse response) {
            HttpStatus status = getStatus(request);
            Map<String, Object> model = Collections.unmodifiableMap(getErrorAttributes(
                    request, isIncludeStackTrace(request, MediaType.TEXT_HTML)));
            response.setStatus(status.value());
            
            //去哪个页面作为错误页面;包含页面地址和页面内容
            ModelAndView modelAndView = resolveErrorView(request, response, status, model);
            return (modelAndView == null ? new ModelAndView("error", model) : modelAndView);
        }
    
        @RequestMapping
        @ResponseBody    //产生json数据,其他客户端来到这个方法处理;
        public ResponseEntity<Map<String, Object>> error(HttpServletRequest request) {
            Map<String, Object> body = getErrorAttributes(request,
                    isIncludeStackTrace(request, MediaType.ALL));
            HttpStatus status = getStatus(request);
            return new ResponseEntity<Map<String, Object>>(body, status);
        }
    

    ​ 3、ErrorPageCustomizer:

        @Value("${error.path:/error}")
        private String path = "/error";  系统出现错误以后来到error请求进行处理;(web.xml注册的错误页面规则)
    

    ​ 4、DefaultErrorViewResolver:

    @Override
        public ModelAndView resolveErrorView(HttpServletRequest request, HttpStatus status,
                Map<String, Object> model) {
            ModelAndView modelAndView = resolve(String.valueOf(status), model);
            if (modelAndView == null && SERIES_VIEWS.containsKey(status.series())) {
                modelAndView = resolve(SERIES_VIEWS.get(status.series()), model);
            }
            return modelAndView;
        }
    
        private ModelAndView resolve(String viewName, Map<String, Object> model) {
            //默认SpringBoot可以去找到一个页面?  error/404
            String errorViewName = "error/" + viewName;
            
            //模板引擎可以解析这个页面地址就用模板引擎解析
            TemplateAvailabilityProvider provider = this.templateAvailabilityProviders
                    .getProvider(errorViewName, this.applicationContext);
            if (provider != null) {
                //模板引擎可用的情况下返回到errorViewName指定的视图地址
                return new ModelAndView(errorViewName, model);
            }
            //模板引擎不可用,就在静态资源文件夹下找errorViewName对应的页面   error/404.html
            return resolveResource(errorViewName, model);
        }
    

    ​ 步骤:

    ​ 一但系统出现4xx或者5xx之类的错误;ErrorPageCustomizer就会生效(定制错误的响应规则);就会来到/error请求;就会被BasicErrorController处理;

    ​ 1)响应页面;去哪个页面是由DefaultErrorViewResolver解析得到的;

    protected ModelAndView resolveErrorView(HttpServletRequest request,
          HttpServletResponse response, HttpStatus status, Map<String, Object> model) {
        //所有的ErrorViewResolver得到ModelAndView
       for (ErrorViewResolver resolver : this.errorViewResolvers) {
          ModelAndView modelAndView = resolver.resolveErrorView(request, status, model);
          if (modelAndView != null) {
             return modelAndView;
          }
       }
       return null;
    }
    

    2)、如果定制错误响应:

    1)、如何定制错误的页面;

    1)、有模板引擎的情况下;error/状态码; 【将错误页面命名为 错误状态码.html 放在模板引擎文件夹里面的 error文件夹下】,发生此状态码的错误就会来到 对应的页面;

    ​ 我们可以使用4xx和5xx作为错误页面的文件名来匹配这种类型的所有错误,精确优先(优先寻找精确的状态码.html);

    ​ 页面能获取的信息;

    ​ timestamp:时间戳

    ​ status:状态码

    ​ error:错误提示

    ​ exception:异常对象

    ​ message:异常消息

    ​ errors:JSR303数据校验的错误都在这里

    ​ 2)、没有模板引擎(模板引擎找不到这个错误页面),静态资源文件夹下找;

    ​ 3)、以上都没有错误页面,就是默认来到SpringBoot默认的错误提示页面;

    2)、如何定制错误的json数据;

    ​ 1)、自定义异常处理&返回定制json数据;

    @ControllerAdvice
    public class MyExceptionHandler {
    
        @ResponseBody
        @ExceptionHandler(UserNotExistException.class)
        public Map<String,Object> handleException(Exception e){
            Map<String,Object> map = new HashMap<>();
            map.put("code","user.notexist");
            map.put("message",e.getMessage());
            return map;
        }
    }
    //没有自适应效果...
    

    ​ 2)、转发到/error进行自适应响应效果处理

     @ExceptionHandler(UserNotExistException.class)
        public String handleException(Exception e, HttpServletRequest request){
            Map<String,Object> map = new HashMap<>();
            //传入我们自己的错误状态码  4xx 5xx,否则就不会进入定制错误页面的解析流程
            /**
             * Integer statusCode = (Integer) request
             .getAttribute("javax.servlet.error.status_code");
             */
            request.setAttribute("javax.servlet.error.status_code",500);
            map.put("code","user.notexist");
            map.put("message",e.getMessage());
            //转发到/error
            return "forward:/error";
        }
    

    3)、将我们的定制数据携带出去;

    出现错误以后,会来到/error请求,会被BasicErrorController处理,响应出去可以获取的数据是由getErrorAttributes得到的(是AbstractErrorController(ErrorController)规定的方法);

    ​ 1、完全来编写一个ErrorController的实现类【或者是编写AbstractErrorController的子类】,放在容器中;

    ​ 2、页面上能用的数据,或者是json返回能用的数据都是通过errorAttributes.getErrorAttributes得到;

    ​ 容器中DefaultErrorAttributes.getErrorAttributes();默认进行数据处理的;

    自定义ErrorAttributes

    //给容器中加入我们自己定义的ErrorAttributes
    @Component
    public class MyErrorAttributes extends DefaultErrorAttributes {
    
        @Override
        public Map<String, Object> getErrorAttributes(RequestAttributes requestAttributes, boolean includeStackTrace) {
            Map<String, Object> map = super.getErrorAttributes(requestAttributes, includeStackTrace);
            map.put("company","atguigu");
            return map;
        }
    }
    

    最终的效果:响应是自适应的,可以通过定制ErrorAttributes改变需要返回的内容,

    搜狗截图20180228135513.png

    8、配置嵌入式Servlet容器

    SpringBoot默认使用Tomcat作为嵌入式的Servlet容器;

    搜狗截图20180301142915.png

    问题?

    1)、如何定制和修改Servlet容器的相关配置;

    1、修改和server有关的配置(ServerProperties【也是EmbeddedServletContainerCustomizer】);

    server.port=8081
    server.context-path=/crud
    
    server.tomcat.uri-encoding=UTF-8
    
    //通用的Servlet容器设置
    server.xxx
    //Tomcat的设置
    server.tomcat.xxx
    

    2、编写一个EmbeddedServletContainerCustomizer:嵌入式的Servlet容器的定制器;来修改Servlet容器的配置

    @Bean  //一定要将这个定制器加入到容器中
    public EmbeddedServletContainerCustomizer embeddedServletContainerCustomizer(){
        return new EmbeddedServletContainerCustomizer() {
    
            //定制嵌入式的Servlet容器相关的规则
            @Override
            public void customize(ConfigurableEmbeddedServletContainer container) {
                container.setPort(8083);
            }
        };
    }
    

    2)、注册Servlet三大组件【Servlet、Filter、Listener】

    由于SpringBoot默认是以jar包的方式启动嵌入式的Servlet容器来启动SpringBoot的web应用,没有web.xml文件。

    注册三大组件用以下方式

    ServletRegistrationBean

    //注册三大组件
    @Bean
    public ServletRegistrationBean myServlet(){
        ServletRegistrationBean registrationBean = new ServletRegistrationBean(new MyServlet(),"/myServlet");
        return registrationBean;
    }
    
    

    FilterRegistrationBean

    @Bean
    public FilterRegistrationBean myFilter(){
        FilterRegistrationBean registrationBean = new FilterRegistrationBean();
        registrationBean.setFilter(new MyFilter());
        registrationBean.setUrlPatterns(Arrays.asList("/hello","/myServlet"));
        return registrationBean;
    }
    

    ServletListenerRegistrationBean

    @Bean
    public ServletListenerRegistrationBean myListener(){
        ServletListenerRegistrationBean<MyListener> registrationBean = new ServletListenerRegistrationBean<>(new MyListener());
        return registrationBean;
    }
    

    SpringBoot帮我们自动SpringMVC的时候,自动的注册SpringMVC的前端控制器;DIspatcherServlet;

    DispatcherServletAutoConfiguration中:

    @Bean(name = DEFAULT_DISPATCHER_SERVLET_REGISTRATION_BEAN_NAME)
    @ConditionalOnBean(value = DispatcherServlet.class, name = DEFAULT_DISPATCHER_SERVLET_BEAN_NAME)
    public ServletRegistrationBean dispatcherServletRegistration(
          DispatcherServlet dispatcherServlet) {
       ServletRegistrationBean registration = new ServletRegistrationBean(
             dispatcherServlet, this.serverProperties.getServletMapping());
        //默认拦截: /  所有请求;包静态资源,但是不拦截jsp请求;   /*会拦截jsp
        //可以通过server.servletPath来修改SpringMVC前端控制器默认拦截的请求路径
        
       registration.setName(DEFAULT_DISPATCHER_SERVLET_BEAN_NAME);
       registration.setLoadOnStartup(
             this.webMvcProperties.getServlet().getLoadOnStartup());
       if (this.multipartConfig != null) {
          registration.setMultipartConfig(this.multipartConfig);
       }
       return registration;
    }
    
    

    2)、SpringBoot能不能支持其他的Servlet容器;

    3)、替换为其他嵌入式Servlet容器

    搜狗截图20180302114401.png

    默认支持:

    Tomcat(默认使用)

    <dependency>
       <groupId>org.springframework.boot</groupId>
       <artifactId>spring-boot-starter-web</artifactId>
       引入web模块默认就是使用嵌入式的Tomcat作为Servlet容器;
    </dependency>
    

    Jetty

    <!-- 引入web模块 -->
    <dependency>
       <groupId>org.springframework.boot</groupId>
       <artifactId>spring-boot-starter-web</artifactId>
       <exclusions>
          <exclusion>
             <artifactId>spring-boot-starter-tomcat</artifactId>
             <groupId>org.springframework.boot</groupId>
          </exclusion>
       </exclusions>
    </dependency>
    
    <!--引入其他的Servlet容器-->
    <dependency>
       <artifactId>spring-boot-starter-jetty</artifactId>
       <groupId>org.springframework.boot</groupId>
    </dependency>
    

    Undertow

    <!-- 引入web模块 -->
    <dependency>
       <groupId>org.springframework.boot</groupId>
       <artifactId>spring-boot-starter-web</artifactId>
       <exclusions>
          <exclusion>
             <artifactId>spring-boot-starter-tomcat</artifactId>
             <groupId>org.springframework.boot</groupId>
          </exclusion>
       </exclusions>
    </dependency>
    
    <!--引入其他的Servlet容器-->
    <dependency>
       <artifactId>spring-boot-starter-undertow</artifactId>
       <groupId>org.springframework.boot</groupId>
    </dependency>
    

    4)、嵌入式Servlet容器自动配置原理;

    EmbeddedServletContainerAutoConfiguration:嵌入式的Servlet容器自动配置?

    @AutoConfigureOrder(Ordered.HIGHEST_PRECEDENCE)
    @Configuration
    @ConditionalOnWebApplication
    @Import(BeanPostProcessorsRegistrar.class)
    //导入BeanPostProcessorsRegistrar:Spring注解版;给容器中导入一些组件
    //导入了EmbeddedServletContainerCustomizerBeanPostProcessor:
    //后置处理器:bean初始化前后(创建完对象,还没赋值赋值)执行初始化工作
    public class EmbeddedServletContainerAutoConfiguration {
        
        @Configuration
        @ConditionalOnClass({ Servlet.class, Tomcat.class })//判断当前是否引入了Tomcat依赖;
        @ConditionalOnMissingBean(value = EmbeddedServletContainerFactory.class, search = SearchStrategy.CURRENT)//判断当前容器没有用户自己定义EmbeddedServletContainerFactory:嵌入式的Servlet容器工厂;作用:创建嵌入式的Servlet容器
        public static class EmbeddedTomcat {
    
            @Bean
            public TomcatEmbeddedServletContainerFactory tomcatEmbeddedServletContainerFactory() {
                return new TomcatEmbeddedServletContainerFactory();
            }
    
        }
        
        /**
         * Nested configuration if Jetty is being used.
         */
        @Configuration
        @ConditionalOnClass({ Servlet.class, Server.class, Loader.class,
                WebAppContext.class })
        @ConditionalOnMissingBean(value = EmbeddedServletContainerFactory.class, search = SearchStrategy.CURRENT)
        public static class EmbeddedJetty {
    
            @Bean
            public JettyEmbeddedServletContainerFactory jettyEmbeddedServletContainerFactory() {
                return new JettyEmbeddedServletContainerFactory();
            }
    
        }
    
        /**
         * Nested configuration if Undertow is being used.
         */
        @Configuration
        @ConditionalOnClass({ Servlet.class, Undertow.class, SslClientAuthMode.class })
        @ConditionalOnMissingBean(value = EmbeddedServletContainerFactory.class, search = SearchStrategy.CURRENT)
        public static class EmbeddedUndertow {
    
            @Bean
            public UndertowEmbeddedServletContainerFactory undertowEmbeddedServletContainerFactory() {
                return new UndertowEmbeddedServletContainerFactory();
            }
    
        }
    

    1)、EmbeddedServletContainerFactory(嵌入式Servlet容器工厂)

    public interface EmbeddedServletContainerFactory {
    
       //获取嵌入式的Servlet容器
       EmbeddedServletContainer getEmbeddedServletContainer(
             ServletContextInitializer... initializers);
    
    }
    
    搜狗截图20180302144835.png

    2)、EmbeddedServletContainer:(嵌入式的Servlet容器)

    搜狗截图20180302144910.png

    3)、以TomcatEmbeddedServletContainerFactory为例

    @Override
    public EmbeddedServletContainer getEmbeddedServletContainer(
          ServletContextInitializer... initializers) {
        //创建一个Tomcat
       Tomcat tomcat = new Tomcat();
        
        //配置Tomcat的基本环节
       File baseDir = (this.baseDirectory != null ? this.baseDirectory
             : createTempDir("tomcat"));
       tomcat.setBaseDir(baseDir.getAbsolutePath());
       Connector connector = new Connector(this.protocol);
       tomcat.getService().addConnector(connector);
       customizeConnector(connector);
       tomcat.setConnector(connector);
       tomcat.getHost().setAutoDeploy(false);
       configureEngine(tomcat.getEngine());
       for (Connector additionalConnector : this.additionalTomcatConnectors) {
          tomcat.getService().addConnector(additionalConnector);
       }
       prepareContext(tomcat.getHost(), initializers);
        
        //将配置好的Tomcat传入进去,返回一个EmbeddedServletContainer;并且启动Tomcat服务器
       return getTomcatEmbeddedServletContainer(tomcat);
    }
    

    4)、我们对嵌入式容器的配置修改是怎么生效?

    ServerProperties、EmbeddedServletContainerCustomizer
    

    EmbeddedServletContainerCustomizer:定制器帮我们修改了Servlet容器的配置?

    怎么修改的原理?

    5)、容器中导入了EmbeddedServletContainerCustomizerBeanPostProcessor

    //初始化之前
    @Override
    public Object postProcessBeforeInitialization(Object bean, String beanName)
          throws BeansException {
        //如果当前初始化的是一个ConfigurableEmbeddedServletContainer类型的组件
       if (bean instanceof ConfigurableEmbeddedServletContainer) {
           //
          postProcessBeforeInitialization((ConfigurableEmbeddedServletContainer) bean);
       }
       return bean;
    }
    
    private void postProcessBeforeInitialization(
                ConfigurableEmbeddedServletContainer bean) {
        //获取所有的定制器,调用每一个定制器的customize方法来给Servlet容器进行属性赋值;
        for (EmbeddedServletContainerCustomizer customizer : getCustomizers()) {
            customizer.customize(bean);
        }
    }
    
    private Collection<EmbeddedServletContainerCustomizer> getCustomizers() {
        if (this.customizers == null) {
            // Look up does not include the parent context
            this.customizers = new ArrayList<EmbeddedServletContainerCustomizer>(
                this.beanFactory
                //从容器中获取所有这葛类型的组件:EmbeddedServletContainerCustomizer
                //定制Servlet容器,给容器中可以添加一个EmbeddedServletContainerCustomizer类型的组件
                .getBeansOfType(EmbeddedServletContainerCustomizer.class,
                                false, false)
                .values());
            Collections.sort(this.customizers, AnnotationAwareOrderComparator.INSTANCE);
            this.customizers = Collections.unmodifiableList(this.customizers);
        }
        return this.customizers;
    }
    
    ServerProperties也是定制器
    

    步骤:

    1)、SpringBoot根据导入的依赖情况,给容器中添加相应的EmbeddedServletContainerFactory【TomcatEmbeddedServletContainerFactory】

    2)、容器中某个组件要创建对象就会惊动后置处理器;EmbeddedServletContainerCustomizerBeanPostProcessor;

    只要是嵌入式的Servlet容器工厂,后置处理器就工作;

    3)、后置处理器,从容器中获取所有的EmbeddedServletContainerCustomizer,调用定制器的定制方法

    5)、嵌入式Servlet容器启动原理;

    什么时候创建嵌入式的Servlet容器工厂?什么时候获取嵌入式的Servlet容器并启动Tomcat;

    获取嵌入式的Servlet容器工厂:

    1)、SpringBoot应用启动运行run方法

    2)、refreshContext(context);SpringBoot刷新IOC容器【创建IOC容器对象,并初始化容器,创建容器中的每一个组件】;如果是web应用创建AnnotationConfigEmbeddedWebApplicationContext,否则:AnnotationConfigApplicationContext

    3)、refresh(context);刷新刚才创建好的ioc容器;

    public void refresh() throws BeansException, IllegalStateException {
       synchronized (this.startupShutdownMonitor) {
          // Prepare this context for refreshing.
          prepareRefresh();
    
          // Tell the subclass to refresh the internal bean factory.
          ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();
    
          // Prepare the bean factory for use in this context.
          prepareBeanFactory(beanFactory);
    
          try {
             // Allows post-processing of the bean factory in context subclasses.
             postProcessBeanFactory(beanFactory);
    
             // Invoke factory processors registered as beans in the context.
             invokeBeanFactoryPostProcessors(beanFactory);
    
             // Register bean processors that intercept bean creation.
             registerBeanPostProcessors(beanFactory);
    
             // Initialize message source for this context.
             initMessageSource();
    
             // Initialize event multicaster for this context.
             initApplicationEventMulticaster();
    
             // Initialize other special beans in specific context subclasses.
             onRefresh();
    
             // Check for listener beans and register them.
             registerListeners();
    
             // Instantiate all remaining (non-lazy-init) singletons.
             finishBeanFactoryInitialization(beanFactory);
    
             // Last step: publish corresponding event.
             finishRefresh();
          }
    
          catch (BeansException ex) {
             if (logger.isWarnEnabled()) {
                logger.warn("Exception encountered during context initialization - " +
                      "cancelling refresh attempt: " + ex);
             }
    
             // Destroy already created singletons to avoid dangling resources.
             destroyBeans();
    
             // Reset 'active' flag.
             cancelRefresh(ex);
    
             // Propagate exception to caller.
             throw ex;
          }
    
          finally {
             // Reset common introspection caches in Spring's core, since we
             // might not ever need metadata for singleton beans anymore...
             resetCommonCaches();
          }
       }
    }
    

    4)、 onRefresh(); web的ioc容器重写了onRefresh方法

    5)、webioc容器会创建嵌入式的Servlet容器;createEmbeddedServletContainer();

    6)、获取嵌入式的Servlet容器工厂:

    EmbeddedServletContainerFactory containerFactory = getEmbeddedServletContainerFactory();

    ​ 从ioc容器中获取EmbeddedServletContainerFactory 组件;TomcatEmbeddedServletContainerFactory创建对象,后置处理器一看是这个对象,就获取所有的定制器来先定制Servlet容器的相关配置;

    7)、使用容器工厂获取嵌入式的Servlet容器:this.embeddedServletContainer = containerFactory .getEmbeddedServletContainer(getSelfInitializer());

    8)、嵌入式的Servlet容器创建对象并启动Servlet容器;

    先启动嵌入式的Servlet容器,再将ioc容器中剩下没有创建出的对象获取出来;

    IOC容器启动创建嵌入式的Servlet容器

    9、使用外置的Servlet容器

    嵌入式Servlet容器:应用打成可执行的jar

    ​ 优点:简单、便携;

    ​ 缺点:默认不支持JSP、优化定制比较复杂(使用定制器【ServerProperties、自定义EmbeddedServletContainerCustomizer】,自己编写嵌入式Servlet容器的创建工厂【EmbeddedServletContainerFactory】);

    外置的Servlet容器:外面安装Tomcat---应用war包的方式打包;

    步骤

    1)、必须创建一个war项目;(利用idea创建好目录结构)

    • new project or new module
    1537583437482.png
    • create
    1537583796091.png
    • web.xml
    1537584525195.png
    • 添加外部tomcat启动

    2)、将嵌入式的Tomcat指定为provided;

    <dependency>
       <groupId>org.springframework.boot</groupId>
       <artifactId>spring-boot-starter-tomcat</artifactId>
       <scope>provided</scope>
    </dependency>
    

    3)、必须编写一个SpringBootServletInitializer的子类,并调用configure方法

    public class ServletInitializer extends SpringBootServletInitializer {
    
       @Override
       protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
           //传入SpringBoot应用的主程序
          return application.sources(SpringBoot04WebJspApplication.class);
       }
    
    }
    

    4)、启动服务器就可以使用;

    原理

    jar包:执行SpringBoot主类的main方法,启动ioc容器,创建嵌入式的Servlet容器;

    war包:启动服务器,服务器启动SpringBoot应用【SpringBootServletInitializer】,启动ioc容器;

    servlet3.0(Spring注解版):

    8.2.4 Shared libraries / runtimes pluggability:

    规则:

    ​ 1)、服务器启动(web应用启动)会创建当前web应用里面每一个jar包里面ServletContainerInitializer实例:

    ​ 2)、ServletContainerInitializer的实现放在jar包的META-INF/services文件夹下,有一个名为javax.servlet.ServletContainerInitializer的文件,内容就是ServletContainerInitializer的实现类的全类名

    ​ 3)、还可以使用@HandlesTypes,在应用启动的时候加载我们感兴趣的类;

    流程:

    1)、启动Tomcat

    2)、org\springframework\spring-web\4.3.14.RELEASE\spring-web-4.3.14.RELEASE.jar!\META-INF\services\javax.servlet.ServletContainerInitializer:

    Spring的web模块里面有这个文件:org.springframework.web.SpringServletContainerInitializer

    3)、SpringServletContainerInitializer将@HandlesTypes(WebApplicationInitializer.class)标注的所有这个类型的类都传入到onStartup方法的Set<Class<?>>;为这些WebApplicationInitializer类型的类创建实例;

    4)、每一个WebApplicationInitializer都调用自己的onStartup;

    搜狗截图20180302221835.png

    5)、相当于我们的SpringBootServletInitializer的类会被创建对象,并执行onStartup方法

    6)、SpringBootServletInitializer实例执行onStartup的时候会createRootApplicationContext;创建容器

    protected WebApplicationContext createRootApplicationContext(
          ServletContext servletContext) {
        //1、创建SpringApplicationBuilder
       SpringApplicationBuilder builder = createSpringApplicationBuilder();
       StandardServletEnvironment environment = new StandardServletEnvironment();
       environment.initPropertySources(servletContext, null);
       builder.environment(environment);
       builder.main(getClass());
       ApplicationContext parent = getExistingRootWebApplicationContext(servletContext);
       if (parent != null) {
          this.logger.info("Root context already created (using as parent).");
          servletContext.setAttribute(
                WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE, null);
          builder.initializers(new ParentContextApplicationContextInitializer(parent));
       }
       builder.initializers(
             new ServletContextApplicationContextInitializer(servletContext));
       builder.contextClass(AnnotationConfigEmbeddedWebApplicationContext.class);
        
        //调用configure方法,子类重写了这个方法,将SpringBoot的主程序类传入了进来
       builder = configure(builder);
        
        //使用builder创建一个Spring应用
       SpringApplication application = builder.build();
       if (application.getSources().isEmpty() && AnnotationUtils
             .findAnnotation(getClass(), Configuration.class) != null) {
          application.getSources().add(getClass());
       }
       Assert.state(!application.getSources().isEmpty(),
             "No SpringApplication sources have been defined. Either override the "
                   + "configure method or add an @Configuration annotation");
       // Ensure error pages are registered
       if (this.registerErrorPageFilter) {
          application.getSources().add(ErrorPageFilterConfiguration.class);
       }
        //启动Spring应用
       return run(application);
    }
    

    7)、Spring的应用就启动并且创建IOC容器

    public ConfigurableApplicationContext run(String... args) {
       StopWatch stopWatch = new StopWatch();
       stopWatch.start();
       ConfigurableApplicationContext context = null;
       FailureAnalyzers analyzers = null;
       configureHeadlessProperty();
       SpringApplicationRunListeners listeners = getRunListeners(args);
       listeners.starting();
       try {
          ApplicationArguments applicationArguments = new DefaultApplicationArguments(
                args);
          ConfigurableEnvironment environment = prepareEnvironment(listeners,
                applicationArguments);
          Banner printedBanner = printBanner(environment);
          context = createApplicationContext();
          analyzers = new FailureAnalyzers(context);
          prepareContext(context, environment, listeners, applicationArguments,
                printedBanner);
           
           //刷新IOC容器
          refreshContext(context);
          afterRefresh(context, applicationArguments);
          listeners.finished(context, null);
          stopWatch.stop();
          if (this.logStartupInfo) {
             new StartupInfoLogger(this.mainApplicationClass)
                   .logStarted(getApplicationLog(), stopWatch);
          }
          return context;
       }
       catch (Throwable ex) {
          handleRunFailure(context, listeners, analyzers, ex);
          throw new IllegalStateException(ex);
       }
    }
    

    启动Servlet容器,再启动SpringBoot应用

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