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;
自动配置原理?
这个场景SpringBoot帮我们配置了什么?能不能修改?能修改哪些配置?能不能扩展?xxx
xxxxAutoConfiguration:帮我们给容器中自动配置组件;
xxxxProperties:配置类来封装配置文件的内容;
2、SpringBoot对静态资源的映射规则;
@ConfigurationProperties(prefix
="spring.resources", ignoreUnknownFields
=false)publicclassResourcePropertiesimplementsResourceLoaderAware{//可以设置和静态资源有关的参数,缓存时间等
WebMvcAuotConfiguration:@OverridepublicvoidaddResourceHandlers(ResourceHandlerRegistry
registry){if(!this.resourceProperties.isAddMappings())
{logger.debug("Default resource handling disabled");return;}Integer
cachePeriod
=this.resourceProperties.getCachePeriod();if(!registry.hasMappingForPattern("/webjars/**"))
{customizeResourceHandlerRegistration(registry.addResourceHandler("/webjars/**").addResourceLocations("classpath:/META-INF/resources/webjars/").setCachePeriod(cachePeriod));}String
staticPathPattern
=this.mvcProperties.getStaticPathPattern();//静态资源文件夹映射if(!registry.hasMappingForPattern(staticPathPattern))
{customizeResourceHandlerRegistration(registry.addResourceHandler(staticPathPattern).addResourceLocations(this.resourceProperties.getStaticLocations()).setCachePeriod(cachePeriod));}}//配置欢迎页映射@BeanpublicWelcomePageHandlerMappingwelcomePageHandlerMapping(
ResourceProperties
resourceProperties){returnnewWelcomePageHandlerMapping(resourceProperties.getWelcomePage(),this.mvcProperties.getStaticPathPattern());}//配置喜欢的图标@Configuration@ConditionalOnProperty(value
="spring.mvc.favicon.enabled", matchIfMissing
=true)publicstaticclassFaviconConfiguration{privatefinalResourceProperties
resourceProperties;publicFaviconConfiguration(ResourceProperties
resourceProperties){this.resourceProperties =
resourceProperties;}@BeanpublicSimpleUrlHandlerMappingfaviconHandlerMapping(){SimpleUrlHandlerMapping
mapping
=newSimpleUrlHandlerMapping();mapping.setOrder(Ordered.HIGHEST_PRECEDENCE
+1);//所有 **/favicon.ico
mapping.setUrlMap(Collections.singletonMap("**/favicon.ico",faviconRequestHandler()));returnmapping;}@BeanpublicResourceHttpRequestHandlerfaviconRequestHandler(){ResourceHttpRequestHandler
requestHandler
=newResourceHttpRequestHandler();requestHandler.setLocations(this.resourceProperties.getFaviconLocations());returnrequestHandler;}}
==1)、所有 /webjars/** ,都去 classpath:/META-INF/resources/webjars/ 找资源;==
webjars:以jar包的方式引入静态资源;
localhost:8080/webjars/jquery/3.3.1/jquery.js
在访问的时候只需要写webjars下面资源的名称即可org.webjarsjquery3.3.1
==2)、"/**" 访问当前项目的任何资源,都去(静态资源的文件夹)找映射==
"classpath:/META-INF/resources/",
"classpath:/resources/",
"classpath:/static/",
"classpath:/public/"
"/":当前项目的根路径
localhost:8080/abc === 去静态资源文件夹里面找abc
==3)、欢迎页; 静态资源文件夹下的所有index.html页面;被"/**"映射;==
localhost:8080/ 找index页面
==4)、所有的 **/favicon.ico 都是在静态资源文件下找;==
3、模板引擎
JSP、Velocity、Freemarker、Thymeleaf
SpringBoot推荐的Thymeleaf;
语法更简单,功能更强大;
1、引入thymeleaf;
org.springframework.bootspring-boot-starter-thymeleaf2.1.6切换thymeleaf版本3.0.9.RELEASE2.2.2
2、Thymeleaf使用
@ConfigurationProperties(prefix
="spring.thymeleaf")publicclassThymeleafProperties{privatestaticfinalCharset
DEFAULT_ENCODING = Charset.forName("UTF-8");privatestaticfinalMimeType
DEFAULT_CONTENT_TYPE =
MimeType.valueOf("text/html");publicstaticfinalString DEFAULT_PREFIX
="classpath:/templates/";publicstaticfinalString 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
2、使用thymeleaf语法;
<!DOCTYPE html>
成功!
这是显示欢迎信息
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
2)、表达式?
Simple expressions:(表达式语法)
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.
${session.foo}
3)、内置的一些工具对象:
#execInfo : information about the template being processed.
#messages
: methods for obtaining externalized messages inside variables
expressions, in the same way as they would be obtained using #{…}
syntax.
#uris : methods for escaping parts of URLs/URIs
#conversions : methods for executing the configured conversion service (if any).
#dates : methods for java.util.Date objects: formatting, component extraction, etc.
#calendars : analogous to #dates , but for java.util.Calendar objects.
#numbers : methods for formatting numeric objects.
#strings : methods for String objects: contains, startsWith, prepending/appending, etc.
#objects : methods for objects in general.
#bools : methods for boolean evaluation.
#arrays : methods for arrays.
#lists : methods for lists.
#sets : methods for sets.
#maps : methods for maps.
#aggregates : methods for creating aggregates on arrays or collections.
#ids : methods for dealing with id attributes that might be repeated (for example, as a result of an iteration).
Selection Variable Expressions: *{...}:选择表达式:和${}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>
Message Expressions: #{...}:获取国际化内容
Link URL Expressions: @{...}:定义URL;
@{/order/process(execId=${execId},execType='FAST')}
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: _
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