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[java]48、SSM整合

[java]48、SSM整合

作者: 史记_d5da | 来源:发表于2022-08-13 17:47 被阅读0次

1、概念

所谓的SSM整合即前面学的SpringSpringMVCMyBatis对其进行的整合 整合前存在的问题:所有的bean都存储在同一个IoC容器中,无法避免service注入controller`等问题
解决方案:

2、采用父子容器

2.1、父子容器关系
父子容器
1、特点:
父容器和子容器是相互隔离的,它们内部可以存在名称相同的bean
子容器可以访问父容器中的bean,而父容器不能访问子容器中的bean
调用子容器的getBean方法时,会沿着当前容器开始向父容器进行查找,直到找到对应的bean为止
子容器中可以通过注入父容器中的bean,而父容器中无法注入子容器中的bean
2、优点
采用父子容器可以避免依赖层次混乱(service注入controller
将相互不关心的东西隔开,可以有效避免一些不必要的错误,而父子容器加载的速度也会快一些
2.2、父子容器配置

1、子容器的配置文件:dispatcherServlet.xml
<context:component-scan base-package="com.sj.controller" />
controllerSpringMVC专用的一些bean
2、父容器配置文件:applicationContext.xml
servicedao、其他(非SpringMVC专用的bean、共用的bean等)
<context:component-scan base-package="com.sj.service" />

2.3、父子容器加载创建

1、子容器加载创建

 <servlet>
        <servlet-name>DispatcherServlet</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <!-- 子容器 -->
            <param-value>classpath:dispatcherServlet.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
    <servlet-name>DispatcherServlet</servlet-name>
    <url-pattern>/</url-pattern>
</servlet-mapping>

2、父容器加载创建

<context-param>
    <param-name>contextConfigLocation</param-name>
    <param-value>classpath:applicationContext.xml</param-value>
</context-param>
<listener>
    <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
2.3、MyBatis补充

如果将Mapper文件跟dao放在相同目录下,且文件名跟dao一样
那么通过MapperScannerConfigurer就可以找到Mapper文件
不需要在配置SqlSessionFactoryBeanmapperLocation属性

SkillDao
可以设置SqlSessionFactoryBeanconfigLocation属性,指定MyBatis核心配置文件的位置
<property name="configLocation" value="classpath:mybatis-config.xml" />
2.4、Maven配置

默认情况下,Maven并不会将源代码文件夹中的配置文件(propertisxml等)打包
如想打包的话,需要额外配置

 <build>
<!--        说明资源文件位置-->
    <resources>
        <resource>
            <directory>src/main/resources</directory>
        </resource>
        <resource>
            <directory>src/main/java</directory>
            <includes>
                <include>**/*.properties</include>
                <include>**/*.xml</include>
            </includes>
        </resource>
    </resources>
</build>

3、纯注解

1、继承自 AbstractAnnotationConfigDispatcherServletInitializer类取代web.xml文件

public class  WebInitializer extends AbstractAnnotationConfigDispatcherServletInitializer {
//    父容器的配置类
    @Override
    protected Class<?>[] getRootConfigClasses() {
        return new Class[]{SpringConfig.class};
    }

//    子容器的配置类(SpringMVC相关的配置类)
    @Override
    protected Class<?>[] getServletConfigClasses() {
        return new Class[]{SpringMVCConfig.class};
    }
//    配置DispatcherServlet的url-pattern
    @Override
    protected String[] getServletMappings() {
        return new String[]{"/"};
    }
}

2、纯注解实现<mvc:default-servlet-handler/>,实现在webapp下可以访问静态资源
3、拦截器的原来实现

<mvc:interceptors>
        <mvc:interceptor>
<!--            需要拦截的路径可以写多个-->
<!--            **代表当前目录下的所有内容(包括子目录)-->
            <mvc:mapping path="/**"/>
<!--            排除asset目录的所有内容-->
            <mvc:exclude-mapping path="/asset/**"/>
<!--            排除所有html-->
            <mvc:exclude-mapping path="/**/*.html"/>
            <bean class="com.sj.interceptor.MyInterceptor" />
        </mvc:interceptor>
    </mvc:interceptors>

4、InternalResourceViewResolver原来实现

<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" >
    <property name="order" value="1" />
    <property name="prefix" value="/WEB-INF/page2/"/>
    <property name="suffix" value=".jsp"/>
    <property name="viewClass" value="com.sj.view.MyView" />
</bean>

5、MappingJackson2HttpMessageConverter原来实现

<mvc:annotation-driven conversion-service="conversionService">
        <mvc:message-converters>
<!--            影响string返回值内容--> 
            <bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
                <property name="defaultCharset" value="UTF-8"/>
            </bean>
        </mvc:message-converters>
    </mvc:annotation-driven>

对应的注解实现方式如下:

@ComponentScan({"com.sj.controller", "com.sj.interceptor"})
@EnableWebMvc // 纯注解开发MVC,必须添加
public class SpringMVCConfig implements WebMvcConfigurer {
    @Autowired
    private MyInterceptor myInterceptor;
    @Autowired
    private DateConverter dateConverter;
    // 相当于<mvc:default-servlet-handler/>
    // 用以处理静态资源
    @Override
    public void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {
        configurer.enable();
    }

    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(myInterceptor)
                .addPathPatterns("/**")
                .excludePathPatterns("/asset/**", "/**/*.html");
    }

    @Bean
    public InternalResourceViewResolver viewResolver() {
        InternalResourceViewResolver resolver = new InternalResourceViewResolver();
        resolver.setPrefix("/WEB-INF/page/");
        resolver.setSuffix(".jsp");
        return resolver;
    }

    @Override
    public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
        StringHttpMessageConverter converter = new StringHttpMessageConverter();
        converter.setDefaultCharset(StandardCharsets.UTF_8);
        converters.add(converter);
    }

    @Override
    public void addFormatters(FormatterRegistry registry) {
        registry.addConverter(dateConverter);
    }
}

6、异常处理SimpleMappingExceptionResolver原来实现

<bean class="org.springframework.web.servlet.handler.SimpleMappingExceptionResolver">
    <property name="exceptionMappings">
        <props>
            <prop key="java.lang.RuntimeException">/WEB-INF/page/rumtime.jsp</prop>
            <prop key="java.io.IOException">/WEB-INF/page/io.jsp</prop>
            <prop key="java.lang.ClassNotFoundException">/WEB-INF/page/not.jsp</prop>
        </props>
    </property>
<!--        异常对象的属性名(可以通过EL表达式访问)-->
    <property name="exceptionAttribute" value="ex" />
<!--        其他错误页面异常-->
    <property name="defaultErrorView" value="/WEB-INF/page/error.jsp" />
</bean>

注解实现类前面加上@ControllerAdvice

@ControllerAdvice
public class MyExceptionResolver2 {
    @ExceptionHandler({ArithmeticException.class, IOException.class})
    public ModelAndView resolveException1(Exception ex) {
        ModelAndView mv = new ModelAndView();
        mv.addObject("ex", ex);
        mv.setViewName("/WEB-INF/page/rumtime.jsp");
        return mv;
    }

    @ExceptionHandler()
    public ModelAndView resolveException2(Exception ex) {
        ModelAndView mv = new ModelAndView();
        mv.addObject("ex", ex);
        mv.setViewName("/WEB-INF/page/error.jsp");
        return mv;
    }
}

7、设置拦截器,实现WebApplicationInitializer接口
之前用法在web.xml实现

 <!--解决post请求乱码问题-->
<filter>
    <filter-name>CharacterEncodingFilter</filter-name>
      <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
    <init-param>
        <param-name>encoding</param-name>
        <param-value>UTF-8</param-value>
    </init-param>
</filter>
<filter-mapping>
    <filter-name>CharacterEncodingFilter</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>

使用注解实现

public class  WebInitializer extends AbstractAnnotationConfigDispatcherServletInitializer {
    @Override
    public void onStartup(ServletContext servletContext) throws ServletException {
        super.onStartup(servletContext);
        // 添加filter
        FilterRegistration.Dynamic encodingFilter = servletContext.addFilter("CharacterEncodingFilter", new CharacterEncodingFilter("UTF-8"));
        encodingFilter.addMappingForUrlPatterns(null, false, "/*");
    }
}

8、 MultipartResolver注解实现
xml的实现方式

<bean id="multipartResolver"
          class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
    <property name="defaultEncoding" value="UTF-8"/>
    <property name="maxInMemorySize" value="20480"/>
</bean>

注解的实现方式

@Bean
public CommonsMultipartResolver multipartResolver() {
    CommonsMultipartResolver resolver = new CommonsMultipartResolver();
    resolver.setDefaultEncoding("UTF-8");
    return resolver;
}

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