分析讲解SpringMVC注解配置如何实现

简介

使用配置类和注解代替web.xml和SpringMVC配置文件的功能

在Servlet3.0环境中，容器会在类路径中查找实现javax.servlet.ServletContainerInitializer接口的类，如果找到的话就用它来配置Servlet容器。 Spring提供了这个接口的实现，名为SpringServletContainerInitializer，这个类又会查找实现WebApplicationInitializer的类并将配置的任务交给它们来完成。Spring3.2引入了一个便利的WebApplicationInitializer基础实现，名为AbstractAnnotationConfigDispatcherServletInitializer，当我们的类扩展了AbstractAnnotationConfigDispatcherServletInitializer并将其部署到Servlet3.0容器的时候，容器会自动发现它，并用它来配置Servlet上下文。

意思就是容器会自动发现继承了AbstractAnnotationConfigDispatcherServletInitializer的子类，并用它来配置servlet上下文。（用来代替web.xml）

注解类代替web.xml

package com.hxut.rj1192.annoation;
import org.springframework.web.filter.CharacterEncodingFilter;
import org.springframework.web.filter.HiddenHttpMethodFilter;
import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer;
import javax.servlet.Filter;
//代替web.xml   filter过滤器   spring  springmvc的配置类    dispracture的映射路径
public class webXml extends AbstractAnnotationConfigDispatcherServletInitializer {
   //    指定spring配置类
   @Override
   protected Class<?>[] getRootConfigClasses() {
       return new Class[] {SpringConfig.class};
   }
   //    指定springmvc配置类
   @Override
   protected Class<?>[] getServletConfigClasses() {
       return new Class[]{SpringMvcConfig.class};
   }
   //    指定dispracture的映射路径 即url-pattern
   @Override
   protected String[] getServletMappings() {
       return new String[]{"/"};
   }
//注册编码过滤器
   @Override
   protected Filter[] getServletFilters() {
       CharacterEncodingFilter encodingFilter = new CharacterEncodingFilter();
       encodingFilter.setEncoding("UTF-8");
       encodingFilter.setForceRequestEncoding(true);
       HiddenHttpMethodFilter hiddenHttpMethodFilter = new HiddenHttpMethodFilter();
       return new Filter[]{encodingFilter, hiddenHttpMethodFilter};
   }
}

注解类代替Spring-mvc.xml

Spring-mvc配置文件（不管是xml还是注解的类）有如下八个功能

• 视图解析器  

• 扫描包的范围（组件扫描）  

• view-controller（只返回视图的控制方法）  

• defalut-servlet-handler  静态资源处理

• mvc注解驱动  

• 文件上传解析器  

• 异常处理  

• *

package com.hxut.rj1192.annoation;
import com.hxut.rj1192.InterceptorRegistry01;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.context.ContextLoader;
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.multipart.commons.CommonsMultipartResolver;
import org.springframework.web.servlet.HandlerExceptionResolver;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ViewResolver;
import org.springframework.web.servlet.config.annotation.*;
import org.springframework.web.servlet.handler.SimpleMappingExceptionResolver;
import org.thymeleaf.spring5.SpringTemplateEngine;
import org.thymeleaf.spring5.view.ThymeleafViewResolver;
import org.thymeleaf.templatemode.TemplateMode;
import org.thymeleaf.templateresolver.ITemplateResolver;
import org.thymeleaf.templateresolver.ServletContextTemplateResolver;
import java.util.List;
import java.util.Properties;
//1视图解析器   2扫描包的范围（组件扫描）  3view-controller（只返回视图的控制方法）  4defalut-servlet-handler  静态资源处理和
//5  mvc注解驱动  6文件上传解析器   7异常处理   8 *
//代替springmvc的配置文件
//扫描包的范围（组件扫描）
@ComponentScan("com.hxut.rj1192")
//开启MVC注解驱动
@EnableWebMvc
@Configuration
public class SpringMvcConfig implements WebMvcConfigurer {
   //配置视图解析器
//    这个注解是将类放进ioc容器中  因为web.xml中就是嵌套的,
   @Bean
   public ITemplateResolver templateResolver() {
       WebApplicationContext webApplicationContext = ContextLoader.getCurrentWebApplicationContext();
       // ServletContextTemplateResolver需要一个ServletContext作为构造参数，可通过WebApplicationContext 的方法获得
       ServletContextTemplateResolver templateResolver = new ServletContextTemplateResolver(
               webApplicationContext.getServletContext());
       templateResolver.setPrefix("/WEB-INF/templates/");
       templateResolver.setSuffix(".html");
       templateResolver.setCharacterEncoding("UTF-8");
       templateResolver.setTemplateMode(TemplateMode.HTML);
       return templateResolver;
   }
   //生成模板引擎并为模板引擎注入模板解析器
   @Bean
   public SpringTemplateEngine templateEngine(ITemplateResolver templateResolver) {
       SpringTemplateEngine templateEngine = new SpringTemplateEngine();
       templateEngine.setTemplateResolver(templateResolver);
       return templateEngine;
   }
   //生成视图解析器并未解析器注入模板引擎
   @Bean
   public ViewResolver viewResolver(SpringTemplateEngine templateEngine) {
       ThymeleafViewResolver viewResolver = new ThymeleafViewResolver();
       viewResolver.setCharacterEncoding("UTF-8");
       viewResolver.setTemplateEngine(templateEngine);
       return viewResolver;
   }
//default-servlet configuure
   @Override
   public void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {
       WebMvcConfigurer.super.configureDefaultServletHandling(configurer);
   }
   @Override
   public void addInterceptors(InterceptorRegistry registry) {
       InterceptorRegistry01 interceptorRegistry=new InterceptorRegistry01();
//        addPathPatterns("/");是设置拦截的url
//        excludePathPatterns(); 是设置不拦截的url
       registry.addInterceptor(interceptorRegistry).addPathPatterns("/");
   }
//视图控制器
   @Override
   public void addViewControllers(ViewControllerRegistry registry) {
     registry.addViewController("/hello").setViewName("succes");
   }
   //配置文件上传解析器
   @Bean
   public CommonsMultipartResolver multipartResolver(){
       CommonsMultipartResolver commonsMultipartResolver=new CommonsMultipartResolver();
       return commonsMultipartResolver;
   }
   //配置异常映射
   @Override
   public void configureHandlerExceptionResolvers(List<HandlerExceptionResolver> resolvers) {
       SimpleMappingExceptionResolver exceptionResolver = new SimpleMappingExceptionResolver();
       Properties prop = new Properties();
       prop.setProperty("java.lang.ArithmeticException", "error");
       //设置异常映射
       exceptionResolver.setExceptionMappings(prop);
       //设置共享异常信息的键
       exceptionResolver.setExceptionAttribute("ex");
       resolvers.add(exceptionResolver);
   }
}

 全用xml写：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xmlns:context="http://www.springframework.org/schema/context"
      xmlns:mvc="http://www.springframework.org/schema/mvc"
      xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/mvc https://www.springframework.org/schema/mvc/spring-mvc.xsd">
     <!--2.扫描包的范围（组件扫描）-->
   <context:component-scan base-package="com.hxut.rj1192.zyk"/>
   <!-- 1.配置Thymeleaf视图解析器 -->
   <bean id="viewResolver" class="org.thymeleaf.spring5.view.ThymeleafViewResolver">
       <property name="order" value="1"/>
       <property name="characterEncoding" value="UTF-8"/>
       <property name="templateEngine">
           <bean class="org.thymeleaf.spring5.SpringTemplateEngine">
               <property name="templateResolver">
                   <bean class="org.thymeleaf.spring5.templateresolver.SpringResourceTemplateResolver">
                       <property name="prefix" value="/WEB-INF/templates/"/>
                       <property name="suffix" value=".html"/>
                       <property name="templateMode" value="HTML5"/>
                       <property name="characterEncoding" value="UTF-8"/>
                   </bean>
               </property>
           </bean>
       </property>
   </bean>
   <!--4.静态资源处理-->
   <mvc:default-servlet-handler/>
   <!--5.mvc注解驱动-->
   <mvc:annotation-driven/>
<mvc:interceptors>
   <bean class="com.hxut.rj1192.zyk.interceptor.interceptor01"/>
</mvc:interceptors>
   <bean class="org.springframework.web.servlet.handler.SimpleMappingExceptionResolver">
       <property name="exceptionMappings">
           <props>
               <prop key="java.lang.ArithmeticException">error</prop>
           </props>
       </property>
       <property name="exceptionAttribute" value="ex"></property>
   </bean>
<! --3.view-controller-->
<mvc:view-controller path="/testView" view-name="success"></mvc:view-controller>
<! --4.文件上传解析器-->
   <bean id="multipartResolver"
         class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
   </bean>
<! --7.异常处理-->
   <bean class="org.springframework.web.servlet.handler.SimpleMappingExceptionResolver">
           <property name="exceptionMappings">
               <props>
                   <prop key="java.lang.ArithmeticException">error</prop>
               </props>
           </property>
           <!--        将错误信息放到ex这个变量中，并放进model中-->
           <property name="exceptionAttribute" value="ex"></property>
       </bean>
<! --8. * -->
<mvc:interceptors>
       <ref bean="first"></ref>
       <ref bean="second"></ref>
   </mvc:interceptors>
</beans>

* 文件

package com.hxut.rj1192;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class InterceptorRegistry01 implements HandlerInterceptor {
   @Override
   public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
       System.out.println("prehandle 执行");
       return true;
   }
   @Override
   public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
       System.out.println("posthandle 执行");
       HandlerInterceptor.super.postHandle(request, response, handler, modelAndView);
   }
   @Override
   public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
       System.out.println("afterhandle 执行");
       HandlerInterceptor.super.afterCompletion(request, response, handler, ex);
   }
}

来源：https://blog.csdn.net/sharesb/article/details/124715584