13.2、异常处理——ResponseStatusExceptionResolver和@ResponseStatus

当程序发生异常时，ResponseStatusExceptionResolver异常解释器用来解析@ResponseStatus标注的异常类，并把异常的状态码返回给客户端。DispatcherServlet默认装配了ResponseStatusExceptionResolver 的Bean*示例如下：*

1、web.xml和spring的配置文件
web.xml

<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns="http://xmlns.jcp.org/xml/ns/javaee"
    xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
    id="WebApp_ID" version="3.1">

    
    <servlet>
        <servlet-name>springDispatcherServletservlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServletservlet-class>
        <init-param>
            <param-name>contextConfigLocationparam-name>
            <param-value>classpath:springmvc.xmlparam-value>
        init-param>
        <load-on-startup>1load-on-startup>
    servlet>

    
    <servlet-mapping>
        <servlet-name>springDispatcherServletservlet-name>
        <url-pattern>/url-pattern>
    servlet-mapping>

web-app>

spring的配置文件springmvc.xml

<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:aop="http://www.springframework.org/schema/aop"
    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/aop http://www.springframework.org/schema/aop/spring-aop-4.0.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd
        http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd">

    <context:component-scan base-package="com.lzj.springmvc">context:component-scan>
    
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/views/">property>
        <property name="suffix" value=".jsp">property>
    bean>

    <mvc:annotation-driven>mvc:annotation-driven>
beans>

2、创建请求
在WebContent下面创建index.jsp，内容为：

<a href="springMVC/testResponseStatusExceptionResolver?i=10">Test ResponseStatusExceptionResolvera>

3、创建请求控制器
控制器用于截获index.jsp中的请求

@Controller
@RequestMapping("/springMVC")
public class TestSpringMVC {

    @RequestMapping("/testResponseStatusExceptionResolver")
    public String testResponseStatusExceptionResolver(@RequestParam("i") int i){
        if(i == 10){
            throw new MyTestException();
        }
        System.out.println("testResponseStatusExceptionResolver");
        return "success";
    }
}

4、自定义异常类

package com.lzj.springmvc.exception;

import org.springframework.http.HttpStatus;
import org.springframework.web.bind.annotation.ResponseStatus;

/*value表示返回给客户端的状态码，reason表示返回的原因*/
@ResponseStatus(value=HttpStatus.FORBIDDEN, reason="请求的网页不存在")
public class MyTestException extends RuntimeException {

}

当发送index.jsp中的请求时，testResponseStatusExceptionResolver控制器方法处理请求，并抛出一个MyTestException 的异常，由于MyTestException 异常上有注解@ResponseStatus。该注解的异常类会被ResponseStatusExceptionResolver解析器解析，把异常状态码和异常原因返回给客户端。客户端显示如下

图中圈起部分分别为状态码和异常原因