十一(一)、springMVC之异常处理@ExceptionHandler注解
一、概述:
springMVC通过HandlerExceptionResolver处理程序的异常,异常包括 Handler映射、数据绑定以及目标方法执行时发生的异常;
springMVC提供的HandlerExceptionResolver的实现类有:
- ExceptionHandler:处理异常,可以把异常写到页面上;
- DefaultHandlerExceptionResplver 处理指定异常;
- ResponseStatusExceptionResource 更改自定义异常的状态码和异常原因
- simpleMappingExceptionResolver 指定异常跳转页面
ExceptionHandler:
@ExceptionHandler注解:
1.在@ExceptionHandler 方法的入参中可以加入Exception 类型的参数,该参数即对应发生的异常的对象
2.在@ExceptionHandler 方法的入参不能传入 map;若希望吧异常信息传到页面上,需要使用ModelAndView做返回值
3.@ExceptionHandler 存在优先级为,从小到大;越匹配优先级越高;
4.@ControllerAdvice:如果当前Handler中找不到@ExceptionHandler,则去@ControllerAdvice标记的类中查找@ExceptionHandler标记的方法来处理异常
1.目录结构为:
2.配置:
web.xml配置:只配置了DispatcherServlet
1 <?xml version="1.0" encoding="UTF-8"?> 2 <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 3 xmlns="http://xmlns.jcp.org/xml/ns/javaee" 4 xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" 5 id="WebApp_ID" version="3.1"> 6 <servlet> 7 <servlet-name>springDispatcherServlet</servlet-name> 8 <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class> 9 <!-- 配置DispatcherServletd 一个初始化参数:配置springmvc配置文件的位置和名称 --> 10 <!-- 实际上也可以不通过 contextConfigLocation 来配置Springmvc的配置文件,而是用默认的 即默认的配置文件为 11 /WEB-INF/<servlet-name>-servlet.xml 本项目默认位置配置文件即为: /WEB-INF/springDispatcherServlet-servlet.xml --> 12 <init-param> 13 <param-name>contextConfigLocation</param-name> 14 <param-value>classpath:spring.xml</param-value> 15 </init-param> 16 <!-- 表示springDispatcherServlet在加载的时候被创建 --> 17 <load-on-startup>1</load-on-startup> 18 </servlet> 19 20 <!-- Map all requests to the DispatcherServlet for handling --> 21 <servlet-mapping> 22 <servlet-name>springDispatcherServlet</servlet-name> 23 <url-pattern>/</url-pattern> 24 </servlet-mapping> 25 </web-app>
spring.xmp配置:基础配置
基础配置包括:包扫描的配置、视图解析器配置、<mvc:annotation-driven></mvc:annotation-driven>;
1 <?xml version="1.0" encoding="UTF-8"?> 2 <beans xmlns="http://www.springframework.org/schema/beans" 3 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 4 xmlns:mvc="http://www.springframework.org/schema/mvc" 5 xmlns:context="http://www.springframework.org/schema/context" 6 xsi:schemaLocation="http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd 7 http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd 8 http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd"> 9 10 <context:component-scan base-package="handler"></context:component-scan> 11 <!-- 配置视图解析器 如何把handler 方法返回值解析为实际的物理视图 --> 12 <bean 13 class="org.springframework.web.servlet.view.InternalResourceViewResolver"> 14 <property name="prefix" value="/WEB-INF/views/"></property> 15 <property name="suffix" value=".jsp"></property> 16 </bean> 17 18 <mvc:annotation-driven></mvc:annotation-driven> 19 20 </beans>
3.EceptionController.java
- 方法的入参中可以加入Exception 类型的参数,该参数即对应发生的异常的对象
- 异常信息传到页面上,需要使用ModelAndView做返回值
1 package handler; 2 3 import org.springframework.stereotype.Controller; 4 import org.springframework.web.bind.annotation.ExceptionHandler; 5 import org.springframework.web.bind.annotation.RequestMapping; 6 import org.springframework.web.bind.annotation.RequestParam; 7 import org.springframework.web.servlet.ModelAndView; 8 9 @RequestMapping("/emp") 10 @Controller 11 public class EceptionController { 12 13 @RequestMapping("/testError") 14 public String testError(@RequestParam("i") int i) { 15 System.out.println(10 / i); 16 return "success"; 17 } 18 19 @ExceptionHandler({ ArithmeticException.class }) 20 public ModelAndView handleArithmeticException(Exception ex) { 21 System.out.println("出异常了:" + ex); 22 ModelAndView md = new ModelAndView("error"); 23 md.addObject("ex", ex); 24 return md; 25 } 26 }
4.success.jsp&&error.jsp
1 <%@ page language="java" contentType="text/html; charset=UTF-8" 2 pageEncoding="UTF-8"%> 3 <!DOCTYPE html> 4 <html> 5 <head> 6 <meta charset="UTF-8"> 7 <title>Insert title here</title> 8 </head> 9 <body> 10 success 11 </body> 12 </html>
1 <%@ page language="java" contentType="text/html; charset=UTF-8" 2 pageEncoding="UTF-8"%> 3 <!DOCTYPE html> 4 <html> 5 <head> 6 <meta charset="UTF-8"> 7 <title>Insert title here</title> 8 </head> 9 <body> 10 <h4>Error Page</h4> 11 ${ex} 12 </body> 13 </html>
5.运行结果:
当访问:http://localhost:8080/DataOperate/emp/testError?i=10时,页面跳转到success页面;当访问http://localhost:8080/DataOperate/emp/testError?i=0时,访问了error页面,且error页面打印了异常信息;
6.如果异常不匹配:
也就是说@ExceptionHandler标记的异常和实际抛出的异常不匹配,如下,比如EceptionController.java中异常时算术异常,但是@ExceptionHandler标记的只有运行时异常:那么异常存在优先级为,从小到大;越匹配优先级越高;
1 package handler; 2 3 import org.springframework.stereotype.Controller; 4 import org.springframework.web.bind.annotation.ExceptionHandler; 5 import org.springframework.web.bind.annotation.RequestMapping; 6 import org.springframework.web.bind.annotation.RequestParam; 7 import org.springframework.web.servlet.ModelAndView; 8 9 @RequestMapping("/emp") 10 @Controller 11 public class EceptionController { 12 13 @RequestMapping("/testError") 14 public String testError(@RequestParam("i") int i) { 15 System.out.println(10 / i); 16 return "success"; 17 } 18 19 @ExceptionHandler({ RuntimeException.class }) 20 public ModelAndView handleRuntimeException(Exception ex) { 21 System.out.println("【出异常了]:" + ex); 22 ModelAndView md = new ModelAndView("error"); 23 md.addObject("ex", ex); 24 return md; 25 } 26 }
此时,访问;http://localhost:8080/DataOperate/emp/testError?i=0,也会跳转到error页面且显示异常信息同上图,且控制台打印:
【出异常了]:java.lang.ArithmeticException: / by zero
7.如果当前Handler中找不到@ExceptionHandler
@ControllerAdvice:如果当前Handler中找不到@ExceptionHandler,则去@ControllerAdvice标记的类中查找@ExceptionHandler标记的方法来处理异常
EceptionController.java
1 package handler; 2 3 import org.springframework.stereotype.Controller; 4 import org.springframework.web.bind.annotation.RequestMapping; 5 import org.springframework.web.bind.annotation.RequestParam; 6 7 @RequestMapping("/emp") 8 @Controller 9 public class EceptionController { 10 11 @RequestMapping("/testError") 12 public String testError(@RequestParam("i") int i) { 13 System.out.println(10 / i); 14 return "success"; 15 } 16 }
ExceptionHandlerProcess.java
1 package handler; 2 3 import org.springframework.web.bind.annotation.ControllerAdvice; 4 import org.springframework.web.bind.annotation.ExceptionHandler; 5 import org.springframework.web.servlet.ModelAndView; 6 7 @ControllerAdvice 8 public class ExceptionHandlerProcess { 9 10 @ExceptionHandler({ ArithmeticException.class }) 11 public ModelAndView handleArithmeticException(Exception ex) { 12 System.out.println("出异常了:" + ex); 13 ModelAndView md = new ModelAndView("error"); 14 md.addObject("ex", ex); 15 return md; 16 } 17 18 @ExceptionHandler({ RuntimeException.class }) 19 public ModelAndView handleRuntimeException(Exception ex) { 20 System.out.println("【出异常了]:" + ex); 21 ModelAndView md = new ModelAndView("error"); 22 md.addObject("ex", ex); 23 return md; 24 } 25 26 }
运行结果:
此时,访问;http://localhost:8080/DataOperate/emp/testError?i=0,也会跳转到error页面且显示异常信息同上图,且控制台打印相关信息:
出异常了:java.lang.ArithmeticException: / by zero