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A custom exception handler Introduction
During the development of software coding, in other business logic layer up just to throw an exception to that:
dao ---> service --->controlerFinally, an exception to the controller layer must be dealt with, it may be an exception to the unified exception handler.
Advantages : the ability to reduce duplication of code complexity and help maintain code.
Second, the test custom exception handler
The following code demonstrates throwing an exception, the test uses a custom exception handler for processing.
1. Packaging custom exception information
Class requires custom exception information
继承Exception类, a message attribute, a reference structure, and a corresponding set and get methods.
package com.gql.ex;
/**
* 类说明:
* 自定义异常处理器
* @guoqianliang1998.
*/
public class MyException extends Exception{
private String message;
public MyException(String message) {
super();
this.message = message;
}
public String getMessage() {
return message;
}
public void setMessage(String message) {
this.message = message;
}
}
2. exception resolvers
Exception resolvers need
实现HandlerExceptionResolver接口the exception into a custom exception is bound to the request scope, an exception is forwarded to the interface.
package com.gql.ex;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.web.servlet.HandlerExceptionResolver;
import org.springframework.web.servlet.ModelAndView;
/**
* 类说明:
* 异常解析器
* @guoqianliang1998.
*/
public class MyHandlerExceptionResolver implements HandlerExceptionResolver {
@Override
public ModelAndView resolveException(HttpServletRequest request, HttpServletResponse response, Object handler,
Exception ex) {
MyException myEx = null;
//如果是自己定义的异常
if (ex instanceof MyException) {
myEx = (MyException) ex;
}
//如果是系统的异常,仍转换为自己的异常
else {
myEx = new MyException("您好,系统正在维护,请联系管理员!");
}
//将信息绑定到request作用域
String message = myEx.getMessage();
request.setAttribute("message", message);
//转发到异常页面
try {
request.getRequestDispatcher("/WEB-INF/error.jsp").forward(request, response);
} catch (ServletException | IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return new ModelAndView();
}
}
3. Add to the bean configuration SpringMVC
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:aop="http://www.springframework.org/schema/aop"
xmlns:tx="http://www.springframework.org/schema/tx"
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
http://www.springframework.org/schema/context/spring-context.xsd
http://www.springframework.org/schema/aop
http://www.springframework.org/schema/aop/spring-aop.xsd
http://www.springframework.org/schema/tx
http://www.springframework.org/schema/tx/spring-tx.xsd
http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc/spring-mvc.xsd ">
<!-- 处理器(手写) -->
<context:component-scan base-package="com.gql.upload"></context:component-scan>
<!-- 代替处理器映射器和处理器适配器 -->
<mvc:annotation-driven/>
<!-- 视图解析器 -->
<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="prefix" value="/WEB-INF/product/"></property>
<property name="suffix" value=".jsp"></property>
</bean>
<!-- 自定义异常解析器 -->
<bean id="myHandlerExceptionResolver" class="com.gql.ex.MyHandlerExceptionResolver">
</bean>
</beans>
4. The final jump page
Error error.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="content-type" content="text/html,charset=utf-8"/>
<title>系统正在维护</title>
</head>
<body>
${message}
</body>
</html>
No error success.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="content-type" content="text/html,charset=utf-8"/>
<title></title>
</head>
<body>
用户添加成功.
</body>
</html>
5. Test page
Were tested code throws a custom exception or system anomalies.
Encounter custom exception
package com.gql.upload;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import com.gql.ex.MyException;
import com.gql.pojo.User;
/**
* 类说明:
* 测试异常处理器
* @guoqianliang1998.
*/
@Controller
@RequestMapping("/user")
public class UserController {
@RequestMapping("/add")
public String add(User user) throws MyException{
if(true){
throw new MyException("添加用户失败");//自定义异常
}
return "success";
}
}
Program execution to go if branch instructions detected is a custom exception information,
The system comes with experience abnormal
@RequestMapping("/add")
public String add(User user) throws MyException{
int i = 1/0;//系统自带的异常
return "success";
}
Custom exception handler end of the test.
