springboot实战笔记(十四)----springboot异常处理

叁歲伎倆 2022-01-25 14:36 249阅读 0赞

### 一 前言 ###

在系统中异常的出现是无可避免的，那么对于异常的处理，如何将出现异常后返回给前台不同的提示呢？而且以不同页面效果展示给前端呢？接下来说一下springboot其中常见两种处理异常的方式，自定义 HandlerExceptionResolver 的类处理异常。还有一个是@ControllerAdvice+@ExceptionHandler 注解处理异常。

### 二 自定义 HandlerExceptionResolver ###

**1. pom.xml**

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
      <modelVersion>4.0.0</modelVersion>
      <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.10.RELEASE</version>
      </parent>
      <groupId>com.bjsxt</groupId>
      <artifactId>18-spring-boot-exception5</artifactId>
      <version>0.0.1-SNAPSHOT</version>
      
      <properties>
      <java.version>1.7</java.version>
      <thymeleaf.version>3.0.2.RELEASE</thymeleaf.version>
      <thymeleaf-layout-dialect.version>2.0.4</thymeleaf-layout-dialect.version>
      </properties>
      
      <dependencies>
      	
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
    
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
        </dependency>
      </dependencies>
    </project>

**2.创建Controller**

package com.bjsxt.controller;
    
    import org.springframework.stereotype.Controller;
    import org.springframework.web.bind.annotation.RequestMapping;
    
    @Controller
    public class UsersController {
    
    	@RequestMapping("/showUsers")
    	public String showUser(){
    		String str = null;
    		str.length();
    		//空指针异常
    		return "index";
    	}
    	
    	@RequestMapping("/showUsers2")
    	public String showUser2(){
    		int a = 100/0;
    		//算术异常
    		return "index";
    	}
    }

**3.创建前端页面**

error1.html

<!DOCTYPE html>
    <html>
    <head>
    <meta charset="UTF-8">
    <title>错误提示页面-ArithmeticException</title>
    </head>
    <body>
    <h3>算术异常提示页面</h3>
    	出错了，请与管理员联系。。。
    	<span th:text="${error}"></span>
    </body>
    </html>

error2.html

<!DOCTYPE html>
    <html>
    <head>
    <meta charset="UTF-8">
    <title>错误提示页面-NullPointerException</title>
    </head>
    <body>
    <h3>空指针异常提示页面</h3>
    	出错了，请与管理员联系。。。
    	<span th:text="${error}"></span>
    </body>
    </html>

**4.自定义 HandlerExceptionResolver 类**

package com.bjsxt.exception;
    
    import java.util.Properties;
    
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    import org.springframework.context.annotation.Bean;
    import org.springframework.context.annotation.Configuration;
    import org.springframework.web.bind.annotation.ControllerAdvice;
    import org.springframework.web.bind.annotation.ExceptionHandler;
    import org.springframework.web.servlet.HandlerExceptionResolver;
    import org.springframework.web.servlet.ModelAndView;
    import org.springframework.web.servlet.handler.SimpleMappingExceptionResolver;
    
    /**
     * 通过实现HandlerExceptionResolver接口做全局异常处理
     */
    @Configuration
    public class GlobalException implements HandlerExceptionResolver {
    
    	@Override
    	public ModelAndView resolveException(HttpServletRequest request, HttpServletResponse response, Object handler,
    			Exception ex) {
    		ModelAndView mv = new ModelAndView();
    		//判断不同异常类型，做不同视图跳转
    		if(ex instanceof ArithmeticException){
    			mv.setViewName("error1");
    		}
    		
    		if(ex instanceof NullPointerException){
    			mv.setViewName("error2");
    		}
    		mv.addObject("error", ex.toString());
    		
    		return mv;
    	}
    }

**5.启动测试**

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzMzMjIzMjk5_size_16_color_FFFFFF_t_70][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzMzMjIzMjk5_size_16_color_FFFFFF_t_70 1][]

### 三 @ControllerAdvice+@ExceptionHandler 注解处理异常 ###

package com.chp.springbootdemo.Exception;
    
    import java.util.HashMap;
    import java.util.Map;
    
    import org.springframework.web.bind.annotation.ControllerAdvice;
    import org.springframework.web.bind.annotation.ExceptionHandler;
    import org.springframework.web.bind.annotation.ResponseBody;
    
    @ControllerAdvice
    public class MyControllerAdvice {
    	@ResponseBody
    	@ExceptionHandler(value = java.lang.Exception.class)
    	public Map<String, Object> myException(Exception ex) {
    		Map<String, Object> map = new HashMap<>();
    		map.put("code", 500);
    		map.put("msg", "出错了,请联系管理员");
    		return map;
    	}
    
    	@ResponseBody
    	@ExceptionHandler(value = java.lang.NullPointerException.class)
    	public Map<String, Object> myException2(Exception ex) {
    		Map<String, Object> map = new HashMap<>();
    		map.put("code", -500);
    		map.put("msg", "空指针异常");
    		return map;
    	}
    
    	//自定义异常
    	@ResponseBody
    	@ExceptionHandler(value=com.chp.springbootdemo.Exception.MyException.class)
    	public Map<String, Object> myException3(Exception ex) {
    		Map<String, Object> map = new HashMap<>();
    		map.put("code", -800);
    		map.put("msg", ex.getMessage());
    		return map;
    	}
    }

自定义的异常：

package com.chp.springbootdemo.Exception;
    
    public class MyException extends RuntimeException {
    	
    	public MyException() {
    		super();
    		// TODO Auto-generated constructor stub
    	}
    
    	public MyException(String message, Throwable cause) {
    		super(message, cause);
    	}
    }

###  ###

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzMzMjIzMjk5_size_16_color_FFFFFF_t_70]: /images/20220125/4b5b2ac1727c488da4fbc6193e913203.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzMzMjIzMjk5_size_16_color_FFFFFF_t_70 1]: /images/20220125/ff17545133e34799b9d99bfc112cae07.png