SpringBoot2：web开发常用功能实现及原理解析-@ControllerAdvice实现全局异常统一处理

前言

本篇主要针对前后端分离的项目，做的一个统一响应包装、统一异常捕获处理。

在Spring里，我们可以使用@ControllerAdvice来声明一些关于controller的全局性的东西，其用法主要有以下三点：

1、@ExceptionHandler注解标注的方法：用于捕获Controller中抛出的不同类型的异常，从而达到异常全局处理的目的；
2、@ModelAttribute注解标注的方法：表示此方法会在执行目标Controller方法之前执行；
3、@InitBinder注解标注的方法：用于请求中注册自定义参数的解析，从而达到自定义请求参数格式的目的；

参考：
@ControllerAdvice注解作用及源码解析
@ControllerAdvice 的介绍及三种用法

1、工程包结构

2、POM依赖

		<dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency>

3、Java代码

AppExceptionCodeMsg

//这个枚举类中定义的都是跟业务有关的异常
public enum AppExceptionCodeMsg {INVALID_CODE(10000,"验证码无效"),USERNAME_NOT_EXISTS(10001,"用户名不存在"),USER_CREDIT_NOT_ENOUTH(10002,"用户积分不足");;private int code ;private String msg ;public int getCode() {return code;}public String getMsg() {return msg;}AppExceptionCodeMsg(int code, String msg){this.code = code;this.msg = msg;}}

AppException

public class AppException extends RuntimeException{private int code = 500;private String msg = "服务器异常";public AppException(AppExceptionCodeMsg appExceptionCodeMsg){super();this.code = appExceptionCodeMsg.getCode();this.msg = appExceptionCodeMsg.getMsg();}public AppException(int code,String msg){super();this.code = code;this.msg = msg;}public int getCode() {return code;}public String getMsg() {return msg;}}

Resp

import com.atguigu.boot.exception.AppExceptionCodeMsg;public class Resp<T> {//服务端返回的错误码private int code = 200;//服务端返回的错误信息private String msg = "success";//我们服务端返回的数据private T data;private Resp(int code,String msg,T data){this.code = code;this.msg = msg;this.data = data;}public static <T> Resp success(T data){Resp resp = new Resp(200, "success", data);return resp;}public static <T> Resp success(String msg,T data){Resp resp = new Resp(200,msg, data);return resp;}public static <T> Resp error(AppExceptionCodeMsg appExceptionCodeMsg){Resp resp = new Resp(appExceptionCodeMsg.getCode(), appExceptionCodeMsg.getMsg(), null);return resp;}public static <T> Resp error(int code,String msg){Resp resp = new Resp(code,msg, null);return resp;}public int getCode() {return code;}public String getMsg() {return msg;}public T getData() {return data;}}

GlobalExceptionHandler

import com.atguigu.boot.bean.Resp;
import com.atguigu.boot.exception.AppException;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.ResponseBody;@ControllerAdvice
public class GlobalExceptionHandler {@ExceptionHandler(value = {Exception.class})@ResponseBodypublic <T> Resp<T> exceptionHandler(Exception e){//这里先判断拦截到的Exception是不是我们自定义的异常类型if(e instanceof AppException){AppException appException = (AppException)e;return Resp.error(appException.getCode(),appException.getMsg());}//如果拦截的异常不是我们自定义的异常(例如：数据库主键冲突)return Resp.error(500,"服务器端异常");}
}

ExpTestController

import com.atguigu.boot.bean.Resp;
import com.atguigu.boot.exception.AppException;
import com.atguigu.boot.exception.AppExceptionCodeMsg;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;import java.util.Arrays;
import java.util.List;@RestController
public class ExpTestController {@GetMapping("demo")public Resp<String> demo(String name){if("ok".equals(name)){return Resp.success("succ");}if("err".equals(name)){//抛业务相关的异常throw new AppException(AppExceptionCodeMsg.USERNAME_NOT_EXISTS);}if("errcode".equals(name)){throw new AppException(AppExceptionCodeMsg.INVALID_CODE);}if("0".equals(name)){int i=1/0;}//检查用户积分是否足够，如果不够，就抛出异常if("notenough".equals(name)){throw new AppException(AppExceptionCodeMsg.USER_CREDIT_NOT_ENOUTH);}return Resp.success("default");}@GetMapping("list")public Resp<List> list(){List<String> list = Arrays.asList("zhangsan","lisi","wangwu");return Resp.success(list);}
}