SpringBoot--异常统一处理

　　先上代码，不捕获异常和手动捕获异常处理：

@GetMapping("/error1")
    public String error1() {
        int i = 10 / 0;
        return "test1";
    }

    @ResponseBody
    @GetMapping("/error2")
    public Map<String, String> error2() {
        Map<String, String> result = new HashMap<>(16);
        try{
            int i = 10 / 0;
            result.put("code", "200");
            result.put("data", "具体返回的结果集");
        } catch (Exception e) {
            result.put("code", "500");
            result.put("message", "请求错误");
        }
        return result;
    }

　　其中的各种问题就不再多说了，由于各种问题，因此需要对异常进行统一捕获

　　1、导入依赖

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

　　2、自定义异常类

package com.example.demo.entity;

import lombok.Data;

@Data
public class ErrorResponse {
    private int code;
    private String message;

    public ErrorResponse(int code, String message) {
        this.code = code;
        this.message = message;
    }

    public ErrorResponse() {

    }

    public ErrorResponse OK(String message){
        this.code = 200;
        this.message = message;
        return this;
    }

    public void OK(){
        this.code = 200;
        this.message = "";
    }
}

　　3、定义异常模板

package com.example.demo.entity;

import lombok.Data;

@Data
public class ErrorResponse {
    private int code;
    private String message;

    public ErrorResponse(int code, String message) {
        this.code = code;
        this.message = message;
    }
}

　　4、异常拦截器

　　此步时重点，需要特殊说明一下，

　　@ControllerAdvice 捕获 Controller 层抛出的异常，如果添加 @ResponseBody 返回信息则为JSON 格式。

　　@RestControllerAdvice 相当于 @ControllerAdvice 与 @ResponseBody 的结合体。

　　 @ExceptionHandler 统一处理一种类的异常，减少代码重复率，降低复杂度。 创建一个 GlobalExceptionHandler 类，并添加上 @RestControllerAdvice 注解就可以定义出异常通知类了，然后在定义的方法中添加上 @ExceptionHandler 即可实现异常的捕捉…

package com.example.demo.utils;

import com.example.demo.entity.ErrorResponse;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.lang.Nullable;
import org.springframework.web.bind.MethodArgumentNotValidException;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.RestControllerAdvice;
import org.springframework.web.context.request.WebRequest;
import org.springframework.web.method.annotation.MethodArgumentTypeMismatchException;
import org.springframework.web.servlet.mvc.method.annotation.ResponseEntityExceptionHandler;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@RestControllerAdvice
public class GlobalExceptionHandler extends ResponseEntityExceptionHandler {

    @ExceptionHandler(LclException.class)
    public ErrorResponse lclExceptionHandler(HttpServletRequest request, final Exception e, HttpServletResponse response){
        response.setStatus(HttpStatus.BAD_REQUEST.value());
        LclException exception = (LclException) e;
        return new ErrorResponse(exception.getCode(),exception.getMessage());
    }

    @ExceptionHandler(RuntimeException.class)
    public ErrorResponse runtimeExcetionHandler(HttpServletRequest request, final Exception e,HttpServletResponse response){
        response.setStatus(HttpStatus.BAD_REQUEST.value());
        RuntimeException exception = (RuntimeException) e;
        return new ErrorResponse(400,exception.getMessage());
    }


    @Override
    protected ResponseEntity<Object> handleExceptionInternal(Exception ex, @Nullable Object body, HttpHeaders headers, HttpStatus status, WebRequest request) {
        if(ex instanceof MethodArgumentNotValidException){
            MethodArgumentNotValidException exception = (MethodArgumentNotValidException) ex;
            return new ResponseEntity<>(new ErrorResponse(status.value(),exception.getBindingResult().getAllErrors().get(0).getDefaultMessage()), status);
        }

        if(ex instanceof MethodArgumentTypeMismatchException){
            MethodArgumentTypeMismatchException exception = (MethodArgumentTypeMismatchException) ex;
            return new ResponseEntity<>(new ErrorResponse(status.value(),"参数转换异常"),status);
        }

        return new ResponseEntity<>(new ErrorResponse(status.value(), "参数转换异常"), status);
    }


}

　　5、测试类

@ResponseBody
@GetMapping("/error3")
public ErrorResponse error3(Integer num) throws LclException{
    if(num == null){
        throw new LclException(12345,"num不允许为空");
    }
    int i = 10/num;
    return (new ErrorResponse()).OK(i+"");
}

　　6、测试