项目中遇到运行时异常，总不能每个异常处理都去添加try catch逻辑，甚至有的时候一个偶然条件发生而导致异常，而我们没有进行对应的处理则会直接给请求者返回未知的错误，这在正式的上线的项目中是不允许，所以我们来配置全局异常处理
今天讲解一下如何在SpringBoot实现全局异常机制,在没有用springboot大家要实现这一的功能基本上都是通过aop的思想,还是有点麻烦，而现在springboot中对它要进行了一次封装,开发者使用起来更加的简单,接下先通过代码演示效果,然后再分析一下原理,好了废话不多说直接上代码,看代码结构: 1、使用到的注解：@ControllerAdvice注解是用来配置控制器通知的，我们可以配置过滤拦截具体一种或者多种类型的注解，添加annotations属性即可，在类的上方我们配置了@ControllerAdvice的annotations属性值为RestController.class，也就是只有添加了@RestController注解的控制器才会进入全局异常处理；因为我们全局返回的都是统一的Json格式的字符串，所以需要再类上配置@ResponseBody注解；@ExceptionHandler注解用来配置需要拦截的异常类型，默认是全局类型，可以通过value属性配置只对某个类型的异常起作用；@ResponseStatus注解用于配置遇到该异常后返回数据时的StatusCode的值，我们这里默认使用值500
定义一个返回的DTO工具类
//
// 定义一个返回的DTO工具类
//
package com.zkml.common.obj.dto;
import com.zkml.common.obj.enums.ResultStatusEnum;
import java.io.Serializable;
public class ResultModelDTO<T> implements Serializable {
private ResultStatusEnum result;
private Long code;
private String message;
private T model;
public ResultModelDTO() {
}
public boolean successResult() {
return this.result.equals(ResultStatusEnum.success);
}
public boolean failResult() {
return !this.successResult();
}
public ResultModelDTO(ResultStatusEnum result, long code, String message, T model) {
this.result = result;
this.code = Long.valueOf(code);
this.message = message;
this.model = model;
}
public ResultModelDTO(ResultStatusEnum result, ResultCode remoteResultCode, T model) {
this(result, remoteResultCode.getCode(), remoteResultCode.getMessage(), model);
}
public ResultStatusEnum getResult() {
return this.result;
}
public void setResult(ResultStatusEnum result) {
this.result = result;
}
public Long getCode() {
return this.code;
}
public void setCode(Long code) {
this.code = code;
}
public String getMessage() {
return this.message;
}
public void setMessage(String message) {
this.message = message;
}
public T getModel() {
return this.model;
}
public void setModel(T model) {
this.model = model;
}
}
定义一个全局异常处理类
package com.springboot.exception.global_excep;
import com.springboot.exception.json.JsonResult;
import org.springframework.beans.ConversionNotSupportedException;
import org.springframework.beans.TypeMismatchException;
import org.springframework.http.converter.HttpMessageNotReadableException;
import org.springframework.http.converter.HttpMessageNotWritableException;
import org.springframework.web.HttpMediaTypeNotAcceptableException;
import org.springframework.web.HttpRequestMethodNotSupportedException;
import org.springframework.web.bind.MissingServletRequestParameterException;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.ResponseBody;
import lombok.extern.slf4j.Slf4j
import java.io.IOException;
/**
* @Author fanghui
* @Description 全局异常拦截器
* @Date 16:38 2019/8/14
* @Modify By
*/
@ControllerAdvice
@ResponseBody
@Slf4j
public class GlobalExceptionHandler {
private String getMessage(BindingResult result) {
return result.getFieldErrors().stream().map(error -> {
return error.getField() + "[" + error.getRejectedValue() + "]:" + error.getDefaultMessage();
}).collect(Collectors.joining(", "));
}
/**
* 捕获 controller 实体类参数@Validate验证报错
*
* @param e
* @param request
* @param response
* @return
*/
@ExceptionHandler(BindException.class)
@ResponseBody
public JsonResult validExceptionHandler(BindException e, HttpServletRequest request, HttpServletResponse response) {
return JsonResult.error(getMessage(e.getBindingResult()), ErrorCode.ILLEGAL_PARAM.name());
}
/**
* 捕获 普通方法传参@Validate验证报错
*
* @param e
* @param request
* @param response
* @return
*/
@ExceptionHandler(MethodArgumentNotValidException.class)
@ResponseBody
public JsonResult validExceptionHandler(MethodArgumentNotValidException e, HttpServletRequest request, HttpServletResponse response) {
return JsonResult.error(getMessage(e.getBindingResult()), ErrorCode.ILLEGAL_PARAM.name());
}
/**
* 捕获 controller 平铺参数@Validate验证报错
*
* @param e
* @param request
* @param response
* @return
*/
@ExceptionHandler(ConstraintViolationException.class)
@ResponseBody
public JsonResult validExceptionHandler(ConstraintViolationException e, HttpServletRequest request, HttpServletResponse response) {
return JsonResult.error(e.getMessage(), ErrorCode.ILLEGAL_PARAM.name());
}
//运行时异常
@ExceptionHandler(RuntimeException.class)
public String runtimeExceptionHandler(HttpServletRequest request,RuntimeException ex) {
log.info("请求路径："+request.getRequestURL().toString()+"+"RuntimeException :"+ex);
return ResultModelUtil.failResult(DefaultResultCodeEnum.ADD_ERROR);
}
//空指针异常
@ExceptionHandler(NullPointerException.class)
public String nullPointerExceptionHandler(HttpServletRequest request,NullPointerException ex) {
log.info("请求路径："+request.getRequestURL().toString()+"+"NullPointerException :"+ex);
return ResultModelUtil.failResult(DefaultResultCodeEnum.ADD_ERROR);
}
//类型转换异常
@ExceptionHandler(ClassCastException.class)
public String classCastExceptionHandler(HttpServletRequest request,ClassCastException ex) {
log.info("请求路径："+request.getRequestURL().toString()+"+"ClassCastException :"+ex);
return resultFormat(3, ex);
}
//IO异常
@ExceptionHandler(IOException.class)
public String iOExceptionHandler(HttpServletRequest request,IOException ex) {
log.info("请求路径："+request.getRequestURL().toString()+"+"IOException :"+ex);
return resultFormat(4, ex);
}
//未知方法异常
@ExceptionHandler(NoSuchMethodException.class)
public String noSuchMethodExceptionHandler(NoSuchMethodException ex) {
return resultFormat(5, ex);
}
//数组越界异常
@ExceptionHandler(IndexOutOfBoundsException.class)
public String indexOutOfBoundsExceptionHandler(IndexOutOfBoundsException ex) {
return resultFormat(6, ex);
}
//400错误
@ExceptionHandler({HttpMessageNotReadableException.class})
public String requestNotReadable(HttpMessageNotReadableException ex) {
System.out.println("400..requestNotReadable");
return resultFormat(7, ex);
}
//400错误
@ExceptionHandler({TypeMismatchException.class})
public String requestTypeMismatch(TypeMismatchException ex) {
System.out.println("400..TypeMismatchException");
return resultFormat(8, ex);
}
//400错误
@ExceptionHandler({MissingServletRequestParameterException.class})
public String requestMissingServletRequest(MissingServletRequestParameterException ex) {
System.out.println("400..MissingServletRequest");
return resultFormat(9, ex);
}
//405错误
@ExceptionHandler({HttpRequestMethodNotSupportedException.class})
public String request405(HttpRequestMethodNotSupportedException ex) {
return resultFormat(10, ex);
}
//406错误
@ExceptionHandler({HttpMediaTypeNotAcceptableException.class})
public String request406(HttpMediaTypeNotAcceptableException ex) {
System.out.println("406...");
return resultFormat(11, ex);
}
//500错误
@ExceptionHandler({ConversionNotSupportedException.class, HttpMessageNotWritableException.class})
public String server500(RuntimeException ex) {
System.out.println("500...");
return resultFormat(12, ex);
}
//栈溢出
@ExceptionHandler({StackOverflowError.class})
public String requestStackOverflow(StackOverflowError ex) {
return resultFormat(13, ex);
}
//除数不能为0
@ExceptionHandler({ArithmeticException.class})
public String arithmeticException(ArithmeticException ex) {
return resultFormat(13, ex);
}
//其他错误
@ExceptionHandler({Exception.class})
public String exception(Exception ex) {
return resultFormat(14, ex);
}
private <T extends Throwable> String resultFormat(Integer code, T ex) {
ex.printStackTrace();
log.error(String.format(logExceptionFormat, code, ex.getMessage()));
return JsonResult.failed(code, ex.getMessage());
}
}
除了上面的运行时异常之外，还有一个是专门来处理业务异常的，接下来我们再来处理一个自定义业务异常类：
自定义业务异常类BaseException
package com.izkml.mlyun.framework.common.exception;
public class BaseException extends RuntimeException {
private String errorCode;
public String getErrorCode() {
return this.errorCode;
}
public void setErrorCode(String errorCode) {
this.errorCode = errorCode;
}
public BaseException(String errorCode, String message) {
this(errorCode, message, (Throwable)null);
}
public BaseException(String errorCode, String message, Throwable cause) {
super(message, cause);
this.errorCode = errorCode;
}
public BaseException(ErrorEnum errorEnum) {
this(errorEnum.getCode(), errorEnum.getText(), (Throwable)null);
}
public BaseException(ErrorEnum errorEnum, Throwable cause) {
this(errorEnum.getCode(), errorEnum.getText(), cause);
}
}
SpringMVC@ResponseStatus注解的使用
有时候，我们在实战项目中并不关心返回消息体的内容，前端只关系后端返回的状态码到底是什么，这个时候我们就要做的专业点，那么此时这个注解就派上用场了
//405-Method Not Allowed
@ExceptionHandler(HTTPRequestMethodNotSupportedException.class)
@ResponseStatus(HttpStatus.METHOD_NOT_ALLOWED) //这个HttpStatus是个枚举类，可以点击进去有很多不同枚举
public Map<String,Object> server500(RuntimeException ex) {
Map<String,Object> map = new HashMap<String,Object>();
map.put("code",400);
map.put("message",e.getMessage());
return map;
}
总结
我们开发无论什么服务都大体分为三层，controller，service，dao；其中servic一般不做任何系统类型异常处理（RuntimeException和Exception）,只关注业务分析，但是有一种情况需要往上进行抛异常（比如，业务层中车牌号重复，需要告诉上游你的车牌号已经重复，需要一层一层的往上进行抛直到前端页面告知用户）；除了这种业务需要判断的异常往上抛之外，异常需要在controller进行捕捉，通过try..catch..进行捕获或者使用全局异常进行拦截，事实上,对于服务器来说,它是200,正常返回的,而对不业务模块来说,它的状态是个500,嘿嘿,这点要清楚
