SpringBoot通用返回处理总结

IntelliJ IDEA 2021.2.2
JDK 1.8.0
SpringBoot 2.6.2

简单来说是返回给前端的对应返回值（成功or失败），让前端明确的知晓对应的正确or报错信息。

此类定义通用对象的处理。

package com.gzh.dianping.common;
public class CommonRes {
    //表明对应请求的返回处理结果, "success"或"fail"
    private String status;
    //若status=success，表明返回对应的json类数据
    //若status=fail，则data内将使用通用的错误码对应的格式
    private Object data;
    //定义一个通用的创建返回对象的方法
    public static CommonRes create(Object result){
        return CommonRes.create(result, "success");
    }
    public static CommonRes create(Object result, String status){
         CommonRes commonRes = new CommonRes();
         commonRes.setStatus(status);
         commonRes.setData(result);
         return commonRes;
    }
    public String getStatus() {
        return status;
    }
    public void setStatus(String status) {
        this.status = status;
    }
    public Object getData() {
        return data;
    }

    public void setData(Object data) {
        this.data = data;
    }
}

此类定义通用的返回对象的错误处理的方式。

package com.gzh.dianping.common;

public class CommonError {
	//错误码
    private Integer errCode;
	//错误信息
    private String errMsg;

    public CommonError(Integer errCode, String errMsg) {
        this.errCode = errCode;
        this.errMsg = errMsg;
    }
    //企业级的方式：错误穷举
    public CommonError(EmBusinessError emBusinessError){
        this.errCode = emBusinessError.getErrCode();
        this.errMsg = emBusinessError.getErrMsg();
    }
    public Integer getErrCode() {
        return errCode;
    }

    public void setErrCode(Integer errCode) {
        this.errCode = errCode;
    }

    public String getErrMsg() {
        return errMsg;
    }

    public void setErrMsg(String errMsg) {
        this.errMsg = errMsg;
    }
}

通过枚举类预先定义的错误往CommonError里赋值（与上一个类里的第二个构造函数组装）。

package com.gzh.dianping.common;

public enum EmBusinessError {

    NO_OBJECT_FOUND(10001, "请求对象不存在"),
    UNKNOWN_ERROR(10002, "未知错误"),
    NO_HANDLER_FOUND(10003, "找不到执行的路径操作"),
    BIND_EXCEPTION_ERROR(10004,"请求参数错误");
	//与CommonError对应
    private Integer errCode;
    private String errMsg;

    public Integer getErrCode() {
        return errCode;
    }

    public void setErrCode(Integer errCode) {
        this.errCode = errCode;
    }

    public String getErrMsg() {
        return errMsg;
    }

    public void setErrMsg(String errMsg) {
        this.errMsg = errMsg;
    }

    EmBusinessError(Integer errCode, String errMsg) {
        this.errCode = errCode;
        this.errMsg = errMsg;
    }
}

package com.gzh.dianping.common;

public class BusinessException extends Exception{
    private CommonError commonError;
    public BusinessException(EmBusinessError emBusinessError){
        super();//创建自己的异常
        this.commonError = new CommonError(emBusinessError);
    }
        public CommonError getCommonError() {
        return commonError;
    }
}

package com.gzh.dianping.common;
import org.springframework.web.bind.ServletRequestBindingException;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.servlet.NoHandlerFoundException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.util.logging.Handler;

@ControllerAdvice
public class GlobalExceptionHandler {

	//只要对应的controller抛出异常，都来这里统一处理。(即controller往上抛，会被这个方法拦截)
    @ExceptionHandler(Exception.class)
    @ResponseBody
    public CommonRes doError(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Exception ex){
        if(ex instanceof BusinessException){
            return CommonRes.create(((BusinessException)ex).getCommonError(), "fail");
        }else if(ex instanceof NoHandlerFoundException){
            CommonError commonError = new CommonError(EmBusinessError.NO_HANDLER_FOUND);
            return CommonRes.create(commonError, "fail");
        }else if(ex instanceof ServletRequestBindingException){
            CommonError commonError = new CommonError(EmBusinessError.BIND_EXCEPTION_ERROR);
            return CommonRes.create(commonError, "fail");
        }else
        {
            CommonError commonError = new CommonError(EmBusinessError.UNKNOWN_ERROR);
            return CommonRes.create(commonError, "fail");
        }

    }
}

    @RequestMapping("/get")
    @ResponseBody
    public CommonRes getUser(@RequestParam(name="id")Integer id) throws BusinessException {
        User user =  userService.getUserById(id);
        if(user == null){
            throw new BusinessException(EmBusinessError.NO_OBJECT_FOUND);
        }else {
            return CommonRes.create(user);
        }
    }

本文为自学梳理，细节可以共同讨论。