(五)整合统一异常和统一返回值

项目地址：https://gitee.com/springzb/admin-boot
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简介：
这是一个基础的企业级基础后端脚手架项目，主要由springboot为基础搭建，后期整合一些基础插件例如：redis、xxl-job、flowable、minioio、easyexcel、skyWalking、rabbitmq

目录

• 一、统一返回值

  • 测试

• 二、统一异常处理

  • 自定义异常

  • 统一异常处理

  • 测试统一异常

一、统一返回值

统一返回结果 R

package cn.mesmile.admin.common.result;

import com.sun.istack.internal.Nullable;

import java.io.Serializable;
import java.util.Optional;

/**
 * @author zb
 * @Description 公共返回信息
 */
public class R<T> implements Serializable {

    private static final long serialVersionUID = 1L;

    /**
     * 状态码
     */
    private int code;

    /**
     * 是否成功
     */
    private boolean success;

    /**
     * 承载数据
     */
    private T data;

    /**
     * 返回消息
     */
    private String msg;

    private R(IResultCode resultCode) {
        this(resultCode, null, resultCode.getMessage());
    }

    private R(IResultCode resultCode, String msg) {
        this(resultCode, null, msg);
    }

    private R(IResultCode resultCode, T data) {
        this(resultCode, data, resultCode.getMessage());
    }

    private R(IResultCode resultCode, T data, String msg) {
        this(resultCode.getCode(), data, msg);
    }

    private R(int code, T data, String msg) {
        this.code = code;
        this.data = data;
        this.msg = msg;
        this.success = ResultCode.SUCCESS.code == code;
    }

    public static boolean isSuccess(@Nullable R<?> result) {
        return (Boolean) Optional.ofNullable(result).map((x) -> {
            return ResultCode.SUCCESS.code == x.code;
        }).orElse(Boolean.FALSE);
    }

    public static boolean isNotSuccess(@Nullable R<?> result) {
        return !isSuccess(result);
    }

    public static <T> R<T> data(T data) {
        return data(data, "操作成功");
    }

    public static <T> R<T> data(T data, String msg) {
        return data(200, data, msg);
    }

    public static <T> R<T> data(int code, T data, String msg) {
        return new R(code, data, data == null ? "暂无承载数据" : msg);
    }

    public static <T> R<T> success(String msg) {
        return new R(ResultCode.SUCCESS, msg);
    }

    public static <T> R<T> success(IResultCode resultCode) {
        return new R(resultCode);
    }

    public static <T> R<T> success(IResultCode resultCode, String msg) {
        return new R(resultCode, msg);
    }

    public static <T> R<T> fail(String msg) {
        return new R(ResultCode.FAILURE, msg);
    }

    public static <T> R<T> fail(int code, String msg) {
        return new R(code, (Object)null, msg);
    }

    public static <T> R<T> fail(IResultCode resultCode) {
        return new R(resultCode);
    }

    public static <T> R<T> fail(IResultCode resultCode, String msg) {
        return new R(resultCode, msg);
    }

    public static <T> R<T> status(boolean flag) {
        return flag ? success("操作成功") : fail("操作失败");
    }

    public int getCode() {
        return this.code;
    }

    public boolean isSuccess() {
        return this.success;
    }

    public T getData() {
        return this.data;
    }

    public String getMsg() {
        return this.msg;
    }

    public void setCode(final int code) {
        this.code = code;
    }

    public void setSuccess(final boolean success) {
        this.success = success;
    }

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

    public void setMsg(final String msg) {
        this.msg = msg;
    }

    @Override
    public String toString() {
        return "R(code=" + this.getCode() + ", success=" + this.isSuccess() + ", data=" + this.getData() + ", msg=" + this.getMsg() + ")";
    }

    public R() {
    }
}

IResultCode

package cn.mesmile.admin.common.result;

import java.io.Serializable;

/**
 * @author zb
 * @Description
 */
public interface IResultCode extends Serializable {
    /**
     * 获取结果消息
     * @return 结果消息
     */
    String getMessage();

    /**
     *  获取返回状态码
     * @return 结果状态码
     */
    int getCode();
}

ResultCode

package cn.mesmile.admin.common.result;

/**
 * @author zb
 * @Description
 */
public enum ResultCode implements IResultCode {
    /**
     * 返回状态码，以及返回消息
     */
    SUCCESS(200, "操作成功"),
    FAILURE(400, "业务异常"),
    UN_AUTHORIZED(401, "请求未授权"),
    CLIENT_UN_AUTHORIZED(401, "客户端请求未授权"),
    NOT_FOUND(404, "404 没找到请求"),
    MSG_NOT_READABLE(400, "消息不能读取"),
    METHOD_NOT_SUPPORTED(405, "不支持当前请求方法"),
    MEDIA_TYPE_NOT_SUPPORTED(415, "不支持当前媒体类型"),
    REQ_REJECT(403, "请求被拒绝"),
    INTERNAL_SERVER_ERROR(500, "服务器异常"),
    PARAM_MISS(400, "缺少必要的请求参数"),
    PARAM_TYPE_ERROR(400, "请求参数类型错误"),
    PARAM_BIND_ERROR(400, "请求参数绑定错误"),
    PARAM_VALID_ERROR(400, "参数校验失败");

    final int code;
    final String message;

    @Override
    public int getCode() {
        return this.code;
    }

    @Override
    public String getMessage() {
        return this.message;
    }

    private ResultCode(final int code, final String message) {
        this.code = code;
        this.message = message;
    }

}

测试

package cn.mesmile.admin.modules.system.controller;

import cn.mesmile.admin.common.result.R;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

/**
 * @author zb
 * @Description
 */
@RequestMapping("/api/v1/hello")
@RestController
public class HelloController {

    @GetMapping("/get")
    public R hello () {
        return R.data("hello world");
    }

}

启动 cn.mesmile.admin.AdminApplication 启动类，访问 localhost:8080/api/v1/hello/get

看到统一返回结果如下：

{
  "code": 200,
  "success": true,
  "data": "hello world",
  "msg": "操作成功"
}

二、统一异常处理

自定义异常

package cn.mesmile.admin.common.exceptions;


import cn.mesmile.admin.common.result.IResultCode;
import cn.mesmile.admin.common.result.ResultCode;

/**
 * @author zb
 * @Description 自定义业务异常
 */
public class BusinessException extends RuntimeException {

    private final long serialVersionUID = 1L;

    private int code = ResultCode.FAILURE.getCode();

    private String msg = ResultCode.FAILURE.getMessage();

    public BusinessException() {
        super();
    }

    public BusinessException(String msg) {
        super(msg);
        this.msg = msg;
    }

    public BusinessException(IResultCode resultCode, String msg) {
        super(msg);
        this.code = resultCode.getCode();
        this.msg = msg;
    }

    public BusinessException(String msg, Throwable cause) {
        super(msg, cause);
        this.msg = msg;
    }

    public BusinessException(IResultCode resultCode, String msg, Throwable cause) {
        super(msg, cause);
        this.code = resultCode.getCode();
        this.msg = msg;
    }

    public BusinessException(Throwable cause) {
        super(cause);
    }

    public int getCode() {
        return code;
    }

    public void setCode(int code) {
        this.code = code;
    }

    public String getMsg() {
        return msg;
    }

    public void setMsg(String msg) {
        this.msg = msg;
    }
}

统一异常处理

package cn.mesmile.admin.common.handler;

import cn.mesmile.admin.common.constant.AdminConstant;
import cn.mesmile.admin.common.exceptions.*;
import cn.mesmile.admin.common.result.R;
import lombok.extern.slf4j.Slf4j;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.RestControllerAdvice;

/**
 * @author zb
 * @Description 全局异常拦截
 * <p>
 * 如果我同时捕获了父类和子类，那么到底能够被那个异常处理器捕获呢？比如 Exception 和 BusinessException
 * 当然是 BusinessException 的异常处理器捕获了，精确匹配，如果没有 BusinessException 的异常处理器才会轮到它的 父亲 ，
 * 父亲 没有才会到 祖父 。总之一句话， 精准匹配，找那个关系最近的
 * </p>
 */
@Slf4j
@RestControllerAdvice
public class GlobalExceptionHandler {

    /**
     * @param businessException 业务异常
     * @return @ResponseBody
     * @ExceptionHandler相当于controller的@RequestMapping 如果抛出的的是BusinessException，则调用该方法
     */
    @ExceptionHandler(BusinessException.class)
    public R handle(BusinessException businessException) {
        // 获取指定包名前缀的异常信息，减少不必要的日志
        String stackTraceByPn = getStackTraceByPn(businessException, AdminConstant.basePackage);
        log.error("记录业务异常信息: 消息{} 编码{} {}", businessException.getMessage(), businessException.getCode(), stackTraceByPn);
        return R.fail(businessException.getCode(), businessException.getMessage());
    }

    /**
    * 日志信息： 业务异常在全局处理的时候只记录了 指定头开始的日志，减少了堆栈信息
    */
    private String getStackTraceByPn(Throwable e, String packagePrefix) {
        StringBuilder append = new StringBuilder("\n").append(e);
        for (StackTraceElement stackTraceElement : e.getStackTrace()) {
            if (stackTraceElement.getClassName().startsWith(packagePrefix)) {
                append.append("\n\tat ").append(stackTraceElement);
            }
        }
        return append.toString();
    }


    /**
     * 捕获空指针异常
     **/
    @ExceptionHandler(value = NullPointerException.class)
    public R handlerBindException(NullPointerException exception) {
        String message = exception.getMessage();
        log.error("全局捕获null错误信息: {}", exception.toString(), exception);
        return R.fail(message);
    }

    /**
     * 捕获最大异常
     **/
    @ExceptionHandler(value = Exception.class)
    public R handlerBindException(Exception exception) {
        String message = exception.getMessage();
        log.error("全局捕获错误信息: {}", exception.toString(), exception);
        return R.fail(message);
    }
}

测试统一异常

package cn.mesmile.admin.modules.system.controller;

import cn.mesmile.admin.common.exceptions.BusinessException;
import cn.mesmile.admin.common.result.R;
import cn.mesmile.admin.common.result.ResultCode;
import lombok.extern.slf4j.Slf4j;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

/**
 * @author zb
 * @Description
 */
@Slf4j
@RequestMapping("/api/v1/hello")
@RestController
public class HelloController {

    @GetMapping("/get")
    public R hello () {
        if (true){
            throw new BusinessException(ResultCode.FAILURE, "hello业务发送异常了");
        }
        return R.data("hello world");
    }

}

启动 cn.mesmile.admin.AdminApplication 启动类，访问 localhost:8080/api/v1/hello/get

看到统一返回结果如下：

{
  "code": 400,
  "success": false,
  "data": null,
  "msg": "hello业务发送异常了"
}

日志信息： 业务异常在全局处理的时候只记录了 指定头开始的日志，减少了堆栈信息

2022-07-09 16:15:42.050  INFO 13512 --- [nio-8080-exec-1] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring DispatcherServlet 'dispatcherServlet'
2022-07-09 16:15:42.051  INFO 13512 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : Initializing Servlet 'dispatcherServlet'
2022-07-09 16:15:42.051  INFO 13512 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : Completed initialization in 0 ms
2022-07-09 16:15:42.074 ERROR 13512 --- [nio-8080-exec-1] c.m.a.c.handler.GlobalExceptionHandler   : 记录业务异常信息: 消息hello业务发送异常了 编码400 
cn.mesmile.admin.common.exceptions.BusinessException: hello业务发送异常了
  at cn.mesmile.admin.modules.system.controller.HelloController.hello(HelloController.java:23)