1.定义实体

1.1 错误码枚举类

@Getter
public enum ErrorEnum {
    // 数据操作错误定义
    SUCCESS(200, "成功"),
    NO_REQUEST(400,"请求无效"),
    NO_AUTH(401,"未授权：登录失败"),
    NO_PERMISSION(403,"你没得权限"),
    NOT_FOUND(404, "未找到该资源!"),
    INTERNAL_SERVER_ERROR(500, "服务器跑路了"),
    BUSINESS_ERROR(501, "客户端业务异常"),
    ;
    /** 错误码 */
    private Integer errorCode;
    /** 错误信息 */
    private String errorMsg;
    ErrorEnum(Integer errorCode, String errorMsg) {
        this.errorCode = errorCode;
        this.errorMsg = errorMsg;
    }

1.2 统一返回Json实体类

@Data
public class Result<T> {

    //是否成功
    private Boolean success;
    //状态码
    private Integer code;
    //提示信息
    private String msg;
    //数据
    private T data;
    public Result() {

    }
    
    public Result(Boolean success, Integer code, String msg, T data) {
        this.success = success;
        this.code = code;
        this.msg = msg;
        this.data = data;
    }
    /** 业务成功返回业务代码,描述和返回的参数 */
    public static <T> Result<T> success(T data) {
        return new Result<T>(true,ErrorEnum.SUCCESS.getErrorCode(),ErrorEnum.SUCCESS.getErrorMsg(),data);
    }

    //自定义异常返回的结果
    public static Result defineError(DefinitionException de){
        Result result = new Result();
        result.setSuccess(false);
        result.setCode(de.getErrorCode());
        result.setMsg(de.getErrorMsg());
        result.setData(null);
        return result;
    }
    //其他异常处理方法返回的结果
    public static Result otherError(ErrorEnum errorEnum){
        Result result = new Result();
        result.setMsg(errorEnum.getErrorMsg());
        result.setCode(errorEnum.getErrorCode());
        result.setSuccess(false);
        result.setData(null);
        return result;
    }

}

1.3 自定义异常实体类(提供两个构造方法)

@Data
public class DefinitionException extends RuntimeException {

    protected Integer errorCode;
    protected String errorMsg;

    /**
     * 自定义错误码和错误描述
     * @param errorCode
     * @param errorMsg
     */
    public DefinitionException(Integer errorCode, String errorMsg) {
        this.errorCode = errorCode;
        this.errorMsg = errorMsg;
    }

    /**
     *  只指定错误描述，不指定错误码
     * @param errorMsg
     */
    public DefinitionException(String errorMsg) {
        this.errorCode = errorCode;
        this.errorMsg = errorMsg;
    }

}

1.4 在提供一个可以业务使用的业务异常类

public class BusinessException extends DefinitionException {

    public BusinessException(Integer errorCode, String errorMsg) {
        super(errorCode, errorMsg);
    }

    public BusinessException(String errorMsg) {
        super(ErrorEnum.BUSINESS_ERROR.getErrorCode(),errorMsg);
    }

}

2.创建两个处理器

2.1 全局异常处理器

@RestControllerAdvice
public class GlobalExceptionHandler {

    /**
     * 处理自定义异常
     *
     */
    @ExceptionHandler(value = DefinitionException.class)
    @ResponseBody
    public Result bizExceptionHandler(DefinitionException e) {
        return Result.defineError(e);
    }

    /**
     * 处理其他异常
     *
     */
    @ExceptionHandler(value = Exception.class)
    @ResponseBody
    public Result exceptionHandler( Exception e) {
        return Result.otherError(ErrorEnum.INTERNAL_SERVER_ERROR);
    }

2.2 统一Json返回处理器

@RestControllerAdvice
public class ResponseResultBodyAdvice implements ResponseBodyAdvice {
    @Override
    public boolean supports(MethodParameter methodParameter, Class aClass) {
        return true;
    }

    @Override
    public Object beforeBodyWrite(Object body, MethodParameter methodParameter, MediaType mediaType, Class aClass, ServerHttpRequest serverHttpRequest, ServerHttpResponse serverHttpResponse) {
        if (body instanceof Result){
            return body;
        }
        return Result.success(body);
    }

3.打包成start,这样其他项目直接引入pom就可以使用了

3.1 创建一个配置类(将两个处理器交给spring管理)

@Configuration
public class StarterAutoConfigure {

    @Bean
    public GlobalExceptionHandler globalExceptionHandler(){
        return new GlobalExceptionHandler();
    }

    @Bean
    public ResponseResultBodyAdvice responseResultBodyAdvice(){
        return new ResponseResultBodyAdvice();
    }
}

3.2 需要在resources目录下新建一个META-INF的目录，并创建一个spring.factories配置文件，并写上下面的配置
注：第一行是固定的，第二行是配置类的地址

org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
com.example.springbootdemo02.StarterAutoConfigure

4.大功告成，我们在另外个项目引入试一下

4.1 测试一下正常返回

    @GetMapping("result")
    public User result(){
        User user = new User();
        user.setId(886);
        user.setName("张三");
        return user;
    }

  输出结果：
{
    "success": true,
    "code": 200,
    "msg": "成功",
    "data": {
        "id": 886,
        "name": "张三"
    }
}

4.2 再试一下系统发生异常的情况

@GetMapping("result")
   public User result(){
       User user = new User();
       user.setId(886);
       user.setName("张三");
       // 这里会报数学计算错误异常
       Integer a = 1/0;
       return user;
   }
输出结果：
{
   "success": false,
   "code": 500,
   "msg": "服务器跑路了",
   "data": null
}

4.3 试试业务异常的情况

@GetMapping("result")
    public User result(){
        User user = new User();
        user.setId(886);
        user.setName("张三");
        if (user.getId() > 100){
            throw new BusinessException("年龄大于100啦...");
        }
        return user;
    }
输出结果：
{
    "success": false,
    "code": 501,
    "msg": "年龄大于100啦...",
    "data": null
}