public class BusinessException extends RuntimeException {
    private Integer code;
    public BusinessException(Integer code, String message) {
        super(message);
        this.code = code;
    }
    public Integer getCode() {
        return code;
    }
    public void setCode(Integer code) {
        this.code = code;
    }
}

public class SystemException extends RuntimeException {
    private Integer code;
    public SystemException(Integer code, String message, Throwable cause) {
        super(message, cause);
        this.code = code;
    }
    public Integer getCode() {
        return code;
    }
    public void setCode(Integer code) {
        this.code = code;
    }
}

public class Code {
    public static final Integer SYSTEM_ERR = 50001;
    public static final Integer SYSTEM_TIMEOUT_ERR = 50002;
    public static final Integer SYSTEM_UNKNOWN_ERR = 59999;
    public static final Integer BUSINESS_ERR = 60001;
}

@RestControllerAdvice
public class ProjectExceptionAdvice {
    // 攔截處理業(yè)務(wù)異常
    @ExceptionHandler(BusinessException.class)
    public Result doBusinessException(BusinessException ex) {
        return new Result(ex.getCode(), null, ex.getMessage());
    }
    // 攔截處理系統(tǒng)異常
    @ExceptionHandler(SystemException.class)
    public Result doSystemException(SystemException ex) {
        // 記錄日志，發(fā)送消息給運(yùn)維人員，發(fā)送郵件給開發(fā)人員
        return new Result(ex.getCode(), null, ex.getMessage());
    }
    //攔截處理其他異常
    @ExceptionHandler(Exception.class)
    public Result doException(Exception ex) {
        // 記錄日志，發(fā)送消息給運(yùn)維人員，發(fā)送郵件給開發(fā)人員
        return new Result(Code.SYSTEM_UNKNOWN_ERR, null, "系統(tǒng)繁忙，請(qǐng)聯(lián)系管理員。");
    }
}

@Service
public class BookServiceImpl implements BookService {
    @Autowired
    private BookDao bookDao;
    @Override
    public Book getById(Integer id) {
        // id 小于等于零時(shí)拋出業(yè)務(wù)異常
        if (id <= 0) {
            throw new BusinessException(Code.BUSINESS_ERR, "參數(shù)不合法，請(qǐng)檢查傳入?yún)?shù)！");
        }
        // 將可能出現(xiàn)的異常進(jìn)行包裝，裝換成自定義異常
        try {
            int x = 1 / 0;  // 加入此行出現(xiàn)異常
            return bookDao.getById(id); // 模擬數(shù)據(jù)庫(kù)訪問(wèn)出錯(cuò)
        } catch (Exception e) {
            throw new SystemException(Code.SYSTEM_TIMEOUT_ERR, "數(shù)據(jù)庫(kù)訪問(wèn)異常，請(qǐng)稍后重試！", e);
        }
    }
}