妙用CommonException

在开发wawaji项目时，我们有个校验用户身份的逻辑。如果校验成功，返回用户信息；如果用户不存在，返回4001008；如果token失效，返回4001010；如果token不正确，返回4001011。

由于多处逻辑需要校验用户身份，所有我们希望在校验过程中，如果校验失败，直接返回失败结果，程序不再继续执行。

1.编写检验失败返回错误代码及错误提示枚举类：

public enum EnumSystemCode {

    SUCC(, "SUCC"),

    ERROR_USER_NOT_EXIST(, "用户不存在"),

    ERROR_TOKEN_TIMEOUT(, "token失效"),

    ERROR_TOKEN(, "token不正确"),   

    COMMON(, "错误");

    @Getter
    private final int code;
    @Getter
    private final String conent;

    EnumSystemCode(int code, String content) {
        this.code = code;
        this.conent = content;
    }

    public static EnumSystemCode findByCode(int code) {
        for (EnumSystemCode sCode : EnumSystemCode.values()) {
            if (sCode.getCode() == code) {
                return sCode;
            }
        }
        return null;
    }

}
           

2：编写检验失败抛出的CommonException类：

public class CommonException extends RuntimeException {
    private static final long serialVersionUID = L;

    @Getter
    private int code;
    @Getter
    private EnumSystemCode systemCode;

    public CommonException(int code, String msg) {
        super(msg);
        this.code = code;
        this.systemCode = EnumSystemCode.findByCode(code);
    }

    public CommonException(EnumSystemCode systemCode) {
        super(systemCode.getConent());
        this.code = systemCode.getCode();
        this.systemCode = systemCode;
    }

    public CommonException(EnumSystemCode systemCode, String msg) {
        super(msg);
        this.code = systemCode.getCode();
        this.systemCode = systemCode;
    }

    public CommonException(String msg) {
        this(EnumSystemCode.COMMON.getCode(), msg);
    }

    public static CommonException getInstance(String msg, Object... args) {
        for (Object object : args) {
            msg = msg.replaceFirst("\\{\\}", object.toString());
        }
        return new CommonException(msg);
    }

    public static CommonException getInstance(String msg) {
        return new CommonException(msg);
    }

}
           

3.业务判断时，根据不同情况提示错误信息：

if (code == EnumSystemCode.SUCC.getCode()) {
    //校验成功
} else if (code == EnumSystemCode.ERROR_USER_NOT_EXIST.getCode()) {
    logger.info("用户不存在 , userId:{}", userId);
    throw new CommonException(code, EnumSystemCode.ERROR_USER_NOT_EXIST.getConent());
} else if (code == EnumSystemCode.ERROR_TOKEN_TIMEOUT.getCode()) {
    logger.info("token失效 , userId:{}, token:{}", userId, token);
    throw new CommonException(code, EnumSystemCode.ERROR_TOKEN_TIMEOUT.getConent());
} else if (code == EnumSystemCode.ERROR_TOKEN.getCode()) {
    logger.info("token不正确 , userId:{}, token:{}", userId, token);
    throw new CommonException(code, EnumSystemCode.ERROR_TOKEN.getConent());
}
           

4.抛出异常后，异常拦截器拦截：

@ControllerAdvice("com.***.web.resource")
public class ResponseAdvice implements ResponseBodyAdvice<Object> {

    @Override
    public boolean supports(MethodParameter methodParameter, Class<? extends HttpMessageConverter<?>> aClass) {
        return true;
    }

    @Override
    public Object beforeBodyWrite(Object o, MethodParameter methodParameter, MediaType mediaType,
            Class<? extends HttpMessageConverter<?>> aClass, ServerHttpRequest serverHttpRequest,
            ServerHttpResponse serverHttpResponse) {
        ServletServerHttpResponse response = (ServletServerHttpResponse) serverHttpResponse;    

        return ApiResponse.builder().status(response.getServletResponse().getStatus()).msg("OK").data(o).build();
    }

    @ExceptionHandler(CommonException.class)
    @ResponseBody
    public ApiResponse<?> handleControllerException(HttpServletRequest request, CommonException e) {
        return ApiResponse.builder().status(e.getCode()).msg(e.getMessage()).build();
    }

    @ExceptionHandler(Exception.class)
    @ResponseBody
    public ApiResponse<?> handleControllerException(HttpServletRequest request, Throwable e) {
        HttpStatus status = getStatus(request);
        return ApiResponse.builder().status(status.value()).msg(e.getMessage()).build();
    }

    private HttpStatus getStatus(HttpServletRequest request) {
        Integer statusCode = (Integer) request.getAttribute("javax.servlet.error.status_code");
        if (statusCode == null) {
            return HttpStatus.INTERNAL_SERVER_ERROR;
        }
        return HttpStatus.valueOf(statusCode);
    }
}
           

通过上述配置，我们便实现了一旦校验失败，程序中止执行，立刻返回错误代码的效果。