在你的代码中使用自定义异常类

时间:2022-03-29 00:45:48

  在代码中使用自定义的异常类,可以对异常进行统一的封装处理。使得整个项目的异常处理更规范、更统一、更优雅。同时,使得日志的记录上更加清晰,便于后续查日志定位问题。

  以下为自定义异常类的完整过程:

1、需要自定义一个类,继承自系统的异常类。具体需要什么样类型的异常类,就继承自相应的系统类。

  • 如果希望写一个检查性异常类,则需要继承 Exception 类。

如果你想写一个运行时异常类,那么需要继承 RuntimeException 类。

public class InvalidReqException extends Exception {

    private final String userErrMsg;
    private final ErrorCode errorCode;

    public InvalidReqException(ErrorCode errorCode, String sysErrMsg, String userErrMsg) {
        super(sysErrMsg);
        this.userErrMsg = userErrMsg;
        this.errorCode = errorCode;
    }

    public InvalidReqException(ErrorCode errorCode, String sysErrMsg, String userErrMsg, Throwable cause) {
        super(sysErrMsg, cause);
        this.userErrMsg = userErrMsg;
        this.errorCode = errorCode;
    }

    public InvalidReqException(ErrorCode errorCode, String sysErrMsg) {
        super(sysErrMsg);
        this.userErrMsg = null;
        this.errorCode = errorCode;
    }

    public ErrorCode getErrorCode() {
        return errorCode;
    }

    public String getUserErrMsg() {
        return userErrMsg;
    }

    public String getSysErrMsg() {
        return getMessage();
    }

}

 

2、在需要抛出该异常的类或方法中,定义当出现异常时抛出自定义的异常。

static void checkTemplateValid(String content) throws InvalidReqException {
        if (content.length() > 100 * 1024) {
            throw new InvalidReqException(ErrorCode.TEMPLATE_INVALID, "template is too large, over 100KB",
                    "模板HTML原文不得超过100KB");
        }
}  

3、在使用到该类或方法的地方捕捉该异常(或继续抛出,交给上级去处理),并对异常进行业务相关的响应与处理。

public void onMessage(Message message) {
        String tenantId = (String) message.getMessageProperties().getHeaders().get(MQRouting.HEADER_TENANT_ID);
        String requestId = (String) message.getMessageProperties().getHeaders().get(MQRouting.HEADER_REQ_ID);
        String body = null;
        CertApplyMsg msg;
        try {
            body = new String(message.getBody(), "utf8");
            log.debug("received cert apply message: {}", body);
            msg = JsonUtil.parse(body, CertApplyMsg.class);
        } catch (IOException e) { // impossible to happen
            log.error("message failed due to invalid format:" + body, e);
            failMsg(MQRouting.EXCH_CERT, MQRouting.RK_CERT_APPLY_FAILED, message, e);
            return;
        }

        LegalEntityCertBo entity = msg.getLegalEntityCert();
        try {
            if (entity.getCert().getStatus() != CertStatus.APPLYING) {
                reconcileConcurrentUpdate(tenantId, requestId, msg); // due to retry
                return;
            }
            LegalEntityCertBo created = certService.applyCert(entity.getOrganization(),
                    entity.getCert().getCa(), entity.getLegalEntity());
            if (!certService.updateCert(created, entity.getCert().getStatus())) { // due to data race
                reconcileConcurrentUpdate(tenantId, requestId, msg);
            } else {
                enqueueCallback(tenantId, requestId, msg, created, null, null);
                log.info("successfully processed cert application:" + body);
            }
        } catch (InvalidReqException e) {
            log.error("applying cert rejected. body=" + body + ", message=" + message, e);
            enqueueCallback(tenantId, requestId, msg, entity, e.getErrorCode(), e.getSysErrMsg());
            rejectMsg(MQRouting.EXCH_CERT, MQRouting.RK_CERT_APPLY_REJECTED, message, e);
        } catch (RuntimeException e) {
            log.error("cert application failed, probably will retry, body=" + body + ", msg=" + e.getMessage(), e);
            throw e;
        }
    }