Java在MVC开发模式中使用try-catch以及throws避免踩坑

场景

1.throws是在方法上抛出异常，throw是在语句上抛出异常。

2.try-catch是在catch里处理try捕获异常并处理。

3.一般try-catch是在上层Controller中使用，而在Service以及dao层的接口上用throws向上级抛出异常。

避免踩坑：

在Controller中添加了try-catch，没有在sevice以及dao层添加throws，导致在dao层调用mapper文件中

某方法时在if标签中有错误时：

<if test="wmsReceiveOrder != null and wmsReceiveOrder.purchaseCode!=null and wmsReceiveOrder.purchaseCode!=''" >and ro.purchase_code=#{wmsReceiveOrder.purchaseCode} </if>

不会输出异常信息。

实现

1.在Controller层添加try-catch

try {
           
            IPage<WmsReceiveOrderVO> page = receiveOrderService.pageTray(pageEntity, vo);
            Log.getInst(this).debug("doPageForRoleTable test:" + vo.getColumns().get(0).getSearch());
            return dataTablesResultJsonVO;
        } catch (Exception ex) {
            Log.getInst().debug("获取收货单数据接口:",ex);
            Log.getInst(this).debug("doPageForRoleTable test:" + vo.getColumns().get(0).getSearch());
            return dataTablesResultJsonVO;
        }

2.调用service层时，需要在service的接口上添加throws

public interface IWmsReceiveOrderService extends IService<WmsReceiveOrder> {

    IPage<WmsReceiveOrderVO> pageTray(Page<WmsReceiveOrderVO> page, DataTablesJsonVO vo)  throws Exception;
}

3.同样在dao层接口上也要添加throws

public interface IWmsReceiveOrderService extends IService<WmsReceiveOrder> {

    IPage<WmsReceiveOrderVO> pageTray(Page<WmsReceiveOrderVO> page, DataTablesJsonVO vo)  throws Exception;
}

4.其中Controller中分Log是在slf4j基础上封装的打印日志的工具类。

package com.ws.kernel.log;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.HashMap;
import java.util.Map;

public class Log {
    private static String logPrefix = " log -> ";
    private static Log instance;
    private static Logger logger = null;
    private static Map<Class, Logger> loggerList = new HashMap<Class, Logger>(); //用于缓存logger对象

    /**
     * 定义私有构造方法实现单例
     */
    private Log() {
    }

    /**
     * 功能说明：获取服务实例的静态方法
     * 修改说明：
     * @author badao
     * @date
     * @param obj 传入调用此方法的对象
     * @return
     */
    public synchronized static Log getInst(Object obj) {
        if (instance == null) {
            instance = new Log();
        }
        Log.logger = loggerList.get(obj.getClass());
        if (Log.logger == null) {
            Log.logger = LoggerFactory.getLogger(obj.getClass());
            //Log.logger = Logger.getLogger(obj.getClass());
            loggerList.put(obj.getClass(), Log.logger);
        }
        return instance;
    }

    /**
     * 功能说明：获取服务实例的静态方法
     * 修改说明：
     * @author baadao
     * @date
     * @param clazz 传入调用此方法的类型
     * @return
     */
    public synchronized static Log getInst(Class clazz) {
        if (instance == null) {
            instance = new Log();
        }
        Log.logger = loggerList.get(clazz);
        if (Log.logger == null) {
            Log.logger = LoggerFactory.getLogger(clazz);
            loggerList.put(clazz, Log.logger);
        }
        return instance;
    }

    /**
     * 功能说明：获取服务实例的静态方法
     * 修改说明：
     * @author badao
     * @date
     * @return
     */
    public synchronized static Log getInst() {
        if (instance == null) {
            instance = new Log();
        }
        Log.logger = loggerList.get(Log.class);
        if (Log.logger == null) {
            Log.logger = LoggerFactory.getLogger(Log.class);
            loggerList.put(Log.class, Log.logger);
        }
        return instance;
    }

    public void trace(String message) {
        Log.logger.trace(logPrefix + message);
    }

    public void trace(String message, Throwable t) {
        Log.logger.trace(logPrefix + message, t);
    }

    public void debug(String message) {
        Log.logger.debug(logPrefix + message);
    }

    public void debug(String message, Throwable t) {
        Log.logger.debug(logPrefix + message, t);
    }

    public void info(String message) {
        Log.logger.info(logPrefix + message);
    }

    public void info(String message, Throwable t) {
        Log.logger.info(logPrefix + message, t);
    }

    public void warn(String message) {
        Log.logger.warn(logPrefix + message);
    }

    public void warn(String message, Throwable t) {
        Log.logger.warn(logPrefix + message, t);
    }

    public void error(String message,Object... arguments) {
        Log.logger.error(logPrefix + message,arguments);
    }

    public void error(String message, Throwable t, Object... arguments) {
        Log.logger.error(logPrefix + message,t,arguments);
    }
}