java项目中自定义业务异常

在java  Web开发过程中会遇到各种的业务异常，如扣款余额不足，重复提交，重复秒杀等，我们在后台java代码中最好的方式是将这种通过异常的方式来捕获，然后逐级上抛，最终在页面上给出提示，在网上看到的一些代码贴出来供大家学习

1.定义异常类

package org.seckill.exception;

/**
 * Created by zhangfx on 2017/7/7.
 */
public class SeckillException extends RuntimeException {
    public SeckillException(String message) {
        super(message);
    }

    public SeckillException(String message, Throwable cause) {
        super(message, cause);
    }
}

2.在接口的实现类中跑出异常

 @Override
    @Transactional
    public SeckillExecution executeSeckill(long seckillId, long userPhone, String md5) throws SeckillException, RepeatKillException, SeckillCloseException {
       if(md5==null||!md5.equals(getMD5(seckillId))){
           throw new SeckillException("seckill data rewrite");
       }
        //执行秒杀逻辑
        Date nowTime = new Date();
        try{
            //记录购买行为
            int insertCount = successKilledDao.insertSuccessKilled(seckillId,userPhone);
            if(insertCount<=0){
                throw  new RepeatKillException("seckill repeated");
            }else{
                //减库存，热点商品竞争
                int updateCount = seckillDao.reduceNumber(seckillId,nowTime);
                if(updateCount<=0){
                    //没有更新到秒杀记录，秒杀结束，rollback
                    throw new SeckillCloseException("seckill data rewrite");
                }else{
                    //commit
                    SuccessKilled successKilled=successKilledDao.queryByIdWithSeckill(seckillId,userPhone);
                    return new SeckillExecution(seckillId, SeckillStatEnum.SUCCESS,successKilled);
                }
            }
        }catch (SeckillCloseException e1){
            throw e1;
        }catch (RepeatKillException e2){
            throw e2;
        }catch (Exception e){
            logger.error(e.getMessage(), e);
            //所有编译异常转化为运行期异常
            throw new SeckillException("seckill inner error:"+e.getMessage());
        }
    }

3.在controller中接到异常，转为相应的状态码，返回到前台

   @RequestMapping(value = "/{seckillId}/{md5}/execution",
            method = RequestMethod.POST,
            produces={"application/json;charset=UTF-8"})
    @ResponseBody
    public SeckillResult execute(@PathVariable("seckillId") Long seckillId,
                                                   @PathVariable("md5")String md5,
                                                   @CookieValue(value="killPhone",required = false) Long phone){
        if(phone==null){
            return new SeckillResult(false,"未注册");
        }
        SeckillResult  result;
        try{
            //调用代码执行秒杀
            //SeckillExecution  execution= seckillService.executeSeckill(seckillId,phone,md5);
            //调用存储过程执行秒杀
            SeckillExecution  execution= seckillService.executeSeckillProcedure(seckillId,phone,md5);
            return new SeckillResult(true,execution);
        }catch (RepeatKillException e){
            SeckillExecution execution = new SeckillExecution(seckillId, SeckillStatEnum.REPEAT_KILL);
            return new SeckillResult(true,execution);
        }catch (SeckillCloseException e){
            SeckillExecution execution = new SeckillExecution(seckillId, SeckillStatEnum.END);
            return new SeckillResult(true,execution);
        }catch(Exception e){
            SeckillExecution execution = new SeckillExecution(seckillId, SeckillStatEnum.INNER_ERROR);
            return new SeckillResult(true,execution);
        }

    }

4.界面上接到相应的异常状态码，然后做出相应的提示

 handleSeckillkill : function(seckillId,node){
      //处理秒杀逻辑
        node.hide()
            .html("开始秒杀");
        $.post(seckill.URL.exposer(seckillId),{},function(result){
            //在回调函数中，执行交互
            if(result && result['success']){
                var exposer = result['data'];
                if(exposer['exposed']){
                    //开启秒杀
                    //获取秒杀地址
                    var md5 = exposer['md5'];
                    var killUrl = seckill.URL.execution(seckillId,md5);
                    console.log("killUrl:"+killUrl);
                    //绑定一次点击事件
                    $('#killBtn').one('click',function(){
                        //绑定秒杀请求
                        //1.先禁用按钮
                        $(this).addClass('disabled');
                        //2.发送秒杀请求
                        $.post(killUrl,{},function(result){
                            if(result && result['success']){
                                var killResult = result['data'];
                                var state = killResult['state'];
                                var stateInfo = killResult['stateinfo'];
                                //显示秒杀结果
                                node.html(''+stateInfo+'');
                            }
                        });
                    });
                    node.show();
                }else{
                    //未开启秒杀
                    var now = exposer['now'];
                    var start = exposer['start'];
                    var end = exposer['end'];
                    //重新计算逻辑
                    seckill.countdown(seckillId,now,start,end);
                }
            }else{
                console.log('result'+result);
            }

        });
    }