[DAO编写之后的总结]
DAO层 --> 接口设计 + SQL编写
DAO拼接等逻辑 --> 统一在Service层完成
[Service层的接口设计]
1.接口设计原则：站在'使用者'的角度设计接口
2.方法定义粒度：从'使用者'的行为角度来思考-- 减库存+插入购买明细 --> 执行秒杀
3.参数：越简练越直接
4.返回类型：return 类型/Exception 返回类型要友好，使用DTO
package org.azcode.service; import org.azcode.dto.Exposer;
import org.azcode.dto.SeckillExecution;
import org.azcode.entity.Seckill;
import org.azcode.exception.RepeatKillException;
import org.azcode.exception.SeckillCloseException;
import org.azcode.exception.SeckillException; import java.util.List; /**
* Created by azcod on 2017/4/15.
*/
public interface SeckillService { /**
* 查询所有的秒杀记录
* @return
*/
List<Seckill> getSeckillList(); /**
* 根据id查询单个秒杀记录
* @param seckillId
* @return
*/
Seckill getById(long seckillId); /**
* 秒杀开启时输出秒杀接口地址，
* 否则输出系统时间和秒杀时间
* @param seckillId
* @return Exposer
*/
Exposer exportSeckillUrl(long seckillId); /**
* 执行秒杀操作
* @param seckillId
* @param userPhone
* @param md5
* @return SeckillExecution
*/
SeckillExecution executeSeckill(long seckillId, long userPhone, String md5)
throws SeckillException,RepeatKillException,SeckillCloseException;
}
[Service接口实现编码]
1.防止数据篡改的措施，使用MD5给数据加密
2.具体业务逻辑的编码，对异常的处理
3.异常的多重catch，将编译期异常转换为运行期异常
4.使用枚举表述常量数据字典
package org.azcode.service.impl; import org.azcode.dao.SeckillDao;
import org.azcode.dao.SuccessKilledDao;
import org.azcode.dto.Exposer;
import org.azcode.dto.SeckillExecution;
import org.azcode.entity.Seckill;
import org.azcode.entity.SuccessKilled;
import org.azcode.enums.SeckillStateEnum;
import org.azcode.exception.RepeatKillException;
import org.azcode.exception.SeckillCloseException;
import org.azcode.exception.SeckillException;
import org.azcode.service.SeckillService;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.util.DigestUtils; import java.util.Date;
import java.util.List; /**
* Created by azcod on 2017/4/15.
*/
public class SeckillServiceImpl implements SeckillService { private Logger logger = LoggerFactory.getLogger(this.getClass()); private SeckillDao seckillDao; private SuccessKilledDao successKilledDao; //MD5盐值字符串,用于混淆MD5
private final String slat = "r#^*T*(&F)HHU!&@T#456465"; public List<Seckill> getSeckillList() {
return seckillDao.queryAll(0, 4);
} public Seckill getById(long seckillId) {
return seckillDao.queryById(seckillId);
} public Exposer exportSeckillUrl(long seckillId) {
Seckill seckill = seckillDao.queryById(seckillId);
//step1:判断秒杀产品是否存在
if (seckill == null) {
return new Exposer(false, seckillId);
}
//step2:判断秒杀是否开启
Date startTime = seckill.getStartTime();
Date endTime = seckill.getEndTime();
Date nowTime = new Date();
if (nowTime.getTime() < startTime.getTime()
|| nowTime.getTime() > endTime.getTime()) {
return new Exposer(false, seckillId,
nowTime.getTime(), startTime.getTime(), endTime.getTime());
}
//MD5：一种转换特定字符串的过程,不可逆
String md5 = getMD5(seckillId);
return new Exposer(true, md5, seckillId);
} public SeckillExecution executeSeckill(long seckillId, long userPhone, String md5)
throws SeckillException, RepeatKillException, SeckillCloseException {
//step1：校验是否篡改秒杀数据
if (md5 == null || !md5.equals(getMD5(seckillId))) {
throw new SeckillException("seckill data rewrite");
}
//step2：秒杀逻辑-减库存+插入购买明细
Date nowTime = new Date();
// 异常捕获的IDEA快捷键：包选代码块后->ctrl+alt+t
try {
//减库存
int updateCount = seckillDao.reduceNumber(seckillId, nowTime);
if (updateCount <= 0) {
//秒杀结束
throw new SeckillCloseException("seckill is closed");
} else {
//插入购买明细
int insertCount = successKilledDao.insertSuccessKilled(seckillId, userPhone);
if (insertCount <= 0) {
//重复秒杀
throw new RepeatKillException("seckill repeated");
} else {
//秒杀成功
SuccessKilled successKilled = successKilledDao.queryByIdWithSeckill(seckillId, userPhone);
return new SeckillExecution(seckillId, SeckillStateEnum.SUCCESS, successKilled);
}
}
} catch (SeckillCloseException e1) {
throw e1;
} catch (RepeatKillException e2) {
throw e2;
} catch (Exception e) {
logger.error(e.getMessage(), e);
//所有编译期异常转换为运行期异常,Spring声明式事务只支持运行期异常的回滚
//转换的目的是为了出现编译期异常时,rollback回滚
throw new SeckillException("seckill inner error" + e.getMessage());
}
} /**
* 生成MD5的通用方法
*
* @param seckillId
* @return
*/
private String getMD5(long seckillId) {
String base = seckillId + slat;
String md5 = DigestUtils.md5DigestAsHex(base.getBytes());
return md5;
}
}
package org.azcode.enums; /**
* 使用枚举表述常量数据字典
* Created by azcod on 2017/4/15.
*/
public enum SeckillStateEnum {
SUCCESS(1, "秒杀成功"),
END(0, "秒杀结束"),
REPEAT_KILL(-1, "重复秒杀"),
INNER_ERROR(-2, "系统异常"),
DATA_REWRITE(-3, "数据篡改"); private int state; private String stateInfo; SeckillStateEnum(int state, String stateInfo) {
this.state = state;
this.stateInfo = stateInfo;
} public int getState() {
return state;
} public String getStateInfo() {
return stateInfo;
} public static SeckillStateEnum stateOf(int index) {
for (SeckillStateEnum stateEnum : values()) {
if (stateEnum.getState() == index) {
return stateEnum;
}
}
return null;
}
}