在Dao层我们只完成了针对表的相关操作，包括写了接口方法和映射文件中的sql语句，并没有编写逻辑的代码，例如对多个Dao层方法的拼接，当我们用户成功秒杀商品时我们需要进行商品的减库存操作(调用SeckillDao接口)和增加用户明细(调用SuccessKilledDao接口)，这些逻辑我们都需要在Service层完成。Dao层只进行数据的访问操作，接下来我们便进行Service层代码的编写。秒杀Service接口设计如下：
（1）创建service包用于存放我们的Service接口和其实现类。
（2）创建exception包用于存放service层出现的异常，例如重复秒杀商品异常、秒杀已关闭等异常。
（3）创建dto包作为传输层, 用于完成web和service层的数据传递。
（4）创建entity包用于业务数据的封装。
service包需要的相关类名和函数名如表6-10所示。
SeckillService.java:
public interface SeckillService {
List<Seckill> getSeckillList();
Seckill getById(long seckillId);
Exposer exportSeckillUrl(long seckillId);
SeckillExecution executeSeckill(long seckillId, long userPhone, String md5)
throws SeckillException,RepeatKillException,SeckillCloseException;
SeckillExecution executeSeckillProcedure(long seckillId, long userPhone, String md5);
}
SeckillServiceImpl.java：
public class SeckillServiceImpl implements SeckillService {
private Logger logger = LoggerFactory.getLogger(this.getClass());
@Autowired
private SeckillDao seckillDao;
@Autowired
private SuccessKilledDao successKilledDao;
@Autowired
private RedisDao redisDao;
private final String salt = "sadkfjalsdjfalksj23423^&*^&%&!EBJKH#e™£4";
@Override
public List<Seckill> getSeckillList() {
return seckillDao.queryAll(0, 4);
}
@Override
public Seckill getById(long seckillId) {
return seckillDao.queryById(seckillId);
}
@Override
public Exposer exportSeckillUrl(long seckillId) {
Seckill seckill = redisDao.getSeckill(seckillId);
if (seckill == null) {
seckill = seckillDao.queryById(seckillId);
if (seckill == null) {
return new Exposer(false, seckillId);
} else {
redisDao.putSeckill(seckill);
}
}
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());
}
String md5 = getMD5(seckillId);
return new Exposer(true, md5, seckillId);
}
private String getMD5(long seckillId) {
String base = seckillId + "/" + salt;
String md5 = DigestUtils.md5DigestAsHex(base.getBytes());
return md5;
}
@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");
}
Date nowTime = new Date();
try {
int insertCount = successKilledDao.insertSuccessKilled(seckillId, userPhone);
if (insertCount <= 0) {
throw new RepeatKillException("seckill repeated");
} else {
int updateCount = seckillDao.reduceNumber(seckillId, nowTime);
if (updateCount <= 0) {
throw new SeckillCloseException("seckill is closed");
} else {
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);
throw new SeckillException("seckill inner error:" + e.getMessage());
}
}
@Override
public SeckillExecution executeSeckillProcedure(long seckillId, long userPhone, String md5) {
if (md5 == null || !md5.equals(getMD5(seckillId))) {
return new SeckillExecution(seckillId, SeckillStatEnum.DATA_REWRITE);
}
Date killTime = new Date();
Map<String, Object> map = new HashMap<String, Object>();
map.put("seckillId", seckillId);
map.put("phone", userPhone);
map.put("killTime", killTime);
map.put("result", null);
try {
seckillDao.killByProcedure(map);
int result = MapUtils.getInteger(map, "result", -2);
if (result == 1) {
SuccessKilled sk = successKilledDao.
queryByIdWithSeckill(seckillId, userPhone);
return new SeckillExecution(seckillId, SeckillStatEnum.SUCCESS, sk);
} else {
return new SeckillExecution(seckillId, SeckillStatEnum.stateOf(result));
}
} catch (Exception e) {
logger.error(e.getMessage(), e);
return new SeckillExecution(seckillId, SeckillStatEnum.INNER_ERROR);
}
}
}
在dto包中创建Exposer.java，用于封装秒杀的地址信息。SeckillExecution.java，用于判断秒杀是否成功，成功就返回秒杀成功的所有信息(包括秒杀的商品id、秒杀成功状态、成功信息、用户明细)，失败就抛出一个我们允许的异常(重复秒杀异常、秒杀结束异常)。
Exposer.java：
public class Exposer {
private boolean exposed;
private String md5;
private long seckillId;
private long now;
private long start;
private long end;
@Override
public String toString() {
return "Exposer{" +
"exposed=" + exposed +
", md5='" + md5 + '\'' +
", seckillId=" + seckillId +
", now=" + now +
", start=" + start +
", end=" + end +
'}';
}
public Exposer(boolean exposed, String md5, long seckillId) {
this.exposed = exposed;
this.md5 = md5;
this.seckillId = seckillId;
}
public Exposer(boolean exposed, long seckillId, long now, long start, long end) {
this.exposed = exposed;
this.seckillId = seckillId;
this.now = now;
this.start = start;
this.end = end;
}
public Exposer(boolean exposed, long seckillId) {
this.exposed = exposed;
this.seckillId = seckillId;
}
public boolean isExposed() {
return exposed;
}
public void setExposed(boolean exposed) {
this.exposed = exposed;
}
public String getMd5() {
return md5;
}
public void setMd5(String md5) {
this.md5 = md5;
}
public long getSeckillId() {
return seckillId;
}
public void setSeckillId(long seckillId) {
this.seckillId = seckillId;
}
public long getNow() {
return now;
}
public void setNow(long now) {
this.now = now;
}
public long getStart() {
return start;
}
public void setStart(long start) {
this.start = start;
}
public long getEnd() {
return end;
}
public void setEnd(long end) {
this.end = end;
}
}
SeckillExecution.java：
public class SeckillExecution {
private long seckillId;
private int state;
private String stateInfo;
private SuccessKilled successKilled;
@Override
public String toString() {
return "SeckillExecution{" +
"seckillId=" + seckillId +
", state=" + state +
", stateInfo='" + stateInfo + '\'' +
", successKilled=" + successKilled +
'}';
}
public SeckillExecution(long seckillId, SeckillStatEnum statEnum, SuccessKilled successKilled) {
this.seckillId = seckillId;
this.state = statEnum.getState();
this.stateInfo = statEnum.getStateInfo();
this.successKilled = successKilled;
}
public SeckillExecution(long seckillId, SeckillStatEnum statEnum) {
this.seckillId = seckillId;
this.state = statEnum.getState();
this.stateInfo = statEnum.getStateInfo();
}
public long getSeckillId() {
return seckillId;
}
public void setSeckillId(long seckillId) {
this.seckillId = seckillId;
}
public int getState() {
return state;
}
public void setState(int state) {
this.state = state;
}
public String getStateInfo() {
return stateInfo;
}
public void setStateInfo(String stateInfo) {
this.stateInfo = stateInfo;
}
public SuccessKilled getSuccessKilled() {
return successKilled;
}
public void setSuccessKilled(SuccessKilled successKilled) {
this.successKilled = successKilled;
}
}
然后需要在exception包下创建我们在秒杀业务过程中允许的异常，RepeatKillException.java用于处理重复的秒杀异常；SeckillCloseException.java用于处理秒杀关闭异常；SeckillException.java用于处理秒杀相关业务的异常。
RepeatKillException.java:
public class RepeatKillException extends SeckillException {
public RepeatKillException(String message) {
super(message);
}
public RepeatKillException(String message, Throwable cause) {
super(message, cause);
}
}
SeckillCloseException.java:
public class SeckillCloseException extends SeckillException {
public SeckillCloseException(String message) {
super(message);
}
public SeckillCloseException(String message, Throwable cause) {
super(message, cause);
}
}
SeckillException.java:
public class SeckillException extends RuntimeException {
public SeckillException(String message) {
super(message);
}
public SeckillException(String message, Throwable cause) {
super(message, cause);
}
}
在实现类SeckillServiceImpl.java中，我们用枚举的方式将异常函数中返回的常量进行封装，在enums包下创建一个枚举类型SeckillStatEnum.java，用于返回state和stateInfo这两个参数的相关数据。
SeckillStatEnum.java：
public enum SeckillStatEnum {
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;
SeckillStatEnum(int state, String stateInfo) {
this.state = state;
this.stateInfo = stateInfo;
}
public int getState() {
return state;
}
public String getStateInfo() {
return stateInfo;
}
public static SeckillStatEnum stateOf(int index) {
for (SeckillStatEnum state : values()) {
if (state.getState() == index) {
return state;
}
}
return null;
}
}
使用Spring托管Service依赖配置：
在spring包下创建一个spring-service.xml文件，然后采用注解的方式将Service的实现类加入到Spring IOC容器中，然后在Service实现类的方法中，在需要进行事务声明的方法上加上事务的注解，配置如下。
spring-service.xml：
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:tx="http://www.springframework.org/schema/tx"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context.xsd
http://www.springframework.org/schema/tx
http://www.springframework.org/schema/tx/spring-tx.xsd">
<context:component-scan base-package="org.seckill.service"/>
<bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
<property name="dataSource" ref="dataSource"/>
</bean>
<tx:annotation-driven transaction-manager="transactionManager"/>
</beans>
