在Dao層我們只完成了針對表的相關操作，包括寫了接口方法和映射文件中的sql語句，並沒有編寫邏輯的代碼，例如對多個Dao層方法的拼接，當我們用戶成功秒殺商品時我們需要進行商品的減庫存操作(調用SeckillDao接口)和增加用戶明細(調用SuccessKilledDao接口)，這些邏輯我們都需要在Service層完成。Dao層只進行數據的訪問操作，接下來我們便進行Service層代碼的編寫。秒殺Service接口設計如下：
（1）創建service包用於存放我們的Service接口和其實現類。
（2）創建exception包用於存放service層出現的異常，例如重復秒殺商品異常、秒殺已關閉等異常。
（
 
3）創建dto包作為傳輸層, 用於完成web和service層的數據傳遞。
（4）創建entity包用於業務數據的封裝。
service包需要的相關類名和函數名如表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包中創建Exposer.java，用於封裝秒殺的地址信息。SeckillExecution.java，用於判斷秒殺是否成功，成功就返回秒殺成功的所有信息(包括秒殺的商品id、秒殺成功狀態、成功信息、用戶明細)，失敗就拋出一個我們允許的異常(重復秒殺異常、秒殺結束異常)。
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;
    }
}
然後需要在exception包下創建我們在秒殺業務過程中允許的異常，RepeatKillException.java用於處理重復的秒殺異常；SeckillCloseException.java用於處理秒殺關閉異常；SeckillException.java用於處理秒殺相關業務的異常。
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);
    }
}
在實現類SeckillServiceImpl.java中，我們用枚舉的方式將異常函數中返回的常量進行封裝，在enums包下創建一個枚舉類型SeckillStatEnum.java，用於返回state和stateInfo這兩個參數的相關數據。
SeckillStatEnum.java：
public enum SeckillStatEnum {
    SUCCESS(1,"秒殺成功"),
    END(0,"秒殺結束"),
    REPEAT_KILL(-1,"重復秒殺"),
    INNER_ERROR(-2,"系統異常"),
    DATA_REWRITE(-3,"數據篡改");
    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依賴配置：
在spring包下創建一個spring-service.xml文件，然後采用註解的方式將Service的實現類加入到Spring IOC容器中，然後在Service實現類的方法中，在需要進行事務聲明的方法上加上事務的註解，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>

秒殺系統-service