select lock_name from lock where lock_name = #{lockName} for update

@Select("select lock_name from lock where lock_name = #{lockName} for update")
List<String> queryLockNameForUpdate(@Param("lockName") String lockName);

public class MySqlDistributeLock {

    //加鎖的KEY，也就是我們提前存到表lock的值
    private String lockName;

    //手動(dòng)提交事務(wù)需要的事務(wù)管理器,由外部傳入
    private DataSourceTransactionManager dataSourceTransactionManager;

    //自定義編寫(xiě)的mybatis的mapper文件
    private MySqlLockMapper mySqlLockMapper;

    private TransactionStatus status;

    public MySqlDistributeLock(String lockName,DataSourceTransactionManager dataSourceTransactionManager,MySqlLockMapper mySqlLockMapper) {
        this.lockName = lockName;
        this.dataSourceTransactionManager = dataSourceTransactionManager;
        this.mySqlLockMapper = mySqlLockMapper;
    }


    
    public void lock() {
        TransactionDefinition transactionDefinition = new DefaultTransactionDefinition();
        status = dataSourceTransactionManager.getTransaction(transactionDefinition);
        while (true) {
            try{
                mySqlLockMapper.queryLockNameForUpdate(this.lockName);
                //如果加鎖成功，就退出該循環(huán)
                break;
            }catch (Exception e) {
                //說(shuō)明拋出異常了,讓線(xiàn)程重試
                try {
                    //讓線(xiàn)程休眠一會(huì)
                    Thread.sleep(100);
                } catch (InterruptedException ignored) { }
            }
        }
    }


    public void unLock() {
        //手動(dòng)提交事務(wù),也就是釋放鎖
        dataSourceTransactionManager.commit(this.status);
    }
}

@Service
public class LockService {


    @Resource
    private DataSourceTransactionManager dataSourceTransactionManager;

    @Resource
    private MySqlDistributeLock.MySqlLockMapper mySqlLockMapper;



    public String deductStockMysqlLock(String productId,Integer count) {
        MySqlDistributeLock lock = null;
        try{
            lock = new MySqlDistributeLock(productId,dataSourceTransactionManager,mySqlLockMapper);
            //加鎖
            lock.lock();

            //加鎖成功，開(kāi)始執(zhí)行我們自己的業(yè)務(wù)邏輯
        }finally {
            if(lock != null) {
                lock.unLock();
            }
        }
        return "success";
    }
}

//加鎖語(yǔ)句
@Insert("insert into record_lock (lock_name, uuid) values (#{lockName}, #{uuid})")
Integer insert(@Param("lockName") String lockName, @Param("uuid") String uuid);

//解鎖語(yǔ)句
@Delete("delete from record_lock where lock_name = #{lockName} and uuid = #{uuid}")
Integer delete(@Param("lockName") String lockName,  @Param("uuid") String uuid);

public class MySqlDistributeLock {


    private String lockName;

    //自定義編寫(xiě)的mybatis的mapper文件
    private MySqlLockMapper mySqlLockMapper;

    private String uuid;


    public MySqlDistributeLock(String lockName,MySqlLockMapper mySqlLockMapper,String uuid) {
        this.lockName = lockName;
        this.mySqlLockMapper = mySqlLockMapper;
        this.uuid = uuid;
    }


    
    public void lock() {
        while (true) {
              try{
                  int result = mySqlLockMapper.insert(this.lockName, this.uuid);
                  if(result > 0) {
                      //代表加鎖成功
                      break;
                  }
              } catch (Exception e) {
              }

            //唯一索引加鎖失敗
            try {
                Thread.sleep(100);
            } catch (InterruptedException interruptedException) {
                throw new RuntimeException();
            }
        }
    }


    public void unLock() {
        mySqlLockMapper.delete(this.lockName,this.uuid);
    }
}

@Service
public class LockService {
    
    @Resource
    private MySqlDistributeLock.MySqlLockMapper mySqlLockMapper;



    public String deductStockMysqlLock(String productId,Integer count) {
        MySqlDistributeLock lock = null;
        try{
            lock = new MySqlDistributeLock(productId, mySqlLockMapper,UUID.randomUUID().toString());
            //加鎖
            lock.lock();

            //加鎖成功，開(kāi)始執(zhí)行我們自己的業(yè)務(wù)邏輯
        }finally {
            if(lock != null) {
                lock.unLock();
            }
        }
        return "success";
    }
}