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This article will explain in detail how to achieve a distributed lock in the MySQL database. The content of the article is of high quality, so the editor shares it for you as a reference. I hope you will have some understanding of the relevant knowledge after reading this article.

Build a table

CREATE TABLE `globallocktable` (`id` int (11) NOT NULL AUTO_INCREMENT, `lockKey` varchar (60) NOT NULL COMMENT 'lock name', `createTime` datetime NOT NULL COMMENT 'creation time', PRIMARY KEY (`id`), UNIQUE KEY `lockKey` (`lockKey`) ENGINE=InnoDB DEFAULT CHARSET=utf8 ROW_FORMAT=DYNAMIC COMMENT=' global lock'

Components for others to use

@ Componentpublic class GlobalLockComponent {@ Resource GlobalLockTableDAO globalLockDAO; / * attempted to acquire the lock with success of true and failure of false * / public boolean tryLock (String key) {return GlobalLockUtil.tryLock (this.globalLockDAO, key) } / * if another program already occupies the lock and exceeds the timeoutMs (millisecond) time, the lock occupation will be forcibly cleared * that is, delete the record first according to key, and then add the record * / public boolean tryLockWithClear (String key, Long timeoutMs) {return GlobalLockUtil.tryLockWithClear (this.globalLockDAO, key, timeoutMs) Release the lock and delete the record according to key * / public void releasLock (String key) {GlobalLockUtil.releasLock (this.globalLockDAO, key);}}

The lock object is defined as follows

Public class GlobalLockTable {private Integer id; private String lockKey; private Date createTime; / / omit get and set methods} GlobalLockTableDAO is defined as follows: public interface GlobalLockTableDAO {int deleteByPrimaryKey (Integer id); int deleteByLockKey (String lockKey); GlobalLockTable selectByLockKey (String key); int insertSelectiveWithTest (GlobalLockTable record);}

Specific locking and unlocking logic

Public class GlobalLockUtil {private static Logger logger = LoggerFactory.getLogger (GlobalLockUtil.class); private static GlobalLockTable tryLockInternal (GlobalLockTableDAO lockDAO, String key) {GlobalLockTable insert = new GlobalLockTable (); insert.setCreateTime (new Date ()); insert.setLockKey (key); / / attention 1 int count = lockDAO.insertSelectiveWithTest (insert); if (count = = 0) {GlobalLockTable ready = lockDAO.selectByLockKey (key) Logger.warn ("can not lock the key: {}, {}", insert.getLockKey (), ready.getCreateTime (), ready.getId ()); return ready;} logger.info ("yes got the lock by key: {}", insert.getId (), insert.getLockKey ()); return null } / * * timeout clears lock occupancy and relocks * * / public static boolean tryLockWithClear (GlobalLockTableDAO lockDAO, String key, Long timeoutMs) {GlobalLockTable lock = tryLockInternal (lockDAO, key); if (lock = = null) return true; if (System.currentTimeMillis ()-lock.getCreateTime (). GetTime ()

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