\n
\u4ee3\u7801\u5b9e\u73b0<\/h1>\n\u7ec4\u4ef6\u4f9d\u8d56<\/h2>\n
\u9996\u5148\u6211\u4eec\u8981\u901a\u8fc7Maven\u5f15\u5165 <\/p>\n<\/div>\n<\/div>\n Talk is cheap, show me the code\u3002\u5148\u5c55\u793a\u4ee3\u7801\uff0c\u518d\u5e26\u5927\u5bb6\u6162\u6162\u89e3\u91ca\u4e3a\u4ec0\u4e48\u8fd9\u6837\u5b9e\u73b0\uff1a<\/p>\n \u53ef\u4ee5\u770b\u5230\uff0c\u6211\u4eec\u52a0\u9501\u5c31\u4e00\u884c\u4ee3\u7801\uff1a \u603b\u7684\u6765\u8bf4\uff0c\u6267\u884c\u4e0a\u9762\u7684set()\u65b9\u6cd5\u5c31\u53ea\u4f1a\u5bfc\u81f4\u4e24\u79cd\u7ed3\u679c\uff1a1. \u5f53\u524d\u6ca1\u6709\u9501\uff08key\u4e0d\u5b58\u5728\uff09\uff0c\u90a3\u4e48\u5c31\u8fdb\u884c\u52a0\u9501\u64cd\u4f5c\uff0c\u5e76\u5bf9\u9501\u8bbe\u7f6e\u4e2a\u6709\u6548\u671f\uff0c\u540c\u65f6value\u8868\u793a\u52a0\u9501\u7684\u5ba2\u6237\u7aef\u30022. \u5df2\u6709\u9501\u5b58\u5728\uff0c\u4e0d\u505a\u4efb\u4f55\u64cd\u4f5c\u3002<\/p>\n \u5fc3\u7ec6\u7684\u7ae5\u978b\u5c31\u4f1a\u53d1\u73b0\u4e86\uff0c\u6211\u4eec\u7684\u52a0\u9501\u4ee3\u7801\u6ee1\u8db3\u6211\u4eec\u53ef\u9760\u6027\u91cc\u63cf\u8ff0\u7684\u4e09\u4e2a\u6761\u4ef6\u3002\u9996\u5148\uff0cset()\u52a0\u5165\u4e86NX\u53c2\u6570\uff0c\u53ef\u4ee5\u4fdd\u8bc1\u5982\u679c\u5df2\u6709key\u5b58\u5728\uff0c\u5219\u51fd\u6570\u4e0d\u4f1a\u8c03\u7528\u6210\u529f\uff0c\u4e5f\u5c31\u662f\u53ea\u6709\u4e00\u4e2a\u5ba2\u6237\u7aef\u80fd\u6301\u6709\u9501\uff0c\u6ee1\u8db3\u4e92\u65a5\u6027\u3002\u5176\u6b21\uff0c\u7531\u4e8e\u6211\u4eec\u5bf9\u9501\u8bbe\u7f6e\u4e86\u8fc7\u671f\u65f6\u95f4\uff0c\u5373\u4f7f\u9501\u7684\u6301\u6709\u8005\u540e\u7eed\u53d1\u751f\u5d29\u6e83\u800c\u6ca1\u6709\u89e3\u9501\uff0c\u9501\u4e5f\u4f1a\u56e0\u4e3a\u5230\u4e86\u8fc7\u671f\u65f6\u95f4\u800c\u81ea\u52a8\u89e3\u9501\uff08\u5373key\u88ab\u5220\u9664\uff09\uff0c\u4e0d\u4f1a\u53d1\u751f\u6b7b\u9501\u3002\u6700\u540e\uff0c\u56e0\u4e3a\u6211\u4eec\u5c06value\u8d4b\u503c\u4e3arequestId\uff0c\u4ee3\u8868\u52a0\u9501\u7684\u5ba2\u6237\u7aef\u8bf7\u6c42\u6807\u8bc6\uff0c\u90a3\u4e48\u5728\u5ba2\u6237\u7aef\u5728\u89e3\u9501\u7684\u65f6\u5019\u5c31\u53ef\u4ee5\u8fdb\u884c\u6821\u9a8c\u662f\u5426\u662f\u540c\u4e00\u4e2a\u5ba2\u6237\u7aef\u3002\u7531\u4e8e\u6211\u4eec\u53ea\u8003\u8651Redis\u5355\u673a\u90e8\u7f72\u7684\u573a\u666f\uff0c\u6240\u4ee5\u5bb9\u9519\u6027\u6211\u4eec\u6682\u4e0d\u8003\u8651\u3002<\/p>\n \u6bd4\u8f83\u5e38\u89c1\u7684\u9519\u8bef\u793a\u4f8b\u5c31\u662f\u4f7f\u7528 setnx()\u65b9\u6cd5\u4f5c\u7528\u5c31\u662fSET IF NOT EXIST\uff0cexpire()\u65b9\u6cd5\u5c31\u662f\u7ed9\u9501\u52a0\u4e00\u4e2a\u8fc7\u671f\u65f6\u95f4\u3002\u4e4d\u4e00\u770b\u597d\u50cf\u548c\u524d\u9762\u7684set()\u65b9\u6cd5\u7ed3\u679c\u4e00\u6837\uff0c\u7136\u800c\u7531\u4e8e\u8fd9\u662f\u4e24\u6761Redis\u547d\u4ee4\uff0c\u4e0d\u5177\u6709\u539f\u5b50\u6027\uff0c\u5982\u679c\u7a0b\u5e8f\u5728\u6267\u884c\u5b8csetnx()\u4e4b\u540e\u7a81\u7136\u5d29\u6e83\uff0c\u5bfc\u81f4\u9501\u6ca1\u6709\u8bbe\u7f6e\u8fc7\u671f\u65f6\u95f4\u3002\u90a3\u4e48\u5c06\u4f1a\u53d1\u751f\u6b7b\u9501\u3002\u7f51\u4e0a\u4e4b\u6240\u4ee5\u6709\u4eba\u8fd9\u6837\u5b9e\u73b0\uff0c\u662f\u56e0\u4e3a\u4f4e\u7248\u672c\u7684jedis\u5e76\u4e0d\u652f\u6301\u591a\u53c2\u6570\u7684set()\u65b9\u6cd5\u3002<\/p>\n \u8fd9\u4e00\u79cd\u9519\u8bef\u793a\u4f8b\u5c31\u6bd4\u8f83\u96be\u4ee5\u53d1\u73b0\u95ee\u9898\uff0c\u800c\u4e14\u5b9e\u73b0\u4e5f\u6bd4\u8f83\u590d\u6742\u3002\u5b9e\u73b0\u601d\u8def\uff1a\u4f7f\u7528 \u90a3\u4e48\u8fd9\u6bb5\u4ee3\u7801\u95ee\u9898\u5728\u54ea\u91cc\uff1f1. \u7531\u4e8e\u662f\u5ba2\u6237\u7aef\u81ea\u5df1\u751f\u6210\u8fc7\u671f\u65f6\u95f4\uff0c\u6240\u4ee5\u9700\u8981\u5f3a\u5236\u8981\u6c42\u5206\u5e03\u5f0f\u4e0b\u6bcf\u4e2a\u5ba2\u6237\u7aef\u7684\u65f6\u95f4\u5fc5\u987b\u540c\u6b65\u3002 2. \u5f53\u9501\u8fc7\u671f\u7684\u65f6\u5019\uff0c\u5982\u679c\u591a\u4e2a\u5ba2\u6237\u7aef\u540c\u65f6\u6267\u884c \u8fd8\u662f\u5148\u5c55\u793a\u4ee3\u7801\uff0c\u518d\u5e26\u5927\u5bb6\u6162\u6162\u89e3\u91ca\u4e3a\u4ec0\u4e48\u8fd9\u6837\u5b9e\u73b0\uff1a<\/p>\n \u53ef\u4ee5\u770b\u5230\uff0c\u6211\u4eec\u89e3\u9501\u53ea\u9700\u8981\u4e24\u884c\u4ee3\u7801\u5c31\u641e\u5b9a\u4e86\uff01\u7b2c\u4e00\u884c\u4ee3\u7801\uff0c\u6211\u4eec\u5199\u4e86\u4e00\u4e2a\u7b80\u5355\u7684Lua\u811a\u672c\u4ee3\u7801\uff0c\u4e0a\u4e00\u6b21\u89c1\u5230\u8fd9\u4e2a\u7f16\u7a0b\u8bed\u8a00\u8fd8\u662f\u5728\u300a\u9ed1\u5ba2\u4e0e\u753b\u5bb6\u300b\u91cc\uff0c\u6ca1\u60f3\u5230\u8fd9\u6b21\u5c45\u7136\u7528\u4e0a\u4e86\u3002\u7b2c\u4e8c\u884c\u4ee3\u7801\uff0c\u6211\u4eec\u5c06Lua\u4ee3\u7801\u4f20\u5230Jedis<\/code>\u5f00\u6e90\u7ec4\u4ef6\uff0c\u5728pom.xml<\/code>\u6587\u4ef6\u52a0\u5165\u4e0b\u9762\u7684\u4ee3\u7801\uff1a<\/p>\n<dependency>\r\n <groupId>redis.clients<\/groupId>\r\n <artifactId>jedis<\/artifactId>\r\n <version>2.9.0<\/version>\r\n<\/dependency><\/pre>\n<\/div>\n
\u52a0\u9501\u4ee3\u7801<\/h2>\n
\u6b63\u786e\u59ff\u52bf<\/h3>\n
public class RedisTool {\r\n\r\n private static final String LOCK_SUCCESS = \"OK\";\r\n private static final String SET_IF_NOT_EXIST = \"NX\";\r\n private static final String SET_WITH_EXPIRE_TIME = \"PX\";\r\n\r\n \/**\r\n * \u5c1d\u8bd5\u83b7\u53d6\u5206\u5e03\u5f0f\u9501\r\n * @param jedis Redis\u5ba2\u6237\u7aef\r\n * @param lockKey \u9501\r\n * @param requestId \u8bf7\u6c42\u6807\u8bc6\r\n * @param expireTime \u8d85\u671f\u65f6\u95f4\r\n * @return \u662f\u5426\u83b7\u53d6\u6210\u529f\r\n *\/\r\n public static boolean tryGetDistributedLock(Jedis jedis, String lockKey, String requestId, int expireTime) {\r\n\r\n String result = jedis.set(lockKey, requestId, SET_IF_NOT_EXIST, SET_WITH_EXPIRE_TIME, expireTime);\r\n\r\n if (LOCK_SUCCESS.equals(result)) {\r\n return true;\r\n }\r\n return false;\r\n\r\n }\r\n\r\n}<\/pre>\n<\/div>\n<\/div>\n<\/div>\njedis.set(String key, String value, String nxxx, String expx, int time)<\/code>\uff0c\u8fd9\u4e2aset()\u65b9\u6cd5\u4e00\u5171\u6709\u4e94\u4e2a\u5f62\u53c2\uff1a<\/p>\n\n
UUID.randomUUID().toString()<\/code>\u65b9\u6cd5\u751f\u6210\u3002<\/li>\n\u9519\u8bef\u793a\u4f8b1<\/h3>\n
jedis.setnx()<\/code>\u548cjedis.expire()<\/code>\u7ec4\u5408\u5b9e\u73b0\u52a0\u9501\uff0c\u4ee3\u7801\u5982\u4e0b\uff1a<\/p>\npublic static void wrongGetLock1(Jedis jedis, String lockKey, String requestId, int expireTime) {\r\n\r\n Long result = jedis.setnx(lockKey, requestId);\r\n if (result == 1) {\r\n \/\/ \u82e5\u5728\u8fd9\u91cc\u7a0b\u5e8f\u7a81\u7136\u5d29\u6e83\uff0c\u5219\u65e0\u6cd5\u8bbe\u7f6e\u8fc7\u671f\u65f6\u95f4\uff0c\u5c06\u53d1\u751f\u6b7b\u9501\r\n jedis.expire(lockKey, expireTime);\r\n }\r\n\r\n}<\/pre>\n<\/div>\n<\/div>\n<\/div>\n\u9519\u8bef\u793a\u4f8b2<\/h3>\n
public static boolean wrongGetLock2(Jedis jedis, String lockKey, int expireTime) {\r\n\r\n long expires = System.currentTimeMillis() + expireTime;\r\n String expiresStr = String.valueOf(expires);\r\n\r\n \/\/ \u5982\u679c\u5f53\u524d\u9501\u4e0d\u5b58\u5728\uff0c\u8fd4\u56de\u52a0\u9501\u6210\u529f\r\n if (jedis.setnx(lockKey, expiresStr) == 1) {\r\n return true;\r\n }\r\n\r\n \/\/ \u5982\u679c\u9501\u5b58\u5728\uff0c\u83b7\u53d6\u9501\u7684\u8fc7\u671f\u65f6\u95f4\r\n String currentValueStr = jedis.get(lockKey);\r\n if (currentValueStr != null && Long.parseLong(currentValueStr) < System.currentTimeMillis()) {\r\n \/\/ \u9501\u5df2\u8fc7\u671f\uff0c\u83b7\u53d6\u4e0a\u4e00\u4e2a\u9501\u7684\u8fc7\u671f\u65f6\u95f4\uff0c\u5e76\u8bbe\u7f6e\u73b0\u5728\u9501\u7684\u8fc7\u671f\u65f6\u95f4\r\n String oldValueStr = jedis.getSet(lockKey, expiresStr);\r\n if (oldValueStr != null && oldValueStr.equals(currentValueStr)) {\r\n \/\/ \u8003\u8651\u591a\u7ebf\u7a0b\u5e76\u53d1\u7684\u60c5\u51b5\uff0c\u53ea\u6709\u4e00\u4e2a\u7ebf\u7a0b\u7684\u8bbe\u7f6e\u503c\u548c\u5f53\u524d\u503c\u76f8\u540c\uff0c\u5b83\u624d\u6709\u6743\u5229\u52a0\u9501\r\n return true;\r\n }\r\n }\r\n \r\n \/\/ \u5176\u4ed6\u60c5\u51b5\uff0c\u4e00\u5f8b\u8fd4\u56de\u52a0\u9501\u5931\u8d25\r\n return false;\r\n\r\n}<\/pre>\n<\/div>\njedis.setnx()<\/code>\u547d\u4ee4\u5b9e\u73b0\u52a0\u9501\uff0c\u5176\u4e2dkey\u662f\u9501\uff0cvalue\u662f\u9501\u7684\u8fc7\u671f\u65f6\u95f4\u3002\u6267\u884c\u8fc7\u7a0b\uff1a1. \u901a\u8fc7setnx()\u65b9\u6cd5\u5c1d\u8bd5\u52a0\u9501\uff0c\u5982\u679c\u5f53\u524d\u9501\u4e0d\u5b58\u5728\uff0c\u8fd4\u56de\u52a0\u9501\u6210\u529f\u30022. \u5982\u679c\u9501\u5df2\u7ecf\u5b58\u5728\u5219\u83b7\u53d6\u9501\u7684\u8fc7\u671f\u65f6\u95f4\uff0c\u548c\u5f53\u524d\u65f6\u95f4\u6bd4\u8f83\uff0c\u5982\u679c\u9501\u5df2\u7ecf\u8fc7\u671f\uff0c\u5219\u8bbe\u7f6e\u65b0\u7684\u8fc7\u671f\u65f6\u95f4\uff0c\u8fd4\u56de\u52a0\u9501\u6210\u529f\u3002\u4ee3\u7801\u5982\u4e0b\uff1a<\/p>\njedis.getSet()<\/code>\u65b9\u6cd5\uff0c\u90a3\u4e48\u867d\u7136\u6700\u7ec8\u53ea\u6709\u4e00\u4e2a\u5ba2\u6237\u7aef\u53ef\u4ee5\u52a0\u9501\uff0c\u4f46\u662f\u8fd9\u4e2a\u5ba2\u6237\u7aef\u7684\u9501\u7684\u8fc7\u671f\u65f6\u95f4\u53ef\u80fd\u88ab\u5176\u4ed6\u5ba2\u6237\u7aef\u8986\u76d6\u30023. \u9501\u4e0d\u5177\u5907\u62e5\u6709\u8005\u6807\u8bc6\uff0c\u5373\u4efb\u4f55\u5ba2\u6237\u7aef\u90fd\u53ef\u4ee5\u89e3\u9501\u3002<\/p>\n\u89e3\u9501\u4ee3\u7801<\/h2>\n
\u6b63\u786e\u59ff\u52bf<\/h3>\n
public class RedisTool {\r\n\r\n private static final Long RELEASE_SUCCESS = 1L;\r\n\r\n \/**\r\n * \u91ca\u653e\u5206\u5e03\u5f0f\u9501\r\n * @param jedis Redis\u5ba2\u6237\u7aef\r\n * @param lockKey \u9501\r\n * @param requestId \u8bf7\u6c42\u6807\u8bc6\r\n * @return \u662f\u5426\u91ca\u653e\u6210\u529f\r\n *\/\r\n public static boolean releaseDistributedLock(Jedis jedis, String lockKey, String requestId) {\r\n\r\n String script = \"if redis.call('get', KEYS[1]) == ARGV[1] then return redis.call('del', KEYS[1]) else return 0 end\";\r\n Object result = jedis.eval(script, Collections.singletonList(lockKey), Collections.singletonList(requestId));\r\n\r\n if (RELEASE_SUCCESS.equals(result)) {\r\n return true;\r\n }\r\n return false;\r\n\r\n }\r\n\r\n}<\/pre>\n<\/div>\n<\/div>\n<\/div>\njedis.eval()<\/code>\u65b9\u6cd5\u91cc\uff0c\u5e76\u4f7f\u53c2\u6570KEYS[1]\u8d4b\u503c\u4e3alockKey\uff0cARGV[1]\u8d4b\u503c\u4e3arequestId\u3002eval()\u65b9\u6cd5\u662f\u5c06Lua\u4ee3\u7801\u4ea4\u7ed9Redis\u670d\u52a1\u7aef\u6267\u884c\u3002<\/p>\n
![\"\"](\"\/2018\/07\/3152a80b27db51e84c97e7d1966a1285.png\")
<\/p>\n