依赖Zookeeper生成全局唯一序列号

下面2张图来自：http://www.open-open.com/doc/view/2e0a82e0081d489dace301a2c512053c

关于Zookeeper服务安装，配置，启动,客户端操作参见：

http://www.jb51.cc/article/p-czczykuq-kn.html

http://www.jb51.cc/article/p-atkufdff-kn.html

1.利用Zookeeper的znode数据版本生成序列号

利用zkClient封装包操作实现：

//提前创建好存储Seq的"/createSeq"结点CreateMode.PERSISTENT
publicstaticfinalStringSEQ_ZNODE="/seq"

//通过znode数据版本实现分布式seq生成
publicstaticclasstask1implementsRunnable{

privatefinalStringtaskName;

publicTask1(StringtaskName){
this.taskName=taskName;
}

@Override
publicvoidrun(){
ZkClientzkClient=newZkClient("192.168.88.153:2181",3000,1000);
Statstat=zkClient.writeData(SEQ_ZNODE,newbyte[0],-1);
intversionAsSeq=stat.getVersion();
System.out.println(taskName+"obtainseq="+versionAsSeq);
zkClient.close();
}
}

//main
finalExecutorServiceservice=Executors.newFixedThreadPool(20);

for(inti=0;i<20;i++){
service.execute(newTask1("[Concurrent-"+i+"]"));
}

2.利用临时带序列号的znode实现和分布式锁持久化znode实现

2.1 下图是利用分布式锁持久化znode实现

客户端采用apache curator 框架，代码：https://code.csdn.net/snippets/929300

2.2利用临时带序列号的znode实现

客户端采用：zkClient （https://github.com/adyliu/zkclient）

//提前创建好锁对象的结点"/lock"CreateMode.PERSISTENT
publicstaticfinalStringLOCK_ZNODE="/lock";

//分布式锁实现分布式seq生成
publicstaticclasstask2implementsRunnable,IZkChildListener{

privatefinalStringtaskName;

privatefinalZkClientzkClient;

privatefinalStringlockPrefix="/loc";

privatefinalStringselfZnode;

publicTask2(StringtaskName){
this.taskName=taskName;
zkClient=newZkClient("192.168.88.153:2181",30000,10000);
selfZnode=zkClient.createEphemeralSequential(LOCK_ZNODE+lockPrefix,newbyte[0]);
}

@Override
publicvoidrun(){
zkClient.subscribeChildChanges(LOCK_ZNODE,this);
do{
}while(zkClient.isConnected());
}


privatevoidcreateSeq(){
Statstat=newStat();
byte[]oldData=zkClient.readData(LOCK_ZNODE,stat);
byte[]newData=update(oldData);
zkClient.writeData(LOCK_ZNODE,newData);
System.out.println(taskName+selfZnode+"obtainseq="+newString(newData));
}

privatebyte[]update(byte[]currentData){
Strings=newString(currentData);
intd=Integer.parseInt(s);
d=d+1;
s=String.valueOf(d);
returns.getBytes();
}

@Override
publicvoidhandleChildChange(StringparentPath,List<String>currentChildren)throwsException{
String[]childrensZnode=currentChildren.toArray(newString[currentChildren.size()]);
Arrays.sort(childrensZnode);
StringminZnode=LOCK_ZNODE+"/"+childrensZnode[0];
if(selfZnode.equals(minZnode)){
createSeq();
zkClient.unsubscribeChildChanges(LOCK_ZNODE,this);
zkClient.delete(selfZnode);
zkClient.close();
}
}
}

完整代码参见：https://code.csdn.net/snippets/929320

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