2019独角兽企业重金招聘Python工程师标准>>> 
zookeeper可能平时大家直接操作的并不多,而zookeeper的要点就在于4个节点状态(永久,有序,临时,临时有序)以及1个watcher的监控.
1.模拟注册:
pom引用(本人使用的zookeeper为3.4.6)
org.apache.zookeeper zookeeper 3.4.6 com.alibaba fastjson 1.2.47
application.yml的内容为
server:
port: 8081
address: localhost
zookeeper:
address: 192.168.5.129:2181
sessionouttime: 4000
spring:
application:
name: zk
先写一个注册中心
/**
* 注册中心,对外提供注册服务
* Created by Administrator on 2018/9/12.
*/
@Component
public class ZookeeperServer {
private ZooKeeper zk;
public ZooKeeper getConnection(String host,Watcher watcher) throws IOException {
zk = new ZooKeeper(host, 500, watcher);
return zk;
}
}
再写一个提供者注册类向Zookeeper注册
@Component
public class ZookRegister implements Watcher {
//获得配置资源
@Autowired
Environment env;
@Autowired
private ZookeeperServer zkServer ;
private ZooKeeper zk;
//固定的根目录比如公司名
final String fixedpath = "/guanjian";
@Value("spring.application.name")
String servername;
//spring容器初始化ZookRegister的实例时执行
@PostConstruct
public void register() throws Exception {
String servername = env.getProperty("spring.application.name");
String port = env.getProperty("server.port");
String ip = env.getProperty("server.address");
String address = env.getProperty("zookeeper.address");
// PrivderServer.zooKeeper = zook.create();
// ZooKeeper zooKeeper = PrivderServer.zooKeeper;
this.zk = zkServer.getConnection(address ,this);
Stat existsFixedpath = this.zk.exists(fixedpath, false);
if (existsFixedpath == null) {
//参数分别是创建的节点路径、节点的数据、权限（此处对所有用户开放）、节点的类型（此处是持久节点）
zk.create(fixedpath, "".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
}
String svnode = fixedpath + "/" + servername;
Stat existsSvnode = zk.exists(svnode, false);
//create(String path, byte[] data, List acl, CreateMode createMode)
if (existsSvnode == null) {
zk.create(svnode, "".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
}
if (ip == null || "".equals(null)) {
//如果配置文件中没有指定服务ip获取本机ip
ip = InetAddress.getLocalHost().getHostAddress();
}
if (port == null || "".equals(null)) {
port = "8080";
}
NodeStat nodeStat = new NodeStat();
nodeStat.setIp(ip);
nodeStat.setPort(port);
nodeStat.setName(servername);
nodeStat.setNum(0);
nodeStat.setStatus(Status.wait);
//临时节点的前缀是服务名称,节点数据是服务address
String svipmlNode = fixedpath + "/" + servername + "/" + servername;
//重点在于这里创建的是临时有序节点
zk.create(svipmlNode, JSONObject.toJSONString(nodeStat).getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL_SEQUENTIAL);
}
@Override
public void process(WatchedEvent watchedEvent) {
}
}
其中NodeStat,Status类如下
@Data
public class NodeStat implements Serializable {
private String ip;
private String name;
private String port;
private Integer num;
private String status;
private String node;
private String client;
}
public class Status {
//wait无消费者,run运行中,stop禁用中
public static final String run = "run";
public static final String wait = "wait";
public static final String stop = "stop";
}
启动Springboot
@SpringBootApplication
public class ZkApplication {
public static void main(String[] args) throws InterruptedException {
ApplicationContext applicationContext = SpringApplication.run(ZkApplication.class, args);
Thread.sleep(Long.MAX_VALUE);
}
}
因为有一个长时间的休眠,当我们进入zookeeper查询的时候,我们会发现在/guanjian/zk下多了一个zk0000000004的节点.
WatchedEvent state:SyncConnected type:None path:null
[zk: localhost:2181(CONNECTED) 0] ls /
[zookeeper, guanjian]
[zk: localhost:2181(CONNECTED) 1] ls /guanjian
[zk]
[zk: localhost:2181(CONNECTED) 2] ls /guanjian/zk
[]
[zk: localhost:2181(CONNECTED) 3] ls /guanjian/zk
[zk0000000004]
[zk: localhost:2181(CONNECTED) 4] get /guanjian/zk/zk0000000004
{"ip":"localhost","name":"zk","num":0,"port":"8081","status":"wait"}
cZxid = 0x2b
ctime = Thu Sep 13 11:20:03 CST 2018
mZxid = 0x2b
mtime = Thu Sep 13 11:20:03 CST 2018
pZxid = 0x2b
cversion = 0
dataVersion = 0
aclVersion = 0
ephemeralOwner = 0x165cc5492840010
dataLength = 68
numChildren = 0
当我们手动结束main方法后,再查询zookeeper(注:/guanjian/zk是永久节点)
[zk: localhost:2181(CONNECTED) 5] ls /guanjian/zk
[]
我们发现这个节点没有了,即这个临时节点消失.
2.模拟发现:
发现为在/guanjian/zk下随机获取一个临时排序节点作为我们要用的注册进来的服务,以进行后续操作,并更新这个节点的状态为run.
@Component
public class ClientComsumer implements Watcher {
//本地缓存服务列表
private static Map> servermap;
@Autowired
private ZookeeperServer zkServer ;
private ZooKeeper zk;
@Autowired
Environment env;
@PostConstruct
private void init() throws IOException {
String address = env.getProperty("zookeeper.address");
this.zk = zkServer.getConnection(address,this);
}
private List getNodeList(String serverName) throws KeeperException, InterruptedException, IOException {
if (servermap == null) {
servermap = new HashMap<>();
}
Stat exists = null;
try {
String s = "/guanjian/" + serverName;
exists = zk.exists(s,this);
} catch (Exception e) {
}
//判断是否存在该服务
if (exists == null) return null;
List serverList = servermap.get(serverName);
if (serverList != null && serverList.size() > 0) {
return serverList;
}
List children = zk.getChildren("/guanjian/" + serverName,this);
List list = new ArrayList<>();
for (String s : children) {
byte[] data = zk.getData("/guanjian/" + serverName + "/" + s, this, null);
String datas = new String(data);
NodeStat nodeStat = JSONObject.parseObject(datas, NodeStat.class);
if (!Status.stop.equals(nodeStat.getStatus())) {
list.add(datas);
}
}
servermap.put(serverName, list);
return list;
}
public String getServerinfo(String serverName) throws KeeperException, InterruptedException, IOException {
try {
List nodeList = getNodeList(serverName);
if (nodeList == null|| nodeList.size()<1) {
return null;
}
//这里使用得随机负载策略，如需需要自己可以实现其他得负载策略
String snode = nodeList.get((int) (Math.random() * nodeList.size()));
NodeStat nodeStat = JSONObject.parseObject(snode, NodeStat.class);
List children = zk.getChildren("/guanjian/" + serverName,this);
//随机负载后,将随机取得节点后的状态更新为run
for (String s : children) {
byte[] data = zk.getData("/guanjian/" + serverName + "/" + s, this, null);
String datas = new String(data);
if (snode.equals(datas)) {
nodeStat.setStatus(Status.run);
zk.setData("/guanjian/" + serverName + "/" + s,JSONObject.toJSONString(nodeStat).getBytes(),0);
break;
}
}
return JSONObject.toJSONString(nodeStat);
} catch (Exception e) {
e.printStackTrace();
return null;
}
}
@Override
public void process(WatchedEvent watchedEvent) {
//如果服务节点数据发生变化则清空本地缓存
if (watchedEvent.getType().equals(Event.EventType.NodeChildrenChanged)) {
servermap = null;
}
}
}
调整main方法
@SpringBootApplication
public class ZkApplication {
public static void main(String[] args) throws InterruptedException, IOException, KeeperException {
ApplicationContext applicationContext = SpringApplication.run(ZkApplication.class, args);
ClientComsumer getServer = applicationContext.getBean(ClientComsumer.class);
System.out.println(getServer.getServerinfo("zk"));
Thread.sleep(Long.MAX_VALUE);
}
}
查看zookeeper内容如下:
[zk: localhost:2181(CONNECTED) 6] ls /guanjian/zk
[zk0000000005]
[zk: localhost:2181(CONNECTED) 7] get /guanjian/zk/zk0000000005
{"ip":"localhost","name":"zk","num":0,"port":"8081","status":"run"}
cZxid = 0x31
ctime = Thu Sep 13 13:41:27 CST 2018
mZxid = 0x32
mtime = Thu Sep 13 13:41:27 CST 2018
pZxid = 0x31
cversion = 0
dataVersion = 1
aclVersion = 0
ephemeralOwner = 0x165cc5492840013
dataLength = 67
numChildren = 0