学习TDD(5)--实例2：基于ZooKeeper的服务器注册和探测类[实战ServerDetector]

接下来我们来写发现可用服务器的工具类ServerDetector。以后不再写这种复杂实例的博客了，写了好久啊。示例代码已上传到http://download.csdn.net/detail/mrbcy/9753008

测试类

package tech.mrbcy.mrpc.test.client;import java.net.InetSocketAddress;import java.util.concurrent.CountDownLatch;import java.util.concurrent.TimeUnit;import org.junit.Assert;import org.junit.Before;import org.junit.Test;import tech.mrbcy.mrpc.client.ServerDetector;import tech.mrbcy.mrpc.server.ServerRegister;public class ServerDetectorTest {    private String zkConnetionString = "amaster:2181,anode1:2181,anode2:2181";    private String groupName = "/MrpcServer";    private String serverNode = "/ServiceImplServer";    private int closeCount = 0;    private CountDownLatch latch;    private boolean reconnect = false;    @Before    public void init(){        closeCount = 0;        latch = new CountDownLatch(1);        reconnect = false;    }    @Test    public void testServerChange() throws Exception{        final ServerRegister sr1 = new ServerRegister(zkConnetionString, groupName);        sr1.registServer(serverNode,"localhost:8000");        final ServerRegister sr2 = new ServerRegister(zkConnetionString, groupName);        sr2.registServer(serverNode,"localhost:8001");        final ServerRegister sr3 = new ServerRegister(zkConnetionString, groupName);        sr3.registServer(serverNode,"localhost:8002");        ServerDetector serverDetector = new ServerDetector(zkConnetionString,groupName);        InetSocketAddress serverAddr = serverDetector.getAServer(new ServerSwitchListener() {            public void serverSwitched(InetSocketAddress newServerAddr) {                if(newServerAddr == null){                    latch.countDown();                }else{                    try {                        closeServer(sr1,sr2,sr3,newServerAddr);                    } catch (Exception e) {                        // TODO Auto-generated catch block                        e.printStackTrace();                    }                }            }        });        Assert.assertNotNull(serverAddr);        closeServer(sr1,sr2,sr3,serverAddr);        latch.await();        Assert.assertEquals(closeCount, 3);    }    @Test(expected = RuntimeException.class)    public void testUnAvailableZk() throws Exception{        new ServerDetector("anode3:2181",groupName);    }    @Test    public void testNoListener() throws Exception{        final ServerRegister sr1 = new ServerRegister(zkConnetionString, groupName);        sr1.registServer(serverNode,"localhost:8000");        final ServerRegister sr2 = new ServerRegister(zkConnetionString, groupName);        sr2.registServer(serverNode,"localhost:8001");        final ServerRegister sr3 = new ServerRegister(zkConnetionString, groupName);        sr3.registServer(serverNode,"localhost:8002");        ServerDetector serverDetector = new ServerDetector(zkConnetionString,groupName);        InetSocketAddress serverAddr = serverDetector.getAServer(null);        System.out.println("获得服务器地址：" + serverAddr.getHostString() + ":" + serverAddr.getPort());    }    @Test    public void testNoServer() throws Exception{        ServerDetector serverDetector = new ServerDetector(zkConnetionString,groupName);        InetSocketAddress serverAddr = serverDetector.getAServer(null);        Assert.assertNull(serverAddr);    }    @Test(expected = RuntimeException.class)    public void testEmptyNodeString() throws Exception{        new ServerDetector(zkConnetionString,"");    }    @Test(expected = RuntimeException.class)    public void testObliqueNodeString() throws Exception{        new ServerDetector(zkConnetionString,"");    }    @Test    public void testNodePathNotStartWithOblique() throws Exception{        final ServerRegister sr1 = new ServerRegister(zkConnetionString, groupName);        sr1.registServer(serverNode,"localhost:8000");        final ServerRegister sr2 = new ServerRegister(zkConnetionString, groupName);        sr2.registServer(serverNode,"localhost:8001");        final ServerRegister sr3 = new ServerRegister(zkConnetionString, groupName);        sr3.registServer(serverNode,"localhost:8002");        ServerDetector serverDetector = new ServerDetector(zkConnetionString,"MrpcServer");        InetSocketAddress serverAddr = serverDetector.getAServer(null);        System.out.println("获得服务器地址：" + serverAddr.getHostString() + ":" + serverAddr.getPort());    }    @Test    public void testReconnect() throws Exception {        final ServerRegister sr1 = new ServerRegister(zkConnetionString, groupName);        sr1.registServer(serverNode,"localhost:8000");        final ServerRegister sr2 = new ServerRegister(zkConnetionString, groupName);        sr2.registServer(serverNode,"localhost:8001");        final ServerRegister sr3 = new ServerRegister(zkConnetionString, groupName);        sr3.registServer(serverNode,"localhost:8002");        ServerDetector serverDetector = new ServerDetector(zkConnetionString,"MrpcServer");        InetSocketAddress serverAddr = serverDetector.getAServer(new ServerSwitchListener() {            public void serverSwitched(InetSocketAddress newServerAddr) {                System.out.println("获得服务器地址：" + newServerAddr.getHostString() + ":" + newServerAddr.getPort());                reconnect = true;                latch.countDown();            }        });        System.out.println("获得服务器地址：" + serverAddr.getHostString() + ":" + serverAddr.getPort());        // 手动重启zk集群        latch.await(200, TimeUnit.SECONDS);        closeServer(sr1, sr2, sr3, serverAddr);        Thread.sleep(10000);        Assert.assertTrue(reconnect);    }    private void closeServer(ServerRegister sr1, ServerRegister sr2,            ServerRegister sr3, InetSocketAddress serverAddr) throws Exception {        closeCount += 1;        if(serverAddr.getPort() == 8000){            sr1.unregist();        }else if(serverAddr.getPort() == 8001){            sr2.unregist();        }else if(serverAddr.getPort() == 8002){            sr3.unregist();        }    }}

根据测试类，写出的ServerDetector

package tech.mrbcy.mrpc.client;import java.io.IOException;import java.net.InetSocketAddress;import java.util.ArrayList;import java.util.List;import java.util.Random;import java.util.concurrent.CountDownLatch;import java.util.concurrent.TimeUnit;import org.apache.zookeeper.WatchedEvent;import org.apache.zookeeper.Watcher;import org.apache.zookeeper.ZooKeeper;import org.apache.zookeeper.Watcher.Event.EventType;import tech.mrbcy.mrpc.test.client.ServerSwitchListener;public class ServerDetector implements Watcher {    private String zkConnetionString;    private String nodePath;    private int sessionTimeout = 2000;    private ZooKeeper zk;    private ServerSwitchListener serverSwitchListener;    private InetSocketAddress curServer;    private CountDownLatch latch;    /**     * 使用连接zk集群的字符串和节点路径创建探测器类     * @param zkConnetionString zk集群的连接字符串     * @param nodePath 节点路径     * @throws Exception 连接到zk集群过程中出错将抛出异常     */    public ServerDetector(String zkConnetionString, String nodePath) throws Exception {        this.zkConnetionString = zkConnetionString;        if(nodePath.equals("") || nodePath.equals("/")){            throw new RuntimeException("nodePath can't be empty");        }        if(!nodePath.startsWith("/")){            nodePath = "/" + nodePath;        }        this.nodePath = nodePath;        initZk();    }    // 初始化zk客户端    private void initZk() throws Exception {        latch = new CountDownLatch(1);        this.zk = new ZooKeeper(zkConnetionString, sessionTimeout, this);        latch.await(sessionTimeout, TimeUnit.MILLISECONDS);        if(latch.getCount() > 0){            throw new RuntimeException("Can not connect to ZooKeeper cluster "                     + zkConnetionString + ", please check and try again later");        }        // 注册监听        getServerList();    }    // 刷新服务器列表    private InetSocketAddress refreshServerList() throws Exception {        // 获取服务器列表        List<String> serversList = getServerList();        boolean isCurServerAvailable = checkServerList(serversList);        if(!isCurServerAvailable){            this.curServer = chooseAServer(serversList);            if(this.serverSwitchListener != null){                serverSwitchListener.serverSwitched(this.curServer);            }        }        return curServer;    }    private InetSocketAddress chooseAServer(List<String> servers) {        if(servers == null || servers.size() == 0){            return null;        }        // 随机选择一个服务器        String serverAddr = servers.get(0);        if(servers.size() > 1){            int index = new Random().nextInt(servers.size());            serverAddr = servers.get(index);        }        String[] addrAndPort = serverAddr.split(":");        if(addrAndPort.length != 2){            throw new RuntimeException("不合法的server地址：" + serverAddr);        }        return new InetSocketAddress(addrAndPort[0], Integer.parseInt(addrAndPort[1]));    }    private boolean checkServerList(List<String> servers) {        if(servers == null || servers.size() == 0){            return false;        }        // 未指定服务器地址或原服务器已失效，迁移到新的服务器        if(servers.size() > 0 && curServer != null){            for(String server:servers){                if(server.equals(curServer.getHostString() + ":" + curServer.getPort())){                    return true;                }            }        }        return false;    }    private List<String> getServerList() throws Exception {        List<String> serverNodes = zk.getChildren(nodePath, true);        List<String> serverAddrs = new ArrayList<String>();        for(String serverNode : serverNodes){            serverAddrs.add(new String(zk.getData(nodePath+"/" + serverNode, null, null)));        }        return serverAddrs;    }    /**     * 获取一个可用的服务器连接地址     * @param serverSwitchListener 如果之前返回的服务器连接地址失效，将回调通知     * @return 没有可用的服务器时返回null     * @throws Exception     */    public InetSocketAddress getAServer(            ServerSwitchListener serverSwitchListener) throws Exception {        this.serverSwitchListener = null;        InetSocketAddress newAddress = refreshServerList();        this.serverSwitchListener = serverSwitchListener;        return newAddress;    }    public void process(WatchedEvent event) {        System.out.println("detector:------" + event);        if(event.getState() == Event.KeeperState.SyncConnected){            latch.countDown();        }        if(event.getState() == Event.KeeperState.Expired){            try {                // 会话过期，重新连接ZooKeeper集群                initZk();                       } catch (Exception e1) {                e1.printStackTrace();            }        }        if(event.getType() == EventType.NodeChildrenChanged){            try {                refreshServerList();            } catch (Exception e) {                e.printStackTrace();            }        }    }}