socket.io是一个不错的websocket项目，github上有它的java实现：netty-socketio 及 示例项目 netty-socketio-demo，基本上看看demo示例项目就能很快上手了，但是demo中的示例代码场景为js做客户端，如果需要在java中连接websocket server，可以参考下面的示例:
一、服务端代码
package com.corundumstudio.socketio.demo.server;
import com.corundumstudio.socketio.AckRequest;
import com.corundumstudio.socketio.Configuration;
import com.corundumstudio.socketio.SocketIOClient;
import com.corundumstudio.socketio.SocketIOServer;
import com.corundumstudio.socketio.listener.ConnectListener;
import com.corundumstudio.socketio.listener.DataListener;
import io.socket.client.Socket;
/**
* Created by yangjunming on 2017/1/13.
*/
public class DemoSocketServer {
public static void main(String[] args) throws InterruptedException {
Configuration config = new Configuration();
config.setHostname("localhost");
config.setPort(9092);
final SocketIOServer server = new SocketIOServer(config);
server.addConnectListener(new ConnectListener() {
@Override
public void onConnect(SocketIOClient client) {
String token = client.getHandshakeData().getUrlParams().get("token").get(0);
if (!token.equals("87df42a424c48313ef6063e6a5c63297")) {
client.disconnect();//校验token示例
}
System.out.println("sessionId:" + client.getSessionId() + ",token:" + token);
}
});
server.addEventListener(Socket.EVENT_MESSAGE, String.class, new DataListener<String>() {
@Override
public void onData(SocketIOClient client, String data, AckRequest ackSender) throws Exception {
System.out.println("client data:" + data);
server.getBroadcastOperations().sendEvent(Socket.EVENT_MESSAGE, "hi");
}
});
server.start();
Thread.sleep(Integer.MAX_VALUE);
server.stop();
}
}
服务端的主要工作，就是添加各种事件的监听，然后在监听处理中，做相应的处理即可。
二、客户端代码
java连接netty-socketio，还要借助另一个开源项目:socket.io-client-java
package com.corundumstudio.socketio.demo.client;
import io.socket.client.IO;
import io.socket.client.Socket;
import io.socket.emitter.Emitter;
import java.net.URISyntaxException;
/**
* Created by yangjunming on 2017/1/13.
*/
public class DemoSocketClient {
public static void main(String[] args) throws URISyntaxException, InterruptedException {
IO.Options options = new IO.Options();
options.transports = new String[]{"websocket"};
options.reconnectionAttempts = 2;
options.reconnectionDelay = 1000;//失败重连的时间间隔
options.timeout = 500;//连接超时时间(ms)
// final Socket socket = IO.socket("http://localhost:9092/?token=123456", options);//错误的token值连接示例
final Socket socket = IO.socket("http://localhost:9092/?token=87df42a424c48313ef6063e6a5c63297", options);
socket.on(Socket.EVENT_CONNECT, new Emitter.Listener() {
@Override
public void call(Object... args) {
socket.send("hello");
}
});
socket.on(Socket.EVENT_DISCONNECT, new Emitter.Listener() {
@Override
public void call(Object... args) {
System.out.println("连接关闭");
}
});
socket.on(Socket.EVENT_MESSAGE, new Emitter.Listener() {
@Override
public void call(Object... args) {
System.out.println("sessionId:" + socket.id());
for (Object obj : args) {
System.out.println(obj);
}
System.out.println("收到服务器应答，将要断开连接...");
socket.disconnect();
}
});
socket.connect();
}
}
客户端类似，也是加一些事件监听，然后做相应处理即可。
上面的例子，演示了client向server连接时，如何做基本的连接认证(基于token），以及基本的消息收发。
运行效果：
服务端输出
sessionId:f52e9fa3-6216-4742-87de-3228a74469f9,token:87df42a424c48313ef6063e6a5c63297
client data:hello
客户端输出
sessionId:f52e9fa3-6216-4742-87de-3228a74469f9
hi
收到服务器应答，将要断开连接...
连接关闭
注：框架已经自带了一些预设的事件，见下面的代码片段
/**
* Called on a successful connection.
*/
public static final String EVENT_OPEN = "open";
/**
* Called on a disconnection.
*/
public static final String EVENT_CLOSE = "close";
public static final String EVENT_PACKET = "packet";
public static final String EVENT_ERROR = "error";
/**
* Called on a connection error.
*/
public static final String EVENT_CONNECT_ERROR = "connect_error";
/**
* Called on a connection timeout.
*/
public static final String EVENT_CONNECT_TIMEOUT = "connect_timeout";
/**
* Called on a successful reconnection.
*/
public static final String EVENT_RECONNECT = "reconnect";
/**
* Called on a reconnection attempt error.
*/
public static final String EVENT_RECONNECT_ERROR = "reconnect_error";
public static final String EVENT_RECONNECT_FAILED = "reconnect_failed";
public static final String EVENT_RECONNECT_ATTEMPT = "reconnect_attempt";
public static final String EVENT_RECONNECTING = "reconnecting";
public static final String EVENT_PING = "ping";
public static final String EVENT_PONG = "pong";
如果不够的话，可以自行扩展，无非就是一些字符串常量。
原文：http://www.cnblogs.com/yjmyzz/p/netty-socketio-demo.html