java WebSocket 简易聊天消息推送

环境：

JDK.1.7.0_51

apache-tomcat-7.0.53

java jar包：tomcat-coyote.jar、tomcat-juli.jar、websocket-api.jar

ChatAnnotation消息发送类：

import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.atomic.AtomicInteger;

import javax.websocket.OnClose;
import javax.websocket.OnError;
import javax.websocket.OnMessage;
import javax.websocket.OnOpen;
import javax.websocket.Session;
import javax.websocket.server.ServerEndpoint;

import org.apache.juli.logging.Log;
import org.apache.juli.logging.LogFactory;

import com.util.HTMLFilter; 

/**
 * WebSocket 消息推送服务类
 * @author 胡汉三
 *
 * 2014-11-18 下午7:53:13
 */
@ServerEndpoint(value = "/websocket/chat")
public class ChatAnnotation {

    private static final Log log = LogFactory.getLog(ChatAnnotation.class);

    private static final String GUEST_PREFIX = "Guest";
    private static final AtomicInteger connectionIds = new AtomicInteger(0);
    private static final Map connections = new HashMap();

    private final String nickname;
    private Session session;

    public ChatAnnotation() {
        nickname = GUEST_PREFIX + connectionIds.getAndIncrement();
    }


    @OnOpen
    public void start(Session session) {
        this.session = session;
        connections.put(nickname, this); 
        String message = String.format("* %s %s", nickname, "has joined.");
        broadcast(message);
    }


    @OnClose
    public void end() {
        connections.remove(this);
        String message = String.format("* %s %s",
                nickname, "has disconnected.");
        broadcast(message);
    }


    /**
     * 消息发送触发方法
     * @param message
     */
    @OnMessage
    public void incoming(String message) {
        // Never trust the client
        String filteredMessage = String.format("%s: %s",
                nickname, HTMLFilter.filter(message.toString()));
        broadcast(filteredMessage);
    }

    @OnError
    public void onError(Throwable t) throws Throwable {
        log.error("Chat Error: " + t.toString(), t);
    }

    /**
     * 消息发送方法
     * @param msg
     */
    private static void broadcast(String msg) {
    	if(msg.indexOf("Guest0")!=-1){
    		sendUser(msg);
    	} else{
    		sendAll(msg);
    	}
    } 
    
    /**
     * 向所有用户发送
     * @param msg
     */
    public static void sendAll(String msg){
    	for (String key : connections.keySet()) {
        	ChatAnnotation client = null ;
            try {
            	client = (ChatAnnotation) connections.get(key);
                synchronized (client) {
                    client.session.getBasicRemote().sendText(msg);
                }
            } catch (IOException e) { 
                log.debug("Chat Error: Failed to send message to client", e);
                connections.remove(client);
                try {
                    client.session.close();
                } catch (IOException e1) {
                    // Ignore
                }
                String message = String.format("* %s %s",
                        client.nickname, "has been disconnected.");
                broadcast(message);
            }
        }
    }
    
    /**
     * 向指定用户发送消息 
     * @param msg
     */
    public static void sendUser(String msg){
    	ChatAnnotation c = (ChatAnnotation)connections.get("Guest0");
		try {
			c.session.getBasicRemote().sendText(msg);
		} catch (IOException e) {
			log.debug("Chat Error: Failed to send message to client", e);
            connections.remove(c);
            try {
                c.session.close();
            } catch (IOException e1) {
                // Ignore
            }
            String message = String.format("* %s %s",
                    c.nickname, "has been disconnected.");
            broadcast(message);  
		} 
    }
}

HTMLFilter工具类：

/**
 * HTML 工具类 
 *
 * @author 胡汉三
 */
public final class HTMLFilter {
    public static String filter(String message) {
        if (message == null)
            return (null);
        char content[] = new char[message.length()];
        message.getChars(0, message.length(), content, 0);
        StringBuilder result = new StringBuilder(content.length + 50);
        for (int i = 0; i < content.length; i++) {
            switch (content[i]) {
            case '<':
                result.append("<");
                break;
            case '>':
                result.append(">");
                break;
            case '&':
                result.append("&");
                break;
            case '"':
                result.append(""");
                break;
            default:
                result.append(content[i]);
            }
        }
        return (result.toString());
    }
}

页面：

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>




    
    
    


Seems your browser doesn't support Javascript! Websockets rely on Javascript being enabled. Please enable
    Javascript and reload this page!

    

        
    
    

        

    

可指定发送给某个用户，也可全部发送，详情见ChatAnnotation类的broadcast方法。

程序发布时记得删除tomcat-coyote.jar、tomcat-juli.jar、websocket-api.jar这三个jar包在启动Tomcat。

程序截图，Guest0用户发送信息的信息，在后台进行了判断只发送给自己：

Guest1：

Guest2：