HTML5:WebSocket实现
搞定这个的过程远比想象的困难许多。网上许多教程,一一尝试,大多随着库版本的改变以及浏览器对协议支持的改变以失败告终,即使成功的也语焉不详,以下为步骤。
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1. 运行环境
Java EE IDE
apache-tomcat-7.0.29(7.0.27之后才支持websocket)
IE(版本:10.0.9200.16384)
Firefox(版本:15.0)
Google Chrome(版本:23.0.1251.2)
2. 详细步骤
(1) 在Java EE IDE中,File->New->Dynamic Web Project,使其如下配置
Target runtime中必须是Apache Tomcat v7.0,并且最好是引用7.0.29(可在New Runtime中配置)
注意,点击Next->,再点击Next->,如下图,注意勾选Generate web.xml deployment descriptor,点击Finish
(2) 在Java Resources下src下New->Class,如下图
再在src下New->Class,如下图
下面贴上上述类的代码
package com.trump.web.servlet; import java.util.ArrayList; import java.util.List; import java.util.logging.Logger; import javax.servlet.http.HttpServletRequest; import org.apache.catalina.websocket.StreamInbound; import org.apache.catalina.websocket.WebSocketServlet; public class EchoServlet extends WebSocketServlet { private static final long serialVersionUID = -4104682919545889813L; private Logger logger = Logger.getLogger(EchoServlet.class.getName()); private static ListsocketList = new ArrayList (); @Override protected StreamInbound createWebSocketInbound(String subProtocol, HttpServletRequest request) { // TODO Auto-generated method stub logger.info("receive ws request"); return new MyMessageInbound(); } public static synchronized List getSocketList() { return socketList; } }
package com.trump.web.servlet; import java.io.IOException; import java.nio.ByteBuffer; import java.nio.CharBuffer; import java.util.logging.Logger; import org.apache.catalina.websocket.MessageInbound; import org.apache.catalina.websocket.WsOutbound; public class MyMessageInbound extends MessageInbound { private int userIdName = 0; private Logger logger = Logger.getLogger(MyMessageInbound.class.getName()); public int getUserIdName() { return userIdName; } protected void onOpen(WsOutbound outbound) { super.onOpen(outbound); userIdName = outbound.hashCode(); EchoServlet.getSocketList().add(this); logger.info("Server onOpen"); } protected void onClose(int status) { EchoServlet.getSocketList().remove(this); super.onClose(status); logger.info("Server onClose"); } // 有二进制消息数据到达,比如音频等文件传输 @Override protected void onBinaryMessage(ByteBuffer buffer) throws IOException { logger.info("Binary Message Receive: " + buffer.remaining()); } @Override protected void onTextMessage(CharBuffer buffer) throws IOException { String msgOriginal = buffer.toString(); int startIndex = msgOriginal.indexOf("!@#$%"); String nikeName = msgOriginal.substring(0, startIndex); String textMsg = msgOriginal.substring(startIndex + 5); // 将字符数组包装到缓冲区中 // 给定的字符数组将支持新缓冲区;即缓冲区修改将导致数组修改,反之亦然 String countMsg = EchoServlet.getSocketList().size() + "人同时在线"; logger.info("Server onTextMessage: " + countMsg + nikeName + ":" + textMsg); String msg1 = nikeName + ": " + textMsg; String msg2 = "我: " + textMsg; for (MyMessageInbound messageInbound : EchoServlet.getSocketList()) { CharBuffer msgBuffer1 = CharBuffer.wrap(msg1); CharBuffer msgBuffer2 = CharBuffer.wrap(msg2); WsOutbound outbound = messageInbound.getWsOutbound(); if (messageInbound.getUserIdName() != this.getUserIdName()) { outbound.writeTextMessage(msgBuffer1); outbound.flush(); } else { outbound.writeTextMessage(msgBuffer2); } } } }
(3) 打开WebContent下WEB-INF下web.xml,编辑为
myWebSocket index.html index.htm index.jsp default.html default.htm default.jsp echo com.trump.web.servlet.EchoServlet echo *.ws
(4) 右击项目myWebSocket->Run As->Run on Server,如下图,点击Finish,
可以看到Tomacat正常运行,如下图
(5) 在任意位置新建一个客户端,命名为client.html,内容如下
Web Socket Demo
(6) OK!打开浏览器,输入http://localhost:8080/webSocketTest/client.html
此时注意Tomcat打印出的信息,如下
3. WebSocket之所以受关注,是因为它的服务器端能主动发消息给客户端,即MyMessageInbound中onOpen函数可以让服务器做想做的事情。
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