Java现实WebSocket
前言
伴随着HTML5技术的新起,WebSocket?作为一种浏览器与服务器的核心通信技术,被嵌入到了浏览器的内核中。WebSocket 的出现使得浏览器提供对 Socket 的支持成为可能,从而在浏览器和服务器之间提供了一个基于 TCP 连接的双向通道。
所有新的技术都会第一时间在Java社区,出现对应的开源项目!WebSocket也被实现在多种Java的开源库中。WebSocket实现列表:https://java.net/projects/websocket-spec/pages/WebSocketAPIs/text。
今天就让我们用Java来解密一下WebSocket的服务器端和客户端 实现。
目录
用Java实现的websocket,在Server端是通过Tomcat内嵌支持的,我们需要开发一个继承WebSocketServlet 的servlet就可以了,与普通的HttpServlet没有太大区别。
1). JAVA环境:
~ D:\workspace\java>java -versionjava version "1.6.0_45"Java(TM) SE Runtime Environment (build 1.6.0_45-b06)Java HotSpot(TM) 64-Bit Server VM (build 20.45-b01, mixed mode)~ D:\workspace\java>mvn -versionApache Maven 3.0.5 (r01de14724cdef164cd33c7c8c2fe155faf9602da; 2013-02-19 21:51:28+0800)Maven home: D:\toolkit\maven3\bin\..Java version: 1.6.0_45, vendor: Sun Microsystems Inc.Java home: D:\toolkit\java\jdk6\jreDefault locale: zh_CN, platform encoding: GBKOS name: "windows 7", version: "6.1", arch: "amd64", family: "windows"~ D:\toolkit\tomcat7\bin>catalina.bat versionUsing CATALINA_BASE: "D:\toolkit\tomcat7"Using CATALINA_HOME: "D:\toolkit\tomcat7"Using CATALINA_TMPDIR: "D:\toolkit\tomcat7\temp"Using JRE_HOME: "D:\toolkit\java\jdk6"Using CLASSPATH: "D:\toolkit\tomcat7\bin\bootstrap.jar;D:\toolkit\tomcat7\bin\tomcat-juli.jar"Server version: Apache Tomcat/7.0.39Server built: Mar 22 2013 12:37:24Server number: 7.0.39.0OS Name: Windows 7OS Version: 6.1Architecture: amd64JVM Version: 1.6.0_45-b06JVM Vendor: Sun Microsystems Inc.
2). maven构建一个简单的webapp项目。
~ D:\workspace\java>mvn archetype:generate -DgroupId=org.conan.websocket -DartifactId=websocketServer -DarchetypeArtifactId=maven-archetype-webapp[INFO] ----------------------------------------------------------------------------[INFO] Using following parameters for creating project from Old (1.x) Archetype: maven-archetype-webapp:1.0[INFO] ----------------------------------------------------------------------------[INFO] Parameter: groupId, Value: org.conan.websocket[INFO] Parameter: packageName, Value: org.conan.websocket[INFO] Parameter: package, Value: org.conan.websocket[INFO] Parameter: artifactId, Value: websocketServer[INFO] Parameter: basedir, Value: D:\workspace\java[INFO] Parameter: version, Value: 1.0-SNAPSHOT[INFO] project created from Old (1.x) Archetype in dir: D:\workspace\java\websocketServer[INFO] ------------------------------------------------------------------------[INFO] BUILD SUCCESS[INFO] ------------------------------------------------------------------------[INFO] Total time: 1:42.200s[INFO] Finished at: Tue Aug 20 13:57:05 CST 2013[INFO] Final Memory: 9M/179M[INFO] ------------------------------------------------------------------------
3). 配置项目目录
~ D:\workspace\java>cd websocketServer~ D:\workspace\java\websocketServer>mkdir src\main\java~ D:\workspace\java\websocketServer>rm src\main\webapp\index.jsp
导入到Eclipse的项目截图
4). 编辑pom.xml配置文件,增加tomcat的依赖
~ vi pom.xml<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd"><modelVersion>4.0.0</modelVersion><groupId>org.conan.websocket</groupId><artifactId>websocketServer</artifactId><packaging>war</packaging><version>1.0-SNAPSHOT</version><name>websocketServer Maven Webapp</name><url>http://maven.apache.org</url><dependencies><dependency><groupId>org.apache.tomcat</groupId><artifactId>tomcat-catalina</artifactId><version>7.0.27</version><scope>provided</scope></dependency><dependency><groupId>org.apache.tomcat</groupId><artifactId>tomcat-coyote</artifactId><version>7.0.39</version><scope>provided</scope></dependency></dependencies><build><finalName>websocketServer</finalName></build></project>
下载并安装类库
~ D:\workspace\java\websocketServer>mvn clean install
5). 创建DemoServlet,服务器端运行类
~ vi src/main/java/org/conan/websocket/DemoServlet.javapackage org.conan.websocket;import java.io.IOException;import java.nio.ByteBuffer;import java.nio.CharBuffer;import java.util.ArrayList;import javax.servlet.http.HttpServletRequest;import org.apache.catalina.websocket.MessageInbound;import org.apache.catalina.websocket.StreamInbound;import org.apache.catalina.websocket.WebSocketServlet;import org.apache.catalina.websocket.WsOutbound;public class DemoServlet extends WebSocketServlet { private static final long serialVersionUID = -4853540828121130946L; private static ArrayList mmiList = new ArrayList(); @Override protected StreamInbound createWebSocketInbound(String str, HttpServletRequest request) { return new MyMessageInbound(); } private class MyMessageInbound extends MessageInbound { WsOutbound myoutbound; @Override public void onOpen(WsOutbound outbound) { try { System.out.println("Open Client."); this.myoutbound = outbound; mmiList.add(this); outbound.writeTextMessage(CharBuffer.wrap("Hello!")); } catch (IOException e) { e.printStackTrace(); } } @Override public void onClose(int status) { System.out.println("Close Client."); mmiList.remove(this); } @Override public void onTextMessage(CharBuffer cb) throws IOException { System.out.println("Accept Message : " + cb); for (MyMessageInbound mmib : mmiList) { CharBuffer buffer = CharBuffer.wrap(cb); mmib.myoutbound.writeTextMessage(buffer); mmib.myoutbound.flush(); } } @Override public void onBinaryMessage(ByteBuffer bb) throws IOException { } }}
6). 修改web.xml文件
~ vi src/main/webapp/WEB-INF/web.xml<?xml version="1.0" encoding="UTF-8"?><web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"><display-name>Archetype Created Web Application</display-name><servlet><servlet-name>wsServlet</servlet-name><servlet-class>org.conan.websocket.DemoServlet</servlet-class></servlet><servlet-mapping><servlet-name>wsServlet</servlet-name><url-pattern>/wsServlet</url-pattern></servlet-mapping></web-app>
7). 编译,打包,部署到tomcat
~ D:\workspace\java\websocketServer>mvn clean install~ D:\workspace\java\websocketServer>cp target\websocketServer.war D:\toolkit\tomcat7\webapps
启动tomcat
~ D:\toolkit\tomcat7>bin\catalina.bat runUsing CATALINA_BASE: "D:\toolkit\tomcat7"Using CATALINA_HOME: "D:\toolkit\tomcat7"Using CATALINA_TMPDIR: "D:\toolkit\tomcat7\temp"Using JRE_HOME: "D:\toolkit\java\jdk6"Using CLASSPATH: "D:\toolkit\tomcat7\bin\bootstrap.jar;D:\toolkit\tomcat7\bin\tomcat-juli.jar"2013-8-20 14:43:29 org.apache.catalina.core.AprLifecycleListener init信息: The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: D:\toolkit\java\jdk6\bin;C:\Windows\Sun\Java\bin;C:\Windows\system32;C:\Windows;D:\toolkit\Rtools\bin;D:\toolkit\Rtools\gcc-4.6.3\bin;C:\Program Files (x86)\Common Files\NetSarang;C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\Windows\System32\WindowsPowerShell\v1.0\;D:\toolkit\Git\cmd;D:\toolkit\Git\bin;C:\Program Files (x86)\Microsoft SQL Server\100\Tools\Binn\;C:\Program Files\Microsoft SQL Server\100\Tools\Binn\;C:\Program Files\Microsoft SQL Server\100\DTS\Binn\;c:\Program Files (x86)\Common Files\Ulead Systems\MPEG;C:\Program Files (x86)\QuickTime\QTSystem\;D:\toolkit\MiKTex\miktex\bin\x64\;D:\toolkit\sshclient;D:\toolkit\ant19\bin;D:\toolkit\eclipse;D:\toolkit\gradle15\bin;D:\toolkit\java\jdk6\bin;D:\toolkit\maven3\bin;D:\toolkit\mysql56\bin;D:\toolkit\python27;D:\toolkit\putty;C:\Program Files\R\R-3.0.1\bin\x64;D:\toolkit\mongodb243\bin;D:\toolkit\php54;D:\toolkit\nginx140;D:\toolkit\nodejs;D:\toolkit\npm12\bin;D:\toolkit\java\jdk6\jre\bin\server;.2013-8-20 14:43:30 org.apache.coyote.AbstractProtocol init信息: Initializing ProtocolHandler ["http-bio-8080"]2013-8-20 14:43:30 org.apache.coyote.AbstractProtocol init信息: Initializing ProtocolHandler ["ajp-bio-8009"]2013-8-20 14:43:30 org.apache.catalina.startup.Catalina load信息: Initialization processed in 1409 ms2013-8-20 14:43:30 org.apache.catalina.core.StandardService startInternal信息: Starting service Catalina2013-8-20 14:43:30 org.apache.catalina.core.StandardEngine startInternal信息: Starting Servlet Engine: Apache Tomcat/7.0.392013-8-20 14:43:30 org.apache.catalina.startup.HostConfig deployWAR信息: Deploying web application archive D:\toolkit\tomcat7\webapps\websocketServer.war2013-8-20 14:43:30 org.apache.catalina.startup.HostConfig deployDirectory信息: Deploying web application directory D:\toolkit\tomcat7\webapps\docs2013-8-20 14:43:30 org.apache.catalina.startup.HostConfig deployDirectory信息: Deploying web application directory D:\toolkit\tomcat7\webapps\examples2013-8-20 14:43:31 org.apache.catalina.startup.HostConfig deployDirectory信息: Deploying web application directory D:\toolkit\tomcat7\webapps\host-manager2013-8-20 14:43:31 org.apache.catalina.startup.HostConfig deployDirectory信息: Deploying web application directory D:\toolkit\tomcat7\webapps\manager2013-8-20 14:43:31 org.apache.catalina.startup.HostConfig deployDirectory信息: Deploying web application directory D:\toolkit\tomcat7\webapps\ROOT2013-8-20 14:43:31 org.apache.coyote.AbstractProtocol start信息: Starting ProtocolHandler ["http-bio-8080"]2013-8-20 14:43:31 org.apache.coyote.AbstractProtocol start信息: Starting ProtocolHandler ["ajp-bio-8009"]2013-8-20 14:43:31 org.apache.catalina.startup.Catalina start信息: Server startup in 996 ms
websocket的服务地址:
ws://localhost:8080/websocketServer/wsServlet
通过Java实现websocket的客户端,这里将介绍的是”Java-WebSocket”。另外,我发现Java7已经原生支持了websocket, “JSR 365, Java API for WebSocket” (看来要开始学学java7和java8了,我在java6的时代停滞3-4年了。)
现在我们使用“Java-WebSocket”
1). 修改pom.xml文件,增加jetty websocket依赖库
~ vi pom.xml<dependency><groupId>org.java-websocket</groupId><artifactId>Java-WebSocket</artifactId><version>1.3.0</version></dependency>
下载依赖库
~ D:\workspace\java\websocketServer>mvn clean install
2). 新建文件,ChatClient.java
~ vi src/main/java/org/conan/websocket/ChatClient.javapackage org.conan.websocket;import java.awt.Container;import java.awt.GridLayout;import java.awt.event.ActionEvent;import java.awt.event.ActionListener;import java.awt.event.WindowEvent;import java.net.URI;import java.net.URISyntaxException;import javax.swing.JButton;import javax.swing.JComboBox;import javax.swing.JFrame;import javax.swing.JScrollPane;import javax.swing.JTextArea;import javax.swing.JTextField;import org.java_websocket.WebSocketImpl;import org.java_websocket.client.WebSocketClient;import org.java_websocket.drafts.Draft;import org.java_websocket.drafts.Draft_10;import org.java_websocket.drafts.Draft_17;import org.java_websocket.drafts.Draft_75;import org.java_websocket.drafts.Draft_76;import org.java_websocket.handshake.ServerHandshake;public class ChatClient extends JFrame implements ActionListener { private static final long serialVersionUID = -6056260699202978657L; private final JTextField uriField; private final JButton connect; private final JButton close; private final JTextArea ta; private final JTextField chatField; private final JComboBox draft; private WebSocketClient cc; public ChatClient( String defaultlocation ) { super( "WebSocket Chat Client" ); Container c = getContentPane(); GridLayout layout = new GridLayout(); layout.setColumns( 1 ); layout.setRows( 6 ); c.setLayout( layout ); Draft[] drafts = { new Draft_17(), new Draft_10(), new Draft_76(), new Draft_75() }; draft = new JComboBox( drafts ); c.add( draft ); uriField = new JTextField(); uriField.setText( defaultlocation ); c.add( uriField ); connect = new JButton( "Connect" ); connect.addActionListener( this ); c.add( connect ); close = new JButton( "Close" ); close.addActionListener( this ); close.setEnabled( false ); c.add( close ); JScrollPane scroll = new JScrollPane(); ta = new JTextArea(); scroll.setViewportView( ta ); c.add( scroll ); chatField = new JTextField(); chatField.setText( "" ); chatField.addActionListener( this ); c.add( chatField ); java.awt.Dimension d = new java.awt.Dimension( 300, 400 ); setPreferredSize( d ); setSize( d ); addWindowListener( new java.awt.event.WindowAdapter() { @Override public void windowClosing( WindowEvent e ) { if( cc != null ) { cc.close(); } dispose(); } } ); setLocationRelativeTo( null ); setVisible( true ); } public void actionPerformed( ActionEvent e ) { if( e.getSource() == chatField ) { if( cc != null ) { cc.send( chatField.getText() ); chatField.setText( "" ); chatField.requestFocus(); } } else if( e.getSource() == connect ) { try { // cc = new ChatClient(new URI(uriField.getText()), area, ( Draft ) draft.getSelectedItem() ); cc = new WebSocketClient( new URI( uriField.getText() ), (Draft) draft.getSelectedItem() ) { @Override public void onMessage( String message ) { ta.append( "got: " + message + "\n" ); ta.setCaretPosition( ta.getDocument().getLength() ); } @Override public void onOpen( ServerHandshake handshake ) { ta.append( "You are connected to ChatServer: " + getURI() + "\n" ); ta.setCaretPosition( ta.getDocument().getLength() ); } @Override public void onClose( int code, String reason, boolean remote ) { ta.append( "You have been disconnected from: " + getURI() + "; Code: " + code + " " + reason + "\n" ); ta.setCaretPosition( ta.getDocument().getLength() ); connect.setEnabled( true ); uriField.setEditable( true ); draft.setEditable( true ); close.setEnabled( false ); } @Override public void onError( Exception ex ) { ta.append( "Exception occured ...\n" + ex + "\n" ); ta.setCaretPosition( ta.getDocument().getLength() ); ex.printStackTrace(); connect.setEnabled( true ); uriField.setEditable( true ); draft.setEditable( true ); close.setEnabled( false ); } }; close.setEnabled( true ); connect.setEnabled( false ); uriField.setEditable( false ); draft.setEditable( false ); cc.connect(); } catch ( URISyntaxException ex ) { ta.append( uriField.getText() + " is not a valid WebSocket URI\n" ); } } else if( e.getSource() == close ) { cc.close(); } } public static void main( String[] args ) { WebSocketImpl.DEBUG = true; String location; if( args.length != 0 ) { location = args[ 0 ]; System.out.println( "Default server url specified: \'" + location + "\'" ); } else { location = "ws://localhost:8887"; System.out.println( "Default server url not specified: defaulting to \'" + location + "\'" ); } new ChatClient( location ); }}
运行程序:
这里会启动一个Java的GUI界面。输入websocket服务的地址:ws://localhost:8080/websocketServer/wsServlet
查看Java客户端和HTML客户端的对话,在Java客户端中,输入”你好,小朋友”。
我们发现在html的客户端中,同样出现的”你好,小朋友”的消息记录。
这样,我们就在Java6的环境中,实现了Java WebSocket的客户端程序。
编写一个纯HTML的网页,通过浏览器原生的websocketAPI实现对websocket的服务的调用。
~ vi D:\workspace\javascript\tomcatClient.html<!DOCTYPE html><html><head><meta charset=UTF-8><title>Tomcat WebSocket Chat</title><script>var ws = new WebSocket("ws://localhost:8080/websocketServer/wsServlet");ws.onopen = function(){};ws.onmessage = function(message){document.getElementById("chatlog").textContent += message.data + "\n";};function postToServer(){ws.send(document.getElementById("msg").value);document.getElementById("msg").value = "";}function closeConnect(){ws.close();}</script></head><body><textarea id="chatlog" readonly></textarea><br/><input id="msg" type="text" /><button type="submit" id="sendButton" onClick="postToServer()">Send!</button><button type="submit" id="sendButton" onClick="closeConnect()">End</button></body></html>
通过浏览器刚刚编写的文件:file:///D:/workspace/javascript/tomcatClient.html
打开两个窗口:
在右边窗口输入”我是BBB”,然后点击send。左边,右这,和后台日志,同时增加了”我是BBB”。
原来在浏览器上面,实现聊天功能是如此地简单!!
转载请注明出处:
http://blog.fens.me/nodejs-websocket-intro/