Glassfish 和 Jetty 的 Java WebSockets 教程 · JavaTutorialNetwork 中文系列教程

# Glassfish 和 Jetty 的 Java WebSockets 教程 > 原文： [https://javatutorial.net/java-websockets-tutorial](https://javatutorial.net/java-websockets-tutorial) 在本教程中，我将向您展示如何制作一个在 Glassfish 4 上运行的简单聊天应用程序。我将使用两个 API 来实现此目的：Jetty 和 JSON API。我们将首先从基于 Web 的客户端开始。看下面的图片。它的用户名有一个字段，您可以在其中输入聊天消息的一个字段，以及到目前为止保存对话的文本区域。 ![WebSocket chat client](https://img.kancloud.cn/5d/e2/5de214732139c3cc6f1e549911844f22_553x448.jpg) ## 网络客户端和 Javascript 我们可以在 JavaScript 中使用`WebSocket`在客户端和服务器之间创建全双工连接。 JavaScript `Websocket`具有 3 种方法 `onopen` – 在客户端和服务器创建连接时调用 `onmessage` – 服务器向客户端发送消息时执行此方法 `onclose` – 客户端和服务器之间的连接被破坏时调用此方法用户单击“发送”按钮后，用户名和消息本身将转换为 JSON 格式并发送到服务器。您将在下面找到客户端的完整代码： ```java <?xml version='1.0' encoding='UTF-8' ?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xmlns:h="http://java.sun.com/jsf/html"> <h:head> <title>WebSockets Chat</title> <meta name="author" content="javatutorial.net" /> <script type="text/javascript" charset="utf-8" src="js/jquery-1.3.2.js"></script> <link type="text/css" rel="stylesheet" href="css/style.css" /> <script type="text/javascript"> var ws; $(document).ready( function() { ws = new WebSocket("ws://localhost:8080/chat"); ws.onopen = function(event) { } ws.onmessage = function(event) { var $textarea = $('#messages'); var json = JSON.parse(event.data); $textarea.val($textarea.val() + json.username + ": " + json.message + "\n"); $textarea.animate({ scrollTop : $textarea.height() }, 1000); } ws.onclose = function(event) { } }); function sendMessage() { var message = { "username": $('#username').val(), "message": $('#message').val() } ws.send(JSON.stringify(message)); $('#message').val(''); } </script> </h:head> <h:body> <div id="body"> <div id="menu"> <p class="welcome"> User: <input id="username" value="anonymous" /> </p> <div style="clear: both"></div> </div> <div id="chatbox"> <textarea id="messages" rows="16" cols="50" readonly="readonly"></textarea> </div> <form name="message" action=""> <input name="usermsg" type="text" id="message" size="63" /> <input type="button" name="submitmsg" value="Send..." onclick="sendMessage();" /> </form> </div> </h:body> </html> ``` ## 实现 Websocket 服务器我将使用 Glassfish 4.1 部署 WebSocket 服务器。我们将使用 Jetty 9.x 作为 Websocket 服务器，而 Glassfish 已在 Jetty 中内置。我们将使用的另一个 API 是 JSON API，它也是 Glassfish 4 的一部分。请查看下面的 Maven pom 文件以获取所需的依赖关系 ```java <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/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>net.javatutorial</groupId> <artifactId>ChatServer</artifactId> <version>0.0.1</version> <packaging>war</packaging> <name>ChatServer</name> <url>http://javatutorial.net</url> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> </properties> <dependencies> <dependency> <groupId>javax</groupId> <artifactId>javaee-api</artifactId> <version>6.0</version> <scope>provided</scope> </dependency> <dependency> <groupId>org.eclipse.jetty</groupId> <artifactId>jetty-server</artifactId> <version>9.2.7.v20150116</version> <scope>provided</scope> </dependency> <dependency> <groupId>org.eclipse.jetty.websocket</groupId> <artifactId>javax-websocket-server-impl</artifactId> <version>9.2.7.v20150116</version> <scope>provided</scope> </dependency> <dependency> <groupId>org.eclipse.jetty</groupId> <artifactId>jetty-annotations</artifactId> <version>9.2.7.v20150116</version> <scope>provided</scope> </dependency> <dependency> <groupId>org.eclipse.jetty</groupId> <artifactId>jetty-webapp</artifactId> <version>9.2.7.v20150116</version> <scope>provided</scope> </dependency> <dependency> <groupId>javax.json</groupId> <artifactId>javax.json-api</artifactId> <version>1.0</version> <scope>provided</scope> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <version>3.1</version> <inherited>true</inherited> <configuration> <source>1.6</source> <target>1.6</target> </configuration> </plugin> <plugin> <artifactId>maven-war-plugin</artifactId> <version>2.3</version> <configuration> <webXml>src/main/webapp/WEB-INF/web.xml</webXml> </configuration> </plugin> </plugins> </build> </project> ``` `ChatMessage`对象保存用户名和消息字符串，以提供`Decoder`和`Encoder`将结构转换为 JSON 格式。 ```java package net.javatutorial.chatserver.pojos; import java.io.StringReader; import java.util.Collections; import javax.json.Json; import javax.json.JsonObject; import javax.json.JsonReader; import javax.json.JsonReaderFactory; import javax.websocket.DecodeException; import javax.websocket.Decoder; import javax.websocket.EncodeException; import javax.websocket.Encoder; import javax.websocket.EndpointConfig; public class ChatMessage { public static class MessageEncoder implements Encoder.Text<ChatMessage> { @Override public void init(EndpointConfig config) { } @Override public String encode(ChatMessage message) throws EncodeException { return Json.createObjectBuilder() .add("username", message.getUsername()) .add("message", message.getMessage()).build().toString(); } @Override public void destroy() { } } public static class MessageDecoder implements Decoder.Text<ChatMessage> { private JsonReaderFactory factory = Json .createReaderFactory(Collections.<String, Object> emptyMap()); @Override public void init(EndpointConfig config) { } @Override public ChatMessage decode(String str) throws DecodeException { ChatMessage message = new ChatMessage(); JsonReader reader = factory.createReader(new StringReader(str)); JsonObject json = reader.readObject(); message.setUsername(json.getString("username")); message.setMessage(json.getString("message")); return message; } @Override public boolean willDecode(String str) { return true; } @Override public void destroy() { } } private String username; private String message; public ChatMessage() { } public ChatMessage(String username, String message) { super(); this.username = username; this.message = message; } public String getUsername() { return username; } public void setUsername(String username) { this.username = username; } public String getMessage() { return message; } public void setMessage(String message) { this.message = message; } } ``` 最后，我们将需要 Websocket 服务器端点。 ```java package net.javatutorial.chatserver.sockets; import java.io.IOException; import java.util.Collections; import java.util.HashSet; import java.util.Set; import javax.websocket.EncodeException; import javax.websocket.OnClose; import javax.websocket.OnMessage; import javax.websocket.OnOpen; import javax.websocket.Session; import javax.websocket.server.ServerEndpoint; import net.javatutorial.chatserver.pojos.ChatMessage; import net.javatutorial.chatserver.pojos.ChatMessage.MessageDecoder; import net.javatutorial.chatserver.pojos.ChatMessage.MessageEncoder; @ServerEndpoint(value = "/chat", encoders = { MessageEncoder.class }, decoders = { MessageDecoder.class }) public class ChatServerEndpoint { private static final Set<Session> sessions = Collections .synchronizedSet(new HashSet<Session>()); @OnOpen public void onOpen(Session session) { sessions.add(session); } @OnClose public void onClose(Session session) { sessions.remove(session); } @OnMessage public void onMessage(ChatMessage message, Session client) throws IOException, EncodeException { for (Session session : sessions) { session.getBasicRemote().sendObject(message); } } } ``` 您可以在此处下载完整的[源代码和 Eclipse 项目](http://javatutorial.net/downloads/WebSocketsChat.zip)。