java 实现websocket的两种方式

简单说明

1.两种方式，一种使用tomcat的websocket实现，一种使用spring的websocket

2.tomcat的方式需要tomcat 7.x，JEE7的支持。

3.spring与websocket整合需要spring 4.x，并且使用了socketjs，对不支持websocket的浏览器可以模拟websocket使用

方式一：tomcat

使用这种方式无需别的任何配置，只需服务端一个处理类，

服务器端代码

package com.Socket;  import java.io.IOException;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import javax.websocket.*;
import javax.websocket.server.PathParam;
import javax.websocket.server.ServerEndpoint;
import net.sf.json.JSONObject;  @ServerEndpoint("/websocket/{username}")
public class WebSocket {  private static int onlineCount = 0;  private static Map<String, WebSocket> clients = new ConcurrentHashMap<String, WebSocket>();  private Session session;  private String username;  @OnOpen  public void onOpen(@PathParam("username") String username, Session session) throws IOException {  this.username = username;  this.session = session;  addOnlineCount();  clients.put(username, this);  System.out.println("已连接");  }  @OnClose  public void onClose() throws IOException {  clients.remove(username);  subOnlineCount();  }  @OnMessage  public void onMessage(String message) throws IOException {  JSONObject jsonTo = JSONObject.fromObject(message);  if (!jsonTo.get("To").equals("All")){  sendMessageTo("给一个人", jsonTo.get("To").toString());  }else{  sendMessageAll("给所有人");  }  }  @OnError  public void onError(Session session, Throwable error) {  error.printStackTrace();  }  public void sendMessageTo(String message, String To) throws IOException {  // session.getBasicRemote().sendText(message);  //session.getAsyncRemote().sendText(message);  for (WebSocket item : clients.values()) {  if (item.username.equals(To) )  item.session.getAsyncRemote().sendText(message);  }  }  public void sendMessageAll(String message) throws IOException {  for (WebSocket item : clients.values()) {  item.session.getAsyncRemote().sendText(message);  }  }  public static synchronized int getOnlineCount() {  return onlineCount;  }  public static synchronized void addOnlineCount() {  WebSocket.onlineCount++;  }  public static synchronized void subOnlineCount() {  WebSocket.onlineCount--;  }  public static synchronized Map<String, WebSocket> getClients() {  return clients;  }
}

客户端js

var websocket = null;
var username = localStorage.getItem("name");  //判断当前浏览器是否支持WebSocket
if ('WebSocket' in window) {  websocket = new WebSocket("ws://" + document.location.host + "/WebChat/websocket/" + username + "/"+ _img);
} else {  alert('当前浏览器 Not support websocket')
}  //连接发生错误的回调方法
websocket.onerror = function() {  setMessageInnerHTML("WebSocket连接发生错误");
};  //连接成功建立的回调方法
websocket.onopen = function() {  setMessageInnerHTML("WebSocket连接成功");
}  //接收到消息的回调方法
websocket.onmessage = function(event) {  setMessageInnerHTML(event.data);
}  //连接关闭的回调方法
websocket.onclose = function() {  setMessageInnerHTML("WebSocket连接关闭");
}  //监听窗口关闭事件，当窗口关闭时，主动去关闭websocket连接，防止连接还没断开就关闭窗口，server端会抛异常。
window.onbeforeunload = function() {  closeWebSocket();
}  //关闭WebSocket连接
function closeWebSocket() {  websocket.close();
}

发送消息只需要使用websocket.send(“发送消息”)，就可以触发服务端的onMessage()方法，当连接时，触发服务器端onOpen()方法，此时也可以调用发送消息的方法去发送消息。关闭websocket时，触发服务器端onclose()方法，此时也可以发送消息，但是不能发送给自己，因为自己的已经关闭了连接，但是可以发送给其他人。

方法二：spring整合

此方式基于spring mvc框架，相关配置可以看我的相关博客文章

WebSocketConfig.java

这个类是配置类，所以需要在spring mvc配置文件中加入对这个类的扫描，第一个addHandler是对正常连接的配置，第二个是如果浏览器不支持websocket，使用socketjs模拟websocket的连接。

package com.websocket;  import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.socket.config.annotation.EnableWebSocket;
import org.springframework.web.socket.config.annotation.WebSocketConfigurer;
import org.springframework.web.socket.config.annotation.WebSocketHandlerRegistry;
import org.springframework.web.socket.handler.TextWebSocketHandler;  @Configuration
@EnableWebSocket
public class WebSocketConfig implements WebSocketConfigurer {  @Override  public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {  registry.addHandler(chatMessageHandler(),"/webSocketServer").addInterceptors(new ChatHandshakeInterceptor());  registry.addHandler(chatMessageHandler(), "/sockjs/webSocketServer").addInterceptors(new ChatHandshakeInterceptor()).withSockJS();  }  @Bean  public TextWebSocketHandler chatMessageHandler(){  return new ChatMessageHandler();  }  }

ChatHandshakeInterceptor.java

这个类的作用就是在连接成功前和成功后增加一些额外的功能，Constants.java类是一个工具类，两个常量。

package com.websocket;  import java.util.Map;
import org.apache.shiro.SecurityUtils;
import org.springframework.http.server.ServerHttpRequest;
import org.springframework.http.server.ServerHttpResponse;
import org.springframework.web.socket.WebSocketHandler;
import org.springframework.web.socket.server.support.HttpSessionHandshakeInterceptor;  public class ChatHandshakeInterceptor extends HttpSessionHandshakeInterceptor {  @Override  public boolean beforeHandshake(ServerHttpRequest request, ServerHttpResponse response, WebSocketHandler wsHandler,  Map<String, Object> attributes) throws Exception {  System.out.println("Before Handshake");  /* * if (request instanceof ServletServerHttpRequest) { * ServletServerHttpRequest servletRequest = (ServletServerHttpRequest) * request; HttpSession session = * servletRequest.getServletRequest().getSession(false); if (session != * null) { //使用userName区分WebSocketHandler，以便定向发送消息 String userName = * (String) session.getAttribute(Constants.SESSION_USERNAME); if * (userName==null) { userName="default-system"; } * attributes.put(Constants.WEBSOCKET_USERNAME,userName); *  * } } */  //使用userName区分WebSocketHandler，以便定向发送消息(使用shiro获取session,或是使用上面的方式)  String userName = (String) SecurityUtils.getSubject().getSession().getAttribute(Constants.SESSION_USERNAME);  if (userName == null) {  userName = "default-system";  }  attributes.put(Constants.WEBSOCKET_USERNAME, userName);  return super.beforeHandshake(request, response, wsHandler, attributes);  }  @Override  public void afterHandshake(ServerHttpRequest request, ServerHttpResponse response, WebSocketHandler wsHandler,  Exception ex) {  System.out.println("After Handshake");  super.afterHandshake(request, response, wsHandler, ex);  }  }

ChatMessageHandler.java

这个类是对消息的一些处理，比如是发给一个人，还是发给所有人，并且前端连接时触发的一些动作

package com.websocket;  import java.io.IOException;
import java.util.ArrayList;
import org.apache.log4j.Logger;
import org.springframework.web.socket.CloseStatus;
import org.springframework.web.socket.TextMessage;
import org.springframework.web.socket.WebSocketSession;
import org.springframework.web.socket.handler.TextWebSocketHandler;  public class ChatMessageHandler extends TextWebSocketHandler {  private static final ArrayList<WebSocketSession> users;// 这个会出现性能问题，最好用Map来存储，key用userid  private static Logger logger = Logger.getLogger(ChatMessageHandler.class);  static {  users = new ArrayList<WebSocketSession>();  }  /** * 连接成功时候，会触发UI上onopen方法 */  @Override  public void afterConnectionEstablished(WebSocketSession session) throws Exception {  System.out.println("connect to the websocket success......");  users.add(session);  // 这块会实现自己业务，比如，当用户登录后，会把离线消息推送给用户  // TextMessage returnMessage = new TextMessage("你将收到的离线");  // session.sendMessage(returnMessage);  }  /** * 在UI在用js调用websocket.send()时候，会调用该方法 */  @Override  protected void handleTextMessage(WebSocketSession session, TextMessage message) throws Exception {  sendMessageToUsers(message);  //super.handleTextMessage(session, message);  }  /** * 给某个用户发送消息 * * @param userName * @param message */  public void sendMessageToUser(String userName, TextMessage message) {  for (WebSocketSession user : users) {  if (user.getAttributes().get(Constants.WEBSOCKET_USERNAME).equals(userName)) {  try {  if (user.isOpen()) {  user.sendMessage(message);  }  } catch (IOException e) {  e.printStackTrace();  }  break;  }  }  }  /** * 给所有在线用户发送消息 * * @param message */  public void sendMessageToUsers(TextMessage message) {  for (WebSocketSession user : users) {  try {  if (user.isOpen()) {  user.sendMessage(message);  }  } catch (IOException e) {  e.printStackTrace();  }  }  }  @Override  public void handleTransportError(WebSocketSession session, Throwable exception) throws Exception {  if (session.isOpen()) {  session.close();  }  logger.debug("websocket connection closed......");  users.remove(session);  }  @Override  public void afterConnectionClosed(WebSocketSession session, CloseStatus closeStatus) throws Exception {  logger.debug("websocket connection closed......");  users.remove(session);  }  @Override  public boolean supportsPartialMessages() {  return false;  }  }

spring-mvc.xml

正常的配置文件，同时需要增加对WebSocketConfig.java类的扫描，并且增加

xmlns:websocket="http://www.springframework.org/schema/websocket"  http://www.springframework.org/schema/websocket   <a target="_blank" href="http://www.springframework.org/schema/websocket/spring-websocket-4.1.xsd">http://www.springframework.org/schema/websocket/spring-websocket-4.1.xsd</a>

客户端

<script type="text/javascript"  src="http://localhost:8080/Bank/js/sockjs-0.3.min.js"></script>  <script>  var websocket;  if ('WebSocket' in window) {  websocket = new WebSocket("ws://" + document.location.host + "/Bank/webSocketServer");  } else if ('MozWebSocket' in window) {  websocket = new MozWebSocket("ws://" + document.location.host + "/Bank/webSocketServer");  } else {  websocket = new SockJS("http://" + document.location.host + "/Bank/sockjs/webSocketServer");  }  websocket.onopen = function(evnt) {};  websocket.onmessage = function(evnt) {  $("#test").html("(<font color='red'>" + evnt.data + "</font>)")  };  websocket.onerror = function(evnt) {};  websocket.onclose = function(evnt) {}  $('#btn').on('click', function() {  if (websocket.readyState == websocket.OPEN) {  var msg = $('#id').val();  //调用后台handleTextMessage方法  websocket.send(msg);  } else {  alert("连接失败!");  }  });  </script>

注意导入socketjs时要使用地址全称，并且连接使用的是http而不是websocket的ws