Java中Spring WebSocket详解

首先 pom.xml

<parent>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-parent</artifactId>
	<version>1.5.8.RELEASE</version>
</parent>
<dependency>
	<groupId>org.apache.commons</groupId>
	<artifactId>commons-io</artifactId>
</dependency>
<dependency>
	<groupId>javax.websocket</groupId>
	<artifactId>javax.websocket-api</artifactId>
	<version>1.0</version>
	<scope>provided</scope>
</dependency>
<dependency>
	<groupId>org.springframework</groupId>
	<artifactId>spring-websocket</artifactId>
</dependency>
<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-web</artifactId>
	<exclusions>
		<exclusion>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-tomcat</artifactId>
		</exclusion>
	</exclusions>
</dependency>
<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-undertow</artifactId>
</dependency>

接收消息后的处理类 GameHandler :

import java.net.URI;
import org.springframework.web.socket.BinaryMessage;
import org.springframework.web.socket.CloseStatus;
import org.springframework.web.socket.PongMessage;
import org.springframework.web.socket.TextMessage;
import org.springframework.web.socket.WebSocketSession;
import org.springframework.web.socket.handler.AbstractWebSocketHandler;

public class GameHandler extends AbstractWebSocketHandler {
 /**
  * 处理字符串类的信息
  *
  * @param session
  * @param message
  * @throws Exception
  */
 @Override
 protected void handleTextMessage(WebSocketSession session, TextMessage message) throws Exception {
  session.sendMessage(new TextMessage(message.asBytes()));
 }

 /**
  * 处理二进制类的信息
  *
  * @param session
  * @param message
  * @throws Exception
  */
 @Override
 protected void handleBinaryMessage(WebSocketSession session, BinaryMessage message) throws Exception {
  session.sendMessage(new BinaryMessage(message.getPayload()));
 }

 /**
  * ping-pong
  *
  * @param session
  * @param message
  * @throws Exception
  */
 @Override
 protected void handlePongMessage(WebSocketSession session, PongMessage message) throws Exception {
	
 }
 /**
  * 传出错误的处理
  *
  * @param session
  * @param exception
  * @throws Exception
  */
 @Override
 public void handleTransportError(WebSocketSession session, Throwable exception) throws Exception {
 }
 /**
  * 连接关闭的处理
  *
  * @param session
  * @param status
  * @throws Exception
  */
 @Override
 public void afterConnectionClosed(WebSocketSession session, CloseStatus status) throws Exception {
 }
 /**
  * 连接建立后的处理
  *
  * @param session
  * @throws Exception
  */
 @Override
 public void afterConnectionEstablished(WebSocketSession session) throws Exception {	
 }
}

 握手信息拦截器 WebSocketHandshakeInterceptor :

import java.util.Map;
import javax.servlet.http.Cookie;
import org.springframework.http.server.ServerHttpRequest;
import org.springframework.http.server.ServerHttpResponse;
import org.springframework.http.server.ServletServerHttpRequest;
import org.springframework.web.socket.WebSocketHandler;
import org.springframework.web.socket.server.HandshakeInterceptor;

public class WebSocketHandshakeInterceptor implements HandshakeInterceptor {
 @Override
 public boolean beforeHandshake(ServerHttpRequest request, ServerHttpResponse shr1, WebSocketHandler wsh, Map<String, Object> attributes) throws Exception {
  // 此处可以做一些权限认证的事情或者其他
  return true;
 }
 @Override
 public void afterHandshake(ServerHttpRequest shr, ServerHttpResponse shr1, WebSocketHandler wsh, Exception excptn) {	
 }
}

使用WebSocket的配置类 WebSocketConfig :

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;
import org.springframework.web.socket.config.annotation.EnableWebSocket;
import org.springframework.web.socket.config.annotation.WebSocketConfigurer;
import org.springframework.web.socket.config.annotation.WebSocketHandlerRegistry;

@Configuration
@EnableWebSocket
public class WebSocketConfig extends WebMvcConfigurerAdapter implements WebSocketConfigurer {
@Override
 public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {
  // 允许连接的域,只能以http或https开头
  String[] allowsOrigins = {"http://127.0.0.1:1213", "http://localhost:1213"};
  registry.addHandler(gameHandler(),"/game").addInterceptors(handshakeInterceptor()).setAllowedOrigins(allowsOrigins);
 }
 @Bean
 public GameHandler gameHandler() {
  return new GameHandler();
 }
 @Bean
 public WebSocketHandshakeInterceptor handshakeInterceptor() {
  return new WebSocketHandshakeInterceptor();
 }
}

启动类 Launcher :

@SpringBootApplication
public class Launcher {
 public static void main(String[] params) {
  SpringApplication.run(Launcher.class, params);
	}
}

配置文件 main/resources/application.properties:

server.port=1213
server.session-timeout=1800
server.undertow.io-threads=4
server.undertow.worker-threads=20
server.undertow.buffer-size=1024
server.undertow.buffers-per-region=1024
server.undertow.direct-buffers=true

前端的测试页面 main\resources\static\index.html

<!DOCTYPE html>
<html lang="zh-CN">
 <head>
  <meta charset="utf-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Platform Gateway</title>
  <link href="https://cdn.bootcss.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="external nofollow" rel="stylesheet">
  <!--<link href="https://cdn.bootcss.com/bootstrap/3.3.7/css/bootstrap-theme.min.css" rel="external nofollow" rel="stylesheet">-->
  <script src="https://cdn.bootcss.com/jquery/3.2.1/jquery.min.js"></script>
  <script src="https://cdn.bootcss.com/jquery-scrollTo/2.1.2/jquery.scrollTo.min.js"></script>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/pako/1.0.6/pako.min.js"></script>
  <!--[if lt IE 9]>
   <script src="https://cdn.bootcss.com/html5shiv/3.7.3/html5shiv.min.js"></script>
   <script src="https://cdn.bootcss.com/respond.js/1.4.2/respond.min.js"></script>
  <![endif]-->
  <style>
   #message{
    height: 600px;
    overflow-y:auto;
   }
  </style>
 </head>
 <body>
  <div class="container">
   <h1>WebSocket Test Page</h1>
   <hr/>
   <div class="form-inline">
    <div class="form-group">
     <label for="wsAddr">WebSocket Address: </label>
     <div class="input-group">
      <span class="input-group-addon" id="basic-ws">ws://127.0.0.1:1213/</span>
      <input type="text" class="form-control" id="basic-ws-addr" aria-describedby="basic-ws" placeholder="game" data-container="body" data-placement="top" data-content="链接地址不能为空,请填写">
     </div>
    </div>
    <button type="button" id="btnConnect" class="btn btn-primary" onclick="connect();">
     <span class="glyphicon glyphicon-resize-small" aria-hidden="true"></span>
     连接
    </button>
    <button type="button" id="btnClose" class="btn btn-danger" disabled="disabled" onclick="closeWebSocket();">
     <span class="glyphicon glyphicon-remove" aria-hidden="true"></span>
     断开
    </button>
    <button type="button" id="btnSend" class="btn btn-info" disabled="disabled" style="margin-left: 50px;" onclick="send();">
     <span class="glyphicon glyphicon-transfer" aria-hidden="true"></span>
     发送消息
    </button>
   </div><br/>
   <textarea class="form-control" id="inMsg" rows="5" placeholder="在这里输入需要发送的信息..."></textarea>
   <hr/>
   <div id="message"></div>
  </div>
  <script src="https://cdn.bootcss.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>
  <script type="text/javascript">
     function zip(str) {
      var binaryString = pako.gzip(str, {to: 'string'});
      return btoa(binaryString);
     }
     function unzip(b64Data) {
      var strData = atob(b64Data);
      var charData = strData.split('').map(function (x) {
       return x.charCodeAt(0);
      });
      var binData = new Uint8Array(charData);
      var data = pako.inflate(binData);
      strData = String.fromCharCode.apply(null, new Uint16Array(data));
      return strData;
     }
     var websocket = null;
     var wsBaseUrl = null;
     var wsUrl = null;
     function init() {
      wsBaseUrl = "ws://" + window.location.host + "/";
      $("#basic-ws").text(wsBaseUrl);
      $(function () {
       $('[data-toggle="popover"]').popover();
      });
      return false;
     }
//关闭WebSocket连接
     function closeWebSocket() {
      if (websocket) {
       websocket.close();
      }
      return false;
     }

//将消息显示在网页上
     function setMessageInnerHTML(who, msg) {
      var message = null;
      if (who === 1) {
       message = '<div class="alert alert-success" role="alert">本地: ' + msg + '</div>';
      } else {
       message = '<div class="alert alert-info" role="alert">服务器: ' + msg + '</div>';
      }
      document.getElementById('message').innerHTML = (document.getElementById('message').innerHTML + message);
      $("#message").scrollTo('100%');
      return false;
     }

//发送消息
     function send() {
      if (websocket) {
       var message = $("#inMsg").val();
       websocket.send(zip(message));
       setMessageInnerHTML(1, message);
      }
      return false;
     }
     function connect() {
      var url = $("#basic-ws-addr").val();
      if (url.length <= 0) {
       $('#basic-ws-addr').popover('show');
       setTimeout(function () {
        $('#basic-ws-addr').popover('hide');
       }, 3000);
      } else {
       wsUrl = wsBaseUrl + url;
       if ('WebSocket' in window) {
        websocket = new WebSocket(wsUrl);
        //连接发生错误的回调方法
        websocket.onerror = function () {
         setMessageInnerHTML(0, "WebSocket连接发生错误 -> " + wsUrl);
         $("#btnConnect").removeAttr("disabled");
         $("#btnClose").attr("disabled", "disabled");
         $("#btnSend").attr("disabled", "disabled");
        };

        //连接成功建立的回调方法
        websocket.onopen = function () {
         setMessageInnerHTML(0, "WebSocket连接成功 -> " + wsUrl);
         $("#btnConnect").attr("disabled", "disabled");
         $("#btnClose").removeAttr("disabled");
         $("#btnSend").removeAttr("disabled");
        };

        //接收到消息的回调方法
        websocket.onmessage = function (event) {
         setMessageInnerHTML(0, unzip(event.data));
        };

        //连接关闭的回调方法
        websocket.onclose = function () {
         setMessageInnerHTML(0, "WebSocket连接关闭 -> " + wsUrl);
         $("#btnConnect").removeAttr("disabled");
         $("#btnClose").attr("disabled", "disabled");
         $("#btnSend").attr("disabled", "disabled");
        };

        //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();
        };
       } else {
        alert('Not support websocket');
       }
      }
      return false;
     }
     window.onload = init();
  </script>
 </body>
</html>

到此就可以使用 WebSocket 进行前后端的通信了，如果大家还有不明白的或者有更好的方法，可以在下方的留言区讨论。