java 实现websocket的两种方式实例详解

一、介绍

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

二、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。

三、方法二：spring整合

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" rel="external nofollow" >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

总结

以上所述是小编给大家介绍的java 实现websocket的两种方式实例详解，希望对大家有所帮助