tomcat+comet实现终端与服务端同步的小例子

sunny03

1、 工程说明
    java project——CometSocket包含一个类：
          Calculate.java：作为客户端，往服务器发送数据  
    web project——CometServer包含：
         ReceiverServlet.java：接收客户端数据，并模拟入库（以存入文件的形式）
         TestServlet.java：模拟从库中取数据（从文件中取值）并推送给浏览器展示
         index.jsp：接收从服务端推送出来的数据并展示
2、部分代码说明
     Calculate.java
      public void sendData(ActionEvent e)
{
try
{
//发送数据
txtResult.setText(e.getActionCommand());
URL url = new URL("http://localhost:8080/CometServer/rs?num="+txtResult.getText());
HttpURLConnection httpURLConnection = (HttpURLConnection)url.openConnection();
httpURLConnection.setRequestProperty("Content-Type", "text/html"); //application/xml
httpURLConnection.setRequestMethod("GET");
httpURLConnection.setReadTimeout(2*1000);
int code = httpURLConnection.getResponseCode();
System.out.println("code_______________"+code);
}
     通过http get请求方式将数据发送给客户端
    ReceiverServlet.java    
public void service(HttpServletRequest request ,HttpServletResponse response){
FileOutputStream fos = null;
try
{
String str = request.getParameter("num");
System.out.println("get________________________________"+str);
File file = new File("D:/1.txt");
fos = new FileOutputStream(file);
if(str != null){
fos.write(str.getBytes());
}
}
catch (FileNotFoundException e)
{
// TODO Auto-generated catch block
e.printStackTrace();
}
catch (IOException e)
{
// TODO Auto-generated catch block
e.printStackTrace();
}finally{
if(fos != null){
try
{
fos.close();
}
catch (IOException e)
{
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
    接收数据并模拟入库
    TestServlet.java
    public void event(CometEvent event) throws IOException, ServletException
{
// 开始
if(event.getEventType() == EventType.BEGIN){
try
{
Thread.sleep(100);   
File file = new File ("D:/1.txt");
BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream(file)));
String str = br.readLine();
System.out.println("ddd1_________"+str);  
if( str != null){
HttpServletResponse response = event.getHttpServletResponse();
PrintWriter out = response.getWriter();
out.write(str);
out.flush();  
out.close();
}
}
catch (Exception e)
{
// TODO Auto-generated catch block
e.printStackTrace();
}
}
if(event.getEventType() == EventType.END){
System.out.println("ddd2");
event.close();
}

}
     定时向服务器推送数据
3、运行    
    tomcat配置： 要使用 Comet，需要对 Tomcat 的配置文件 server.xml 稍作修改。默认情况下启用的是更典型的同步 IO 连接器。现在只需将它切换成异步版本.
  <!-- Connector URIEncoding="utf-8" connectionTimeout="20000" port="8080" protocol="HTTP/1.1" redirectPort="8443"/ -->
<Connector connectionTimeout="20000" port="8080" protocol="org.apache.
coyote.http11.Http11NioProtocol" redirectPort="8443"/>
源码和效果图，如附件：
   启动web工程，点击“start”
   运行Calculate.java