高级：使用异步Servlet扩展AJAX应用程序(1)(2)

  import java.io.IOException; 
import java.io.PrintWriter; 
import java.util.Date; 
import java.util.Stack;  
import javax.servlet.ServletException; 
import javax.servlet.http.HttpServletRequest;  
import weblogic.servlet.FutureResponseServlet; 
import weblogic.servlet.FutureServletResponse;  
// An AsynchronousServlet that handles HTTP requests from a "separate" thread and 
// not the execute thread used to invoke this servlet. 
public class AsynchronousServerResponseServlet extends FutureResponseServlet {  
 
 private final Notifier notifier; 
 
 public AsynchronousServerResponseServlet() {   
  this.notifier = new Notifier();   
  this.notifier.start();  
 }   
 
 public void service(HttpServletRequest request, FutureServletResponse response) throws
IOException,ServletException {    
  // push this client's request to a buffer and return immediately.   
  // asynchronous processing occurs in the run method of the Notifier Thread   
  notifier.poll(request, response);  
 }   
 
 class Notifier extends Thread {    
  private static Stack clients = new Stack();    
  void poll (HttpServletRequest request, FutureServletResponse response) {    
   clients.push(new Client(request, response));   
  }    
  
 public void run() {    
  while (!clients.empty()) {     
   Client client = null;     
   try{      
    client = (Client) clients.pop();      
    PrintWriter pw = client.response.getWriter();      
    for(int j = 0; j < 10; j++) {       
     pw.println("Time is:" + new Date() + "");       
     pw.flush();
    }      
    pw.close();     
   } 
   catch(Throwable t) {      
    t.printStackTrace();     
   } 
   finally {      
    try {      
     client.response.send();       
    } 
    catch(IOException ioe) {      
     ioe.printStackTrace();      
    }     
   }     
  }   
 }  
}  
// inner class that holds o-n to the clients http request and response  
class Client {   
 private HttpServletRequest request;   
 private FutureServletResponse response;    
 private Client(HttpServletRequest request, FutureServletResponse response) {    
  this.request = request;    
  this.response = response;   
 }  
}