4.4学习内容，http长连接、aidl远程服务的回调

秒速五厘米 2022-08-07 11:54 22阅读 0赞

长连接服务器servlet:

public class LongTest extends HttpServlet {
 	public void doGet(HttpServletRequest request, HttpServletResponse response)
 			throws ServletException, IOException {
 		this.doPost(request, response);
 	}
 
 	public void doPost(HttpServletRequest request, HttpServletResponse response)
 			throws ServletException, IOException {
 		for (int i = 0; i < 100; i++) { 
 try { 
 Thread.sleep(1000); 
 } catch (NumberFormatException e) { 
 e.printStackTrace(); 
 } catch (InterruptedException e) { 
 e.printStackTrace(); 
 } 
 
 SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss E"); 
 String date_str = df.format(new Date()); 
 
 writerResponse(response, date_str, "showServerTime");// msg是test.jsp中的那个js方法的名称 
 } 
 return; 
 	}
 	
 	protected void writerResponse(HttpServletResponse response, String body, String client_method) throws IOException { 
 StringBuffer sb = new StringBuffer(); 
 sb.append("<script type=\"text/javascript\">//<![CDATA[\n"); 
 sb.append(" parent.").append(client_method).append("(\"").append(body).append("\");\n"); 
 sb.append("//]]></script>"); 
 // System.out.println(sb.toString()); 
 
 // response.setContentType("text/html;charset=GBK"); 
 response.setCharacterEncoding("utf-8");
 		response.setContentType("text/html");
 		
 response.addHeader("Pragma", "no-cache"); 
 response.setHeader("Cache-Control", "no-cache,no-store,must-revalidate"); 
 response.setHeader("Cache-Control", "pre-check=0,post-check=0"); 
 response.setDateHeader("Expires", 0); 
 response.getWriter().write(sb.toString()); 
 response.flushBuffer(); 
 } 
 
 
 }

测试客户端：

try {  
                 
    	            //确定服务地址  
    	            URL url = new URL("http://touch-pingdembp:8080/apperror/LongTest");  
    	            InputStream in=url.openStream();  
    	            int n = -1;  
    	            byte[] b = new byte[1024];  
    	            //从服务端读取数据并打印  
    	            int readlength = n = in.read(b);
    	            while(readlength!=-1)  
    	            {  
    	                String s=new String(b,0,n, "UTF-8");  
    	                System.out.println(s);  
    	                
    	                readlength = n = in.read(b);
    	            }  
    	              
    	        } catch (IOException e) { 
    	        	LogUtil.print("连接断开!");
    	            e.printStackTrace();  
    	        }

一般的servlet写出数据时是这样的：

PrintWriter out;			out = response.getWriter();			out.print(json);
 			out.flush();
 			out.close();

close之后，网络请求出结果，长链接不同，colse是很少发生的，所以一直在写出数据，客户端需要不断的read数据并处理，而不是普通get、post请求完后处理。

可以使用mina框架做长连接的事情

（参考）http://fulerbakesi.iteye.com/blog/1592209

一般的，aidl常用于远程命令，远程获取数据，但是有时也需要远程调用并不定时回调，此时需要两个aidl(接口)文件：一个是调用接口，一个是回调接口

注册回调：

/** 
              * service的回调方法 
              */  
             private ICallback.Stub mCallback = new ICallback.Stub() {  
       
                 @Override  
                 public void showResult(int result) {  
                     Log.d(TAG, " result : " + result);  
                 }  
             };  
      
             /** 
              * 注册connection 
              */  
             private ServiceConnection mConnection = new ServiceConnection() {  
       
                 @Override  
                 public void onServiceDisconnected(ComponentName name) {  
                     Log.d(TAG, "onServiceDisconnected");  
                     mService = null;  
                 }  
       
                 @Override  
                public void onServiceConnected(ComponentName name, IBinder service) {  
                     Log.d(TAG, "onServiceConnected");  
                     mService = IService.Stub.asInterface(service);  
                     try {  
                         mService.registerCallback(mCallback);  
                     } catch (RemoteException e) {  
                         Log.e(TAG, "", e);  
                     }  
                 }  
             };

注册一个回调：

private RemoteCallbackList<icallback> mCallbacks = new RemoteCallbackList<icallback>(); 
 
 private IService.Stub mBinder = new IService.Stub() { 
 
 @Override 
 public void unregisterCallback(ICallback cb){ 
 if(cb != null) { 
 mCallbacks.unregister(cb); 
 } 
 } 
 
 @Override 
 public void registerCallback(ICallback cb){ 
 if(cb != null) { 
 mCallbacks.register(cb); 
 } 
 } 
 }; 
 
 @Override 
 public IBinder onBind(Intent intent) { 
 Log.d(TAG, "onBind"); 
 return mBinder; 
 }