无法在服务器套接字文件传输中获取输入流

Question

I have developed a screen in swings to download a file from the server. The whole concept works fine when i click the download button once. But when i click the download button second time, i find that the code pauses in getting the inputstream .(this i have followed it using the sysouts shown.)

Below shown are the two separate code snippets in two different files. TCPClient has the serversocket codings whereas the clientUI has the ui components which calls the TCPSever method to accept a socket and for requesting purpose.

In the tcp client side:

  public TCPClient() throws Exception{
    System.out.println("Inside TCPClient constructor---");
    clientSocket = new Socket("localhost", 3500);
    System.out.println("After creating socket instance---");
    oos = new ObjectOutputStream(clientSocket.getOutputStream());
    System.out.println("after getting the ouput stream---");
    ois = new ObjectInputStream(clientSocket.getInputStream());
    System.out.println("after getting the input stream.");
    }

In the Client UI:

private void downloadButton_actionPerformed(ActionEvent e) throws Exception 
{ 
    Object selectedItem = contentsList.getSelectedValue();
        System.out.println("selectedItem---"+selectedItem);
        new TCPClient().downloadContents(nodeName,selectedItem.toString());
    }
} 

Kindly provide me a solution for this...

Below is the server code:

    public void listening() throws Exception{
        ServerSocket ss = new ServerSocket(3500);
            System.out.println( "DataServer Is Listening..." );

            while( true )
            {
                Socket soc = ss.accept();

            ObjectInputStream ois = new ObjectInputStream(soc.getInputStream());                                                            
                ObjectOutputStream oos = new ObjectOutputStream( soc.getOutputStream() );
String input = ( String ) ois.readObject( );

if(input.startsWith("downloadContents")){
            String nodeName = ois.readObject().toString();
            String contentName = ois.readObject().toString();
            List contentsForNode = DBServer.getContentsForNode(nodeName);
            for(Object obj : contentsForNode){
                if(obj.toString().contains(contentName)){
                    new FileServer().send(obj.toString());
                    break;
                }
            }
        }

    }
    }

    public static void main( String[] args ) 
        {
            TCPServer obDataServer  = new TCPServer();

            try
            {
                obDataServer.listening();
            }
            catch ( Exception ioe )
            {
                ioe.printStackTrace();
            }

        }

Answer 1

At a guess, your server is single-threaded and is still reading its input stream, because you haven't closed the client socket. But it's anybody's guess until you post the relevant server code.

Answer 2

Do you take care of closing the socket after the file is downloaded (successfully/unsuccessfully)? It doesn't looks like it from the code snippet.

I'm not sure, but this might be the problem

Answer 3

This Is Server Class:

package client_to_server;

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;`
import java.net.ServerSocket;
import java.net.Socket;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Calendar;

public class Server {
    public static void main(String args[])throws IOException
    {
        ServerSocket serverSocket=new ServerSocket(2222);
        System.out.println("New Server is Waiting");
        Socket socket=serverSocket.accept();
        System.out.println("My Connection Established");
        DateFormat df=new SimpleDateFormat("HH:mm:ss");
        Calendar c=Calendar.getInstance();
        String starttime=df.format(c.getTime());
        System.out.println("Start time is : "+starttime);
        InputStream inputStream=socket.getInputStream();
        byte[] readbyte=new byte[(1024*20)*1024];       
        FileOutputStream fileOutputStream=new FileOutputStream("/home/Manoj/copybulkfile5.zip");
        int writebyte;
        int count=0;
        while((writebyte=inputStream.read(readbyte))!=-1)
        {
            if(writebyte>0)
                count+=writebyte;
            fileOutputStream.write(readbyte, 0, writebyte);
        }
        DateFormat df1=new SimpleDateFormat("HH:mm:ss");
        Calendar c1=Calendar.getInstance();
        String endtime=df1.format(c1.getTime());
        System.out.println("END TIME is "+endtime);
        System.out.println("THE WRITEBYTE VALUE IS "+writebyte+"THE READ BYTE VALUE IS"+count);
        inputStream.close();


    }

}

This Is Client Cass:

package client_to_server;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.net.Socket;

public class Client {
    public static void main(String args[])throws IOException
    {
        //Socket socket=new Socket("localhost",2222);
        Socket socket=new Socket("localhost",2222);
        File file=new File("/home/Checking/Myfile.zip");
        byte[] mybyte=new byte[(1024*20)*1024];
        FileInputStream fileInputStream=new FileInputStream(file);
        int count;
        OutputStream outputStream=socket.getOutputStream();
        while((count=fileInputStream.read(mybyte))!=-1)
        {
            outputStream.write(mybyte);
        }
        System.out.println("THIS FILE HAS BEEN SENT SUCCESSFULLY!!!");

        //System.out.println("END TIME "+hr+"Hours"+min+"Minutes "+sec+"Seconds");
        socket.close();
    }
}