Java套接字编程中的连接拒绝错误

Question

the snippet of code i'm trying to execute is choosing one file using jFileChooser and retrieve, write that data to Socket.

  private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
        File selectedFile;
        FileReader reader = null;
        BufferedReader in;
        try {
            final JFileChooser fc = new JFileChooser();
            fc.setFileSelectionMode(JFileChooser.FILES_ONLY);
            txtSearch.setText((fc.showOpenDialog(CreateNode.this) == JFileChooser.APPROVE_OPTION) ? fc.getSelectedFile().toString() : txtSearch.getText());            
            if (fc.showOpenDialog(this) == JFileChooser.APPROVE_OPTION) {
                //gets file from dialog
                selectedFile = fc.getSelectedFile();
                //makes sure files can be processed before proceeding
                if (selectedFile.canRead() && selectedFile.exists()) {
                    System.out.println("can read:"+selectedFile.canRead()+"exists:"+selectedFile.exists());
                    reader = new FileReader(selectedFile);

                }

            }
            in = new BufferedReader(reader);

            //inputLine recieves file text
            String inputLine = in.readLine();
            int LineNumber = 0;
            while (inputLine != null) {
                //LineNumber isn't needed, but it adds a line count on the left, nice
                LineNumber++;
                StringTokenizer tokenizer = new StringTokenizer(inputLine);
                Socket socket=new Socket("localhost",7788);


                //displays text file
                fileData.append(LineNumber + ": " + inputLine + "\n");
                System.out.println("connected:"+socket.isConnected());

                 // ss.accept();
                DataOutputStream dos4=new DataOutputStream(socket.getOutputStream());
                //next line in File opened
                dos4.writeUTF(LineNumber + ": " + inputLine + "\n");
                dos4.close();
                socket.close();
                ServerSocket ss=new ServerSocket(7788);
                Socket socket1=ss.accept();


               DataInputStream inp=new DataInputStream(socket1.getInputStream());
                //String msg=inp.readUTF();
                //System.out.println("msg:"+msg);

               String input = (String)inp.readUTF();
                System.out.println("inputline: "+input);
                ss.close();

            }
            //close stream, files stops loading
            in.close();

// TODO add your handling code here:
    }                                        
    catch (Exception e) {

        System.out.println("Exception e:"+e);
        e.printStackTrace();
        }

    }

I have tried using disabling the firewall and rebuilding the application in netBeans(IDE i'm using)

The Error Message is

 can read:trueexists:true
Exception e:java.net.ConnectException: Connection refused: connect
java.net.ConnectException: Connection refused: connect
    at java.net.DualStackPlainSocketImpl.connect0(Native Method)
    at java.net.DualStackPlainSocketImpl.socketConnect(DualStackPlainSocketImpl.java:69)
    at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:339)
    at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:200)
    at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:182)
    at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:157)
    at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:391)
    at java.net.Socket.connect(Socket.java:579)
    at java.net.Socket.connect(Socket.java:528)
    at java.net.Socket.<init>(Socket.java:425)
    at java.net.Socket.<init>(Socket.java:208)
    at com.design.CreateNode.jButton1ActionPerformed(CreateNode.java:194)
    at com.design.CreateNode.access$000(CreateNode.java:29)
    at com.design.CreateNode$1.actionPerformed(CreateNode.java:95)
    at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
    at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2341)
    at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
    at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
    at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
    at java.awt.Component.processMouseEvent(Component.java:6505)
    at javax.swing.JComponent.processMouseEvent(JComponent.java:3320)
    at java.awt.Component.processEvent(Component.java:6270)
    at java.awt.Container.processEvent(Container.java:2229)
    at java.awt.Component.dispatchEventImpl(Component.java:4861)
    at java.awt.Container.dispatchEventImpl(Container.java:2287)
    at java.awt.Component.dispatchEvent(Component.java:4687)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4832)
    at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4492)
    at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4422)
    at java.awt.Container.dispatchEventImpl(Container.java:2273)
    at java.awt.Window.dispatchEventImpl(Window.java:2719)
    at java.awt.Component.dispatchEvent(Component.java:4687)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:723)
    at java.awt.EventQueue.access$200(EventQueue.java:103)
    at java.awt.EventQueue$3.run(EventQueue.java:682)
    at java.awt.EventQueue$3.run(EventQueue.java:680)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87)
    at java.awt.EventQueue$4.run(EventQueue.java:696)
    at java.awt.EventQueue$4.run(EventQueue.java:694)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:693)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:242)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:161)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:146)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:91)

I have seen suggestions in the google and stcakoverflow also but none of them find useful

Answer 1

As hinted by E_net4 in the comments, you are creating a client before you open the server.

My guess is that you followed this approach because of the blocking functionality of the ServerSocket.accept method. A better approach would be to

1. Create a server socket
2. Listen to connections in a seperate thread, where you can safely block without disrupting the main flow
3. Open your client socket ( Socket class) after your server started listening for connections

It's all a matter of correct ordering

Answer 2

The server socket must be listening for connections when you try to connect to it.

Try doing the socket stuff in this order:

            ServerSocket ss=new ServerSocket(7788); // Create listening socket.
            Socket socket=new Socket("localhost",7788);  // Connect to listening socket.
            Socket socket1=ss.accept(); // Accept incoming connection.

Answer 3

First create server socket and then socket which will create instance of client socket and then another socket object for accepting the connection.

ServerSocket ss=new ServerSocket(7777); 
            Socket socket=new Socket("localhost",7777); 
            Socket socket1=ss.accept();