JButton不工作[捕获网络流量]

Question

我的代码本应捕获网络流量并将其显示在文本区，但它没有做到。请查看代码并检查是否需要进行任何更正。

public class NewClass {
    public static JTextArea textarea = new JTextArea();
    NewClass() throws IOException{
        JButton capture = new JButton("Capture");
        JFrame frame = new JFrame();        
        JScrollPane scroll;
        NetworkInterface[] NI= JpcapCaptor.getDeviceList();
        int INDEX=0;
        JpcapCaptor JPCAP = JpcapCaptor.openDevice(NI[INDEX], 65536, false, 20);
        frame.setSize(700,500);
        frame.setLocation(200,200);
        frame.getContentPane().setLayout(null);
        frame.setBackground(Color.yellow);        
        textarea.setEditable(false);
        textarea.setFont(new Font("Tahoma",0,14));
        textarea.setForeground(Color.RED);
        textarea.setLineWrap(true);
        //textarea.setBackground(Color.WHITE);
        scroll = new JScrollPane();
        scroll.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);
        scroll.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);
        scroll.setViewportView(textarea);
        frame.getContentPane().add(scroll);
        scroll.setBounds(10,16,740,290);
        capture.setBackground(Color.RED);
        capture.setForeground(Color.GREEN);
        frame.getContentPane().add(capture);
        handler ob = new handler();
        capture.addActionListener(ob);
        capture.setBounds(100, 400, 90, 25);
        frame.setVisible(true);
    }
    public class handler implements ActionListener{
        public void actionPerformed(ActionEvent Event){
            class Print implements PacketReceiver{
                public void receivePacket(Packet packet){
                    String info = packet.toString();
                    textarea.append(info);
                    //System.out.println(packet.toString());
                }                    
            }
    }
}

Answer 1

我的代码本应捕获网络流量并将其显示在文本区，但它没有做到。请查看代码并检查是否有任何更正。

首先，处理程序的actionPerformed方法实际上什么都不做。它定义了一个内部类，但不创建该类的对象，也不对其执行任何操作：

public class handler implements ActionListener {
  public void actionPerformed(ActionEvent Event) {
     class Print implements PacketReceiver {
        public void receivePacket(Packet packet) {
           String info = packet.toString();
           textarea.append(info); // System.out.println(packet.toString());
        }
     }
  }
}

考虑创建Print类的一个对象（对于一个类来说，这是一个糟糕的名称，因为已经有一个Print类是核心Java库的一部分），并让这个Print对象做一些有用的事情，也许是接收数据包（不管它应该做什么）。注意不要在主Swing线程（EDT）中执行长时间运行的进程，否则会冻结Swing GUI。

编辑
例如

// note that class names such as "Handler" should begin with a capital letter.
public class Handler implements ActionListener {
  public void actionPerformed(ActionEvent Event) {
     class Print implements PacketReceiver {
        public void receivePacket(Packet packet) {
           String info = packet.toString();
           textarea.append(info); // System.out.println(packet.toString());
        }
     }
     // create a Print instance so that it can do something:
     final Print myPrint = new Print();
     // do something with myPrint here so that it gets packets and displays them
     // I suspect that you'll likely want to do this in a background thread
     // using a SwingWorker
  }
}

Answer 2

正如Hovercraft所说，您除了定义一个内部类之外什么也没做。这里缺少的是从您的JPCAP类调用processPacket（）或loopPack（）。所以我建议如下：

public class handler implements ActionListener{
  public void actionPerformed(ActionEvent Event){
    class Print implements PacketReceiver{
        public void receivePacket(Packet packet){
            String info = packet.toString();
            textarea.append(info);                                            
        }
    }
    // this captures 10 packets .
    JPCAP.processPacket(10,new Print());
  }
}