JAVA多线程的问题，请兄弟们帮忙看看。

Question

多线程的聊天服务器，每个用户一个线程，同时开一个Socket连接，然后把这个线程实例的句柄保存在一个数组中，每当有新的用户到来时，循环得到数组中的线程实例，调用每一个线程的send函数通知其他人，现在的问题是，如果用户多了，有时候会挂起，不知道什么原因，请帮助分析一下，另外，这样在一个线程中调用另一个线程实例类的一个函数，这个函数会立即执行吗？还是要等另一个线程被激活后才执行？

Answer 1

1),用户多了会挂起,可能是因为CPU时间不够用,自动等待.
2),不会立即执行,所有的线程只是会进入ready状态,只有系统决定何时start.

Answer 2

用不用每个用户一个SOCKET呢？如果服务端只用一个SOCKET，每个客户端的SOCKET都向这一个SOCKET通信，利用信息头来区分用户也可以。因为聊天这种应用，客户端的通信不可能太密集，所以应该够用吧。

Answer 3

给你看看我写的聊天程序，也许对你有帮助：服务器端：import java.io.*;
import java.net.*;
import javax.swing.*;
import java.util.*;
import java.awt.event.*;class ServerTest extends JFrame
{
    JTextArea ta=new JTextArea();
    JScrollPane sp=new JScrollPane(ta);
    OutputStream os;
    PrintWriter pw;
    Vector v=new Vector();
    public ServerTest(String title)
    {
        super(title);
        setSize(400, 300);
        setLocation(380, 260);
        ta.setEnabled(false);
        addWindowListener(new WindowAdapter()
        {
            public void windowClosing(WindowEvent e)
            {
                //pw.println("我要走了!");
                //pw.flush();
                System.exit(0);
            }
        });
        add(sp);
        setVisible(true);
        init();
    }
    public void init()
    {
        try
        {
            ServerSocket ss=new ServerSocket(6000);
            while(true)
            {
                Socket s = ss.accept();
                InputStream is = s.getInputStream();
                BufferedReader br = new BufferedReader(new InputStreamReader(is));
                os = s.getOutputStream();
                pw = new PrintWriter(os);
                v.add(pw);
                Chat c=new Chat(br);
                c.start();
            }
        }
        catch(Exception e)
        {
            e.printStackTrace();
        }
    }    class Chat extends Thread
    {
        BufferedReader br;
        public Chat(BufferedReader br)
        {
            this.br=br;
        }
        public void run()
        {
            while (true)
            {
                try
                {
                    String str = br.readLine();
                    if(str.equals("我要走了!"))
                    {
                        break;
                    }
                    else
                    {
                     Iterator it = v.iterator();
                     while (it.hasNext())
                     {
                         PrintWriter pw = (PrintWriter) it.next();
                         pw.println(str);
                         pw.flush();
                         //System.out.println(it.next());
                     }
                     ta.append(str);
                     ta.append("\n");
                    }
                }catch (Exception e)
                {
                    e.printStackTrace();
                }
            }
        }
    }    public static void main(String[] args) throws Exception
    {
        ServerTest st = new ServerTest("服务器端");
        //st.ta.setEnabled(false);
    }}
客户端：import java.io.*;
import java.net.*;
import javax.swing.*;
import java.awt.event.*;class ClientTest extends JFrame implements ActionListener
{
    Socket s;
    JTextField tf=new JTextField();
    JTextArea ta=new JTextArea();
    JScrollPane sp=new JScrollPane(ta);
    JButton btn=new JButton("发送");
    OutputStream os;
    PrintWriter pw;
    BufferedReader br;
    static String name="";
    public ClientTest(String title)
    {
        super(title);
        setSize(400,300);
        setLocation(380,260);
        setLayout(null);
        addWindowListener(new WindowAdapter()
        {
            public void windowClosing(WindowEvent e)
            {
                pw.println("我要走了!");
                pw.flush();
                System.exit(0);
            }
        });
        sp.setBounds(0,0,390,230);
        add(sp);
        tf.setBounds(10,240,250,20);
        add(tf);
        btn.setBounds(300,240,70,20);
        add(btn);
        btn.addActionListener(this);
        setVisible(true);
        init();
    }
    public void init()
    {
        try
        {
            s=new Socket("127.0.0.1",6000);
            InputStream is = s.getInputStream();
            br = new BufferedReader(new InputStreamReader(is));
            os = s.getOutputStream();
            pw = new PrintWriter(os);
            pw.println(name+"上线了");
            pw.flush();
            Chat c=new Chat();
            c.start();
        } catch (Exception e)
        {
            e.printStackTrace();
        }
    }
    public void actionPerformed(ActionEvent ae)
    {
        if(ae.getActionCommand().equals("发送"))
        {
            try
            {
                String str=tf.getText();
                pw.println(name+" 说: "+str);
                tf.setText("");
                pw.flush();
                tf.requestFocus(true);
            }catch(Exception e)
            {
                e.printStackTrace();
            }
        }
    }
    class Chat extends Thread
    {
        public void run()
        {
            while(true)
            {
                try
                {
                 //if(br.readLine().equals("我要走了!"))
                    //{
                        //break;
                    //}
                    //else
                    //{
                     ta.append(br.readLine());
                     ta.append("\n");
                    //}
                } catch (Exception ex) {                }
            }
        }
    }
    public static void main(String[] args)
    {
        if(args.length!=1)
        {
            JOptionPane.showMessageDialog(null, "请输入一个名称!", "提示", 2);
            System.exit(0);
        }
        name=args[0];
        ClientTest ct=new ClientTest(name+"的聊天室");
        ct.ta.setEnabled(false);
        ct.tf.requestFocus(true);
    }
}