刚接触java，一个模拟多线程的聊天程序，不知道注释掉的代码为什么删掉程序正常运行，保留程序出错...

[追逐永恒]

Server端：

package chatAgain;
import java.net.*;
import java.io.*;
import java.util.*;

public class ChatServer {
	boolean bConnected = false;
	boolean serverAlive = false;
	List<Socket> al = new ArrayList<Socket> ();//java.lang.NullPointerException解决
	
	public static void main(String[] args) {
		new ChatServer().begin();
	}
	
	public void begin() {
		ServerSocket ss;
		try {
			ss = new ServerSocket(7698);
			serverAlive = true;
			while (serverAlive) {
				Socket s = ss.accept();
System.out.println("A client connected!");
				al.add(s);
				bConnected = true;
				if(bConnected) {
					Thread t = new Thread(new Client(s, true));
					t.start();
				}
			}
		} catch (BindException b) {
			System.out.println("端口已经被使用，打开失败。");
			System.exit(0);
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
	
	public class Client implements Runnable {
		Socket s = null;
		DataInputStream dis = null;
		DataOutputStream dos = null;
		boolean sAlive = false;
		
		Client(Socket s, boolean sAlive) {
			this.s = s;
			this.sAlive = sAlive;
		}
		
		public void run() {
			String str = null;
			while (sAlive) {
				try {
					dis = new DataInputStream(s.getInputStream());
					str = dis.readUTF();
					System.out.println(str);
					Iterator<Socket> i = al.iterator();
					while (i.hasNext()) {
						Socket sTemp = i.next();
						if(!(sTemp.equals(this.s))) {
							dos = new DataOutputStream(sTemp.getOutputStream());
							try {
								dos.writeUTF(str);
							} catch (IOException e) {
								
							}
						}
					}
				} catch (IOException e) {
					System.out.println("客户端退出。");
					this.sAlive = false;
					al.remove(this.s);					
				} finally {
					if (this.s != null) {
						try {
							this.s.close();
						} catch (IOException e1) {
							e1.printStackTrace();
						}
					}
					//??????????????????????
//					if (this.dos != null) {
//						try {
//							this.dos.close();
//						} catch (IOException e2) {
//							e2.printStackTrace();
//						}
//					}
					//??????????????????????
					if (this.dis != null)
						try {
							this.dis.close();
						} catch (IOException e3) {
							e3.printStackTrace();
						}
				} 
			}	
		}
	}
	
}

Client端：
package chatAgain;
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.net.*;
public class ChatClient extends Frame {
	Socket s = null;
	TextArea ta = null;
	TextField tf = null;
	boolean bConnected = false;
	DataOutputStream dos;
	DataInputStream dis;
	
	public static void main(String[] args) {
		new ChatClient().launchFrame();
	}
	
	public void launchFrame() {
		this.setLocation(600, 50);
		this.addWindowListener(new CloseMonitor());
		setResizable(true);
		Panel p = new Panel();
		p.setLayout(new BorderLayout());
		ta = new TextArea(20, 50);
		tf = new TextField(20);
		tf.addActionListener(new MyMonitor());
		p.add(ta, BorderLayout.NORTH);
		p.add(tf, BorderLayout.SOUTH);
		add(p);
		pack();
		setVisible(true);
		
		connect();
		Thread t = new Thread(new TextReceive());
		t.start();
	}
	
	public void connect() {
		try {
			s = new Socket("192.168.1.115", 7698);
			bConnected = true;
			dos = new DataOutputStream(s.getOutputStream());
			dis = new DataInputStream(s.getInputStream());
		} catch (UnknownHostException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
	
	class TextReceive implements Runnable {
		public void run() {
			while(bConnected) {
				try {
					ta.append(dis.readUTF());
					ta.append("\n");
				} catch (IOException e) {
				}	
			}
		}
	}
	
	class MyMonitor implements ActionListener {
		public void actionPerformed (ActionEvent e) {
			String str = ((TextField) e.getSource()).getText();
			try {
				ta.append(str);
				ta.append("\n");
				tf.setText("");
				dos.writeUTF(str);
			} catch (IOException e1) {
				e1.printStackTrace();
			}
		}
	}
	
	class CloseMonitor extends WindowAdapter {
		public void windowClosing (WindowEvent e) {
			setVisible(false);
			System.exit(0);
			bConnected = false;
			try {
				dis.close();
				dos.close();
				s.close();
			} catch (IOException i) {
				i.printStackTrace();
			}
		}
	}
	
}

问题如题目，新手不太懂希望高人指点。

[wyc_]

System.out.println("客户端退出。");前面打印一下异常信息

[scmod]

没错啊?我怎么试了下没报错...就是发一次之后断开了然后才会报connect的错误啊

[追逐永恒]

引用 2 楼 scmod 的回复:

没错啊?我怎么试了下没报错...就是发一次之后断开了然后才会报connect的错误啊

有错误，你试一下启3,4个以上的Client端，关闭其中的一个其它的就会出错。但是保留注释行就能正常运行，就是不明白为什么dos不能关闭...

[wyc_]

引用 2 楼 scmod 的回复:

没错啊?我怎么试了下没报错...就是发一次之后断开了然后才会报connect的错误啊

我运行的结果：

[晓风吹雾]

dos 是从socket -> OutputStream 你关闭了dos，间接的会影响 socket http://stackoverflow.com/questions/8890303/behavior-of-java-sockets-when-closing-output-stream from the description above, we know closing the returned OutputStream will close the associated socket.

[追逐永恒]

引用 5 楼 shnulaa 的回复:

dos 是从socket -> OutputStream 你关闭了dos，间接的会影响 socket http://stackoverflow.com/questions/8890303/behavior-of-java-sockets-when-closing-output-stream from the description above, we know closing the returned OutputStream will close the associated socket.

嗯嗯，链接已经看了，正好解决了我的疑惑，非常感谢！

[追逐永恒]

引用 4 楼 cumtwyc 的回复:

[quote=引用 2 楼 scmod 的回复:] 没错啊?我怎么试了下没报错...就是发一次之后断开了然后才会报connect的错误啊

我运行的结果： [/quote] 谢谢帮助，问题已解决

[追逐永恒]

引用 5 楼 shnulaa 的回复:

dos 是从socket -> OutputStream 你关闭了dos，间接的会影响 socket http://stackoverflow.com/questions/8890303/behavior-of-java-sockets-when-closing-output-stream from the description above, we know closing the returned OutputStream will close the associated socket.

不好意思啊还有地方不理解，如果Server端和Client端各自有指向对方Socket的dis和dos，那么Server的dos和Client的dis是一条线路吗，删除会互相影响Socket吗？