一个关于Java Socket的问题,大家看一下

06-04-29 xuechen0721
一个关于Java Socket的问题,大家看一下:

我的目的是从client端发出一段字符串,server端接收后原样返回给客户端。

客户端:ConnClient 服务器端ConnSerer(完整源代码附在最后)

===client端===

建了一个out流和in流:

BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));

PrintWriter Clientout = new PrintWriter(new BufferedWriter(new OutputStreamWriter(socket.getOutputStream())),true);

向server端输出:clientOut.println("hello"); clientout.close();

等待服务器端返回代码片段:

StringBuffer sbuf = new StringBuffer();

char[] buff = new char[10];

int iLen = in.read(buff);

while (iLen>0) {

sbuf.append(buff,0,iLen);

if (sbuf.toString().trim().equals("hello")){

System.out.println(sbuf.toString());

break;

}

iLen = in.read(buff);

}

===server端===

同样建了一个in流和out流

BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));

PrintWriter Serverout = new PrintWriter(new BufferedWriter( new OutputStreamWriter(socket.getOutputStream())),true);

接收client端信息和原样返回信息:

StringBuffer sbuf = new StringBuffer();

char[] buff = new char[10];

int iLen = in.read(buff);

while(iLen>0){

sbuf.append(buff,0,iLen);

if (sbuf.toString().trim().equals("hello")){

System.out.println("Echoing: " + sbuf.toString());

serverout.println(sbuf.toString()); //此处为server端输出流,返回给client端

break;

}

iLen = in.read(buff);

}

问题来了:

1、如果按以上代码运行,server端可以收到client的信息,但client端却收不到返回的信息。为什么?

2、后来我把client端的clientout.close()注释掉后,一切正常,client端能收到server端返回的信息。这又为什么?

难道server端和client端用的是一个out流?为什么client端把out流关掉后(clientout.close()),server端就不能返回信息呢?

以我以前的理解,server端和client端建的两个输出流应该是独立的。不会因为我把client端的out流关掉后,server端out流就不能返回了?不会吧!呵呵!

还有一个问题:server端怎么判断client端数据已经发送完毕?

一开始,我用clientout.print("hello"),运行后,server端显示已经连接成功但一直侦听,没有收到信息,认为client端还没有发送完成。

后来,我改用clientout.println("hello"),运行后,一切正常,服务器端也收到信息(hello)。

从上看出server的地判定就是一个回车符,不知道这样认识对不对?大家指点!

经过我试验,如果client端print后,用clientout.close()也可以使server端接收到信息。但却不能返回信息。也就是我发现上面说述的问题来由。

以上几个问题,请大家和banq大哥多加指点!

源代码如下:

client端:

package com.socket;

import java.net.*;
import java.io.*;

public class ConnClient {
  public static void main(String[] args) throws IOException {

	InetAddress addr = InetAddress.getByName(null);
	
	System.out.println("addr = " + addr);
	
	Socket socket = new Socket(addr, 8080);
	//socket.setSoTimeout(5000);
	
	try {
	  System.out.println("socket = " + socket);
	  BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
	  
	  PrintWriter clientout = new PrintWriter(new BufferedWriter(new OutputStreamWriter(socket.getOutputStream())),true);
	  
	  String strSend = "hello";
	  
	 	
	  clientout.println(strSend);
	  //clientout.println("\r\n");
	  //clientout.println();
	  //clientout.close();
	  StringBuffer sbuf = new StringBuffer();
	  
	char[] buff = new char[10];
	  
	int iLen = in.read(buff);
	  
	while (iLen>0) {  
		sbuf.append(buff,0,iLen);
		if (sbuf.toString().trim().equals(strSend)){
			System.out.println(sbuf.toString());
				  break;
			  }
		 iLen = in.read(buff);
	}
	 
	}catch(Exception e){
		e.printStackTrace();
	} finally {
	  System.out.println("closing...");
	  socket.close();
	}
	
}
}


server端代码:
package com.socket;
import java.io.*;
import java.net.*;

public class ConnServer {  
  
  public static final int PORT = 8080;
  public static void main(String[] args) throws IOException {

	ServerSocket s = new ServerSocket(PORT);
	System.out.println("Started: " + s);
	try {
	  Socket socket = s.accept();
	  try {
	System.out.println("Connection accepted: "+ socket);
	BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));

	PrintWriter serverout = new PrintWriter(new BufferedWriter( new OutputStreamWriter(socket.getOutputStream())),true);
		
      StringBuffer sbuf = new StringBuffer();
			     
	char[] buff = new char[10];
	iLen = in.read(buff);
	         
	while(iLen>0){  
	sbuf.append(buff,0,iLen);
	if(sbuf.toString().trim().equals("hello")){
	
	System.out.println("Echoing: " + sbuf.toString());
	serverout.println(sbuf.toString());
        }
           iLen = in.read(buff);
}		
	  }catch(Exception e) { e.printStackTrace();}
	   finally {
			System.out.println("closing...");
			
			socket.close();
	  }
	
	} finally {
	  s.close();
	}
  } 
}
<p>

xuechen0721
2006-04-30 13:20
怎么没人回应,大家帮下忙啊!

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