java socket服务器怎么给客户端发信息

java做的 socket服务器
客户端是别的语言编写

怎么才能让客户端连接上服务器时
服务器自动给客户端发送一个信息,例如55 C0 A8 01 01 30 30 30 30 30 33 20 30 30 31 32 33
下边是我的代码,我需要怎么修改?哪些是没用的代码?




public class EchoServer

{

     public static void main(String[] args)

     {

         try{

             ServerSocket s = new ServerSocket(5050);

             Socket incoming = s.accept();

             

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

             PrintWriter out = new PrintWriter(incoming.getOutputStream(), true /* autoFlush */);


             out.println("55 C0 A8 01 01 30 30 30 30 30 33 20 30 30 31 32 33");


             

             

             boolean done = false;

             while (!done)

             {

                 String line = in.readLine();

                 if (line == null)

                     done = true;

                 else{

                     out.println("You to Server : " + line);

                     System.out.println("Client to you :"+line);

                     if (line.trim().equals("BYE"))

                         done = true;

                 }


             }


             incoming.close();

         }

         catch (Exception e){

             System.out.println(e);

         }

     }


}

19 个解决方案

#1

客户\服务器模式都是服务器等待客户端的连接请求，然后做出回应的。
如果没有客户端的连接请求，服务器不可能主动寻找客户端的。

如果已经连接上了，则服务器要发送信息给客户端，只需向流中写入即可。

#2

具体怎么写?能说下吗

#3

我用java写了个测试的客户端,如果说这个能接收到数据
是不是就说明服务器端的发送没问题?




mport java.io.*;

import java.net.*;


public class EchoClient {


     public static void main(String args[]) {

         try {


         	Socket connection =new Socket("127.0.0.1", 5050);

         	BufferedReader input = new BufferedReader(new InputStreamReader(

                    connection.getInputStream()));

             

             PrintWriter out = new PrintWriter(connection.getOutputStream(),true );

             String info;

             info = input.readLine();

             System.out.println(info);

             boolean done = false;

             BufferedReader in = new BufferedReader(new InputStreamReader(System.in));

             String sInput;

             

             //out.println("BYE");


             while (!done) {

             	


                 info = input.readLine();

                 System.out.println(info);

                 

             }

             connection.close();

         }

         catch (SecurityException e) {

             System.out.println("SecurityException when connecting Server!");

         }

         catch (IOException e) {

             System.out.println("IOException when connecting Server!");

         }

     }


}

#4

是的，不过你最好输出的时候再flush一下，感觉是因为没有flush的原因

#5

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

public class ChatServer {
boolean started = false;
ServerSocket ss = null;

List<Client> clients = new ArrayList<Client>();

public static void main(String[] args) {
new ChatServer().start();
}

public void start() {
try {
ss = new ServerSocket(8888);
started = true;
} catch (BindException e) {
System.out.println("端口使用中....");
System.out.println("请关掉相关程序并重新运行服务器！");
System.exit(0);
} catch (IOException e) {
e.printStackTrace();
}

try {

while(started) {
Socket s = ss.accept();
Client c = new Client(s);
System.out.println("a client connected!");
new Thread(c).start();
clients.add(c);
//dis.close();
}
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
ss.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}

class Client implements Runnable {
private Socket s;
private DataInputStream dis = null;
private DataOutputStream dos = null;
private boolean bConnected = false;

public Client(Socket s) {
this.s = s;
try {
dis = new DataInputStream(s.getInputStream());
dos = new DataOutputStream(s.getOutputStream());
bConnected = true;
} catch (IOException e) {
e.printStackTrace();
}
}

public void send(String str) {
try {
dos.writeUTF(str);
} catch (IOException e) {
clients.remove(this);
System.out.println("对方退出了！我从List里面去掉了！");
//e.printStackTrace();
}
}

public void run() {
try {
while(bConnected) {
String str = dis.readUTF();
System.out.println(str);
for(int i=0; i<clients.size(); i++) {
Client c = clients.get(i);
c.send(str);
//System.out.println(" a string send !");
}
/*
for(Iterator<Client> it = clients.iterator(); it.hasNext(); ) {
Client c = it.next();
c.send(str);
}
*/
/*
Iterator<Client> it = clients.iterator();
while(it.hasNext()) {
Client c = it.next();
c.send(str);
}
*/
}
} catch (EOFException e) {
System.out.println("Client closed!");
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
if(dis != null) dis.close();
if(dos != null) dos.close();
if(s != null) {
s.close();
//s = null;
}

} catch (IOException e1) {
e1.printStackTrace();
}

}
}

}
}

#6

import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.net.*;

public class ChatClient extends Frame {
Socket s = null;
DataOutputStream dos = null;
DataInputStream dis = null;
private boolean bConnected = false;

TextField tfTxt = new TextField();

TextArea taContent = new TextArea();

Thread tRecv = new Thread(new RecvThread());

public static void main(String[] args) {
new ChatClient().launchFrame();
}

public void launchFrame() {
setLocation(400, 300);
this.setSize(300, 300);
add(tfTxt, BorderLayout.SOUTH);
add(taContent, BorderLayout.NORTH);
pack();
this.addWindowListener(new WindowAdapter() {

@Override
public void windowClosing(WindowEvent arg0) {
disconnect();
System.exit(0);
}

});
tfTxt.addActionListener(new TFListener());
setVisible(true);
connect();

tRecv.start();
}

public void connect() {
try {
s = new Socket("127.0.0.1", 8888);
dos = new DataOutputStream(s.getOutputStream());
dis = new DataInputStream(s.getInputStream());
System.out.println("connected!");
bConnected = true;
} catch (UnknownHostException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}

}

public void disconnect() {
try {
dos.close();
dis.close();
s.close();
} catch (IOException e) {
e.printStackTrace();
}

/*
try {
bConnected = false;
tRecv.join();
} catch(InterruptedException e) {
e.printStackTrace();
} finally {
try {
dos.close();
dis.close();
s.close();
} catch (IOException e) {
e.printStackTrace();
}
}
*/
}

private class TFListener implements ActionListener {

public void actionPerformed(ActionEvent e) {
String str = tfTxt.getText().trim();
//taContent.setText(str);
tfTxt.setText("");

try {
//System.out.println(s);
dos.writeUTF(str);
dos.flush();
//dos.close();
} catch (IOException e1) {
e1.printStackTrace();
}

}

}

private class RecvThread implements Runnable {

public void run() {
try {
while(bConnected) {
String str = dis.readUTF();
//System.out.println(str);
taContent.setText(taContent.getText() + str + '\n');
}
} catch (SocketException e) {
System.out.println("退出了，bye!");
} catch (EOFException e) {
System.out.println("推出了，bye - bye!");
} catch (IOException e) {
e.printStackTrace();
}

}

}
}
这是尚学堂的一个小例子,你看看。主动发消息，这没实现

#7

我把那点改为



out.println("55 C0 A8 01 01 30 30 30 30 30 33 20 30 30 31 32 33");

incoming.getOutputStream().flush();

还是不行

#8

当然不行，你要flush的是out啊

#9

我也是初学者，我曾经编写过类似的程序。
我当时就是指定服务器的端口，然后通过write方法写入信息
程序的一部分，希望对你有启发
String hostname = strServer;
int port = 80;
InetAddress addr = InetAddress.getByName(hostname);//在给定主机名的情况下确定主机的 IP 地址
Socket socket = new Socket(addr, port); // 建立一个Socket
socket.setSoTimeout(30000);
// 发送命令
BufferedWriter wr = new BufferedWriter(new OutputStreamWriter(
socket.getOutputStream()));
StringBuffer PostData = new StringBuffer();

String request=PostData.toString();

wr.write("POST " + strPage + " HTTP/1.1\r\n");
wr.write("Host: " + strServer + ":" + port + "\r\n");
wr.write("Content-Length: " + PostData.length() + "\r\n");
wr.write("Content-Type: application/x-www-form-urlencoded\r\n");
wr.write("\r\n");
wr.write(request);
wr.flush();
// 接收返回的结果

#10

to yuwenbao

郁闷,还是不行

#11

你的代码我试了没有问题，能输出55 C0 A8 01 01 30 30 30 30 30 33 20 30 30 31 32 33。是不是编辑器的问题。

#12

我用的eclipse
我用java写的客户端接收没问题
就是不能和另外语言写的通信

#13

不太会呢

#14

http://blog.csdn.net/weixing979/archive/2006/05/12/725940.aspx
你看这篇文章说c++和java通信都要先把数据进行字节序转换，你是用c++么，会不会是同样的问题。

#15

该回复于2011-10-27 07:47:24被版主删除

#16

程序应该是没有问题，与其他语言写的客户端通信不要用Writer，直接向stream中写二进制。

#17

不要用PrinterWriter,改成DataOutputStream试试,别的语言可能不支持字符传输

#18

该回复于2016-06-17 17:29:00被管理员删除

#19

我也想知道

#20

#1

#2