java网络编程小结1

1 基本的tcp网络编程模式

首先是server端,server端用的是serversocket,

import java.net.*;

import java.io.*;

public class TCPServer {

public static void main(String[] args) throws Exception {

ServerSocket ss = new ServerSocket(6666);

while(true) {

Socket s=ss.accept();

DataInputStream dis=new DataInputStream(s.getInputStream());

System.out.println(dis.readUTF());

dis.close();

s.close();

}

}

}

客户端

import java.net.*;

import java.io.*;

public class TCPClient {

public static void main(String[] args) throws Exception {

Socket s = new Socket("127.0.0.1", 6666);

OutputStream os = s.getOutputStream();

DataOutputStream dos = new DataOutputStream(os);

Thread.sleep(30000);

dos.writeUTF("hello server!");

dos.flush();

dos.close();

s.close();

}

}

对客户端来说，是output输出流到服务端．

２　下面的程序，可以通过服务端把客户端的ip端口等输出给客户端

　　　

import java.net.*;

import java.io.*;

public class TestServer {

public static void main(String args[]) {

try {

ServerSocket s = new ServerSocket(8888);

while (true) {

Socket s1 = s.accept();

OutputStream os = s1.getOutputStream();

DataOutputStream dos = new DataOutputStream(os);

dos.writeUTF("Hello," + s1.getInetAddress() +

"port#" +s1.getPort() + " bye-bye!");

dos.close();

s1.close();

}

}catch (IOException e) {

e.printStackTrace();

System.out.println("程序运行出错:" + e);

}

}

}

客户端，则把服务端输进来的信息显示

　　

import java.net.*;

import java.io.*;

public class TestClient {

public static void main(String args[]) {

try {

Socket s1 = new Socket("127.0.0.1", 8888);

InputStream is = s1.getInputStream();

DataInputStream dis = new DataInputStream(is);

System.out.println(dis.readUTF());

dis.close();

s1.close();

} catch (ConnectException connExc) {

connExc.printStackTrace();

System.err.println("服务器连接失败！");

} catch (IOException e) {

e.printStackTrace();

}

}

}

３　下面的TCP则是客户跟服务端各自发送一句话给对方．

　　服务端：

　　　import java.io.*;

import java.net.*;

public class TestSockServer {

public static void main(String[] args) {

InputStream in = null;

OutputStream out = null;

try {

ServerSocket ss = new ServerSocket(5888);

Socket socket = ss.accept();

in = socket.getInputStream();

out = socket.getOutputStream();

DataOutputStream dos = new DataOutputStream(out);

DataInputStream dis = new DataInputStream(in);

String s = null;

if((s=dis.readUTF())!=null) {

System.out.println(s);

System.out.println("from: "+socket.getInetAddress());

System.out.println("Port: "+socket.getPort());

}

dos.writeUTF("hi，hello");

dis.close();

dos.close();

socket.close();

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

}

}

　　　客户端：

　　　import java.net.*;

import java.io.*;

public class TestSockClient {

public static void main(String[] args) {

InputStream is = null; OutputStream os = null;

try {

Socket socket = new Socket("localhost",5888);

is = socket.getInputStream();

os = socket.getOutputStream();

DataInputStream dis = new DataInputStream(is);

DataOutputStream dos = new DataOutputStream(os);

dos.writeUTF("hey");

String s = null;

if((s=dis.readUTF())!=null);

System.out.println(s);

dos.close();

dis.close();

socket.close();

} catch (UnknownHostException e) {

e.printStackTrace();

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

}

}

５　UDP中，注意datagrampacket的应用，下面的是客户端发一消息给服务端的

　　　public class TestUDPClient

{

public static void main(String args[]) throws Exception

{

byte[] buf = (new String("Hello")).getBytes();

　　Datagrampacket dp=new DatagramPacket(buf, buf.length,

new InetSocketAddress("127.0.0.1", 5678)

);

DatagramSocket ds = new DatagramSocket(9999);

ds.send(dp);

ds.close();

}

服务端：

　　　

import java.net.*;

public class TestUDPServer

{

public static void main(String args[]) throws Exception

{

byte buf[] = new byte[1024];

DatagramPacket dp = new DatagramPacket(buf, buf.length);

DatagramSocket ds = new DatagramSocket(5678);

while(true)

{

ds.receive(dp);

System.out.println(new String(buf,0,dp.getLength()));

}

}

}

　　

　　要注意的知识点是，如果是客户端的其他类型的数据，在转换时要注意，比如下面的例子传一个长整型的到服务端：

客户端：

　　public class TestUDPClient

{

public static void main(String args[]) throws Exception

{

long n = 10000L;

ByteArrayOutputStream baos = new ByteArrayOutputStream();

DataOutputStream dos = new DataOutputStream(baos);

dos.writeLong(n);

byte[] buf = baos.toByteArray();

System.out.println(buf.length);

DatagramPacket dp = new DatagramPacket(buf, buf.length,

new InetSocketAddress("127.0.0.1", 5678)

);

DatagramSocket ds = new DatagramSocket(9999);

ds.send(dp);

ds.close();

}

}

服务端：

　　

import java.net.*;

import java.io.*;

public class TestUDPServer

{

public static void main(String args[]) throws Exception

{

byte buf[] = new byte[1024];

DatagramPacket dp = new DatagramPacket(buf, buf.length);

DatagramSocket ds = new DatagramSocket(5678);

while(true)

{

ds.receive(dp);

ByteArrayInputStream bais = new ByteArrayInputStream(buf);

DataInputStream dis = new DataInputStream(bais);

System.out.println(dis.readLong());

}

}

}