java 网络编程学习笔记 -1

1、将数据发送给那个进程靠端口决定。

2、端口范围0-65535.

21为FTP，25为SMTP，80为HTTP，125为RPC（远程过程调用）

3、TCP、UDP取值独立，允许存在取值相同的TCP、UDP端口。

4、java中3种套接字：java.net.Socket，java.net.ServerSocket（TCP）

java.DatagramSocket（UDP）c/s模式。

客服端与服务端程序：

package ClientEcho;


import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.Socket;


public class ClientEcho {

private String host="127.0.0.1";
private int port=80;
private Socket socket;

public ClientEcho()throws IOException{
socket=new Socket(host,port);

}
public static void main(String[] args) throws IOException {
// TODO Auto-generated method stub
System.out.println("客服端启动");
new ClientEcho().talk();
}
private PrintWriter getWriter(Socket socket)throws IOException{
OutputStream socketOut=socket.getOutputStream();
return new PrintWriter(socketOut,true);

}
private BufferedReader getReader(Socket socket)throws IOException{
InputStream socketIn=socket.getInputStream();
return new BufferedReader(new InputStreamReader(socketIn));

}

public void talk()throws IOException{
try {
BufferedReader br=getReader(socket);
PrintWriter pw=getWriter(socket);
BufferedReader localReader=new BufferedReader(new InputStreamReader(System.in));
String msg=null;
while((msg=localReader.readLine())!=null){
pw.println(msg);
System.out.println(br.readLine());
if(msg.equals("bye"));
break;



}
} catch (IOException e) {
// TODO: handle exception
e.printStackTrace();

}finally{
try {
socket.close();
} catch (IOException e2) {
// TODO: handle exception
e2.printStackTrace();
}

}

}

/**
* @param args
* @throws IOException 
*/



}

package ServeEcho;


import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;


import javax.swing.text.AbstractDocument.LeafElement;


public class ServeEcho {


private int port=80;
private ServerSocket serverSocket;

public ServeEcho() throws IOException{
serverSocket=new ServerSocket(port);
System.out.println("服务器启动");
}

public String echo(String msg){

return "echo:"+msg;
}

private  PrintWriter getPrintWriter(Socket socket)throws IOException {
OutputStream socketOut=socket.getOutputStream();
return new PrintWriter(socketOut, true);
}

private BufferedReader getReader(Socket socket) throws IOException {
InputStream socketIn=socket.getInputStream();
return new BufferedReader(new InputStreamReader(socketIn));
}

public void  service() {
while(true){
Socket socket=null;
try {
socket=serverSocket.accept();
System.out.println("New connection accepted"+socket.getInetAddress()+":"+socket.getPort());
BufferedReader br=getReader(socket);
PrintWriter pw=getPrintWriter(socket);

String msg=null;
while((msg=br.readLine())!=null){
System.out.println(msg);
pw.println(echo(msg));
if(msg.equals("bye"))
break;
}

} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}finally{
try {
if(socket!=null)
socket.close();
} catch (Exception e2) {
// TODO: handle exception
e2.printStackTrace();
}

}

}
}
/**
* @param args
* @throws IOException 
*/
public static void main(String[] args) throws IOException {
// TODO Auto-generated method stub
new ServeEcho().service();
}


}

5、InetAddress类表示服务器的IP地址

6、关闭Socket：

isClosed（）已经连接，还没关闭，返回true。

isConnected（）曾经连接

isBound（）已经绑定。

半关闭：shutdownInput

shutdownOutput

7、设置Socket：

TCP_NODELAY 默认false，采用Negale算法，缓冲之后一次发送，有利于发送大量数据，且要求对方有回应。

小批量数据则需要调用setTCPDelay（true）方法，关闭缓冲，确保及时发送。