Socket编程：(一般的网络编程)
<1> 两个 JAVA 应用程序可通过一个双向的网络通信连接, 实现数据交换, 这个双向链路的一段称为一个 Socket.
<2> Socket 通常用来实现 Client-Server 连接.
<3> java.net 包中定义的两个类 Socket 和 ServerSocket(阻塞式), 分别用来实现双向连接的 Client 和 Server 端.
<4> 建立连接时, 所需的寻址信息为远程计算机的 IP 地址和端口号(Port number, 2个字节, 65536个端口, 一个应用程序可能有多个端口号)
TCP端口、UDP端口分开的, 在技术上来讲, 只有TCP才分 Server 、Client.
每一个有65536个端口, 端口号用来区分同一台机器上的不同应用程序, 一个人占用了某个端口号, 其他人就不能占了.
自己编写程序的话, 占1024以后的端口号, 1024以前的不要占, 系统可能会随时征用.
TCP、UDP二者是不一样的.
<5> 默认的网页 http 端口为 80端口；
SMTP(邮件发送)：25端口
POP3(接收邮件)：110端口
<6> 写 TCPserver、TCPclient 程序时, 首先启动 Server, 再启动 Client, 同时写程序, 一起开发.
Demo_1:
Server端：
import java.io.*;
import java.net.*;
public class TCPserver {
public static void main(String[] args) throws Exception{
ServerSocket ss = new ServerSocket(6666);
while(true){
Socket s = ss.accept();
System.out.println("A client connect: ");
DataInputStream dis = new DataInputStream(s.getInputStream());
System.out.println(dis.readUTF()); //阻塞式(readUTF), 死死地等待
dis.close();
s.close();
}
}
}
Client端：
import java.net.*;
import java.io.*;
public class TCPclient {
public static void main(String[] args) throws Exception{
Socket s = new Socket("192.168.56.1", 6666);
OutputStream os = s.getOutputStream(); //拿到输出的那根管道, 往里面写
DataOutputStream dos = new DataOutputStream(os);
dos.writeUTF("Hello Server");
dos.flush();
dos.close();
s.close();
}
}
运行结果：
A client connect:
Hello Server
Demo_2:
Server端：
import java.net.*;
import java.io.*;
public class TestServer {
public static void main(String[] args) {
try {
Socket s1 = new Socket("192.168.56.1", 8888);
InputStream is = s1.getInputStream();
DataInputStream dis = new DataInputStream(is);
System.out.println(dis.readUTF());
dis.close();
s1.close();
} catch (UnknownHostException e) {
e.printStackTrace();
System.out.println("错误端口号, 请核对------");
} catch (IOException e) {
e.printStackTrace();
}
}
}
Client端：
import java.net.*;
import java.io.*;
public class TestClient {
public static void main(String[] args) {
try {
ServerSocket ss = new ServerSocket(8888);
while(true){
Socket s1 = ss.accept();
OutputStream os = s1.getOutputStream();
DataOutputStream dos = new DataOutputStream(os);
dos.writeUTF("Hello, "+s1.getInetAddress()+"Port#, "+s1.getPort()+"Bye--Bye");
dos.close();
os.close();
}
} catch (IOException e) {
e.printStackTrace();
System.out.println("程序出错啦："+e);
}
}
}
运行结果：Hello, /192.168.56.1Port#, 4391Bye--Bye
Demo_3:
import java.net.*;
import java.io.*;
public class TestSockServer {
public static void main(String[] args) {
InputStream in = null;
OutputStream os = null;
try {
ServerSocket ss = new ServerSocket(5888);
Socket socket = ss.accept();
in = socket.getInputStream();
os = socket.getOutputStream();
DataInputStream dis = new DataInputStream(in);
DataOutputStream dos = new DataOutputStream(os);
String s = null;
if((s=dis.readUTF())!=null){
System.out.println(s);
System.out.println("From: "+socket.getInetAddress());
System.out.println("Port: "+socket.getPort());
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
Client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("192.168.56.1", 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();
} catch (UnknownHostException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
运行结果：
Hey
From: /192.168.56.1
Port: 4531
Demo_4:
Server 端：
import java.net.*;
import java.io.*;
public class TalkServer {
public static void main(String[] args) {
try {
ServerSocket server = new ServerSocket(4702);
Socket socket = server.accept();
BufferedReader is = new BufferedReader(new InputStreamReader(socket.getInputStream()));
BufferedReader sin = new BufferedReader(new InputStreamReader(System.in));
PrintWriter pw = new PrintWriter(socket.getOutputStream());
System.out.println("Client: "+is.readLine());
String line = null;
line = sin.readLine();
while(!line.equalsIgnoreCase("Bye")){
pw.println(line);
pw.flush();
System.out.println("Client: "+is.readLine());
line = sin.readLine();
}
is.close();
pw.close();
socket.close();
server.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
Client 端：
import java.net.*;
import java.io.*;
public class TalkClient {
public static void main(String[] args) {
try {
Socket socket = new Socket("192.168.56.1", 4702);
BufferedReader sin = new BufferedReader(new InputStreamReader(System.in));
BufferedReader is = new BufferedReader(new InputStreamReader(socket.getInputStream()));
PrintWriter os = new PrintWriter(socket.getOutputStream());
String readLine = null;
readLine = sin.readLine();
while(!readLine.equalsIgnoreCase("Bye")){
os.println(readLine);
os.flush();
System.out.println("Servber: "+is.readLine());
readLine = sin.readLine();
}
os.close();
is.close();
socket.close();
} catch (UnknownHostException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
运行结果展示：
