TCP
客户端套接字：Socket
服务端套接字：ServerSocket
TCP（传输控制协议）一种基于连接的通信协议。可靠传输
Server
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package com.tcp;
import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;
/**
* 服务器端
*/
public class Server {
public static void main(String[] args) {
ServerSocket serverSocket = null;
try {
serverSocket = new ServerSocket(12345);
System.out.println("服务启动："+serverSocket.getInetAddress().getHostAddress()+":"+serverSocket.getLocalPort());
Socket accept = serverSocket.accept();
System.out.println("客户端："+accept.getInetAddress().getHostAddress()+":"+accept.getLocalPort());
BufferedReader sis = new BufferedReader(new InputStreamReader(System.in));
BufferedReader is = new BufferedReader(new InputStreamReader(accept.getInputStream()));
PrintWriter os = new PrintWriter(new OutputStreamWriter(accept.getOutputStream()));
while (true){
String line;
if ((line=is.readLine())!=null){
System.out.println("收到客户端："+line);
if (line.equals("bye")){
break;
}else {
os.println(sis.readLine());
os.flush();
}
}
}
is.close();
os.close();
accept.close();
} catch (IOException e) {
e.printStackTrace();
}finally {
try {
serverSocket.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
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Client
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package com.tcp;
import java.io.*;
import java.net.Socket;
/**
* 客户端
*/
public class Client {
public static void main(String[] args) {
try {
Socket socket = new Socket("127.0.0.1",12345);
BufferedReader sis = new BufferedReader(new InputStreamReader(System.in));
BufferedReader is = new BufferedReader(new InputStreamReader(socket.getInputStream()));
PrintWriter os = new PrintWriter(new OutputStreamWriter(socket.getOutputStream()));
String line;
while (true){
if ((line=sis.readLine())!=null){
if ("bye".equals(line)){
System.exit(0);
}
os.println(line);
os.flush();
}
String readLine = is.readLine();
System.out.println("收到服务端："+readLine);
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
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UDP
UDP采用Datagram（数据报）传输，数据包是一种尽力而为的传送数据的方式，它只是 把数据的目的地记录在数据包中，然后就直接放在网络上，系统不保证数据是否能安全到达，或者什么时候可以送到，它并不保证传送质量。
Datagram（数据报）是网络层数据单元在介质上传输信息的一种逻辑分组格式，它是一种在网络中传播的、独立的、自身包含地址信息的消息，它能够到达目的地、到达时间、到达时内容是否会变化是不能准确知道的。它的通信双方不需要建立连接，对于一些不需要很高质量的应用程序来说，数据报通信是一个非常好的选择。还有就是对实时性很高的情况，比如在实时音频和视频应用中，数据包的丢失和位置是静态的，是可以被人们所忍受的，这时就可以利用UDP协议传输。
DatagramSocket（数据报套接字）工作包含了3个信息类：DatagramPacket、DatagramSocket和MulticastSocket。DatagramPacket对象描绘了数据报地址信息，DatagramSocket表示客户程序和服务程序报套接字，MulticastSocket描绘了能够进行多点传输的数据报套接字。
Server
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package com.udp;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
public class Server {
public static void main(String[] args) {
try {
DatagramSocket socket = new DatagramSocket(12345);
byte[] bytes = new byte[1024];
DatagramPacket receivePacket = new DatagramPacket(bytes, bytes.length);
System.out.println("开始接收包。。。");
while (true){
socket.receive(receivePacket);
String name = receivePacket.getAddress().toString();
System.out.println("来自主机："+name+"\n端口："+receivePacket.getPort());
String s = new String(receivePacket.getData(),0,receivePacket.getLength());
System.out.println("接收到数据："+s);
}
}catch (Exception e){
e.printStackTrace();
}
}
}
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Client
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package com.udp;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
public class Client {
public static void main(String[] args) {
try {
DatagramSocket socket = new DatagramSocket();
InetAddress host = InetAddress.getByName("localhost");
String msg = "hello, I'm client";
DatagramPacket sendPacket = new DatagramPacket(msg.getBytes(),msg.length(),host,12345);
socket.send(sendPacket);
}catch (Exception e){
e.printStackTrace();
}
}
}
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DatagramSocket只允许数据报发送一个目的地址，MulticastSocket允许数据报以广播的形式发送到该端口的所有客户。
MultiServer
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package com.udp;
import java.net.DatagramPacket;
import java.net.InetAddress;
import java.net.MulticastSocket;
public class MultiServer {
public static void main(String[] args) {
try {
MulticastSocket socket = new MulticastSocket(12345);
InetAddress group = InetAddress.getByName("231.0.0.0");
socket.joinGroup(group);
//接收数据报
for(int i=0;i<100;i++){
byte[] bytes = new byte[256];
DatagramPacket receivePacket = new DatagramPacket(bytes, bytes.length);
socket.receive(receivePacket);
byte[] bytes1 = new byte[receivePacket.getLength()];
System.arraycopy(receivePacket.getData(),0,bytes1,0,receivePacket.getLength());
System.out.println(new String(bytes1));
}
socket.leaveGroup(group);
socket.close();
}catch (Exception e){
e.printStackTrace();
}
}
}
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MultiClient
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package com.udp;
import java.net.DatagramPacket;
import java.net.InetAddress;
import java.net.MulticastSocket;
public class MultiClient {
public static void main(String[] args) {
try {
MulticastSocket socket = new MulticastSocket();
InetAddress group = InetAddress.getByName("231.0.0.0");
byte[] bytes = new byte[0];
DatagramPacket sendPacket = new DatagramPacket(bytes, 0, group, 12345);
for(int i=0;i<5;i++){
byte[] bytes1 = ("Data line "+i).getBytes();
sendPacket.setData(bytes1);
sendPacket.setLength(bytes1.length);
socket.send(sendPacket);
}
socket.close();
}catch (Exception e){
e.printStackTrace();
}
}
}
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参考：
https://www.cnblogs.com/benjamin77/p/9147146.html
https://blog.51cto.com/aku28907/1782137
