TCP/UDP 协议
通俗解释：
TCP协议和UDP协议的区别类似于电话系统和邮政系统。
<1>TCP：类似于电话系统，建立双向的通信通道，确定连接，话音顺序接听。
<2>UDP：类似于邮政系统，发送方将信件发送到正确的地址，但并不知道准确的邮路，大多数邮件到达了目的地，个别情况一些邮件会在路上丢失。邮件不保证顺序到达目的地。
TCP套接字
Socket
客户端的通信套接字，可指定远端IP地址、端口进行连接通信，也可以通过方法获取已连接的socket的远端IP地址、端口，以及将此socket以字节输入流和输出流的形式返回，当与数据输入流和输出流绑定，便可实现客户端的网络通信。
构造函数均为public修饰类型，如果创建socket时发生I/O错误，均抛出IOException异常。常用构造函数如下：
Socket(InetAddress address,int port):创建一个socket并与规定的IP地址的指定的端口相连接。
Socket(String host,int port):创建一个socket并与指定主机的指定端口连接。
ServerSocket
服务器的通讯套接字，用来侦听客户端请求的连接，并为每个新连接创建一个socket对象，由此创建绑定此socket的输入流和输出流，与客户端实现网络通信。
构造函数均为public修饰类型，如果创建socket时发生I/O错误，均抛出IOException异常。常用构造函数如下：
ServerSocket(int port):在所给定的用来侦听的端口上建立一个服务器套接字。如果端口号为0，则在任意的空闲的端口上建立要给服务器套接字。外来连接请求的数量默认最大为50。
多线程聊天室实例
服务端Cilent
创建ServerSocket并监听设置的端口，调用accpet()方法，直到找到对应的socket与之连接，创建一个线程为止服务。
Launch the Application 部分为Java Swing的窗口部分。
public class ServerCilent {
private JFrame frmServer;
private JTextField textField;
private JTable table;
private JLabel lblNewLabel;
private JButton btnRefresh;
private JButton btnListenstart;
private SocketManager SocketArr=new SocketManager();
//创建 Server端
void getServer(int port)
{
try {
ServerSocket serverSocket=new ServerSocket(port);
System.out.println("已经开启服务端");
while(true)
{
Socket socket=serverSocket.accept();
new W_Thread(socket).start();
SocketArr.add(socket);
SocketArr.sendClientInfo();
}
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}
}
class W_Thread extends Thread
{
Socket socket=null;
private BufferedReader reader;
private PrintWriter writer;
public W_Thread(Socket socket)
{
this.socket=socket;
}
public void run()
{
try {
reader=new BufferedReader(new InputStreamReader(socket.getInputStream()));
writer=new PrintWriter(socket.getOutputStream(),true);
String msg;
while((msg=reader.readLine())!=null )
{
System.out.println(msg);
SocketArr.SendtoAll(msg);
}
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}
}
}
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
ServerCilent window = new ServerCilent();
window.frmServer.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the application.
*/
public ServerCilent() {
initialize();
}
/**
* Initialize the contents of the frame.
*/
private void initialize() {
frmServer = new JFrame();
frmServer.setResizable(false);
frmServer.setTitle("ServerCilent");
frmServer.setBounds(100, 100, 452, 371);
frmServer.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frmServer.getContentPane().setLayout(null);
JPanel panel = new JPanel();
panel.setBorder(new TitledBorder(null, "DefaultSetting", TitledBorder.LEADING, TitledBorder.TOP, null, null));
panel.setBounds(10, 10, 414, 66);
frmServer.getContentPane().add(panel);
panel.setLayout(null);
JLabel lblPort = new JLabel("Port:");
lblPort.setBounds(10, 25, 54, 15);
panel.add(lblPort);
textField = new JTextField();
textField.setBounds(48, 22, 122, 21);
panel.add(textField);
textField.setColumns(10);
btnListenstart = new JButton("Listen&Start");
btnListenstart.addMouseListener(new MouseAdapter() {
@Override
public void mouseClicked(MouseEvent arg0) {
int port=Integer.parseInt(textField.getText());
ServerCilent serverCilent=new ServerCilent();
serverCilent.getServer(port);
textField.setEditable(false);
btnListenstart.setVisible(false);
}
});
btnListenstart.setBounds(254, 21, 136, 23);
panel.add(btnListenstart);
JLabel label = new JLabel("在线人数：");
label.setBounds(10, 298, 82, 15);
frmServer.getContentPane().add(label);
lblNewLabel = new JLabel(String.valueOf(SocketArr.size()));
lblNewLabel.setBounds(75, 298, 54, 15);
frmServer.getContentPane().add(lblNewLabel);
btnRefresh = new JButton("Refresh");
btnRefresh.setBounds(331, 298, 93, 23);
frmServer.getContentPane().add(btnRefresh);
}
}
多线程客户端Cilent
创建Socket，并获取对应的输入输出流即可。
public class Cilent implements Runnable{
/*Swing*/
private JFrame frmLogincilent;
private JTextField IPAdress;
private JTextField Port;
private JTextField Nickname;
private JTextField Sendinfo;
private JButton Sumbit;
private JTextArea ShowArea;
private JButton Send;
/*Stream*/
private BufferedReader reader;
private PrintWriter writer;
@Override
public void run(){
while(true){
try {
ShowArea.append(reader.readLine()+"\n");
} catch (Exception e) {
// TODO: handle exception
}
}
}
public void Create_Socket(InetAddress ip,int port){
ShowArea.append("正在尝试连接到服务端…… ……"+"\n");
try {
Socket socket=new Socket(ip, port);
ShowArea.append("聊天室已经准备好");
frmLogincilent.setTitle("Ip:"+ip+" Port:"+port+" 已连接在线");
reader=new BufferedReader(new InputStreamReader(socket.getInputStream()));
writer=new PrintWriter(socket.getOutputStream(),true);
new Thread(this).start();
} catch (Exception e) {
// TODO: handle exception
}
}
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
Cilent window = new Cilent();
window.frmLogincilent.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the application.
*/
public Cilent() {
initialize();
}
/**
* Initialize the contents of the frame.
*/
private void initialize() {
frmLogincilent = new JFrame();
frmLogincilent.setResizable(false);
frmLogincilent.setTitle("Cilent");
frmLogincilent.setBounds(100, 100, 458, 532);
frmLogincilent.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frmLogincilent.getContentPane().setLayout(null);
JPanel panel = new JPanel();
panel.setBorder(new TitledBorder(null, "Default Setting", TitledBorder.LEADING, TitledBorder.TOP, null, null));
panel.setBounds(10, 10, 424, 84);
frmLogincilent.getContentPane().add(panel);
panel.setLayout(null);
JLabel lblIpAdress = new JLabel("IP Adress:");
lblIpAdress.setBounds(10, 20, 73, 15);
panel.add(lblIpAdress);
IPAdress = new JTextField();
IPAdress.setBounds(82, 17, 142, 21);
panel.add(IPAdress);
IPAdress.setColumns(10);
JLabel lblProt = new JLabel("Prot:");
lblProt.setBounds(10, 48, 54, 15);
panel.add(lblProt);
Port = new JTextField();
Port.setBounds(82, 45, 66, 21);
panel.add(Port);
Port.setColumns(10);
JLabel lblNickname = new JLabel("NickName:");
lblNickname.setBounds(170, 48, 73, 15);
panel.add(lblNickname);
Nickname = new JTextField();
Nickname.setBounds(238, 45, 176, 21);
panel.add(Nickname);
Nickname.setColumns(10);
Sumbit = new JButton("Lock&Login");
Sumbit.addMouseListener(new MouseAdapter() {
@Override
public void mouseClicked(MouseEvent arg0) {
try {
/*Create Socket*/
String ipString=IPAdress.getText();
int port=Integer.parseInt(Port.getText());
String Name=Nickname.getText();
InetAddress ip=InetAddress.getByName(ipString);
Create_Socket(ip, port);
/*Swing*/
IPAdress.setEditable(false);
Port.setEditable(false);
Nickname.setEditable(false);
Sumbit.setVisible(false);
} catch (Exception e) {
// TODO: handle exception
JOptionPane.showMessageDialog(null, "invalid data");
}
}
});
Sumbit.setBounds(272, 16, 142, 23);
panel.add(Sumbit);
ShowArea = new JTextArea();
ShowArea.setBounds(10, 104, 424, 358);
frmLogincilent.getContentPane().add(ShowArea);
Sendinfo = new JTextField();
Sendinfo.setBounds(10, 472, 330, 21);
frmLogincilent.getContentPane().add(Sendinfo);
Sendinfo.setColumns(10);
Send = new JButton("Send");
Send.addMouseListener(new MouseAdapter() {
@Override
public void mouseClicked(MouseEvent arg0) {
writer.println(Nickname.getText()+":"+Sendinfo.getText());
Sendinfo.setText("");
}
});
Send.setBounds(349, 471, 85, 23);
frmLogincilent.getContentPane().add(Send);
}
}
Socket管理类
继承ArrayList，并添加发送的方法SendtoAll(),以及显示当前连接数目的方法SendCilentInfo()
public class SocketManager extends ArrayList{
synchronized void add(Socket x)
{
super.add(x);
}
synchronized void remove(Socket x)
{
super.remove(x);
}
synchronized void SendtoAll(String str)
{
PrintWriter writer=null;
Socket socket;
for(int i=0;i<size();i++)
{
socket=(Socket)get(i);
try {
writer=new PrintWriter(socket.getOutputStream(),true);
if(writer!=null)
{
writer.println(str);
}
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}
}
}
synchronized void sendClientInfo()
{
String info="当前位于聊天室的人数为"+size();
System.out.println(info);
SendtoAll(info);
}
}
示例效果：
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