端口号范围：0~65535，建议选择1024以上

UDP：面向无连接，数据不安全，速度快，不区分客户端和服务器（有发送端和接收端）（发短信）

TCP：面向连接（三次握手），数据安全，速度略低，分为客户端和服务器（打电话）

1.UDP

package day26; import java.io.IOException; import java.net.DatagramPacket; import java.net.DatagramSocket; import java.net.InetAddress; import java.net.SocketException; import java.net.UnknownHostException; import java.util.Scanner; public class Dk1UdpSend { //UDP发送端 public static void main(String[] args) throws IOException { //basic(); advanced(); } public static void basic() throws SocketException, UnknownHostException, IOException { //1.创建DatagramSocket,随机端口号 DatagramSocket socket = new DatagramSocket(); //2.创建DatagramPacket,指定数据，长度，地址，端口 String str = "红鲤鱼绿鲤鱼与驴"; DatagramPacket packet = new DatagramPacket(str.getBytes(), str.getBytes().length,InetAddress.getByName("127.0.0.1"),12345); //3.使用DatagramSocket发送DatagramPacket socket.send(packet); //4.关闭DatagramSocket socket.close(); //底层是IO流所以要关 } public static void advanced() throws SocketException, UnknownHostException, IOException { //1.创建DatagramSocket,随机端口号 DatagramSocket socket = new DatagramSocket(); Scanner sc = new Scanner(System.in); while (true) { //2.创建DatagramPacket,指定数据，长度，地址，端口 String str = sc.nextLine(); if ("quit".equals(str)) { break; } DatagramPacket packet = new DatagramPacket(str.getBytes(), str.getBytes().length,InetAddress.getByName("127.0.0.1"),12345); //3.使用DatagramSocket发送DatagramPacket socket.send(packet); } //4.关闭DatagramSocket socket.close(); //底层是IO流所以要关 } } package day26; import java.io.IOException; import java.net.DatagramPacket; import java.net.DatagramSocket; import java.net.SocketException; public class Dk2UdpReceive { //UDP接收端 public static void main(String[] args) throws IOException { //basic(); advanced(); } public static void basic() throws SocketException, IOException { //1.创建DatagramSocket(码头),指定端口号 DatagramSocket socket = new DatagramSocket(12345); //2.创建DatagramPacket(集装箱),指定数组，长度 DatagramPacket packet = new DatagramPacket(new byte[1024], 1024); //3.使用DatagramSocket接收DatagramPacket socket.receive(packet); //4.从DatagramPacket获取数据 byte[] arr = packet.getData(); int len = packet.getLength(); //获取发过来的有效字节个数 System.out.println(new String(arr,0,len)); //转换len个字节为字符串 //5.关闭DatagramSocket socket.close(); } public static void advanced() throws SocketException, IOException { //1.创建DatagramSocket(码头),指定端口号 DatagramSocket socket = new DatagramSocket(12345); //2.创建DatagramPacket(集装箱),指定数组，长度 DatagramPacket packet = new DatagramPacket(new byte[1024], 1024); while (true) { //3.使用DatagramSocket接收DatagramPacket socket.receive(packet); //4.从DatagramPacket获取数据 byte[] arr = packet.getData(); int len = packet.getLength(); //获取发过来的有效字节个数 String ip = packet.getAddress().getHostAddress(); //获取发送端IP int port = packet.getPort(); //获取发送端端口号 System.out.println(ip + ":"+ port + ":"+new String(arr,0,len)); //转换len个字节为字符串 } } } package day26; import java.io.IOException; import java.net.DatagramPacket; import java.net.DatagramSocket; import java.net.InetAddress; import java.net.SocketException; import java.net.UnknownHostException; import java.util.Scanner; public class Dk3UdpMoreThread { //多线程 public static void main(String[] args) throws InterruptedException { new UdpReceive().start(); Thread.sleep(10); //让接收端先启动 new UdpSend().start(); } } class UdpReceive extends Thread{ public void run() { //异常不能直接抛，用try try { //1.创建DatagramSocket(码头),指定端口号 DatagramSocket socket = new DatagramSocket(12345); //2.创建DatagramPacket(集装箱),指定数组，长度 DatagramPacket packet = new DatagramPacket(new byte[1024], 1024); while (true) { //3.使用DatagramSocket接收DatagramPacket socket.receive(packet); //4.从DatagramPacket获取数据 byte[] arr = packet.getData(); int len = packet.getLength(); //获取发过来的有效字节个数 String ip = packet.getAddress().getHostAddress(); //获取发送端IP int port = packet.getPort(); //获取发送端端口号 System.out.println(ip + ":"+ port + ":"+new String(arr,0,len)); //转换len个字节为字符串 } } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } class UdpSend extends Thread{ public void run() { try { //1.创建DatagramSocket,随机端口号 DatagramSocket socket = new DatagramSocket(); Scanner sc = new Scanner(System.in); while (true) { //2.创建DatagramPacket,指定数据，长度，地址，端口 String str = sc.nextLine(); if ("quit".equals(str)) { break; } DatagramPacket packet = new DatagramPacket(str.getBytes(), str.getBytes().length,InetAddress.getByName("127.0.0.1"),12345); //3.使用DatagramSocket发送DatagramPacket socket.send(packet); } //4.关闭DatagramSocket socket.close(); //底层是IO流所以要关 } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } //输出 你好 127.0.0.1:57978:你好 你好 127.0.0.1:57978:你好 明天好 127.0.0.1:57978:明天好

2.TCP

package day26; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.io.OutputStream; import java.io.PrintStream; import java.net.ServerSocket; import java.net.Socket; public class Dk4TcpServer { //TCP服务端 public static void main(String[] args) throws IOException { //basic(); //advanced(); moreThread(); } public static void basic() throws IOException { //1.创建ServerSocket(需要指定端口号) ServerSocket server = new ServerSocket(9999); //2.调用ServerSocket的accept()方法接收一个客户端请求，得到一个socket Socket socket = server.accept(); //3.调用Socket的getInputStream()和getOutputStream()方法获取和客户端相连的IO流 InputStream is = socket.getInputStream(); OutputStream os = socket.getOutputStream(); //输出流可以写出数据到客户端的输入流 os.write("百度一下，你就知道".getBytes()); //输入流可以读取客户端输出流写出的数据 byte[] arr = new byte[1024]; int len = is.read(arr); System.out.println(new String(arr,0,len)); //关闭套接字 socket.close(); } public static void advanced() throws IOException { //1.创建ServerSocket(需要指定端口号) ServerSocket server = new ServerSocket(9999); //2.调用ServerSocket的accept()方法接收一个客户端请求，得到一个socket Socket socket = server.accept(); BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream())); PrintStream ps = new PrintStream(socket.getOutputStream()); ps.println("欢迎咨询"); //写给客户端 System.out.println(br.readLine());//读客户端 } public static void moreThread() throws IOException { //1.创建ServerSocket(需要指定端口号) final ServerSocket server = new ServerSocket(9999); while (true) { //2.调用ServerSocket的accept()方法接收一个客户端请求，得到一个socket Socket socket = server.accept(); new Thread() { public void run() { try { BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream())); PrintStream ps = new PrintStream(socket.getOutputStream()); ps.println("欢迎咨询"); //写给客户端 System.out.println(br.readLine());//读客户端 socket.close(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } }.start(); } } } package day26; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.io.OutputStream; import java.io.PrintStream; import java.net.Socket; import java.net.UnknownHostException; public class Dk5TcpClient { //TCP客户端 public static void main(String[] args) throws IOException { //basic(); advanced(); } public static void basic() throws UnknownHostException, IOException { //1.创建Socket连接客户端（指定IP地址和端口号），通过IP地址找对应的服务器 Socket socket = new Socket("127.0.0.1",9999); //2.调用Socket的getInputStream()和getOutputStream()方法获取和服务端相连的IO流 InputStream is = socket.getInputStream(); OutputStream os = socket.getOutputStream(); //输入流可以读取服务端输出流写出的数据 byte[] arr = new byte[1024]; int len = is.read(arr); System.out.println(new String(arr,0,len)); //输出流可以写出数据到服务端的输入流 os.write("学习挖掘机哪家强".getBytes()); //关闭套接字 socket.close(); } public static void advanced() throws UnknownHostException, IOException { //1.创建Socket连接客户端（指定IP地址和端口号），通过IP地址找对应的服务器 Socket socket = new Socket("127.0.0.1",9999); BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream())); PrintStream ps = new PrintStream(socket.getOutputStream()); System.out.println(br.readLine()); //读服务器 ps.println("学Java"); //写给服务器 socket.close(); } } package day26; import java.io.BufferedReader; import java.io.File; import java.io.FileInputStream; import java.io.InputStreamReader; import java.io.PrintStream; import java.net.Socket; import java.util.Scanner; public class Dk7UploadClient { //客户端向服务器上传文件 public static void main(String[] args) throws IOException{ //1.提示输入上传的文件路径，验证路径是否存在以及是否是文件夹 File file = getFile(); //2.发送文件名到服务端 Socket socket = new Socket("127.0.0.1",12345); BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream())); PrintStream ps = new PrintStream(socket.getOutputStream()); ps.println(file.getName()); //6.接收结果，如果存在给予提示，程序直接退出 String result = br.readLine(); //结果为"存在"或"不存在" if ("存在".equals(result)) { System.out.println("您上传的文件已经存在"); socket.close(); return; } //7.如果不存在，定义FileInputStream读取文件，写出到网络 FileInputStream fis = new FileInputStream(file); byte[] arr = new byte[8192]; int len; while((len = fis.read(arr)) != -1) { ps.write(arr,0,len); } fis.close(); socket.close(); } //1.上传文件路径 public static File getFile() { Scanner sc = new Scanner(System.in); System.out.println("请输入文件路径："); while (true) { String line = sc.nextLine(); File file = new File(line); if (!file.exists()) { System.out.println("重输："); }else if (file.isDirectory()) { System.out.println("重输："); }else { return file; } } } } package day26; import java.io.BufferedReader; import java.io.File; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.io.PrintStream; import java.net.ServerSocket; import java.net.Socket; public class Dk6UploadServer { //上传文件到服务端 public static void main(String[] args) throws IOException { //3.建立多线程的服务器 ServerSocket server = new ServerSocket(12345); System.out.println("服务器启动"); while (true) { final Socket socket = server.accept(); new Thread() { public void run() { try { //4.读取文件名 InputStream is = socket.getInputStream(); //读文件 BufferedReader br = new BufferedReader(new InputStreamReader(is)); //读文件名 PrintStream ps = new PrintStream(socket.getOutputStream()); String fileName = br.readLine(); File dir = new File("Upload"); dir.mkdir(); //创建文件夹 File file = new File(dir,fileName); //将文件名包装成file对象才可以进行判断 //5.判断文件是否存在，将结果发回客户端 if (file.exists()) { ps.println("存在"); socket.close(); return; }else { ps.println("不存在"); } //8.定义FileOutputStream,从网络读取数据存储到本地 FileOutputStream fos = new FileOutputStream(file); byte[] arr = new byte[8192]; int len; while((len = is.read(arr)) != -1) { fos.write(arr,0,len); } fos.close(); socket.close(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } }.start(); } } }