Java简单实现UDP和TCP的示例

TCP实现

TCP协议需要在双⽅之间建⽴连接，通过输⼊输出流来进⾏数据的交换，建⽴需要通过三次握⼿，断开需要四次挥⼿，保证了数据的完整性，但传输效率也会相应的降低。

简单的TCP实现

//服务端

public class TcpServer {

public static void main(String[] args) throws IOException {

ServerSocket serverSocket = new ServerSocket(8886); // 建⽴服务端，ip为本机ip,端⼝为8886

Socket accept = serverSocket.accept(); // 监听客户端的连接，⼀旦有客户端连接，则会返回客户端对应的accept

InputStream in = accept.getInputStream(); //获取到客户端的输出流 byte b[] = new byte[1024]; int len = in.read(b);

System.out.println(\"接受到客户端数据,返回数据\"+new String(b,0,len));

OutputStream out = accept.getOutputStream(); // 给客户端发送消息 out.write(\"服务端已经接受\".getBytes());

serverSocket.close(); }}

// 客户端

public class TcpClient {

public static void main(String[] args) throws IOException {

Socket socket = new Socket(\"127.0.0.1\通过Socket来建⽴和服务端的连接

OutputStream out = socket.getOutputStream(); // 获取输出流（客户端输出流即向服务端输出信息） out.write(\"hello tcp Server\".getBytes()); // 输出信息

InputStream in = socket.getInputStream(); // 接受服务端的消息 byte b[] = new byte[1024]; int len = in.read(b);

System.out.println(\"接受到服务器消息 ： \"+new String(b,0,len)); // 输出 out.write(\"返回的的数据已经收到 \".getBytes()); // 向服务器返回消息 socket.close(); }}

改进服务端，启⽤多线程来接受客户端的数据

// server

public static void main(String[] args) throws IOException {

ServerSocket serverSocket = new ServerSocket(8886); // 建⽴服务端，ip为本机ip,端⼝为8886 int i=4; while(i>2){

Socket accept = serverSocket.accept(); // 监听客户端的连接，⼀旦有客户端连接，则会返回客户端对应的accept

ServerThread st = new ServerThread(accept); // 启动线程 Thread th = new Thread(st); th.start(); }

serverSocket.close(); }// thread

public class ServerThread implements Runnable { private Socket accept;

public ServerThread(Socket s) { this.accept = s; }

public void run(){ InputStream in; try {

in = accept.getInputStream(); byte b[] = new byte[1024]; int len = in.read(b);

System.out.println(\"接受到客户端数据,返回数据\" + new String(b, 0, len)); OutputStream out = accept.getOutputStream(); // 给客户端发送消息 out.write(\"服务端已经接受\".getBytes()); } catch (IOException e) { e.printStackTrace(); } }}

传递图⽚

// 服务端

public class Server {

public static void main(String[] args) throws IOException {

ServerSocket serverSocket = new ServerSocket(5555); Socket ss = serverSocket.accept();

BufferedInputStream br = new BufferedInputStream(ss.getInputStream());

BufferedOutputStream bw = new BufferedOutputStream(new FileOutputStream(\"copy.jpg\")); // 写出⽂件流

byte b[] = new byte[1024]; int len = 0;

while ((len = br.read(b)) != -1) { // 写出⽂件 bw.write(b, 0, len);

bw.flush(); // 别忘了刷新，要不然最后⼀块缓冲区字符串会缺失 }

BufferedWriter bw2 = new BufferedWriter(new OutputStreamWriter(ss.getOutputStream())); // 输出 bw2.write(\"图⽚传输成功\"); bw2.flush();

bw.close(); ss.close(); }}

// 客户端

public class Client {

public static void main(String[] args) throws UnknownHostException, IOException { Socket socket = new Socket(\"127.0.0.1\

BufferedInputStream in = new BufferedInputStream(new FileInputStream(\"c.jpg\")); BufferedOutputStream out = new BufferedOutputStream(socket.getOutputStream()); byte b[] = new byte[1024]; int len = 0;

while ((len = in.read(b)) != -1) { out.write(b, 0, len);

out.flush(); // 刷新缓冲区 要不然最后⼀块缓冲区字符串会缺失 }

socket.shutdownOutput(); // 关闭流以后Server段才会接收道结束字符结束接受

BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream())); String line;

while ((line = br.readLine()) != null) { System.out.println(line);

}

in.close();

socket.close(); }}

UDP实现

UDP是将数据打成数据包向对⽅发送，只关系是否发送成功，⽽不关⼼是否接收成功，传输速度快，但是可靠性低。udp代码实现

// 发送端

public class SendDemo {

public static void main(String[] args) throws IOException {

DatagramSocket ds = new DatagramSocket(); // 此类表⽰⽤来发送和接收数据报包的套接字。 BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); // 键盘输⼊ String line = null;

while ((line = br.readLine()) != null) { byte[] bytes = line.getBytes();

DatagramPacket dp = new DatagramPacket(bytes, bytes.length, InetAddress.getByName(\"127.0.0.1\"), 10005); // 数据包对象 ds.send(dp);

if (\"886\".equals(line)) { // 当输⼊886时结束发送 break; } }

ds.close(); }}

// 接收端

public class ReciveDemo {

public static void main(String[] args) throws IOException {

DatagramSocket ds = new DatagramSocket(10005); // 建⽴服务端 byte bytes[] = new byte[1024];

DatagramPacket dp = new DatagramPacket(bytes, bytes.length); // 建⽴数据包对象 while (true) {

ds.receive(dp); // 接受数据包

byte[] data = dp.getData(); // 获取数据

String str = new String(data, 0, dp.getLength()); if (\"886\".equals(str)) { break; }

System.out.println(str); }

ds.close(); }}

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