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", 8886); // 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", 5555);

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();

}

}