TCP通信的实现代码

TCP通信

概念

传输控制协议（TCP，Transmission Control Protocol）是一种面向连接的、可靠的、基于字节流的传输层通信协议。

从百科定义中就可以看出，TCP通信的基本条件是连接，传输的是字节流。

• 通信基本流程（类似打招呼的方式）：
  
  1.三次握手
  
  2.四次挥手

客户端

    //客户端
    public class TCPDemo01 {
        public static void main(String[] args) throws Exception {
            //1.要知道服务器的ip，端口号
            InetAddress ip = InetAddress.getByName("127.0.0.1");//ip
            int port = 9999;//端口号
            //创建socket
            Socket socket = new Socket(ip,port);
            //发送消息
            OutputStream os = socket.getOutputStream();

            os.write("你好".getBytes());

            //关闭资源
            os.close();
            socket.close();

        }

    }

服务端

    //服务端
    public class TCPDemo02 {
        public static void main(String[] args) throws Exception {
            //1.有一个端口号
            ServerSocket serverSocket = new ServerSocket(9999);
            //2.等待客户端连接
            Socket socket = serverSocket.accept();//客户端的socket
            //3.读取客户端消息
            InputStream is = socket.getInputStream();

            ByteArrayOutputStream baos = new ByteArrayOutputStream();
            byte[] buf = new byte[1024];
            int len;
            while ((len=is.read(buf))!=-1){
                baos.write(buf,0,len);
            }
            System.out.println(baos.toString());

            //关闭资源
            baos.close();
            is.close();
            socket.close();
            serverSocket.close();

        }
    }

• 用TCP协议实现上传文件到服务端
  
  客户端

    public class client01 {
        public static void main(String[] args) throws Exception {
            //1.获取服务端ip和端口
            InetAddress ip = InetAddress.getByName("127.0.0.1");
            int port = 9999;
            //2.创建socket对象
            Socket socket = new Socket(ip,port);
            //3.获取输出流
            OutputStream os = socket.getOutputStream();
            //4.创建文件输入流
            FileInputStream fis = new FileInputStream("F:/桌面文件/a.txt");
            //5.写文件
            byte[] buf = new byte[1024];//缓冲区
            int len;
            while ((len=fis.read(buf))!=-1){
                os.write(buf,0,len);
            }
            //通知传输结束
            socket.shutdownOutput();//输出完了

            //等服务端接收完
            InputStream is = socket.getInputStream();
            ByteArrayOutputStream baos = new ByteArrayOutputStream();
            byte[] buf2 = new byte[1024];
            int len2;
            while ((len2=is.read(buf2))!=-1){
                baos.write(buf2,0,len2);
            }
            System.out.println(baos.toString());
            //6.关闭资源
            baos.close();
            is.close();
            fis.close();
            os.close();
            socket.close();
        }
    }

服务端

   public class servlet01 {
       public static void main(String[] args) throws IOException {
           //1.创建服务端接口
           ServerSocket serverSocket = new ServerSocket(9999);
           //2.等待连接
           Socket socket = serverSocket.accept();
           //3.输入流
           InputStream is = socket.getInputStream();
           //4.创建文件输出流
           FileOutputStream fos = new FileOutputStream("receive.txt");
           //5.输出文件
           byte[] buf = new byte[1024];
           int len;
           while ((len=is.read(buf))!=-1){
               fos.write(buf,0,len);
           }
           //通知客户端，接收完毕
           OutputStream os = socket.getOutputStream();
           os.write("接受完毕".getBytes());
           //6.关闭资源
           fos.close();
           is.close();
           socket.close();
           serverSocket.close();

       }

   }