TCP和UDP

UDP

发送方

    public static void main(String[] args) throws Exception{
        DatagramSocket datagramSocket = new DatagramSocket();
        String s = "你好UDP协议" ;
        datagramSocket.send(new DatagramPacket(s.getBytes(), 
                                               0,
                                               s.length(),                                                                         InetAddress.getLocalHost(), 
                                               8084));
        System.out.println(datagramSocket);
        datagramSocket.close();
    }

接收方

    public static void main(String[] args) throws Exception{
        DatagramSocket datagramSocket = new DatagramSocket(8084);
        byte[] bytes = new byte[1024];
        DatagramPacket datagramPacket = new DatagramPacket(bytes,bytes.length);

        datagramSocket.receive(datagramPacket);
        System.out.println(datagramPacket.getAddress());
        int length = datagramPacket.getLength();
        System.out.println(new String(bytes,0,length));
        datagramSocket.close();
    }

TCP

服务器端

public static void main(String[] args)  throws Exception{
        ServerSocket serverSocket = new ServerSocket(8085);
    
        //之后都是操作Socket对象
        Socket socket = serverSocket.accept();
        InputStream inputStream = socket.getInputStream();
        byte[] bytes = new byte[1024];
        int len=-1;
        while ((len = inputStream.read(bytes) )!= -1) {
            System.out.println(new String(bytes,0,len));
        }

        OutputStream outputStream = socket.getOutputStream();
        outputStream.write("我已收到信息".getBytes());
        socket.shutdownOutput();
    }

客户端

public static void main(String[] args) throws Exception{
        Socket socket = new Socket("localhost",8085);
        InputStream inputStream = socket.getInputStream();
        OutputStream outputStream = socket.getOutputStream();
        //传过去
        outputStream.write("我是你们的老朋友".getBytes());
        socket.shutdownOutput();
        //传回来
        byte[] bytes = new byte[1024];
        int len=-1;
        while ((len = inputStream.read(bytes) )!= -1) {
            System.out.println(new String(bytes,0,len));
        }

    }

BS架构基本原理

public static void main(String[] args) throws Exception{
        ServerSocket serverSocket = new ServerSocket(8888);
        System.out.println("开启服务器");
        Socket socket = serverSocket.accept();

        //通过socket获得InputStream,获得请求客户端的信息
        InputStream inputStream = socket.getInputStream();
        byte[] bytes = new byte[1024];
        int len = inputStream.read(bytes);
        System.out.println(new String(bytes,0,len));

        //my.html为服务器端的文件
        BufferedReader br = new BufferedReader(new FileReader("my.html"));
        String content = br.readLine();
        br.close();

        //通过socket获取outputStream,向请求客户端发送信息
        OutputStream outputStream = socket.getOutputStream();
        outputStream.write(content.getBytes());
        
    }

IE浏览器测试 http:localhost:8080

服务输出数据

开启服务器
GET / HTTP/1.1
Accept: text/html, application/xhtml+xml, image/jxr, */*
Accept-Language: zh-Hans-CN,zh-Hans;q=0.5
User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; Trident/7.0; rv:11.0) like Gecko
Accept-Encoding: gzip, deflate
Host: localhost:8888
Connection: Keep-Alive

多用户同时文件上传

客户端

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

        for (int i = 0; i <10 ; i++)
        {

            Socket socket = new Socket("localhost",8082);
            OutputStream outputStream = socket.getOutputStream();
            BufferedInputStream stream = new BufferedInputStream(new FileInputStream("a.jpg"));
            int ll=-1;
           byte[] bytes1 = new byte[1024];
            while ((ll = stream.read(bytes1)) != -1) {
                outputStream.write(bytes1);
            }
            stream.close();
            //为什么要有下面这个?因为上面的write传输的时候并没有把结束符传输过去?这样对方执行(len = inputStream.read(bytes)) != -1是永远也无法读取到-1的
            socket.shutdownOutput();
            InputStream inputStream = socket.getInputStream();
            byte[] bytes = new byte[1024];
            int len=-1;
            while ((len = inputStream.read(bytes)) != -1) {
                System.out.println(new String(bytes,0,len));
            }


        }
    }

服务端

 public static void main(String[] args)  throws Exception{
        ServerSocket serverSocket = new ServerSocket(8082);
        System.out.println("正在等待客户端发起请求......");

        while(true){
            Socket socket = serverSocket.accept();

            new Thread(()-> {
                try {
                    InputStream inputStream = socket.getInputStream();
                    String s = System.currentTimeMillis() + "" + ".jpg" ;
                    System.out.println(s);
                    BufferedOutputStream outputStream1 = new BufferedOutputStream(new FileOutputStream(new File(s)));
                    byte[] bytes = new byte[1024];
                    int i = -1;
                    System.out.println("书写图片");
                    while ((i = inputStream.read(bytes)) != -1) {
                        outputStream1.write(bytes, 0, i);
                    }
                    OutputStream outputStream = socket.getOutputStream();
                    outputStream.write("服务端收到信息".getBytes());
                    socket.shutdownOutput();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }).start();


        }


    }