Java之网络编程

一、网络编程

        网络编程的本质是两个设备之间的数据交换，当然，在计算机网络中，设备主要指计算机。数据传递本身没有多大的难度，不就是把一个设备中的数据发送给两外一个设备，然后接受另外一个设备反馈的数据。

目的：传播交流信息、数据交换、通信

二、网络通信的要素

• IP和端口号

• 网络通信的协议

三、TCP实现聊天

• 客户端

1.连接服务器

2.发送消息

//客户端
public class TcpClient {
    public static void main(String[] args) {
        Socket socket =null;
        OutputStream outputStream =null;
        //需要知道服务器的地址
        try {
            //ip和端口号
            InetAddress serverIp = InetAddress.getByName( "127.0.0.1" );
            int port=8888;
            //创建socket连接
            socket = new Socket(serverIp,port);
            //发送消息IO流
            outputStream = socket.getOutputStream();
            outputStream.write( "正在学习网络编程".getBytes() );
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            if (outputStream!=null){
                try {
                    outputStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (socket!=null){
                try {
                    socket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

• 服务器

1.建立服务的端口 ServerSocket

2.等待用户的链接 accept

3.接受用户的消息

//服务器
public class TcpServer1 {
    public static void main(String[] args) {
        ServerSocket socket = null;
        InputStream inputStream = null;
        ByteArrayOutputStream baos = null;
        Socket accept = null;
        //地址
        try {
            socket = new ServerSocket(8888);
            //等待客户端连接
            accept = socket.accept();
            //读取客户端的消息
            inputStream = accept.getInputStream();
            //管道流
            baos = new ByteArrayOutputStream();
            byte[] buffer = new byte[1024];
            int len;
            while ((len= inputStream.read(buffer))!=-1){
                baos.write( buffer,0,len );
            }
            System.out.println(baos.toByteArray());

            baos.close();
            inputStream.close();
            accept.close();
            socket.close();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            //关闭资源
            if (baos!=null){
                try {
                    baos.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (inputStream!=null){
                try {
                    inputStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (accept!=null){
                try {
                    accept.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (socket!=null){
                try {
                    socket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

四、TCP实现文件上传

 客户端

//客户端
public class TcpClient2 {
    public static void main(String[] args) throws IOException {
        //创建一个Socket连接
        Socket socket = new Socket( InetAddress.getByName( "127.0.0.1" ),8888);
        //创建一个输出流
        OutputStream os = socket.getOutputStream();
        //文件流,读取文件
        FileInputStream fis = new FileInputStream( new File( "24134.jpg" ) );
        //写出文件
        byte[] buffer = new byte[1024];
        int len;
        while ((len=fis.read(buffer))!=-1){
            os.write( buffer,0,len );
        }
        //通知服务器传输完毕
        socket.shutdownOutput();//已经传输完了

        //确定服务器端接收完毕，才断开连接
        InputStream inputStream = socket.getInputStream();
        //String byte[]
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        byte[] bt = new byte[1024];
        int len1;
        while ((len1=inputStream.read(bt))!=-1){
            baos.write( bt,0,len1 );
        }
        System.out.println( baos.toByteArray() );

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

服务端

//服务器
public class TcpServer2 {
    public static void main(String[] args) throws IOException {
        //创建服务
        ServerSocket serverSocket = new ServerSocket(8888);
        //监听客户端的连接
        Socket socket = serverSocket.accept();//阻塞式监听，会一直等待客户端连接
        //获取文件输入流
        InputStream is = socket.getInputStream();
        //文件输出
        FileOutputStream fos = new FileOutputStream( new File( "receive" ) );
        byte[] buffer = new byte[1024];
        int len;
        while ((len=is.read(buffer))!=-1){
            fos.write( buffer,0,len );
        }
        //通知客户端接收完毕
        OutputStream os = socket.getOutputStream();
        os.write( "接收完毕".getBytes());
        //关闭资源
        fos.close();
        is.close();
        socket.close();
        serverSocket.close();
    }
}

五、UDP发送消息

发送端

//不需要连接服务器
public class UdpClient1 {
    public static void main(String[] args) throws IOException {
        //建立一个Socket
        DatagramSocket socket = new DatagramSocket();
        //建个包
        String xx = "你好啊，UDP";
        //发送给谁
        InetAddress localhost = InetAddress.getByName( "localhost" );
        int port=8888;
        //数据，数据的长度，要发送给谁
        DatagramPacket packet = new DatagramPacket( xx.getBytes(), 0, xx.getBytes().length, localhost, port );
        //发送包
        socket.send( packet );

        //关闭流
        socket.close();
    }
}

接收端

public class UdpServer1 {
    public static void main(String[] args) throws IOException {
        //开放端口
        DatagramSocket socket = new DatagramSocket(8888);
        //接收数据包
        byte[] buffer = new byte[1024];
        DatagramPacket packet = new DatagramPacket( buffer, 0, buffer.length );
        socket.receive( packet );//阻塞接收

        System.out.println(packet.getAddress().getHostAddress());
        System.out.println(packet.getData());

        //关闭连接
        socket.close();
    }
}

六、UDP实现聊天

发送端

public class UdpSender1 {
    public static void main(String[] args) throws IOException {
        DatagramSocket socket = new DatagramSocket(8888);
        //准备数据：控制台读取
        BufferedReader reader = new BufferedReader( new InputStreamReader( System.in ) );

        while (true){
            String data = reader.readLine();
            byte[] datas = data.getBytes();
            DatagramPacket packet = new DatagramPacket(datas,0,datas.length,new InetSocketAddress( "localhost",6666 ) );

            socket.send( packet );

            if (packet.equals( "bye" )){
                break;
            }
        }


        socket.close();
    }
}

接收端

public class UdpReceive2 {
    public static void main(String[] args) throws IOException {
        DatagramSocket socket = new DatagramSocket( 6666 );
        while (true){
            //准备接收数据
            byte[] bt = new byte[1024];
            DatagramPacket packet = new DatagramPacket(bt,0,bt.length);
            socket.receive( packet );//阻塞式接收数据

            //断开连接
            java.lang.String data = packet.getData().toString();

            System.out.println(data);

            if (data.equals( "bye" )){
                break;
            }
        }
        socket.close();
    }
}

七、UDP多线程实现聊天功能

 TalkSend类

public class TalkSend implements Runnable{
    DatagramSocket socket =null;
    BufferedReader reader =null;

    private int fromPort;
    private String toIP;
    private int toPort;

    public TalkSend(int fromPort, String toIP, int toPort) {
        this.fromPort = fromPort;
        this.toIP = toIP;
        this.toPort = toPort;

        try {
            socket = new DatagramSocket( fromPort );
            //读取数据
            reader = new BufferedReader( new InputStreamReader( System.in ) );
        }catch (Exception e){
            e.printStackTrace();
        }
    }

    @Override
    public void run() {
        while (true){
            try {
                String  data = reader.readLine();
                byte[] datas = data.getBytes();
                DatagramPacket packet = new DatagramPacket(datas,0,datas.length,new InetSocketAddress( this.toIP,this.toPort ) );

                socket.send( packet );

                if (packet.equals( "bye" )){
                    break;
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        socket.close();
    }
}

 TalkReceive类

public class TalkReceive implements Runnable{
    DatagramSocket socket =null;
    private int port;
    private String name;

    public TalkReceive(int port,String name) {
        this.port = port;
        this.name = name;
        try {
            socket = new DatagramSocket( port );
        }catch (Exception e){
            e.printStackTrace();
        }
    }

    @Override
    public void run() {
        while (true){
            try {
                //准备接收数据
                byte[] bt = new byte[1024];
                DatagramPacket packet = new DatagramPacket(bt,0,bt.length);
                socket.receive( packet );//阻塞式接收数据

                //断开连接
                String data = packet.getData().toString();

                System.out.println(name+":"+data.toString());

                if (data.equals( "bye" )){
                    break;
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        socket.close();
    }
}

 TalkStudent类

public class TalkStudent {
    public static void main(String[] args) {
        //开启两个线程
        new Thread(new TalkSend( 7777,"localhost",9999 )).start();
        new Thread(new TalkReceive( 8888,"老师" )).start();
    }
}

 TalkTeacher类

public class TalkTeacher {
    public static void main(String[] args) {
        //开启两个线程
        new Thread(new TalkSend( 5555,"localhost",8888 )).start();
        new Thread(new TalkReceive( 9999,"学生" )).start();
    }
}