詳解Java網絡編程

/*
1 java中使用InetAddress代表IP
2 IP的分類：IPV4和IPV6     萬維網和局域網

3 域名：www.baidu.com www.cnblogs.com

4 本地回路地址：127.0.0.1 對應著：localhost

5 如何實例化InetAddress類的對象，兩個靜態方法：
    InetAddress getByName(String host)
    InetAddress getLocalHost()

6 兩個常用方法
    getHostName()
    getHostAddress()

7 端口號：正在計算機上運行的進程
 */
public class InetAddressTest {
    public static void main(String[] args){
        try {
            // File file = new File("test.txt");
            InetAddress IP1 = InetAddress.getByName("192.168.3.2");
            System.out.println(IP1);

            InetAddress IP2 = InetAddress.getByName("www.baidu.com");
            System.out.println(IP2);
            // 獲取本地IP
            InetAddress localHost = InetAddress.getLocalHost();
            System.out.println(localHost);

            // getHostName()
            System.out.println(IP2.getHostName());
            // getHostAddress()
            System.out.println(IP2.getHostAddress());


        } catch(UnknownHostException e){
            e.printStackTrace();
        }
    }
}

// 構造器一
Socket(String host,int port)throws UnknownHostException,IOException
/* 向服務器(域名是 host。端口號為port)發起TCP連接，若成功，則創建Socket對象，否則拋出異常。*/

// 構造器二
Socket(InetAddress address,int port)throws IOException
/* 根據InetAddress對象所表示的 IP地址以及端口號port發起連接。*/

Socket s = new Socket("192.168.40.165",9999); // 1、創建Socket對象，指明服務端的IP和端口號
OutputStream out = s.getOutputStream(); // 2、獲取一個輸出流，用於輸出數據
out.write("hello".getBytes()); // 3、寫出數據
s.close(); // 4、回收資源

ServerSocket ss = new ServerSocket(9999); // 1、創建服務端的ServerSocket，指明自己的端口號
Socket s = ss.accept (); // 2、調用accept()監聽來自客戶端的連接
InputStream in = s.getInputStream(); // 3、獲取輸入流，讀取輸入流的數據
byte[] buf = new byte[1024]; 
int num = in.read(buf); 
String str = new String(buf,0,num); 
System.out.println(s.getInetAddress().toString()+":"+str); 
s.close(); // 4、回收資源
ss.close();

/**
 * @description: TCP編程，模擬基於C/S架構客戶端與服務端間的通信
 */
public class SocketTest {
    /* 客戶端 */
    @Test
    public void client(){
        OutputStream output = null;
        Socket socket = null;
        try {
            InetAddress localHost = InetAddress.getByName("127.0.0.1");
            socket = new Socket(localHost,8848);
            output = socket.getOutputStream();
            output.write("hello I'm the client".getBytes());
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if(output != null){
                try {
                    output.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if(socket != null){
                try {
                    socket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
    /* 服務端 */
    @Test
    public void server() {
        ServerSocket serverSocket = null;
        Socket socket = null;
        InputStream input = null;
        ByteArrayOutputStream out = null;
        try {
            serverSocket = new ServerSocket(8848);
            socket = serverSocket.accept();
            System.out.println("client IP: " + socket.getInetAddress());
            input = socket.getInputStream();
            /*
            一般不建議這樣書寫，數據傳輸時可能會出現亂碼！！
            byte[] buffer = new byte[1024];
            int len;
            while((len = input.read(buffer)) != -1){
                String data = new String(buffer,0,len);
                System.out.println(data);
            }*/

            out = new ByteArrayOutputStream();
            byte[] buffer = new byte[10];
            int len;
            while((len = input.read(buffer)) != -1){
                out.write(buffer,0,len);
            }
            System.out.println(out.toString());
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if(out != null){
                try {
                    out.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if(input != null){
                try {
                    input.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if(socket != null){
                try {
                    socket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if(serverSocket != null){
                try {
                    serverSocket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

/**
 * @description: TCP編程，客戶端發送文件給服務端，服務端將文件保存在本地。
 */
public class TCPSocketTest {
	/* 客戶端 */
    @Test
    public void client() {
        Socket socket = null;
        OutputStream writer = null;
        BufferedInputStream bis = null;
        try {
            socket = new Socket(InetAddress.getByName("127.0.0.1"),8089);
            writer = socket.getOutputStream();

            bis = new BufferedInputStream(new FileInputStream(new File("me.jpg")));
            byte[] buffer = new byte[1024];
            int len;
            while((len = bis.read(buffer)) != -1){
                writer.write(buffer,0,len);
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if(socket != null){
                try {
                    socket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if(writer != null){
                try {
                    writer.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if(bis != null){
                try {
                    bis.close();
                    System.out.println("發送成功！");
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
	/* 服務端 */
    @Test
    public void server() throws IOException { // 這裡異常應該使用try-catch-finally
        ServerSocket socket = new ServerSocket(8089);
        System.out.println("正在等待客戶端連接...");
        Socket clientSocket = socket.accept();

        System.out.println("客戶端已連接IP地址為："+clientSocket.getInetAddress().getHostName());
        InputStream is = clientSocket.getInputStream();
        BufferedOutputStream reader = new BufferedOutputStream(new FileOutputStream(new File("new_me.jpg")));

        byte[] buffer = new byte[1024];
        int len;
        while((len = is.read(buffer)) != -1){
            reader.write(buffer,0,len);
        }
        System.out.println("接收成功");

        socket.close();
        clientSocket.close();
        is.close();
        reader.close();
    }
}

/**
 * @description: TCP編程，從客戶端發送文件給服務端，服務端保存到本地。並返回“發送成功”給 客戶端。並關閉相應的連接。
 */
public class TCPSocketTest2 {
	/* 客戶端 */
    @Test
    public void client() {
        Socket socket = null;
        OutputStream writer = null;
        BufferedInputStream bis = null;
        try {
            socket = new Socket(InetAddress.getByName("127.0.0.1"),8089);
            writer = socket.getOutputStream();

            bis = new BufferedInputStream(new FileInputStream(new File("me.jpg")));
            byte[] buffer = new byte[1024];
            int len;
            while((len = bis.read(buffer)) != -1){
                writer.write(buffer,0,len);
            }
            // 關閉數據的輸出
            socket.shutdownOutput();

            // 接收服務端反饋的信息並輸出到控制臺
            InputStream is = socket.getInputStream();
            ByteArrayOutputStream byteArray = new ByteArrayOutputStream();
            byte[] buf = new byte[10];
            int l;
            while((l = is.read(buf)) != -1){
                byteArray.write(buf,0,l);
            }
            System.out.println(byteArray.toString());
            is.close();
            byteArray.close();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if(socket != null){
                try {
                    socket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if(writer != null){
                try {
                    writer.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if(bis != null){
                try {
                    bis.close();
                    System.out.println("發送成功！");
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
	/* 服務端 */
    @Test
    public void server() throws IOException { // 這裡異常應該使用try-catch-finally
        ServerSocket socket = new ServerSocket(8089);
        System.out.println("正在等待客戶端連接...");
        Socket clientSocket = socket.accept();

        System.out.println("客戶端已連接IP地址為："+clientSocket.getInetAddress().getHostName());
        InputStream is = clientSocket.getInputStream();
        BufferedOutputStream reader = new BufferedOutputStream(new FileOutputStream(new File("new_me.jpg")));

        byte[] buffer = new byte[1024];
        int len;
        while((len = is.read(buffer)) != -1){
            reader.write(buffer,0,len);
        }
        System.out.println("接收成功");

        // 服務端給客戶端反饋信息
        OutputStream os = clientSocket.getOutputStream();
        os.write("你好客戶端，照片已經收到".getBytes());

        socket.close();
        clientSocket.close();
        is.close();
        reader.close();
        os.close();
    }
}

/*
UDP網絡編程：
    ✔ 將數據、源、目的封裝成數據包，不需要建立連接
    ✔ 每個數據報的大小限制在64K內
    ✔ 發送不管對方是否準備好，接收方收到也不確認，故是不可靠的
    ✔ 可以廣播發送
    ✔ 發送數據結束時無需釋放資源，開銷小，速度快
 */
public class UDPSocketTest {
    @Test // 發送端
    public void send() throws IOException {
        DatagramSocket socket = new DatagramSocket();

        byte[] data = "hello world".getBytes();
        DatagramPacket packet = new DatagramPacket(data,0,data.length, InetAddress.getLocalHost(),8080);

        socket.send(packet);

        socket.close();
    }

    @Test // 接收端
    public void receiver() throws IOException {
        DatagramSocket socket = new DatagramSocket(8080);

        byte[] buffer = new byte[100];
        DatagramPacket packet = new DatagramPacket(buffer,0,buffer.length);

        socket.receive(packet);

        System.out.println(new String(packet.getData(),0,packet.getLength()));

        socket.close();
    }
}