16 Java网络编程（计算机网络+网络模型OSI/TCP/IP+通信协议等）

public class TestIP {
/**
 *
 *  //方式一：获取本机的InetAddress对象
 *         //通过本地的ip地址信息获取InetAddress对象
 *         InetAddress ia = InetAddress.getLocalHost();
 *         //InetAddress对象的常用方法
 *         //获取主机名(域名)
 *         String hostName = ia.getHostName();
 *         System.out.println(hostName);
 *         //获取ip地址
 *         String hostAddress = ia.getHostAddress();
 *         System.out.println(hostAddress);
 *  //方式二：根据指定的主机名获取InetAddress对象
 *         InetAddress ia = InetAddress.getByName("www.baidu.com");
 *         //InetAddress对象的常用方法
 *         String hostName = ia.getHostName();
 *         System.out.println(hostName);
 *         String hostAddress = ia.getHostAddress();
 *         System.out.println(hostAddress);
 *  //方式三：根据指定的ip地址获取InetAddress对象
 *          InetAddress ia = InetAddress.getByName("14.215.177.38");
 *          System.out.println(ia.getHostName());
 *          System.out.println(ia.getHostAddress());
 */
    public static void main(String[] args) throws UnknownHostException {
        //创建InetAddress对象
        //方式四：根据指定的主机名获取所有的InetAddress
        InetAddress[] ias = InetAddress.getAllByName("www.baidu.com");
        //使用lambda表达式遍历
        /*Arrays.stream(ias).forEach(ia ->{
            System.out.println(ia.getHostAddress());
            System.out.println(ia.getHostName());
        });*/
        //使用foreach循环遍历
        for (InetAddress ia : ias) {
            System.out.println(ia.getHostAddress());
            System.out.println(ia.getHostName());
        }
    }
}

特点：面向连接、安全可靠、效率低、基于字节流进行通信、数据大小无限制。

/**
 * 服务端程序
 */
public class Server {
    public static void main(String[] args) throws IOException {
        //1、创建服务端端Socket对象
        ServerSocket ss = new ServerSocket(6666);
        //2、通过ServerSocket对象获取Socket对象
        //ss.accept()阻塞式方法。直到有客户端与之建立连接才会继续向下执行
        Socket socket = ss.accept();
        //3、通过Socket对象获取输入流对象
        InputStream in = socket.getInputStream();
        //4、通过输入流对象读出数据
        int len; //表示读取到的字节的长度
        byte[] buf = new byte[1024]; // 表示缓冲区
        while((len = in.read(buf)) != -1){
            //将字节数组转转成字符串
            String str = new String(buf,0,len);
            System.out.println(str);
        }
        //5、关闭资源
        in.close();
        socket.close();
        ss.close();
    }
}

/**
 * 服务端程序
 */
public class Server {
    public static void main(String[] args) throws IOException {
        //1、创建服务端Socket对象
        ServerSocket ss = new ServerSocket(6677);
        System.out.println("服务端已开启等待客户端连接....");
        while(true){
            //2、获取Socket对象
            Socket socket = ss.accept();
            //获取客户端发送的信息
            String ip = socket.getInetAddress().getHostAddress();
            //创建线程来处理客户端的请求
            new Thread(new Runnable() {
                @Override
                public void run() {
                    try {
                        //3、通过Socket对象获取输入流
                        InputStream in = socket.getInputStream();
                        //4、通过输入流读取内容
                        BufferedReader br = new BufferedReader(new InputStreamReader(in));
                        String readLine = br.readLine();
                        System.out.println(ip+":"+readLine);
                        //5、释放资源
                        in.close();
                        socket.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            }).start();
        }
    }
}

/**
 * 服务端程序
 */
public class Server {

    public static void main(String[] args) throws IOException {
        //1、创建ServerSocket对象
        ServerSocket ss = new ServerSocket(8899);
        System.out.println("图片服务器已开启....");

        while(true){
            //2、获取Socket对象
            Socket socket = ss.accept();
            //开启线程执行上传图片操作
            new Thread(new UploadThread(socket)).start();

        }
    }
}
class UploadThread implements Runnable{
    Socket socket;
    public  UploadThread(Socket socket){
        this.socket = socket;
    }

    @Override
    public void run() {
        //通过socket对象获取输入流
        try {
            InputStream in = socket.getInputStream();
            //思路：文件上传，读取到图片之后将图片保存在服务器上的upload文件夹中
            String newFilename = UUID.randomUUID().toString().replace("-","");
            FileOutputStream fos = new FileOutputStream("upload\\"+newFilename+".jpg");

            byte[] buf = new byte[1024];
            int len ;
            while((len = in.read(buf))!=-1){
                fos.write(buf,0,len);
            }
            //获取输出流向客户端发送数据
            OutputStream out = socket.getOutputStream();
            out.write(("success!!!"+"upload\\"+newFilename+".jpg").getBytes());

            //4、关闭资源
            out.close();
            fos.close();
            in.close();
            socket.close();

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

public class Receive {
    public static void main(String[] args) throws Exception {
        //1、基于UDP协议创建Socket对象
        DatagramSocket ds = new DatagramSocket(9999);
        //2、创建数据包对象
        byte[] buf = new byte[1024];
        DatagramPacket dp = new DatagramPacket(buf,buf.length);
        //3、接受数据包  receive阻塞式的方法
        ds.receive(dp);

        //4、解析数据包的数据
        //从数据包中获取数据
        byte[] data = dp.getData();
        //从数据包中获取InetAddress对象
        InetAddress inetAddress = dp.getAddress();
        //从数据包中获取端口号
        int port = dp.getPort();
        //获取数据包的数据字节数长度
        int length = dp.getLength();


        String str = new String(data,0,length);
        System.out.println("ip:"+inetAddress.getHostAddress());
        System.out.println("port:"+port);
        System.out.println("data:"+str);

        //5、释放资源
        ds.close();
    }
}