Java网络编程之入门篇

目录

• 一、网络基础
• 二、网络协议
• URL类

 实现TCP的网络编程
 例子1：客户端发送信息给服务端，服务端将数据显示在控制台上
public class TCPTest1 {
    //客户端
    @Test
    public void client() {
        Socket socket = null;
        OutputStream os = null;
        try {
            //1.创建Socket对象，指明服务器端的ip和端口号
            InetAddress inet = InetAddress.getByName("127.0.0.1");
            socket = new Socket(inet, 8899);
            //2.获取一个输出流，用于输出数据
            os = socket.getOutputStream();
            //3.写出数据的操作
            os.write("你好，我是客户端mm".getBytes());
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            //4.资源的关闭
            if(os != null){
                try {
                    os.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if(socket != null){
                try {
                    socket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
 
    }
    //服务端
    @Test
    public void server(){
        ServerSocket ss = null;
        Socket socket = null;
        InputStream is = null;
        ByteArrayOutputStream baos = null;
        try {
            //1.创建服务器的ServerSocket,指明自己的端口号
            ss = new ServerSocket(8899);
            //2.调用accept()表示接收来自于客户端的socket
            socket = ss.accept();
            //3.获取输入流
            is = socket.getInputStream();
            //不建议这样写，可能会有乱码
//        byte[] buffer = new byte[1024];
//        int len;
//        while((len = is.read(buffer)) != -1){
//            String str = new String(buffer,0,len);
//            System.out.println(str);
//        }
            //4.读取输入流中的数据
            baos = new ByteArrayOutputStream();
            byte[] buffer = new byte[5];
            int len;
            while((len = is.read(buffer)) != -1){
                baos.write(buffer,0,len);
            }
            System.out.println(baos.toString());
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            //5.关闭资源
            if(baos != null){
                try {
                    baos.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if(is != null){
                try {
                    is.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if(socket != null){
                try {
                    socket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if(ss != null){
                try {
                    ss.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

 实现TCP的网络编程
 例题2：客户端发送文件给服务端，服务端将文件保存在本地。
public class TCPTest2 {
    //这里异常处理的方式应该使用try-catch-finally
    @Test
    public void client() throws IOException {
        Socket socket = new Socket(InetAddress.getByName("127.0.0.1"), 9090);
        OutputStream os = socket.getOutputStream();
        FileInputStream fis = new FileInputStream(new File("beauty.jpg"));
        byte[] buffer = new byte[1024];
        int len;
        while((len = fis.read(buffer)) != -1){
            os.write(buffer,0,len);
        }
        fis.close();
        os.close();
        socket.close();
    }
    //这里异常处理的方式应该使用try-catch-finally
    @Test
    public void server() throws IOException {
        ServerSocket ss = new ServerSocket(9090);
        Socket socket = ss.accept();
        InputStream is = socket.getInputStream();
        FileOutputStream fos = new FileOutputStream(new File("beauty1.jpg"));
        byte[] buffer = new byte[1024];
        int len;
        while((len = is.read(buffer)) != -1){
            fos.write(buffer,0,len);
        }
        fos.close();
        is.close();
        socket.close();
        ss.close();
    }
}

 实现TCP的网络编程
 例题3：从客户端发送文件给服务端，服务端保存到本地，并返回"发送成功"给客户端。并关闭相应的连接
 
public class TCPTest3 {
    @Test
    public void client() throws IOException {
        Socket socket = new Socket(InetAddress.getByName("127.0.0.1"), 9090);
        OutputStream os = socket.getOutputStream();
        FileInputStream fis = new FileInputStream(new File("beauty.jpg"));
        byte[] buffer = new byte[1024];
        int len;
        while((len = fis.read(buffer)) != -1){
            os.write(buffer,0,len);
        }
        //服务区端给予客户端反馈
        OutputStream os1 = socket.getOutputStream();
        os.write("你好，美女，照片我以收到，非常漂亮！".getBytes());
        fis.close();
        os.close();
        socket.close();
        os1.close();
 
    }
    //这里异常处理的方式应该使用try-catch-finally
    @Test
    public void server() throws IOException {
        ServerSocket ss = new ServerSocket(9090);
        Socket socket = ss.accept();
        InputStream is = socket.getInputStream();
        FileOutputStream fos = new FileOutputStream(new File("beauty2.jpg"));
        byte[] buffer = new byte[1024];
        int len;
        while((len = is.read(buffer)) != -1){
            fos.write(buffer,0,len);
        }
        //接受来自于服务器端的数据，并显示到控制台上
        InputStream is1 = socket.getInputStream();
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        byte[] bufferr = new byte[20];
        int len1;
        while((len1 = is1.read(buffer)) != -1){
            baos.write(buffer,0,len1);
        }
        System.out.println(baos.toString());
        fos.close();
        is.close();
        socket.close();
        ss.close();
        baos.close();
    }
}

UDP协议的网络编程
public class UDPTest {
    @Test
    public void sender() throws IOException {
        DatagramSocket socket = new DatagramSocket();
 
        String str = "我是UDP方式发送的导弹";
        byte[] data = str.getBytes();
        InetAddress inet = InetAddress.getLocalHost();
        DatagramPacket packet = new DatagramPacket(data,0,data.length,inet,9090);
        socket.send(packet);
        socket.close();
    }
    @Test
    public void receiver() throws IOException {
        DatagramSocket socket = new DatagramSocket(9090);
        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()));
    }

  URL网络编程
  1.URL:统一资源定位符，对应着互联网的某一资源地址
  2.格式：
    http://localhost:8080/examples/beauty.jpg?username=Tom
    协议   主机名     端口号    资源地址       参数列表
 
public class URLTest {
    public static void main(String[] args) {
        try {
            URL url = new URL("http://localhost:8080/examples/beauty.jpg?username=Tom");
//            public String getProtocol()       获取该URL的协议名
            System.out.println(url.getProtocol());// http
//            public String getHost()           获取该URL的主机名
            System.out.println(url.getHost());//localhost
//            public String getPort()           获取该URL的端口号
            System.out.println(url.getPort());// 8080
//            public String getPath()           获取该URL的文件路径
            System.out.println(url.getPath());//examples/beauty.jpg
//            public String getFile()           获取该URL的文件名
            System.out.println(url.getFile());//examples/beauty.jpg?username=Tom
//            public String getQuery()          获取该URL的查询名
            System.out.println(url.getQuery());//username=Tom
        } catch (MalformedURLException e) {
            e.printStackTrace();
        }
    }
}