Java TCP网络编程：从Socket基础到文件上传实战

public static void main(String[] args) throws IOException {
    //1.创建客户端Socket，绑定服务器IP和端口
    Socket socket = new Socket("127.0.0.1", 8888);
    
    //2.获取网络字节输出流
    OutputStream os = socket.getOutputStream();
    //3.发送数据给服务器
    os.write("你好服务器".getBytes());
    
    //4.获取网络字节输入流
    InputStream is = socket.getInputStream();
    //5.读取服务器回写数据
    byte[] bytes = new byte[1024];
    int len = is.read(bytes);
    System.out.println(new String(bytes, 0, len));
    
    //6.关闭资源
    socket.close();
}

public static void main(String[] args) throws IOException {
    //1.创建服务器ServerSocket，指定端口号
    ServerSocket server = new ServerSocket(8888);
    
    //2.侦听并接受连接，返回Socket对象
    Socket socket = server.accept();
    
    //3.获取网络字节输入流读取客户端数据
    InputStream is = socket.getInputStream();
    byte[] bytes = new byte[1024];
    int len = is.read(bytes);
    System.out.println(new String(bytes, 0, len));
    
    //4.获取网络字节输出流并回写数据
    OutputStream os = socket.getOutputStream();
    os.write("收到谢谢".getBytes());
    
    //5.释放资源
    socket.close();
    server.close();
}

public static void main(String[] args) throws IOException {
    //1.创建本地文件输入流，指向源文件
    FileInputStream fis = new FileInputStream("c:\\1.jpg");
    //2.创建客户端Socket连接服务器
    Socket socket = new Socket("127.0.0.1", 8888);
    //3.获取网络输出流
    OutputStream os = socket.getOutputStream();
    
    //4.循环读取文件内容并发送给服务器
    int len = 0;
    byte[] bytes = new byte[1024];
    while ((len = fis.read(bytes)) != -1) {
        os.write(bytes, 0, len);
    }
    
    //重要：发送完文件后，禁用输出流以通知服务器数据传输结束
    socket.shutdownOutput();
    
    //6.获取网络输入流，读取服务端回写的反馈
    InputStream is = socket.getInputStream();
    while ((len = is.read(bytes)) != -1) {
        System.out.println(new String(bytes, 0, len));
    }
    
    //8.释放资源
    fis.close();
    socket.close();
}

public static void main(String[] args) throws IOException {
    //1.创建服务器Socket监听端口
    ServerSocket server = new ServerSocket(8888);
    //2.获取客户端Socket连接
    Socket socket = server.accept();
    
    //3.获取网络输入流读取上传的文件数据
    InputStream is = socket.getInputStream();
    
    //4.判断目标文件夹是否存在，不存在则创建
    File file = new File("d:\\upload");
    if (!file.exists()) {
        file.mkdirs();
    }
    
    //5.创建本地文件输出流，绑定保存路径
    FileOutputStream fos = new FileOutputStream(file + "\\1.jpg");
    
    //6.循环读取网络数据并保存到本地硬盘
    int len = 0;
    byte[] bytes = new byte[1024];
    while ((len = is.read(bytes)) != -1) {
        fos.write(bytes, 0, len);
    }
    
    //8-9.获取输出流并给客户端回写成功信息
    socket.getOutputStream().write("上传成功".getBytes());
    
    //10.释放资源
    fos.close();
    socket.close();
    server.close();
}