java - 使用Socket发送和接收图像

Question

在带有 ServerSocket 和 Socket 的 Java 中，我可以在本地网络中使用以下代码传输图像文件:

发送

public class Send {

    public static void main(String[] args) throws Exception {
        Socket socket = new Socket(serverIP, serverPORT);
        OutputStream outputStream = socket.getOutputStream();

        BufferedImage image = ImageIO.read(new File("test.jpg"));

        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
        ImageIO.write(image, "jpg", byteArrayOutputStream);

        byte[] size = ByteBuffer.allocate(4).putInt(byteArrayOutputStream.size()).array();
        outputStream.write(size);
        outputStream.write(byteArrayOutputStream.toByteArray());
        outputStream.flush();

        socket.close();
    }
}

接收

public class Receive {

    public static void main(String[] args) throws Exception {
        ServerSocket serverSocket = new ServerSocket(serverPORT);
        Socket socket = serverSocket.accept();
        InputStream inputStream = socket.getInputStream();

        byte[] sizeAr = new byte[4];
        inputStream.read(sizeAr);
        int size = ByteBuffer.wrap(sizeAr).asIntBuffer().get();

        byte[] imageAr = new byte[size];
        inputStream.read(imageAr);

        BufferedImage image = ImageIO.read(new ByteArrayInputStream(imageAr));

        ImageIO.write(image, "jpg", new File("test2.jpg"));

        serverSocket.close();
    }

}

如何使用 Socket 在 Netty 中做到这一点？

我的处理程序

@Override
    protected void channelRead0(ChannelHandlerContext ctx, Object o) throws Exception {
        Channel currentChannel = ctx.channel();
        System.out.println(TAG + "MESSAGE FROM SERVER - " + currentChannel.remoteAddress() + " - " + o);

        List<Object> msg = new ArrayList<>();
        msg.addAll((Collection<? extends Object>) o);

        /*If message in index 0 is Equal to IMAGE then I need to send an Image File*/
        if(msg.get(0).equals("IMAGE")){

            /*
                NO IDEA on how can I send it on Netty.
                I'm not sure if this will work or this is how should I do it.
            */

                BufferedImage image = ImageIO.read(new File("test.jpg"));
                ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
                ImageIO.write(image, "jpg", byteArrayOutputStream);
                byte[] size = ByteBuffer.allocate(4).putInt(byteArrayOutputStream.size()).array();

                msg.clear(); //clear the List Object
                msg.add(0, "IMAGE_FILE"); //Add the Type of message with String
                msg.add(1, size); //Add the size
                msg.add(2, byteArrayOutputStream.toByteArray()); //Add the image file to send 
                sendMessage(ctx, msg);

            ctx.writeAndFlush(msg); //Finally Send it.
        }

        /*If message in index 0 is Equal to IMAGE_FILE then I need to make it viewable*/
        if(msg.get(0).equals("IMAGE_FILE")){

            /*
                NO IDEA on how to decode it as an Image file
            */

        }


    }

我继续在 Netty 中搜索任何这样的示例，我只找到了通过 Http 发送的示例，但我仍然不知道该怎么做。顺便说一句，我在管道中使用 ObjectEncoder() 和 ObjectDecoder(ClassResolvers.cacheDisabled(null)) 。

Answer 1

您的方法很好，但通常在传输大文件(不仅限于图像文件)时可能会遇到问题。我建议您查看 here 中的 ChuckedWriteHandler ，该文档写得很好，可以遵循。