从 c++ 传输 jpeg到安卓（java）

发布于 2024-10-28 08:29:29 字数 824 浏览 2 评论 0原文

我正在努力将 ID3v2 标签内的简单 jpeg 文件从 c++ 通过 TCP 套接字传输到 java (Android)。库“taglib”提供了提取此文件的功能，我可以将 jpeg 保存为新文件。

send 函数如下所示

char *parameter_full = new char[f3->picture().size()+2];
sprintf(parameter_full,"%s\n\0",f3->picture().data());

// send
result = send(c,parameter_full,strlen(parameter_full),0);

delete[] parameter_full;

，其中

f3->picture().data() 返回指向内部数据结构的指针（它返回 char*）并且 f3->picture().size() 返回数组的大小。

然后 Android 接收它，

String imageString = inFromServer.readLine();
byte[] imageBytes = imageString.getBytes();
Bitmap cover = BitmapFactory.decodeByteArray(imageBytes,0,imageBytes.length);

但不知何故，decodeByteArray 总是返回 null。我的想法是，Java 无法正确接收图像，因为 imageString 仅包含 4 个字符......而提取的 jpeg 文件大小为 12.7 KB。但出了什么问题呢？

马丁

原文

I am struggling with the transfer of a simple jpeg file inside an ID3v2 tag from c++ over a TCP socket to java (Android). The library "taglib" offers to extract this file and I am able to save the jpeg as a new file.

The send function looks like this

char *parameter_full = new char[f3->picture().size()+2];
sprintf(parameter_full,"%s\n\0",f3->picture().data());

// send
result = send(c,parameter_full,strlen(parameter_full),0);

delete[] parameter_full;

where

f3->picture().data() returns a pointer to the internal data structure (it returns char*) and
f3->picture().size() returns the size of the array.

Then Android receives it with

String imageString = inFromServer.readLine();
byte[] imageBytes = imageString.getBytes();
Bitmap cover = BitmapFactory.decodeByteArray(imageBytes,0,imageBytes.length);

But somehow decodeByteArray always returns null. My idea is that Java doesn't receive the image correctly because imageString only consists of 4 characters...while the extracted jpeg file has a size of 12.7 KB.
But what has gone wrong?

Martin

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