二进制数据JSONCPP [英] Binary data JSONCPP

问题描述

我试图使用JSON cpp与VS2008。

任何人都可以告诉我是否可能将二进制数据打包成JSON格式？我正在读一个图像文件到 char * buffer ，并把它放在 JSON :: Value 。但是当我尝试解析它时，我在JSON对象中找不到缓冲区内容。

代码如下。

  Json :: Value root; 
 Json :: Reader reader; 
 Json :: StyledWriter writer; 
 int length; 
 char * buffer; 
 ifstream is; 
 is.open（D：\\test.j2k，ios :: binary）; 
 
 //获取文件长度：
 is.seekg（0，ios :: end）; 
 length = is.tellg（）; 
 is.seekg（0，ios :: beg）; 
 
 //分配内存：
 buffer = new char [length]; 
 
 //以块的形式读取数据：
 is.read（buffer，length）; 
 root [sample] = * buffer; 
 writer.write（root）; 
 cout<<根; 
 const string rootAsString = root.toStyledString（）; 
 cout<< rootAsString<< endl; 
  

由于我是VC ++的新手，我不知道读取图像文件到char *正确错误。请让我知道代码的错误。感谢。

解决方案

您必须对其进行编码，因为JSON是JavaScript源代码中出现的JavaScript结构格式的子集。 p>

JSON中二进制数据最常用的编码是Base64。我使用它（在其他语言，而不是c ++）编码图像没有问题。你只需要在编码的图像前面加上 data：image / png; base64，（假设它是png），让它在javascript中自动解码，如果你设置为src一个图像。

编辑：与任何其他语言一样，C64中的base64编码很容易。这里有一个图书馆： https://github.com/ReneNyffenegger/development_misc/tree/master/base64

I am trying to use JSON cpp with VS2008.

Can anyone tell me is it possible to pack binary data into JSON format? I am reading a image file into char* buffer, and putting it in JSON::Value. But when i try to parse it, I don't find the buffer contents in the JSON object.

Code is as follows.

    Json::Value root;
    Json::Reader reader;
    Json::StyledWriter writer;
    int length;
    char * buffer;
    ifstream is;
    is.open ("D:\\test.j2k", ios::binary);

    // get length of file:
    is.seekg (0, ios::end);
    length = is.tellg();
    is.seekg (0, ios::beg);

    // allocate memory:
    buffer = new char [length];

    // read data as a block:
    is.read (buffer,length);
    root["sample"] = *buffer;
    writer.write(root);  
    cout << root;
    const string rootAsString  = root.toStyledString();
    cout << rootAsString << endl;

Since I am new to VC++, I am not sure whether reading a image file to char * buffer is right/wrong. Please let me know whats wrong with the code. Thanks.

解决方案

You must encode it because JSON is a subset of javascript structures format as it appears in javascript source code.

The most frequently used encoding for binary data in JSON is Base64. I use it (in other languages than c++) for encoding images without problems. You simply have to prefix the encoded image with data:image/png;base64, (supposing it's png) to have it automatically decoded in javascript if you set this to the src of an image.

EDIT : as in any other language, base64 encoding in C++ is easy. Here's a library : https://github.com/ReneNyffenegger/development_misc/tree/master/base64

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