如何Encode Binary Data 为 JSON

问题

JSON 仅 supports 文本和 numbers, 但你 need 到包含二进制数据 (e.g., 小图像) 内部 JSON 载荷.

前置条件

• Understanding 的 JSON 结构
• 基础 Base64 知识

步骤

1. 1. Read the binary data as bytes

   Load the file or binary blob into memory as a byte array. Do not attempt to interpret it as text, as null bytes and non-UTF-8 sequences will corrupt the data.

   输入

   image.png (2048 bytes)

   输出

   Uint8Array[2048]

2. 2. Base64-encode the bytes

   Convert the byte array to a Base64 string. This produces an ASCII-safe representation that JSON can carry as a regular string field. The encoded size will be about 4/3 of the original.

   输入

   2048 bytes

   输出

   ~2732 chars Base64

3. 3. Embed in JSON and decode on receipt

   Place the Base64 string as a JSON value. On the receiving end, Base64-decode it back to bytes and reconstruct the file. Add a field for the MIME type so the receiver knows how to handle it.

   输入

   {"data":"iVBOR...","type":"image/png"}

   输出

   reconstructed PNG file

预期结果

JSON 字符串 containing Base64-encoded 二进制数据该 round-trips 到 exact 原始 bytes.

常见错误

JSON parse error due to invalid characters

Ensure the binary data was Base64-encoded and not inserted as raw bytes. Raw binary is not valid JSON.

Corrupted file after decoding

Verify the Base64 string was not truncated by a length limit in transit. Check that the decoded byte count matches the original.

排障指引

• If the payload is too large, consider sending the file via multipart upload instead of embedding in JSON.
• Always include the content type alongside the data so the receiver can interpret it correctly.

安全限制

• Base64 in JSON increases payload size by ~33%. Large binaries should be referenced by URL rather than embedded.