GMail RESTful API：-内容传输编码不一致

Question

我对RESTful API和处理MIME内容都是新手。我正在尝试编写一个应用程序，从Gmail邮箱中检索消息，以便进一步处理。

我使用Google Developers API reference作为工具来熟悉API。使用以下GMail API参考中的“尝试一下”特性

https://developers.google.com/gmail/api/v1/reference/users/messages/get

我检索到一个简单的测试消息，它只有两行文本。第一行包含简单的ASCII，而第二行包含一些Unicode文本。

This the first line of body text in English only

This is second line, 中文睇到嗎 , could you see those Chinese

"parts": [
   {
    "partId": "0",
    "mimeType": "text/plain",
    "filename": "",
    "headers": [
     {
      "name": "Content-Type",
      "value": "text/plain; charset=UTF-8"
     },
     {
      "name": "Content-Transfer-Encoding",
      "value": "quoted-printable"
     }
    ],
    "body": {
     "size": 120,
     "data":  "VGhpcyB0aGUgZmlyc3QgbGluZSBvZiBib2R5IHRleHQgaW4gRW5nbGlzaCBvbmx5DQoNClRoaXMgaXMgc2Vjb25kIGxpbmUsIOS4reaWh-edh-WIsOWXjiAsIGNvdWxkIHlvdSBzZWUgdGhvc2UgQ2hpbmVzZQ0K"
    }
   },
   {
    "partId": "1",
    "mimeType": "text/html",
    "filename": "",
    "headers": [
     {
      "name": "Content-Type",
      "value": "text/html; charset=UTF-8"
     },
     {
      "name": "Content-Transfer-Encoding",
      "value": "quoted-printable"
     }
    ],
    "body": {
     "size": 354,
     "data": "PGRpdiBkaXI9Imx0ciI-PGRpdiBjbGFzcz0iZ21haWxfZGVmYXVsdCIgc3R5bGU9ImZvbnQtZmFtaWx5OnRhaG9tYSxzYW5zLXNlcmlmIj5UaGlzIHRoZSBmaXJzdCBsaW5lIG9mIGJvZHkgdGV4dCBpbiBFbmdsaXNoIG9ubHk8L2Rpdj48ZGl2IGNsYXNzPSJnbWFpbF9kZWZhdWx0IiBzdHlsZT0iZm9udC1mYW1pbHk6dGFob21hLHNhbnMtc2VyaWYiPjxicj48L2Rpdj48ZGl2IGNsYXNzPSJnbWFpbF9kZWZhdWx0IiBzdHlsZT0iZm9udC1mYW1pbHk6dGFob21hLHNhbnMtc2VyaWYiPlRoaXMgaXMgc2Vjb25kIGxpbmUsIOS4reaWh-edh-WIsOWXjiAsIGNvdWxkIHlvdSBzZWUgdGhvc2UgQ2hpbmVzZTwvZGl2PjwvZGl2Pg0K"
    }
   }
  ]

如您所见，虽然“content-transfer-encoding”被指定为“quoted-printable”，但返回的实际数据是base64url编码。

当我使用测试脚本通过GMail RESTful API检索消息时，我得到了相同的64BaseUrl编码响应。

编辑：基于@ericdefriez的评论

如果base64url解码“data”字段

"VGhpcyB0aGUgZmlyc3QgbGluZSBvZiBib2R5IHRleHQgaW4gRW5nbGlzaCBvbmx5DQoNClRoaXMgaXMgc2Vjb25kIGxpbmUsIOS4reaWh-edh-WIsOWXjiAsIGNvdWxkIHlvdSBzZWUgdGhvc2UgQ2hpbmVzZQ0K"

结果似乎已经是原始的utf8编码文本：

This the first line of body text in English only

This is second line, 中文睇到嗎 , could you see those Chinese

This the first line of body text in English only

This is second line, =E4=B8=AD=E6=96=87=E7=9D=87=E5=88=B0=E5=97=8E , could =
you see those Chinese

JSON响应中的'quotered-printable'CTE头似乎不正确。无论CTE头中指定了什么，数据字段始终是base64url编码的。

Answer 1

“data”字段对于在JSON上本地传输不一定是安全的，所以它始终是base64url编码的。一旦你base64url解码“data”，它应该匹配CTE头。