Telegram, Java: 上传文件发送到sendAnimation

Question

Telegram API 中有一个方法叫做 sendAnimation。有两个强制性参数：chat_id 和 animation。 animation的描述是这样的：

Type: InputFile or String

Description: Animation to send. Pass a file_id as String to send an animation that exists on the Telegram servers (recommended), pass an HTTP URL as a String for Telegram to get an animation from the Internet, or upload a new animation using multipart/form-data. More info on Sending Files »

我有一个要发送的本地 .gif 文件。所以看起来我需要使用 multipart/form-data 方法。我不明白那个方法是什么。我查看了 InputFile 类型的描述：

InputFile This object represents the contents of a file to be uploaded. Must be posted using multipart/form-data in the usual way that files are uploaded via the browser.

同样，他们写了 multipart/form-data 东西，但不写它到底是什么。

我想也许我可以使用sendDocument方法上传文件，但上传的文件也必须是InputFile类型。

如何从本地 .gif 中创建 InputFile 对象？我可以将其转换为 Java 的 InputStream，仅此而已。

Answer 1

简单来说multipart/form-data只是发送数据的一种加密方式，形式上有三种加密方式：

application/x-www-form-urlencoded（默认值）
multipart/form-data
text/plain

有关 multipart/form-data 的更多信息，请查看此 link

我不知道 java 中你的 GIF 对象的类型是什么，但让我们将其视为一个二进制文件，然后你可以简单地 post 使用 [=33= 如下所示的文本] 请求：

String url = "uploading url";
String charset = "UTF-8";
String param = "value";
File binaryFile = new File("/path/to/file.bin");
String boundary = Long.toHexString(System.currentTimeMillis()); // Just generate some unique random value.
String CRLF = "\r\n"; // Line separator required by multipart/form-data.

URLConnection connection = new URL(url).openConnection();
connection.setDoOutput(true);
connection.setRequestProperty("Content-Type", "multipart/form-data; boundary=" + boundary);

try {
    OutputStream output = connection.getOutputStream();
    PrintWriter writer = new PrintWriter(new OutputStreamWriter(output, charset), true);
     // Send binary file.
    writer.append("--" + boundary).append(CRLF);
    writer.append("Content-Disposition: form-data; name=\"binaryFile\"; filename=\"" + binaryFile.getName() + "\"").append(CRLF);
    writer.append("Content-Type: " + URLConnection.guessContentTypeFromName(binaryFile.getName())).append(CRLF);
    writer.append("Content-Transfer-Encoding: binary").append(CRLF);
    writer.append(CRLF).flush();
    Files.copy(binaryFile.toPath(), output);
    output.flush(); // Important before continuing with writer!
    writer.append(CRLF).flush(); // CRLF is important! It indicates end of boundary.

    // End of multipart/form-data.
    writer.append("--" + boundary + "--").append(CRLF).flush();
}

// Request is lazily fired whenever you need to obtain information about response.
int responseCode = ((HttpURLConnection) connection).getResponseCode();
System.out.println(responseCode); // Should be 200

Telegram, Java: 上传文件发送到sendAnimation

Telegram, Java: upload file to send in sendAnimation

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