使用 Gmail API 将请求正文写入服务器时出错

Question

I have started messing with the Gmail API for a side project, and was messing around with sending an email with an attachment. The attachment I've been trying to send is a large one, but it's only a 19.5MB audio file, and the documentation only says that the limit is 35MB. I've sent a different audio file that was less than that and it was able to be sent I get the following error every time I try to send the larger audio file:

        java.io.IOException: Error writing request body to server
           at java.base/sun.net.www.protocol.http.HttpURLConnection$StreamingOutputStream.checkError(HttpURLConnection.java:3648)
           at java.base/sun.net.www.protocol.http.HttpURLConnection$StreamingOutputStream.write(HttpURLConnection.java:3631)
           at java.base/java.io.BufferedOutputStream.flushBuffer(BufferedOutputStream.java:81)
           at java.base/java.io.BufferedOutputStream.write(BufferedOutputStream.java:127)
           at java.base/java.util.zip.DeflaterOutputStream.deflate(DeflaterOutputStream.java:253)
           at java.base/java.util.zip.DeflaterOutputStream.write(DeflaterOutputStream.java:211)
           at java.base/java.util.zip.GZIPOutputStream.write(GZIPOutputStream.java:146)
           at com.fasterxml.jackson.core.json.UTF8JsonGenerator._flushBuffer(UTF8JsonGenerator.java:1819)
           at com.fasterxml.jackson.core.json.UTF8JsonGenerator._writeStringSegments(UTF8JsonGenerator.java:1142)
           at com.fasterxml.jackson.core.json.UTF8JsonGenerator._writeLongString(UTF8JsonGenerator.java:456)
           at com.fasterxml.jackson.core.json.UTF8JsonGenerator.writeString(UTF8JsonGenerator.java:425)
           at com.google.api.client.json.jackson2.JacksonGenerator.writeString(JacksonGenerator.java:128)
           at com.google.api.client.json.JsonGenerator.serialize(JsonGenerator.java:117)
           at com.google.api.client.json.JsonGenerator.serialize(JsonGenerator.java:172)
           at com.google.api.client.json.JsonGenerator.serialize(JsonGenerator.java:106)
           at com.google.api.client.http.json.JsonHttpContent.writeTo(JsonHttpContent.java:78)
           at com.google.api.client.http.GZipEncoding.encode(GZipEncoding.java:49)
           at com.google.api.client.http.HttpEncodingStreamingContent.writeTo(HttpEncodingStreamingContent.java:51)
           at com.google.api.client.http.javanet.NetHttpRequest.execute(NetHttpRequest.java:80)
           at com.google.api.client.http.HttpRequest.execute(HttpRequest.java:981)
           at com.google.api.client.googleapis.services.AbstractGoogleClientRequest.executeUnparsed(AbstractGoogleClientRequest.java:419)
           at com.google.api.client.googleapis.services.AbstractGoogleClientRequest.executeUnparsed(AbstractGoogleClientRequest.java:352)
           at com.google.api.client.googleapis.services.AbstractGoogleClientRequest.execute(AbstractGoogleClientRequest.java:469)
           at EmailAPI.sendMessage(EmailAPI.java:179)
           at EmailSender.sendEmailWithAttachment(EmailSender.java:41)
           at EmailSender.sendEmails(EmailSender.java:67)
           at EmailSender.main(EmailSender.java:19)

Everything that I find doesn't seem to help. I have tried:

          //This is the way that it is in the quickstart project
          mimeBodyPart = new MimeBodyPart();
          DataSource source = new FileDataSource(file);
          mimeBodyPart.setDataHandler(new DataHandler(source));
          mimeBodyPart.setFileName(file.getName());

          //I have tried putting both of these inplace of the above code but nothing worked
          mimeBodyPart.setContent(file, "audio/MPEG");
          mimeBodyPart.attachFile(file);

The only thing that I have to go on is that the server might be cutting off the connection while sending the request, but I don't know if that is the issue or if it's something else.

Answer 1

To send emails larger than 5MB you must use either multipart upload or resumable upload (see docs for details).

In Java Gmail API client library, 2-argument version of send method sends a simple upload request, which can upload up to 5MB. To send a resumable upload request, use 3-argument version of send method. Using resumable upload you can send up to 35MB.

Here is a method that sends javax.mail.internet.MimeMessage using resumable upload :

import com.google.api.client.http.ByteArrayContent;
import com.google.api.services.gmail.Gmail;
import com.google.api.services.gmail.model.Message;

import javax.mail.internet.MimeMessage;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.util.List;
import javax.mail.MessagingException;

private Message sendMessage(Gmail gmail, String userId, MimeMessage mimeMessage, List<String> labelIds, String threadId) throws IOException, MessagingException {
    // Create Message instance containing email message metadata
    Message metadata = new Message()
            .setLabelIds(labelIds)
            .setThreadId(threadId);

    // Create byte array containing email message data (in RFC 2822 format)
    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    mimeMessage.writeTo(baos);
    ByteArrayContent rawMessageBytes = new ByteArrayContent("message/rfc822", baos.toByteArray());

    return gmail.users().messages()
            .send(userId, metadata, rawMessageBytes)
            .execute();
}