How to Make a Multipart/Form-Data Post Request Using Java

How can I make a multipart/form-data POST request using Java?

We use HttpClient 4.x to make multipart file post.

UPDATE: As of HttpClient 4.3, some classes have been deprecated. Here is the code with new API:

CloseableHttpClient httpClient = HttpClients.createDefault();
HttpPost uploadFile = new HttpPost("...");
MultipartEntityBuilder builder = MultipartEntityBuilder.create();
builder.addTextBody("field1", "yes", ContentType.TEXT_PLAIN);

// This attaches the file to the POST:
File f = new File("[/path/to/upload]");
builder.addBinaryBody(
    "file",
    new FileInputStream(f),
    ContentType.APPLICATION_OCTET_STREAM,
    f.getName()
);

HttpEntity multipart = builder.build();
uploadFile.setEntity(multipart);
CloseableHttpResponse response = httpClient.execute(uploadFile);
HttpEntity responseEntity = response.getEntity();

Below is the original snippet of code with deprecated HttpClient 4.0 API:

HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost(url);

FileBody bin = new FileBody(new File(fileName));
StringBody comment = new StringBody("Filename: " + fileName);

MultipartEntity reqEntity = new MultipartEntity();
reqEntity.addPart("bin", bin);
reqEntity.addPart("comment", comment);
httppost.setEntity(reqEntity);

HttpResponse response = httpclient.execute(httppost);
HttpEntity resEntity = response.getEntity();

Upload File in form data using Java

This question is similar. But I believe the answer is changing your addBinary to addPart.

final HttpPost httppost = new HttpPost("https://host/upload");
httppost.addHeader("Authorization", "Bearer xxx");
httppost.addHeader("Accept", "application/json");
httppost.addHeader("Content-Type", "multipart/form-data");

final MultipartEntityBuilder builder = MultipartEntityBuilder.create();
final File file = new File("c:\\tmp\\myfile.pdf");
builder.addPart("file", new FileBody(file));
builder.addTextBody("type", "file");
final HttpEntity entity = builder.build();
httppost.setEntity(entity);
final HttpResponse response = httpclient.execute(httppost);
httpclient.close();

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