Comment puis-je faire un multipart/form-data requête POST à l'aide de Java?

Nous utilisons HttpClient 4.x pour faire des fichier en plusieurs parties post.

Mise à JOUR: Comme de HttpClient 4.3, certaines classes ont été dépréciés. Voici le code avec la nouvelle 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();

Ci-dessous est l'original de l'extrait de code avec obsolète 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();

Si la taille des Pots (par exemple, dans le cas de l'applet), on peut aussi utiliser directement httpmime avec java.net.HttpURLConnection au lieu de HttpClient.

httpclient-4.2.4:      423KB
httpmime-4.2.4:         26KB
httpcore-4.2.4:        222KB
commons-codec-1.6:     228KB
commons-logging-1.1.1:  60KB
Sum:                   959KB

httpmime-4.2.4:         26KB
httpcore-4.2.4:        222KB
Sum:                   248KB

Code:

HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setDoOutput(true);
connection.setRequestMethod("POST");

FileBody fileBody = new FileBody(new File(fileName));
MultipartEntity multipartEntity = new MultipartEntity(HttpMultipartMode.STRICT);
multipartEntity.addPart("file", fileBody);

connection.setRequestProperty("Content-Type", multipartEntity.getContentType().getValue());
OutputStream out = connection.getOutputStream();
try {
    multipartEntity.writeTo(out);
} finally {
    out.close();
}
int status = connection.getResponseCode();
...

Dépendance en pom.xml:

<dependency>
    <groupId>org.apache.httpcomponents</groupId>
    <artifactId>httpmime</artifactId>
    <version>4.2.4</version>
</dependency>

Vous pouvez également utiliser Rassurez-vous qui s'appuie sur le Client HTTP. C'est très simple:

given().multiPart(new File("/somedir/file.bin")).when().post("/fileUpload");

J'ai trouvé cet exemple dans Apache Guide De Démarrage Rapide. C'est pour la version 4.5:

/**
* Example how to use multipart/form encoded POST request.
*/
public class ClientMultipartFormPost {
public static void main(String[] args) throws Exception {
if (args.length != 1)  {
System.out.println("File path not given");
System.exit(1);
}
CloseableHttpClient httpclient = HttpClients.createDefault();
try {
HttpPost httppost = new HttpPost("http://localhost:8080" +
"/servlets-examples/servlet/RequestInfoExample");
FileBody bin = new FileBody(new File(args[0]));
StringBody comment = new StringBody("A binary file of some kind", ContentType.TEXT_PLAIN);
HttpEntity reqEntity = MultipartEntityBuilder.create()
.addPart("bin", bin)
.addPart("comment", comment)
.build();
httppost.setEntity(reqEntity);
System.out.println("executing request " + httppost.getRequestLine());
CloseableHttpResponse response = httpclient.execute(httppost);
try {
System.out.println("----------------------------------------");
System.out.println(response.getStatusLine());
HttpEntity resEntity = response.getEntity();
if (resEntity != null) {
System.out.println("Response content length: " + resEntity.getContentLength());
}
EntityUtils.consume(resEntity);
} finally {
response.close();
}
} finally {
httpclient.close();
}
}
}

Nous avons un pur java mise en œuvre de plusieurs parties-soumettre le formulaire sans l'aide de toutes les dépendances externes ou des bibliothèques à l'extérieur du jdk. Reportez-vous https://github.com/atulsm/https-multipart-purejava/blob/master/src/main/java/com/atul/MultipartPure.java

private static String body = "{\"key1\":\"val1\", \"key2\":\"val2\"}";
private static String subdata1 = "@@ -2,3 +2,4 @@\r\n";
private static String subdata2 = "<data>subdata2</data>";
public static void main(String[] args) throws Exception{        
String url = "https://" + ip + ":" + port + "/dataupload";
String token = "Basic "+ Base64.getEncoder().encodeToString((userName+":"+password).getBytes());
MultipartBuilder multipart = new MultipartBuilder(url,token);       
multipart.addFormField("entity", "main", "application/json",body);
multipart.addFormField("attachment", "subdata1", "application/octet-stream",subdata1);
multipart.addFormField("attachment", "subdata2", "application/octet-stream",subdata2);        
List<String> response = multipart.finish();         
for (String line : response) {
System.out.println(line);
}
}