[java] Using the Jersey client to do a POST operation

In a Java method, I'd like to use a Jersey client object to do a POST operation on a RESTful web service (also written using Jersey) but am not sure how to use the client to send the values that will be used as FormParam's on the server. I'm able to send query params just fine.

Simplest:

Form form = new Form();
form.add("id", "1");    
form.add("name", "supercobra");
ClientResponse response = webResource
  .type(MediaType.APPLICATION_FORM_URLENCODED_TYPE)
  .post(ClientResponse.class, form);

Starting from Jersey 2.x, the MultivaluedMapImpl class is replaced by MultivaluedHashMap. You can use it to add form data and send it to the server:

    WebTarget webTarget = client.target("http://www.example.com/some/resource");
    MultivaluedMap<String, String> formData = new MultivaluedHashMap<String, String>();
    formData.add("key1", "value1");
    formData.add("key2", "value2");
    Response response = webTarget.request().post(Entity.form(formData));

Note that the form entity is sent in the format of "application/x-www-form-urlencoded".

Also you can try this:

MultivaluedMap formData = new MultivaluedMapImpl();
formData.add("name1", "val1");
formData.add("name2", "val2");
webResource.path("yourJerseysPathPost").queryParams(formData).post();

It is now the first example in the Jersey Client documentation

Example 5.1. POST request with form parameters

Client client = ClientBuilder.newClient();
WebTarget target = client.target("http://localhost:9998").path("resource");

Form form = new Form();
form.param("x", "foo");
form.param("y", "bar");

MyJAXBBean bean =
target.request(MediaType.APPLICATION_JSON_TYPE)
    .post(Entity.entity(form,MediaType.APPLICATION_FORM_URLENCODED_TYPE),
        MyJAXBBean.class);

If you need to do a file upload, you'll need to use MediaType.MULTIPART_FORM_DATA_TYPE. Looks like MultivaluedMap cannot be used with that so here's a solution with FormDataMultiPart.

InputStream stream = getClass().getClassLoader().getResourceAsStream(fileNameToUpload);

FormDataMultiPart part = new FormDataMultiPart();
part.field("String_key", "String_value");
part.field("fileToUpload", stream, MediaType.TEXT_PLAIN_TYPE);
String response = WebResource.type(MediaType.MULTIPART_FORM_DATA_TYPE).post(String.class, part);