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Assign a different proxy to thread - Java

Hi Guys I am making a bot which can use a an other REST API to create a user but API only supports one user at a time and I dont want to change it. So I am using Multithreading to call the API multiple times, but I want to use proxies in it. So like different proxies for different threads, and all the threads use HttpClient and I tried its #proxy method and gave it the ip and port of the proxy but when I tried to call the API it returned a null response and I tried without the proxy and it did return a valid response.
So is there any other way to assign an proxy to a thread
My Code
HttpClient client = HttpClient.newBuilder()
.version(HttpClient.Version.HTTP_1_1)
.followRedirects(HttpClient.Redirect.NORMAL)
//THIS LINE BELOW IS HOW I USED PROXIES
.proxy(ProxySelector.of(new InetSocketAddress("proxy.example.com", 80)))
.connectTimeout(Duration.ofSeconds(30))
.build();
HttpRequest discordAccNoCaptcha = HttpRequest.newBuilder()
.uri(URI.create("https://myapiserver.com/api/v9/auth/register"))
.timeout(Duration.ofMinutes(2))
.POST(HttpRequest.BodyPublishers.ofString(body))
.build();
String response = client.send(discordAccNoCaptcha, HttpResponse.BodyHandlers.ofString()).body(); /* This is null when using ProxySelector and valid response when using no ProxySelector */

How to add a body to a GET request in JAX-RS

I'm trying to consume a REST API that requires a body with a GET request. But as a GET usually doesn't have a body, I can't find a way to attach a body in my request. I am also building the REST API, but the professor won't allow us to change the method to POST (he gave us a list of the endpoints we are to create, no more, no less).
I'm trying to do it like this:
Response r = target.request().method(method, Entity.text(body));
Where I set the method to GET and the body to my get body. However, using this approach I get an exception:
javax.ws.rs.ProcessingException: RESTEASY004565: A GET request cannot have a body.
Is there any way to do this with JAX-RS? We learned to use JAX-RS so I would prefer a solution using this, as I'm not sure my professor would allow us to use any other REST client. I'm currently using RESTEasy, provided by the WildFly server.
(This is not a duplicate of HTTP GET with request body because I'm asking on how to create a GET request with body in JAX-RS, not if it should be done.)

This depends on what is your JAX-RS implementation. This check can be disabled in Jersey 2.25 using SUPPRESS_HTTP_COMPLIANCE_VALIDATION property:
ClientConfig config = new ClientConfig();
config.property(ClientProperties.SUPPRESS_HTTP_COMPLIANCE_VALIDATION, true);
JerseyClient client = JerseyClientBuilder.createClient(config);
WebTarget target = client.target(URI.create("https://www.stackoverflow.com"));
Response response = target.request().method("GET", Entity.text("BODY HERE"));
Instead of exception you will get an INFO log
INFO: Detected non-empty entity on a HTTP GET request. The underlying HTTP transport connector may decide to change the request method to POST.
However in RESTEasy 3.5.0.Final there is a hardcoded check in both URLConnectionEngine and ApacheHttpClient4Engine:
if (request.getEntity() != null)
{
if (request.getMethod().equals("GET")) throw new ProcessingException(Messages.MESSAGES.getRequestCannotHaveBody());
You would have to create your own implementation of the ClientHttpEngine to skip this. Then you need to supply it when building the client:
ClientHttpEngine engine = new MyEngine();
ResteasyClient client = new ResteasyClientBuilder().httpEngine(engine).build();

How to send data from one webApplication to another

I have two web applications in two different server.I want send some data in header or request to other web application.How can I do that, please help me.

You can pass data by many means:
by making http request from your app:
URLConnection conn = new URL("your other web app servlet url").openConnection();
// pass data using conn. Then on other side you can have a servlet that will receive these calls.
By using JMS for asynchronous communication.
By using webservice (SOAP or REST)
By using RMI
By sharing database between the apps. So one writes to a table and the other reads from that table
By sharing file system file(s)...one writes to a file the other reads from a file.
You can use socket connection.

HttpClient can help
http://hc.apache.org/index.html
Apache HttpComponents
The Apache HttpComponents™ project is responsible for creating and
maintaining a toolset of low level Java components focused on HTTP and
associated protocols.

One web application is functioning as the client of the other. You can use the org.apache.http library to create your HTTP client code in Java. How you will do this depends on a couple of things:
Are you using http or https?
Does the application you are sending data to have a REST API?
Do you have a SOAP based web service?
If you have a SOAP based web service, then creating a Java client for it is very easy. If not, you could do something like this and test the code in a regular Java client before trying to run it in the web application.
import org.apache.http.client.utils.*;
import org.apache.http.*;
import org.apache.http.impl.client.*;
HttpClient httpclient = new DefaultHttpClient();
try {
URIBuilder builder = new URIBuilder();
builder.setHost("yoursite.com").setPath(/appath/rsc/);
builder.addParameter("user", username);
builder.addParameter("param1", "SomeData-sentAsParameter");
URI uri = builder.build();
HttpGet httpget = new HttpGet(uri);
HttpResponse response = httpclient.execute(httpget);
System.out.println(response.getStatusLine().toString());
if (response.getStatusLine().getStatusCode() == 200) {
String responseText = EntityUtils.toString(response.getEntity());
httpclient.getConnectionManager().shutdown();
} else {
log(Level.SEVERE, "Server returned HTTP code "
+ response.getStatusLine().getStatusCode());
}
} catch (java.net.URISyntaxException bad) {
System.out.println("URI construction error: " + bad.toString());
}

Posting to a form based on what HttpGet returns with Apache's HttpClient

I'm posting data to a website form using Apache's HttpClient class. The form is retrieved using the following lines of code:
HttpGet get = new HttpGet(url);
HttpResponse response = client.execute(get);
The website that I'm retrieving the form from requires authentication to access the form. If the request isn't authenticated, the website redirects the request to a login form page that will subsequently redirect back to the original page on successful authentication.
I want to cleanly detect whether or not the GET request returns the login page or the desired form page so that I can either POST login data or form data. The only way I can think of to do this is by reading from the content InputStream of the entity of the response and parsing each line. But that seems somewhat convoluted. I haven't worked with the Apache HttpComponents api before so I'm not sure if this would be the only and best way to accomplish what I want to accomplish.
EDIT: To clarify question, I'm asking if there is a set way to handle forms with Apache's HttpClient. I somewhat know how to achieve what I'm looking to do, but it looks very ugly and I'm hoping there is an easier and faster way to achieve it. For example, if there was some way to do the following:
HttpGet get = new HttpGet(url);
HttpResponse response = client.execute(get);
if(parseElements(response.getEntity()).hasFormWithId("login")) {
// post authentication data
} else {
// post actual form data
}
Because of my inexperience with Apache's HttpClient api, I'm not sure if what I'm looking for in the API is too abstract for the intent of the API.

You can modify the behavior of the HttpClient by setting the HttpClient Parameters
DefaultHttpClient client = new DefaultHttpClient();
client.setDefaultHttpParams(client.getParams().setBoolean(ClientPNames.HANDLE_REDIRECTS, false));
Which disables handling redirects automatically.
See also:
Automatic redirect handling
HTTP Authentication
DefaultHttpClient API

How to tell android to parse an XML response of a page iam redirected to?

I'm trying to parse an XML response within an Android app. The technique of parsing itself is not the problem, but the process of receiving the XML makes it difficult to do it the common way.
More in detail:
I request a xhtml website with the apache httpclient (in Android). The website is located on a Java EE Application Server (AS). I give two GET parameters with the request (username, password).
The website is located in a secure area on the AS, so first of all the AS forwards me to the login page. The loginpage takes the username and password (from the GET parameter) and logs me in automatically. If the login credentials are valid I'll get redirected to the requested XHTML page. This is the site I want to parse with the android SAX parser.
But when I try to do this, the only respose I'm able to parse is the login page, not the page. I'm redirected to after successfull login. Can anyone tell me how to instruct the android apache http client to take the response of the redirected page (for later parsing) after the automatical login process?

The logged-in user is stored in the HTTP session which is identified by a cookie with the name JSESSIONID. You need to ensure that you pass the obtained cookie back on every subsequent request, also on the redirects. Otherwise the server will consider the redirected request as unauthorized and redirect you once again back to the login page.
Managing the obtained cookies can be done with help of the CookieStore which you need to set in the HttpContext which you in turn need to pass on every HttpClient#execute() call.
HttpClient httpClient = new DefaultHttpClient();
CookieStore cookieStore = new BasicCookieStore();
HttpContext httpContext = new BasicHttpContext();
httpContext.setAttribute(ClientContext.COOKIE_STORE, cookieStore);
// ...
HttpResponse response1 = httpClient.execute(yourMethod1, httpContext);
// ...
HttpResponse response2 = httpClient.execute(yourMethod2, httpContext);
// ...

Found my solution with the help of this blog entry:
http://ginger-space.blogspot.com/2007/04/httpclient-for-form-based.html
Just updated the Code to the current Apache Client andere IT worked.