This is the code I tried to use with the apache httpclient, It tries a get and a post request:

package searxTest;

import java.util.ArrayList;

import java.util.List;

import org.apache.http.HttpEntity;

import org.apache.http.NameValuePair;

import org.apache.http.client.entity.UrlEncodedFormEntity;

import org.apache.http.client.methods.CloseableHttpResponse;

import org.apache.http.client.methods.HttpGet;

import org.apache.http.client.methods.HttpPost;

import org.apache.http.impl.client.CloseableHttpClient;

import org.apache.http.impl.client.HttpClients;

import org.apache.http.message.BasicNameValuePair;

import org.apache.http.util.EntityUtils;

public class Main {

    public static void main(String[] args) throws Exception {

        CloseableHttpClient httpclient = HttpClients.createDefault();

        try {

            HttpGet httpGet = new HttpGet("https://searx.laquadrature.net/?q=cat&format=json");

            CloseableHttpResponse response1 = httpclient.execute(httpGet);

            // The underlying HTTP connection is still held by the response object

            // to allow the response content to be streamed directly from the network socket.

            // In order to ensure correct deallocation of system resources

            // the user MUST call CloseableHttpResponse#close() from a finally clause.

            // Please note that if response content is not fully consumed the underlying

            // connection cannot be safely re-used and will be shut down and discarded

            // by the connection manager.

            try {

                System.out.println(response1.getStatusLine());

                HttpEntity entity1 = response1.getEntity();

                // do something useful with the response body

                // and ensure it is fully consumed

                EntityUtils.consume(entity1);

            } finally {

                response1.close();

            }

            HttpPost httpPost = new HttpPost("https://searx.laquadrature.net/?q=cat&format=json");

            List <NameValuePair> nvps = new ArrayList <NameValuePair>();

            nvps.add(new BasicNameValuePair("categories", "images"));

            httpPost.setEntity(new UrlEncodedFormEntity(nvps));

            CloseableHttpResponse response2 = httpclient.execute(httpPost);

            try {

                System.out.println(response2.getStatusLine());

                HttpEntity entity2 = response2.getEntity();

                // do something useful with the response body

                // and ensure it is fully consumed

                EntityUtils.consume(entity2);

            } finally {

                response2.close();

            }

        } finally {

            httpclient.close();

        }

    }

}