Java: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target

I have a class that will download a file from a https server. When I run it, it returns a lot of errors. It seems that I have a problem with my certificate. Is it possible to ignore the client-server authentication? If so, how?

package com.da;

import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.CharBuffer;
import java.util.concurrent.Future;

import org.apache.http.HttpResponse;
import org.apache.http.client.utils.URIUtils;
import org.apache.http.impl.nio.client.DefaultHttpAsyncClient;
import org.apache.http.nio.IOControl;
import org.apache.http.nio.client.HttpAsyncClient;
import org.apache.http.nio.client.methods.AsyncCharConsumer;
import org.apache.http.nio.client.methods.HttpAsyncGet;
import org.apache.http.nio.client.methods.HttpAsyncPost;

public class RSDDownloadFile {
    static FileOutputStream fos;

    public void DownloadFile(String URI, String Request) throws Exception
    {
        java.net.URI uri = URIUtils.createURI("https", "176.66.3.69:6443", -1, "download.aspx",
                "Lang=EN&AuthToken=package", null);
        System.out.println("URI Query: " + uri.toString());

        HttpAsyncClient httpclient = new DefaultHttpAsyncClient();
        httpclient.start();
        try {
            Future<Boolean> future = httpclient.execute(
                    new HttpAsyncGet(uri),
                    new ResponseCallback(), null);

            Boolean result = future.get();
            if (result != null && result.booleanValue()) {
                System.out.println("\nRequest successfully executed");
            } else {
                System.out.println("Request failed");
            }              
        } 
        catch(Exception e){
            System.out.println("[DownloadFile] Exception: " + e.getMessage());
        }
        finally {
            System.out.println("Shutting down");
            httpclient.shutdown();
        }
        System.out.println("Done"