How to send xml message through servlet http post?

I want to send an xml file to a service through servlet http post. After I did some research and I found a way to easily do this.

1. I chose to use Apache HttpComponents.

2. Download the latest HttpClient jars from https://hc.apache.org/downloads.cgi

3. In my servlet, I import the following classes.

 import org.apache.http.HttpResponse;  
 import org.apache.http.client.HttpClient;  
 import org.apache.http.client.methods.HttpPost;  
 import org.apache.http.entity.StringEntity;  
 import org.apache.http.impl.client.HttpClientBuilder;  
 import org.apache.http.util.EntityUtils;  

4. In the doPost method, I add the following code.

  // HTTP post xml document to outside service  
           HttpPost post = new HttpPost("https://testserviceurl");  
           post.setHeader("Content-Type", "application/xml");  
           post.setEntity(new StringEntity(xmlString));  
           HttpClient client = HttpClientBuilder.create().build();  
           HttpResponse resp = client.execute(post);  
           String result = EntityUtils.toString(resp.getEntity());  
           System.out.println("post result:" + result);  

HttpClient really provides a simply way to do the job.