How to call a Restful webservice in JAVA

Posted on 2013-11-21
Last Modified: 2013-12-11
 How do you call a RestFul WebService from a Java Application.  I need to call the URL and Post some data to it and retrive the response.

I was told that the service is written in JAVA and uses the Spring framework

Thanks for your help
Question by:SiemensSEN
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 3
  • 3
  • 2
LVL 27

Accepted Solution

dpearson earned 300 total points
ID: 39666703
Most people use a library like httpclient to handle this sort of web request.

There's details here on how to do a POST here:


(BTW it doesn't matter what the service itself is written in - to you it's just a URL that responds with some data).
LVL 35

Assisted Solution

mccarl earned 200 total points
ID: 39667759
If the webservice is fairly simple (in terms of the data that you send and receive, and perhaps the number of different types of calls/methods that you need to invoke) than you can probably use Doug's suggestions (or even just plain old Java HttpUrlConnection functionality) quite easily.

However, if the use of the webservice is more complex, you might want to investigate using a higher level library to help out. These libraries can handle automatic conversion of JSON/XML data that might be sent/received over the webservice, error handling, etc. There are many options out there but 2 that I have experience in and think are relatively simple to work with are:

JAX-RS on Java 6+ (Jersey Implementation) -
Spring -

Note I agree with Doug, that it doesn't matter what the webservice is written in. I mention Spring above because I think it is a good API to use for this sort of thing, NOT because the webservice uses it.

I know the above is a little bit brief, but if you decide that using a library such as these is the way to go, let us know and I can give you more detailed information.

Author Comment

ID: 39667961
Thank you .

I really will like to use spring. This RestAPI is simple now  but it will get more complicated in future releases.

I will read the links you sent me. However, if it would be very helpful  if you can provide any additional information. As always, I will Google to get more info

Thank you
PeopleSoft Has Never Been Easier

PeopleSoft Adoption Made Smooth & Simple!

On-The-Job Training Is made Intuitive & Easy With WalkMe's On-Screen Guidance Tool.  Claim Your Free WalkMe Account Now


Author Comment

ID: 39668635
As an example.. I need to post the information below to the this rest URI

        "message" => "[Wed Jun 26 22:13:22 2013] [client] PHP Fatal   ...."
        ,"@timestamp" => "2013-06-27T02:13:22.000Z"
        ,"m_level"        => "Info"
        ,"m_cat"           => "THIRD_PARTY"
        ,"m_cor"           => "None"
        ,"m_tenant"      => "xxxxx"
        ,"m_timezone" => "EDT"
        ,"m_tzoffset"    => "-04:00"
        ,"m_host"         =>""
        ,"m_path"         => "/var/log/messages"
        ,"m_type"         => "linux-syslog"

I already constructed  the json object.
LVL 35

Assisted Solution

mccarl earned 200 total points
ID: 39668746
I will have some time later (it is the start of the weekend here and I don't get a lot of spare time over weekends to post on EE) to provide a more complete sample using the example you have given above, but to get you started it would be as simple as defining a bean in Spring for a RestTemplate object, and setting the list of messageConverters to use MappingJacksonHttpMessageConverter. You would probably also create a simple Java bean class to hold the fields in your message that you are sending, lets call it MessageDetail. Then you inject that restTemplate into your code and then the REST API call becomes as simple as...
MessageDetail message = new MessageDetail("[Wed Jun 26 22:13:22 2013] [error]...", "2013-06...", "Info", "THIRD_PARTY", ...);    // Note you don't even have to create the JSON yourself
URI location = restTemplate.postForLocation("", message);

Open in new window

Note that exactly which RestTemplate method you use depends on exactly how your REST service is implemented. The above assumes the REST standard where to add something you use the POST http method and the service returns a URI that describes where the newly added resource lives.

Author Comment

ID: 39670654
Thank you very much for the help. I will have a look at the RestTemplate and try to understand it.

However, I have to get a demo working this week. So, I will try use the HttpClient for now and later convert to REST.  Here is  my code snippet .. am I using the library correctly .  I will pass the JSON string and the URL to the class

public class Alarms 
     String url;
     public Alarms(String url)
          this.url = url;
     public void callRESTAPI(String jsonstring) throws IOException
         CloseableHttpResponse response=null;
         CloseableHttpClient httpclient = HttpClients.createDefault();
         HttpClient c = new HttpClient();
         HttpPost p = new HttpPost(this.url);
         p.setEntity(new StringEntity(jsonstring,ContentType.create("application/json")));
         response = httpclient.execute(p);		

Open in new window

LVL 27

Expert Comment

ID: 39670864
I haven't tried running your code - but it looks pretty good.

Fortunately httpclient is so widely used there's lots of examples on the web.  If you run into trouble a quick google search will show you lots of examples.

E.g. There's a whole tutorial here:

and this part has some more POST examples:

LVL 35

Expert Comment

ID: 39671316
And you can probably delete line 12 from the above code snippet. It's not doing anything useful.

Featured Post

Free Tool: IP Lookup

Get more info about an IP address or domain name, such as organization, abuse contacts and geolocation.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

I had a project requirement for a displaying a user workbench .This workbench would consist multiple data grids .In each grid the user will be able to see a large number of data. These data grids should allow the user to 1. Sort 2. Export the …
Introduction This article is the last of three articles that explain why and how the Experts Exchange QA Team does test automation for our web site. This article covers our test design approach and then goes through a simple test case example, how …
Viewers will learn about basic arrays, how to declare them, and how to use them. Introduction and definition: Declare an array and cover the syntax of declaring them: Initialize every index in the created array: Example/Features of a basic arr…
This tutorial covers a practical example of lazy loading technique and early loading technique in a Singleton Design Pattern.
Suggested Courses

710 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question