REST Spring 3.0 - Simple Introduction

This post is going to be a very simple introduction to the RestTemplate API introduced in Spring 3.0.

Dogs know how to REST!

The RestTemplate is similar to other Spring templates such as JmsTemplate and JdbcTemplate in that Spring eliminates a lot of boot strap code and thus makes your code much cleaner. When applications use the RestTemplate they do not need to worry about HTTP connections, that is all encapsulated by the template. They also get a range of APIs from the RestTemplate which correspond to the well know HTTP methods (GET, PUT, POST, DELETE, HEAD, OPTIONS). These APIs are overloaded to cater for things like different ways of passing parameters to the actual REST API. Ok, so let's look a very simple example. Suppose we want to invoke a well know Twitter REST API to check the Twitter timeline for the user "dublintech". This API would takes form: http://twitter.com/statuses/user_timeline.xml?id=dublintech

Fire it into your web browser and you'll see you get back the timeline for dublintech in XML. But you don't want to fire it into your browser, you want to invoke the API in a Java program! Let's do that.

import org.springframework.web.client.RestTemplate;
 
public class Spring3RestTest {
 
    public static void main(String args[]) {
        Spring3RestTest test = new Spring3RestTest();
        test.getTimeline();
    }
     
    private void getTimeline() {
        RestTemplate restTemplate = new RestTemplate();
        String response =
                restTemplate.getForObject("http://twitter.com/statuses/user_timeline.xml?id=dublintech", String.class, new Object[]{});
        System.out.println("Response is=" + response);
    }
}

That's it. Isn't that incredibly simple. No HTTP Connection handling to worry about. Import one Spring 3.0 class, use it and that's it! Yes, this post was a very simple introduction. In the real world, if you were using this API you'd obviously be doing something a little more sophisticated for example using XPath to get specific information out of the XML returned. But we don't need to cover that. The point of this post was really to point how easy it is to use some of the REST 3.0 Spring features. In future posts we'll be looking at more advanced features.

For now - keep it simple!

References:
1. http://static.springsource.org/spring/docs/3.0.x/javadoc-api/
2. http://blog.springsource.org/2009/03/27/rest-in-spring-3-resttemplate/
3. https://dev.twitter.com/docs/api Twitter REST API
4. Roy Fielding's original REST Paper: http://www.ics.uci.edu/~fielding/pubs/dissertation/rest_arch_style.htm

REST Spring 3.0 - Simple Introduction

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