The Jersey project is very well documented so it makes it easy to learn REST with Java. In this article I’m going to build two projects. The first project will be a very simple HTML page that presents a form to the user and then submits it to a REST project residing on the same server. The second project will be the REST part. For this article I used the following tools: 1. Netbeans 7 2. Apache Tomcat 7 3. Jersey 4. Java I built this on OS X Lion. Go ahead and create a new Maven Web Application with Netbeans 7 called: MyForm Once the project has been generated take the resulting (default) index.jsp file and delete it. In its place add a file called: index.html and add the following content to it: Name: Message: Item 1: Item 2: Basically, I created a simple (ugly) form that takes a few parameters the user enters. They submit the form and the data is sent to the REST project we will soon be building. The idea here is we are using an HTTP POST to create a new message. That’s it for the first project! With Netbean’s Maven integration do a Clean and Build and then deploy the resulting WAR file to Apache Tomcat. Create another new Maven Web Application with Netbeans 7 called: RESTwithForms Add two new Java classes to the new project: 1. MyApplication 2. MessageResource The code for MyApplication.java is as follows: package com.giantflyingsaucer; import com.sun.jersey.api.core.PackagesResourceConfig; import javax.ws.rs.ApplicationPath; @ApplicationPath("/") public class MyApplication extends PackagesResourceConfig { public MyApplication() { super("com.giantflyingsaucer"); } } In a brief nutshell this code allows us to make use of some Servlet 3.0 goodies (we don’t need to create a web.xml file for this project as an example). For more details see the sections titled: Example 2.8. Reusing Jersey implementation in your custom application model and Example 2.9. Deployment of a JAX-RS application using @ApplicationPath with Servlet 3.0 at this link. The real guts of the REST project are in the MessageResource.java file as seen below: package com.giantflyingsaucer; import java.net.URI; import java.util.List; import java.util.UUID; import javax.ws.rs.FormParam; import javax.ws.rs.POST; import javax.ws.rs.Path; import javax.ws.rs.core.Response; import javax.ws.rs.Consumes; import javax.ws.rs.core.MediaType; @Path("/messages") public class MessageResource { @POST @Consumes(MediaType.APPLICATION_FORM_URLENCODED) public Response createMessage(@FormParam("name") String name, @FormParam("message") String message, @FormParam("thelist") List list) { if(name.trim().length() > 0 && message.trim().length() > 0 && !list.isEmpty()) { // Note 1: Normally you would persist the new message to a datastore // of some sort. I'm going to pretend I've done that and // use a unique id for it that obviously points to nothing in // this case. // Note 2: The way I'm returning the data should be more like the commented // out piece, I am being verbose for the sake of showing you how to // get the values and show that it was read. return Response.created(URI.create("/messages/" + String.valueOf(UUID.randomUUID()))).entity( name+ ": " + message + " --> the items: " + list.get(0) + " - " + list.get(1)).build(); // This is a more real world "return" //return Response.created(URI.create("/messages/" + String.valueOf(UUID.randomUUID()))).build(); } return Response.status(Response.Status.PRECONDITION_FAILED).build(); } } Note: Pay special attention to the comments. Please don’t email me stating I shouldn’t be returning text back with the values, also please don’t tell me I should be iterating the list, etc. this is just a demo. You will obviously do this differently in a production environment. The key here is simplicity and minimal code. At this point you need to add jersey-server as a dependency in your POM file. com.sun.jersey jersey-server-linking 1.9.1 With Netbean’s Maven integration do a Clean and Build and then deploy the resulting WAR file to Apache Tomcat. You are now ready to test it out. Load up the HTML file from the first project and enter some data and then submit it. If you have a tool like FireBug for Firefox, you can also see that an HTTP 201 was returned (if successful). If you don’t enter any data in the form then you should get an HTTP 412 back. With not much more work you could just as easily use something like jQuery and submit the form via AJAX.
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