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RESTfu­­l Jav­a­ wit­h ­JAX­-­­RS 2.­0­ (Second Edition)

Example ex05_2: Forms and Cookies

The ex05_2 exercise includes examples of injecting form data, cookies, and HTTP headers using the @FormParam, @CookieParam, and @HeaderParam annotations. This example is a bit different than former examples, as there is no client code. Instead, to see these annotations in action, you will use a browser as your client.

The Server Code

The example starts off with an HTML form defined in src/main/webapp/index.html:

<html>
<body>

<form action="/rest/customers" method="post">
    First Name: <input type="text" name="firstname"/><br/>
    Last Name: <input type="text" name="lastname"/><br/>
    <INPUT type="submit" value="Send">
</form>

</body>
</html>

It is a simple form for creating a customer using our familiar CustomerResource service:

src/main/java/com/restfully/shop/CustomerResource.java

@Path("/customers")
public class CustomerResource {
...
   @POST
   @Produces("text/html")
   public Response createCustomer(
                             @FormParam("firstname") String first,
                             @FormParam("lastname") String last)
   {

The HTML form posts data to the createCustomer() method of CustomerResource when users click the Send button:

      Customer customer = new Customer();
      customer.setId(idCounter.incrementAndGet());
      customer.setFirstName(first);
      customer.setLastName(last);
      customerDB.put(customer.getId(), customer);
      System.out.println("Created customer " + customer.getId());
      String output = "Created customer <a href=\"customers/" +
                  customer.getId() + "\">" + customer.getId()
                            + "</a>";
      String lastVisit = DateFormat.getDateTimeInstance(
                DateFormat.SHORT, DateFormat.LONG).format(new Date());
      return Response.created(URI.create("/customers/"
                                          + customer.getId()))
                     .entity(output)
                     .cookie(new NewCookie("last-visit", lastVisit))
                     .build();

   }

The createCustomer() method does a couple things. First, it uses the form data injected with @FormParam to create a Customer object and insert it into an in-memory map. It then builds an HTML response that shows text linking to the new customer. Finally, it sets a cookie on the client by calling the ResponseBuilder.cookie() method. This cookie, named last-visit, holds the current time and date. This cookie will be used so that on subsequent requests, the server knows the last time the client accessed the website:

   @GET
   @Path("{id}")
   @Produces("text/plain")
   public Response getCustomer(
                        @PathParam("id") int id,
                          @HeaderParam("User-Agent") String userAgent,
                            @CookieParam("last-visit") String date)
   {

The getCustomer() method retrieves a Customer object from the in-memory map referenced by the id path parameter. The @HeaderParam annotation injects the value of the User-Agent header. This is a standard HTTP 1.1 header that denotes the type of client that made the request (Safari, Firefox, Internet Explorer, etc.). The @CookieParam annotation injects the value of the last-visit cookie that the client should be passing along with each request:

      final Customer customer = customerDB.get(id);
      if (customer == null) {
         throw new WebApplicationException(Response.Status.NOT_FOUND);
      }
      String output = "User-Agent: " + userAgent + "\r\n";
      output += "Last visit: " + date + "\r\n\r\n";
      output += "Customer: " + customer.getFirstName() + " "
                     + customer.getLastName();
      String lastVisit = DateFormat.getDateTimeInstance(
                DateFormat.SHORT, DateFormat.LONG).format(new Date());
      return Response.ok(output)
              .cookie(new NewCookie("last-visit", lastVisit))
              .build();
   }

The implementation of this method is very simple. It outputs the User-Agent header and last-visit cookie as plain text (text/plain). It also resets the last-visit cookie to the current time and date.

Build and Run the Example Program

Perform the following steps:

  1. Open a command prompt or shell terminal and change to the ex05_2 directory of the workbook example code.
  2. Make sure your PATH is set up to include both the JDK and Maven, as described in Chapter 17.
  3. Perform the build and run the example by typing maven jetty:run. This command is a bit different than our previous examples. This script builds the WAR file, but it also starts up the Jetty servlet container.

You test-drive ex05_2 by using your browser. The first step is to go to http://localhost:8080, as shown in Figure 20-1.

When you click Send, you will see the screen shown in Figure 20-2.

Clicking the customer link will show you a plain-text representation of the customer, as shown in Figure 20-3.

If you refresh this page, you will see the timestamp of the “last visit” string increment each time as the CustomerResource updates the last-visit cookie.

Figure 20-1
Figure 20-1. Customer creation form

Figure 20-2
Figure 20-2. Creation response

Figure 20-3
Figure 20-3. Customer output