A frequently used content type for submitting files through an HTML form is
multipart/form-data. The IBM® implementation of Java™ API for RESTful Web Services (JAX-RS) greatly simplifies the processing
of such data by automatically splitting the parts and automatically decoding them. If such automatic
processing is not desired, the resource may instead receive the parts in an object so processing of
the parts is under the complete control of the resource method.
About this task
This task shows you how to develop a JAX-RS resource that takes advantage of the IBM implementation of JAX-RS features that automatically split and decode the
parts in a multipart/form-data HTTP form submission. Using these features allows a JAX-RS resource
method to receive a File object, freeing the method from having to process the raw
part payloads itself. You also see how to receive the raw data so that, if desired, the JAX-RS
resource method retains complete control of the processing of the raw part data.
Procedure
- Configure the development environment.
- Before you start developing JAX-RS applications, you must set up your development environment
by adding the JAX-RS libraries on the classpath.
- Define the resources in JAX-RS web applications.
- Resources are the basic building block of a RESTful service. Resources can contain static or
dynamically updated data. Examples of resources from an online book store application include a
book, an order from a store, and a collection of users. By identifying the resources in your
application, you can make the service more useful and easier to develop.
- Configure the JAX-RS application.
You can configure JAX-RS applications in multiple ways depending on your needs. To take advantage
of the Java Platform, Enterprise Edition (Java EE) 6 functionality, you can use the annotation scanning capabilities. By
using annotation scanning, you can omit a JAX-RS javax.ws.rs.core.Application subclass or have a
minimally defined javax.ws.rs.core.Application subclass. Alternatively, you can specify the IBM JAX-RS servlet or filter if you want to use the functionality
available in the IBM JAX-RS servlet and filter.
Using one of the JAX-RS Version 1.1 configuration methods, you can omit a
javax.ws.rs.core.Application subclass in your application or have a javax.ws.rs.core.Application
subclass that returns an empty set of classes to inform the JAX-RS runtime environment to find and
use all the JAX-RS classes in the application. You might want to use this method when you do not
want to have to manually add every relevant JAX-RS class to a javax.ws.rs.core.Application subclass
as you develop the application.
By specifying the specific IBM JAX-RS servlet and filter,
you can take advantage of and ensure specific IBM JAX-RS
behavior. For example, using the IBM JAX-RS filter can be
helpful in developing a web application with a mix of JAX-RS resources and JavaServer Pages (JSP)
files with the same URL patterns.
Even though there is a JAX-RS V1.1 configuration method that supports the use of an optional
web.xml file, if you want to specify security constraints or roles, or you want to take advantage of
other features enabled using a web.xml file, you must specify the information in a web.xml file.
Choose one of the following three methods to configure your JAX-RS application:
- Configure JAX-RS applications
using JAX-RS 1.1 methods
Use this method if you want to use the annotation scanning
capabilities or to use the JAX-RS 1.1 configuration methods. You can use the annotation scanning
capabilities to promote application portability, to minimize the amount of configuration code, or to
dynamically modify the application without changes to the application code.
- Configure the web.xml file for JAX-RS
servlets
Use this method if you want to specify features that are enabled using servlet
initialization parameters to change the behavior and ensure that you get the IBM JAX-RS servlet. When using servlets, you can define a servlet path in the
web.xml file that is appended to the base URL.
- Configure the web.xml file
for JAX-RS filters
Use this method if you want to use the filter when you have JSPs, other
servlets and filters, and JAX-RS resources with a mix of URL patterns. You can configure the web.xml
file to define filters that indicate the possible URLs on which the filter can be invoked.
- Implement a resource method to receive multipart/form-data parts from an HTML form
submission.
- RESTful services can receive content from an HTML form submission.
- Assemble JAX-RS web applications.
- After you develop the Java class files for your JAX-RS
web application and edit the web.xml file to enable the JAX-RS servlet, you are ready to assemble
the application. Assemble the web application into a web application archive (WAR) package. You can
assemble the WAR package into an enterprise archive (EAR) package, if required.
- Deploy JAX-RS web applications.
- After you have assembled your JAX-RS web application, you need to deploy your Web archive (WAR)
package or the enterprise archive (EAR) package onto the application server.
Results
You have developed and deployed a JAX-RS web application on the application server that processes
multipart/form-data content for requests and responses.