JAX-RS - Writing a Context Provider by implementing ContextResolver

[Last Updated: Jul 4, 2017]

Context providers supply a context object to resource classes or to other providers.

A context provider class must implement the ContextResolver<T>interface.

The implementation should be annotated with @Provider for automatic discovery or we can programmatically register it too.

Context provider implementations may restrict the media types they support using the @Produces annotation. The absence of this annotation implies that any media type is supported.

On the usage side (a resource class/method or another provider), we have to inject Providers with @Context annotation to access our context.

Let's see how to write and use a context provider.


In this very simple example, we are focusing on how to use context provider feature rather than implementing a meaningful context object.

Writing a Context Provider

public interface MyContext<T> {
  T get(String key);

Now we are going to implement ContextProvider interface which requires only one method to implement: getContext(Class<?> type):

public class MyContextResolver implements
        ContextResolver<MyContext> {
    private MyContext context = new MyContextImpl();

    public MyContext getContext(Class<?> type) {
        if (type == String.class) {
            return context;
        return null;

    private static class MyContextImpl implements MyContext<String> {
        public String get(String key) {
            return "a context value for key=" + key;

Writing a Resource

public class MyResource {

    public String create(@PathParam("path") String path,
                         @Context Providers providers) {
        ContextResolver<MyContext> cr = providers
                .getContextResolver(MyContext.class, MediaType.WILDCARD_TYPE);
        MyContext<String> c = cr.getContext(String.class);
        String r = c.get(path);
        return "response:  " + r;

To try examples, run embedded tomcat (configured in pom.xml of example project below):

mvn tomcat7:run-war

Writing a JAX-RS client

public class JaxRsClient {

  public static void main(String[] args) {
      Client client = ClientBuilder.newClient();
      WebTarget baseTarget ="http://localhost:8080/example");
      String response = baseTarget.request()


response:  a test context value for key=example

In the next example, we will see a more practical example. We will also learn how to access a ContextResolver in another provider (a class annotated with @Provider).

Example Project

Dependencies and Technologies Used:

  • jersey-server 2.25.1: Jersey core server implementation.
  • jersey-container-servlet 2.25.1: Jersey core Servlet 3.x implementation.
  • JDK 1.8
  • Maven 3.3.9

JAX-RS ContextResolver Example Project Select All Download
  • jaxrs-context-resolver-example
    • src
      • main
        • java
          • com
            • logicbig
              • example

    See Also