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58.5. Client Response Filter

Overview

This section explains how to implement and register a client response filter, which is used to intercept an incoming response message on the client side. Client response filters can be used for any kind of generic response processing on the client side.

ClientResponseFilter interface

The javax.ws.rs.client.ClientResponseFilter interface is defined as follows: 
// Java
package javax.ws.rs.client;
...
import java.io.IOException;

public interface ClientResponseFilter {
    void filter(ClientRequestContext requestContext, ClientResponseContext responseContext)
            throws IOException;
}
By implementing the ClientResponseFilter, you can create a filter for the ClientResponse extension point on the client side, which filters the response message after it is received from the server.

ClientResponseContext interface

The filter method of ClientResponseFilter receives two arguments: an argument of type javax.ws.rs.client.ClientRequestContext (see the section called “ClientRequestContext interface”); and an argument of type javax.ws.rs.client.ClientResponseContext, which can be used to access the outgoing response message and its related metadata.
The ClientResponseContext interface is defined as follows: 
// Java
...
package javax.ws.rs.client;

import java.io.InputStream;
import java.net.URI;
import java.util.Date;
import java.util.Locale;
import java.util.Map;
import java.util.Set;

import javax.ws.rs.core.EntityTag;
import javax.ws.rs.core.Link;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.MultivaluedMap;
import javax.ws.rs.core.NewCookie;
import javax.ws.rs.core.Response;

public interface ClientResponseContext {

    public int getStatus();

    public void setStatus(int code);

    public Response.StatusType getStatusInfo();

    public void setStatusInfo(Response.StatusType statusInfo);

    public MultivaluedMap<String, String> getHeaders();

    public String getHeaderString(String name);

    public Set<String> getAllowedMethods();

    public Date getDate();

    public Locale getLanguage();

    public int getLength();

    public MediaType getMediaType();

    public Map<String, NewCookie> getCookies();

    public EntityTag getEntityTag();

    public Date getLastModified();

    public URI getLocation();

    public Set<Link> getLinks();

    boolean hasLink(String relation);

    public Link getLink(String relation);

    public Link.Builder getLinkBuilder(String relation);

    public boolean hasEntity();

    public InputStream getEntityStream();

    public void setEntityStream(InputStream input);
}

Sample implementation

To implement a client response filter for the ClientResponse extension point (that is, where the filter is executed after receiving a response message from the server), define a class that implements the ClientResponseFilter interface.
For example, the following code shows an example of a simple client response filter that gets installed in the ClientResponse extension point, with a priority of 20: 
// Java
package org.jboss.fuse.example;

import javax.ws.rs.client.ClientRequestContext;
import javax.ws.rs.client.ClientResponseContext;
import javax.ws.rs.client.ClientResponseFilter;
import javax.annotation.Priority;
 
@Priority(value = 20)
public class SampleClientResponseFilter implements ClientResponseFilter {

  public SampleClientResponseFilter() {
    System.out.println("SampleClientResponseFilter starting up");
  }

  @Override
  public void filter(
      ClientRequestContext requestContext,
      ClientResponseContext responseContext
  )
  {
    // Add an extra header on the response
    responseContext.getHeaders().putSingle("MyCustomHeader", "my custom data");
  }
}

Registering the client response filter

Using the JAX-RS 2.0 client API, you can register a client response filter directly on a javax.ws.rs.client.Client object or on a javax.ws.rs.client.WebTarget object. Effectively, this means that the client request filter can optionally be applied to different scopes, so that only certain URI paths are affected by the filter.
For example, the following code shows how to register the SampleClientResponseFilter filter so that it applies to all invocations made using the client object: 
// Java
... 
import javax.ws.rs.client.Client;
import javax.ws.rs.client.ClientBuilder;
import javax.ws.rs.client.Invocation;
import javax.ws.rs.client.WebTarget;
import javax.ws.rs.core.Response;
...
Client client = ClientBuilder.newClient();
client.register(new SampleClientResponseFilter());