Interceptors implement the PhaseInterceptor interface which
extends the base Interceptor interface. This interface defines
a number of methods used by the Fuse Services Framework's runtime to control interceptor execution and
are not appropriate for application developers to implement. To simplify interceptor
development, Fuse Services Framework provides a number of abstract interceptor implementations that can
be extended.
All of the interceptors in Fuse Services Framework implement the base Interceptor
interface shown in Example 2.1.
Example 2.1. Base interceptor interface
package org.apache.cxf.interceptor;
public interface Interceptor<T extends Message>
{
void handleMessage(T message) throws Fault;
void handleFault(T message);
}The Interceptor interface defines the two methods that a
developer needs to implement for a custom interceptor:
- handleMessage()
The
handleMessage()method does most of the work in an interceptor. It is called on each interceptor in a message chain and receives the contents of the message being processed. Developers implement the message processing logic of the interceptor in this method. For detailed information about implementing thehandleMessage()method, see Processing messages.- handleFault()
The
handleFault()method is called on an interceptor when normal message processing has been interrupted. The runtime calls thehandleFault()method of each invoked interceptor in reverse order as it unwinds an interceptor chain. For detailed information about implementing thehandleFault()method, see Unwinding after an error.
Most interceptors do not directly implement the Interceptor interface. Instead, they implement
the PhaseInterceptor interface shown in Example 2.2. The
PhaseInterceptor interface adds four methods that allow an interceptor the participate in interceptor chains.
Example 2.2. The phase interceptor interface
package org.apache.cxf.phase;
...
public interface PhaseInterceptor<T extends Message> extends Interceptor<T>
{
Set<String> getAfter();
Set<String> getBefore();
String getId();
String getPhase();
}Instead of directly implementing the PhaseInterceptor interface, developers should extend the
AbstractPhaseInterceptor class. This abstract class provides implementations for the phase management
methods of the PhaseInterceptor interface. The AbstractPhaseInterceptor class
also provides a default implementation of the handleFault() method.
Developers need to provide an implementation of the handleMessage() method. They can also provide
a different implementation for the handleFault() method. The developer-provided implementations can
manipulate the message data using the methods provided by the generic
org.apache.cxf.message.Message interface.
For applications that work with SOAP messages, Fuse Services Framework provides an AbstractSoapInterceptor
class. Extending this class provides the handleMessage() method and the
handleFault() method with access to the message data as an
org.apache.cxf.binding.soap.SoapMessage object. SoapMessage objects have methods for
retrieving the SOAP headers, the SOAP envelope, and other SOAP metadata from the message.
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