Package org.apache.mina.common

Interface IoFilter

All Known Implementing Classes:

BlacklistFilter, ExecutorFilter, IoFilterAdapter, LoggingFilter, ProtocolCodecFilter, ReferenceCountingIoFilter, StreamWriteFilter

public interface IoFilter

A filter which intercepts IoHandler events like Servlet filters. Filters can be used for these purposes:

• Event logging,
• Performance measurement,
• Authorization,
• Overload control,
• Message transformation (e.g. encryption and decryption, ...),
• and many more.

Please NEVER implement your filters to wrap IoSessions. Users can cache the reference to the session, which might malfunction if any filters are added or removed later.

The Life Cycle

IoFilters are activated only when they are inside IoFilterChain.

When you add an IoFilter to an IoFilterChain:

1. init() is invoked by ReferenceCountingIoFilter if the filter is added at the first time.
2. onPreAdd(IoFilterChain, String, NextFilter) is invoked to notify that the filter will be added to the chain.
3. The filter is added to the chain, and all events and I/O requests pass through the filter from now.
4. onPostAdd(IoFilterChain, String, NextFilter) is invoked to notify that the filter is added to the chain.
5. The filter is removed from the chain if onPostAdd(IoFilterChain, String, org.apache.mina.common.IoFilter.NextFilter) threw an exception. destroy() is also invoked by ReferenceCountingIoFilter if the filter is the last filter which was added to IoFilterChains.

When you remove an IoFilter from an IoFilterChain:

1. onPreRemove(IoFilterChain, String, NextFilter) is invoked to notify that the filter will be removed from the chain.
2. The filter is removed from the chain, and any events and I/O requests don't pass through the filter from now.
3. onPostRemove(IoFilterChain, String, NextFilter) is invoked to notify that the filter is removed from the chain.
4. destroy() is invoked by ReferenceCountingIoFilter if the removed filter was the last one.

See Also:

IoFilterAdapter

Nested Class Summary

Nested Classes

Modifier and Type	Interface	Description
static interface	IoFilter.NextFilter	Represents the next IoFilter in IoFilterChain.
static class	IoFilter.WriteRequest	Represents write request fired by IoSession.write(Object).

Method Summary

Modifier and Type	Method	Description
void	destroy()	Invoked by ReferenceCountingIoFilter when this filter is not used by any IoFilterChain anymore, so you can destroy shared resources.
void	exceptionCaught(IoFilter.NextFilter nextFilter, IoSession session, java.lang.Throwable cause)	Filters IoHandler.exceptionCaught(IoSession,Throwable) event.
void	filterClose(IoFilter.NextFilter nextFilter, IoSession session)	Filters IoSession.close() method invocation.
void	filterWrite(IoFilter.NextFilter nextFilter, IoSession session, IoFilter.WriteRequest writeRequest)	Filters IoSession.write(Object) method invocation.
void	init()	Invoked by ReferenceCountingIoFilter when this filter is added to a IoFilterChain at the first time, so you can initialize shared resources.
void	messageReceived(IoFilter.NextFilter nextFilter, IoSession session, java.lang.Object message)	Filters IoHandler.messageReceived(IoSession,Object) event.
void	messageSent(IoFilter.NextFilter nextFilter, IoSession session, java.lang.Object message)	Filters IoHandler.messageSent(IoSession,Object) event.
void	onPostAdd(IoFilterChain parent, java.lang.String name, IoFilter.NextFilter nextFilter)	Invoked after this filter is added to the specified parent.
void	onPostRemove(IoFilterChain parent, java.lang.String name, IoFilter.NextFilter nextFilter)	Invoked after this filter is removed from the specified parent.
void	onPreAdd(IoFilterChain parent, java.lang.String name, IoFilter.NextFilter nextFilter)	Invoked before this filter is added to the specified parent.
void	onPreRemove(IoFilterChain parent, java.lang.String name, IoFilter.NextFilter nextFilter)	Invoked before this filter is removed from the specified parent.
void	sessionClosed(IoFilter.NextFilter nextFilter, IoSession session)	Filters IoHandler.sessionClosed(IoSession) event.
void	sessionCreated(IoFilter.NextFilter nextFilter, IoSession session)	Filters IoHandler.sessionCreated(IoSession) event.
void	sessionIdle(IoFilter.NextFilter nextFilter, IoSession session, IdleStatus status)	Filters IoHandler.sessionIdle(IoSession,IdleStatus) event.
void	sessionOpened(IoFilter.NextFilter nextFilter, IoSession session)	Filters IoHandler.sessionOpened(IoSession) event.

Method Detail

init

void init()
   throws java.lang.Exception

Invoked by ReferenceCountingIoFilter when this filter is added to a IoFilterChain at the first time, so you can initialize shared resources. Please note that this method is never called if you don't wrap a filter with ReferenceCountingIoFilter.

Throws:

java.lang.Exception

destroy

void destroy()
      throws java.lang.Exception

Invoked by ReferenceCountingIoFilter when this filter is not used by any IoFilterChain anymore, so you can destroy shared resources. Please note that this method is never called if you don't wrap a filter with ReferenceCountingIoFilter.

Throws:

java.lang.Exception

onPreAdd

void onPreAdd(IoFilterChain parent,
              java.lang.String name,
              IoFilter.NextFilter nextFilter)
       throws java.lang.Exception

Invoked before this filter is added to the specified parent. Please note that this method can be invoked more than once if this filter is added to more than one parents. This method is not invoked before init() is invoked.

Parameters:

parent - the parent who called this method

name - the name assigned to this filter

nextFilter - the IoFilter.NextFilter for this filter. You can reuse this object until this filter is removed from the chain.

Throws:

java.lang.Exception

onPostAdd

void onPostAdd(IoFilterChain parent,
               java.lang.String name,
               IoFilter.NextFilter nextFilter)
        throws java.lang.Exception

Invoked after this filter is added to the specified parent. Please note that this method can be invoked more than once if this filter is added to more than one parents. This method is not invoked before init() is invoked.

Parameters:

parent - the parent who called this method

name - the name assigned to this filter

nextFilter - the IoFilter.NextFilter for this filter. You can reuse this object until this filter is removed from the chain.

Throws:

java.lang.Exception

onPreRemove

void onPreRemove(IoFilterChain parent,
                 java.lang.String name,
                 IoFilter.NextFilter nextFilter)
          throws java.lang.Exception

Invoked before this filter is removed from the specified parent. Please note that this method can be invoked more than once if this filter is removed from more than one parents. This method is always invoked before destroy() is invoked.

Parameters:

parent - the parent who called this method

name - the name assigned to this filter

nextFilter - the IoFilter.NextFilter for this filter. You can reuse this object until this filter is removed from the chain.

Throws:

java.lang.Exception

onPostRemove

void onPostRemove(IoFilterChain parent,
                  java.lang.String name,
                  IoFilter.NextFilter nextFilter)
           throws java.lang.Exception

Invoked after this filter is removed from the specified parent. Please note that this method can be invoked more than once if this filter is removed from more than one parents. This method is always invoked before destroy() is invoked.

Parameters:

parent - the parent who called this method

name - the name assigned to this filter

nextFilter - the IoFilter.NextFilter for this filter. You can reuse this object until this filter is removed from the chain.

Throws:

java.lang.Exception

sessionCreated

void sessionCreated(IoFilter.NextFilter nextFilter,
                    IoSession session)
             throws java.lang.Exception

Filters IoHandler.sessionCreated(IoSession) event.

Throws:

java.lang.Exception

sessionOpened

void sessionOpened(IoFilter.NextFilter nextFilter,
                   IoSession session)
            throws java.lang.Exception

Filters IoHandler.sessionOpened(IoSession) event.

Throws:

java.lang.Exception

sessionClosed

void sessionClosed(IoFilter.NextFilter nextFilter,
                   IoSession session)
            throws java.lang.Exception

Filters IoHandler.sessionClosed(IoSession) event.

Throws:

java.lang.Exception

sessionIdle

void sessionIdle(IoFilter.NextFilter nextFilter,
                 IoSession session,
                 IdleStatus status)
          throws java.lang.Exception

Filters IoHandler.sessionIdle(IoSession,IdleStatus) event.

Throws:

java.lang.Exception

exceptionCaught

void exceptionCaught(IoFilter.NextFilter nextFilter,
                     IoSession session,
                     java.lang.Throwable cause)
              throws java.lang.Exception

Filters IoHandler.exceptionCaught(IoSession,Throwable) event.

Throws:

java.lang.Exception

messageReceived

void messageReceived(IoFilter.NextFilter nextFilter,
                     IoSession session,
                     java.lang.Object message)
              throws java.lang.Exception

Filters IoHandler.messageReceived(IoSession,Object) event.

Throws:

java.lang.Exception

messageSent

void messageSent(IoFilter.NextFilter nextFilter,
                 IoSession session,
                 java.lang.Object message)
          throws java.lang.Exception

Filters IoHandler.messageSent(IoSession,Object) event.

Throws:

java.lang.Exception

filterClose

void filterClose(IoFilter.NextFilter nextFilter,
                 IoSession session)
          throws java.lang.Exception

Filters IoSession.close() method invocation.

Throws:

java.lang.Exception

filterWrite

void filterWrite(IoFilter.NextFilter nextFilter,
                 IoSession session,
                 IoFilter.WriteRequest writeRequest)
          throws java.lang.Exception

Filters IoSession.write(Object) method invocation.

Throws:

java.lang.Exception