Apache MINA 框架之Filters介绍

IoFilter是NIMA框架核心组员之一，扮演者重要角色。它过滤所有IoService和IoHandler之间的I/O事件和请求。

一些典型且经常使用的过滤器：

• LoggingFilter 记录所有事件和请求。
• ProtocolCodecFilter 将传入消息ByteBuffer POJO,反之亦然。
• CompressionFilter 压缩数据。
• SSLFilter 添加SSL - TLS - StartTLS支持。

已经实现的Filter接口：

Filter	class	Description
Blacklist	BlacklistFilter	Blocks connections from blacklisted remote addresses
Buffered Write	BufferedWriteFilter	Buffers outgoing requests like the BufferedOutputStream does
Compression	CompressionFilter
ConnectionThrottle	ConnectionThrottleFilter
ErrorGenerating	ErrorGeneratingFilter
Executor	ExecutorFilter
FileRegionWrite	FileRegionWriteFilter
KeepAlive	KeepAliveFilter
Logging	LoggingFilter	Logs event messages, like MessageReceived, MessageSent, SessionOpened, ...
MDC Injection	MdcInjectionFilter	Inject key IoSession properties into the MDC
Noop	NoopFilter	A filter that does nothing. Useful for tests.
Profiler	ProfilerTimerFilter	Profile event messages, like MessageReceived, MessageSent, SessionOpened, ...
ProtocolCodec	ProtocolCodecFilter	A filter in charge of encoding and decoding messages
Proxy	ProxyFilter
Reference counting	ReferenceCountingFilter	Keeps track of the number of usages of this filter
RequestResponse	RequestResponseFilter
SessionAttributeInitializing	SessionAttributeInitializingFilter
StreamWrite	StreamWriteFilter
SslFilter	SslFilter
WriteRequest	WriteRequestFilter

重载事件：

通过实现IoFilter IoAdapter直接替换已有的事件实现，

public class MyFilter extends IoFilterAdapter {
    @Override
    public void sessionOpened(NextFilter nextFilter, IoSession session) throws Exception {
        // Some logic here...
        nextFilter.sessionOpened(session);
        // Some other logic here...
    }
}