apache mina 学习（七）-----IoFilter

han8809

　　IoFilter是mina中一个非常重要的设计，它可以过滤IoService和IoHandler之间的所有的io流，经常会用到的过滤器：
　　1、日志过滤器LoggingFilter
　　2、协议编码过滤器ProtocolCodecFilter（可以把输入的bytebuffer转换为pojo）
　　3、压缩过滤器CompressionFilter用于压缩数据
　　4、sslFilter用于支持ssl
　　已经存在的过滤器及实现类：


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



　　如果想实现自己的Filter只需集成

IoFilterAdapter抽象类即可。
下面是一个字节数组过滤成字符的Filter例子：
public void filterWrite(NextFilter nextFilter, IoSession session, WriteRequest request) {
String m = (String) request.getMessage();
ByteBuffer newBuffer = new MyByteBuffer(m, ByteBuffer.wrap(m.getBytes());
nextFilter.filterWrite(
session, new WriteRequest(newBuffer, request.getFuture(), request.getDestination()));
}
public void messageSent(NextFilter nextFilter, IoSession session, Object message) {
if (message instanceof MyByteBuffer) {
nextFilter.messageSent(session, ((MyByteBuffer) message).originalValue);
} else {
nextFilter.messageSent(session, message);
}
}
private static class MyByteBuffer extends ByteBufferProxy {
private final Object originalValue;
private MyByteBuffer(Object originalValue, ByteBuffer encodedValue) {
super(encodedValue);
this.originalValue = originalValue;
}
}