apache mina 学习（七）-----IoFilter

最新推荐文章于 2022-09-23 09:58:47 发布

最新推荐文章于 2022-09-23 09:58:47 发布 · 183 阅读

本文深入探讨了mina框架中IoFilter的重要设计及其实际应用，包括日志、协议编码、压缩、SSL等常见过滤器的使用，并提供了一个自定义过滤器的例子，展示了如何将字节数组转换为字符串进行处理。

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;
    }
}