androidpn的学习研究（六）Androidpn-server的Mina编码和解码解析过程

在许多网络应用中可能针对传输的数据进行加密操作，接收到数据之后进行解码操作。

在mina中提供许多加密和解密的解析方式：

1.带一定前缀的字符串的解析方式。

2.序列化对象的字符串解析方式。

3.分隔符方式的字符串解析方式。

在mina中提供相关的filterchain支持相关的操作。

Mina的源代码如下：

packageorg.apache.mina.filter.codec;

importorg.apache.mina.core.session.IoSession;

/**
*Provides{@linkProtocolEncoder}and{@linkProtocolDecoder}whichtranslates
*binaryorprotocolspecificdataintomessageobjectandviceversa.
*<p>
*Pleasereferto
*<ahref="../../../../../xref-examples/org/apache/mina/examples/reverser/ReverseProtocolProvider.html"><code>ReverserProtocolProvider</code></a>
*example.
*
*@author<ahref="http://mina.apache.org">ApacheMINAProject</a>
*/
publicinterfaceProtocolCodecFactory{
/**
*Returnsanew(orreusable)instanceof{@linkProtocolEncoder}which
*encodesmessageobjectsintobinaryorprotocol-specificdata.
*/
ProtocolEncodergetEncoder(IoSessionsession)throwsException;

/**
*Returnsanew(orreusable)instanceof{@linkProtocolDecoder}which
*decodesbinaryorprotocol-specificdataintomessageobjects.
*/
ProtocolDecodergetDecoder(IoSessionsession)throwsException;
}

加密处理类：

packageorg.apache.mina.filter.codec;

importorg.apache.mina.core.buffer.IoBuffer;
importorg.apache.mina.core.session.IoSession;

/**
*Encodeshigher-levelmessageobjectsintobinaryorprotocol-specificdata.
*MINAinvokes{@link#encode(IoSession,Object,ProtocolEncoderOutput)}
*methodwithmessagewhichispoppedfromthesessionwritequeue,andthen
*theencoderimplementationputsencodedmessages(typically{@linkIoBuffer}s)
*into{@linkProtocolEncoderOutput}bycalling{@linkProtocolEncoderOutput#write(Object)}.
*<p>
*Pleasereferto
*<ahref="../../../../../xref-examples/org/apache/mina/examples/reverser/TextLineEncoder.html"><code>TextLineEncoder</code></a>
*example.
*
*@author<ahref="http://mina.apache.org">ApacheMINAProject</a>
*
*@seeProtocolEncoderException
*/
publicinterfaceProtocolEncoder{

/**
*Encodeshigher-levelmessageobjectsintobinaryorprotocol-specificdata.
*MINAinvokes{@link#encode(IoSession,Object,ProtocolEncoderOutput)}
*methodwithmessagewhichispoppedfromthesessionwritequeue,andthen
*theencoderimplementationputsencodedmessages(typically{@linkIoBuffer}s)
*into{@linkProtocolEncoderOutput}.
*
*@throwsExceptionifthemessageviolatedprotocolspecification
*/
voidencode(IoSessionsession,Objectmessage,ProtocolEncoderOutputout)
throwsException;

/**
*Releasesallresourcesrelatedwiththisencoder.
*
*@throwsExceptioniffailedtodisposeallresources
*/
voiddispose(IoSessionsession)throwsException;
}

解密类如下：

packageorg.apache.mina.filter.codec;

importorg.apache.mina.core.buffer.IoBuffer;
importorg.apache.mina.core.session.IoSession;

/**
*Decodesbinaryorprotocol-specificdataintohigher-levelmessageobjects.
*MINAinvokes{@link#decode(IoSession,IoBuffer,ProtocolDecoderOutput)}
*methodwithreaddata,andthenthedecoderimplementationputsdecoded
*messagesinto{@linkProtocolDecoderOutput}bycalling
*{@linkProtocolDecoderOutput#write(Object)}.
*<p>
*Pleasereferto
*<ahref="../../../../../xref-examples/org/apache/mina/examples/reverser/TextLineDecoder.html"><code>TextLineDecoder</code></a>
*example.
*
*@author<ahref="http://mina.apache.org">ApacheMINAProject</a>
*
*@seeProtocolDecoderException
*/
publicinterfaceProtocolDecoder{
/**
*Decodesbinaryorprotocol-specificcontentintohigher-levelmessageobjects.
*MINAinvokes{@link#decode(IoSession,IoBuffer,ProtocolDecoderOutput)}
*methodwithreaddata,andthenthedecoderimplementationputsdecoded
*messagesinto{@linkProtocolDecoderOutput}.
*
*@throwsExceptionifthereaddataviolatedprotocolspecification
*/
voiddecode(IoSessionsession,IoBufferin,ProtocolDecoderOutputout)
throwsException;

/**
*Invokedwhenthespecified<tt>session</tt>isclosed.Thismethodisuseful
*whenyoudealwiththeprotocolwhichdoesn'tspecifythelengthofamessage
*suchasHTTPresponsewithout<tt>content-length</tt>header.Implementthis
*methodtoprocesstheremainingdatathat{@link#decode(IoSession,IoBuffer,ProtocolDecoderOutput)}
*methoddidn'tprocesscompletely.
*
*@throwsExceptionifthereaddataviolatedprotocolspecification
*/
voidfinishDecode(IoSessionsession,ProtocolDecoderOutputout)
throwsException;

/**
*Releasesallresourcesrelatedwiththisdecoder.
*
*@throwsExceptioniffailedtodisposeallresources
*/
voiddispose(IoSessionsession)throwsException;
}

在androidpn中的没有采取任何加密方式，但是提供相关的类org.androidpn.server.xmpp.codec，如果需要可以针对传输的数据进行加密和解密工作。

packageorg.androidpn.server.xmpp.codec;

importorg.apache.mina.core.session.IoSession;
importorg.apache.mina.filter.codec.ProtocolCodecFactory;
importorg.apache.mina.filter.codec.ProtocolDecoder;
importorg.apache.mina.filter.codec.ProtocolEncoder;

/**
*FactoryclassthatspecifiestheencodeanddecodertouseforparsingXMPPstanzas.
*
*@authorSehwanNoh([e-mail])
*/
publicclassXmppCodecFactoryimplementsProtocolCodecFactory{

privatefinalXmppEncoderencoder;

privatefinalXmppDecoderdecoder;

/**
*Constructor.
*/
publicXmppCodecFactory(){
encoder=newXmppEncoder();
decoder=newXmppDecoder();
}

/**
*Returnsanew(orreusable)instanceofProtocolEncoder.
*/
publicProtocolEncodergetEncoder(IoSessionsession)throwsException{
returnencoder;
}

/**
*Returnsanew(orreusable)instanceofProtocolDecoder.
*/
publicProtocolDecodergetDecoder(IoSessionsession)throwsException{
returndecoder;
}

}

androidpn的解密类：

packageorg.androidpn.server.xmpp.codec;

importorg.androidpn.server.xmpp.net.XmppIoHandler;
importorg.apache.mina.core.buffer.IoBuffer;
importorg.apache.mina.core.session.IoSession;
importorg.apache.mina.filter.codec.CumulativeProtocolDecoder;
importorg.apache.mina.filter.codec.ProtocolDecoderOutput;
importorg.jivesoftware.openfire.nio.XMLLightweightParser;

/**
*DecoderclassthatparsesByteBuffersandgeneratesXMLstanzas.
*
*@authorSehwanNoh([e-mail])
*/
publicclassXmppDecoderextendsCumulativeProtocolDecoder{

//privatefinalLoglog=LogFactory.getLog(XmppDecoder.class);

@Override
publicbooleandoDecode(IoSessionsession,IoBufferin,
ProtocolDecoderOutputout)throwsException{
//log.debug("doDecode(...)...");

XMLLightweightParserparser=(XMLLightweightParser)session
.getAttribute(XmppIoHandler.XML_PARSER);
parser.read(in);

if(parser.areThereMsgs()){
for(Stringstanza:parser.getMsgs()){
out.write(stanza);
}
}
return!in.hasRemaining();
}

}

androidpn的加密类：

packageorg.androidpn.server.xmpp.codec;

importorg.apache.mina.core.session.IoSession;
importorg.apache.mina.filter.codec.ProtocolEncoder;
importorg.apache.mina.filter.codec.ProtocolEncoderOutput;

/**
*Encoderclassthatdoesnothing(tothealreadyencodeddata).
*
*@authorSehwanNoh([e-mail])
*/
publicclassXmppEncoderimplementsProtocolEncoder{

//privatefinalLoglog=LogFactory.getLog(XmppEncoder.class);

publicvoidencode(IoSessionsession,Objectmessage,
ProtocolEncoderOutputout)throwsException{
//log.debug("encode()...");
}

publicvoiddispose(IoSessionsession)throwsException{
//log.debug("dispose()...");
}

}

最终将编码解析器转换为过滤器使用，具体配置如下：

<beanclass="org.apache.mina.filter.codec.ProtocolCodecFilter">
<constructor-arg>
<beanclass="org.androidpn.server.xmpp.codec.XmppCodecFactory"/>
</constructor-arg>
</bean>