androidpn的学习研究（八）androidpn 中业务类XmppIoHandler实现分析

在androidpn中主要采用Mina进行网络通讯，其中Mina中IoHandler用来处理主要的业务逻辑。

Mina中源代码如下：

Java代码

1. packageorg.apache.mina.core.service;
3. importjava.io.IOException;
5. importorg.apache.mina.core.session.IdleStatus;
6. importorg.apache.mina.core.session.IoSession;
8. /**
9. *HandlesallI/OeventsfiredbyMINA.
10. *
11. *@author<ahref="http://mina.apache.org">ApacheMINAProject</a>
12. *
13. *@seeIoHandlerAdapter
14. */
15. publicinterfaceIoHandler{
16. /**
17. *InvokedfromanI/Oprocessorthreadwhenanewconnectionhasbeencreated.
18. *Becausethismethodissupposedtobecalledfromthesamethreadthat
19. *handlesI/Oofmultiplesessions,pleaseimplementthismethodtoperform
20. *tasksthatconsumesminimalamountoftimesuchassocketparameter
21. *anduser-definedsessionattributeinitialization.
22. */
23. voidsessionCreated(IoSessionsession)throwsException;
25. /**
26. *Invokedwhenaconnectionhasbeenopened.Thismethodisinvokedafter
27. *{@link#sessionCreated(IoSession)}.Thebiggestdifferencefrom
28. *{@link#sessionCreated(IoSession)}isthatit'sinvokedfromotherthread
29. *thananI/Oprocessorthreadoncethreadmodelisconfiguredproperly.
30. */
31. voidsessionOpened(IoSessionsession)throwsException;
33. /**
34. *Invokedwhenaconnectionisclosed.
35. */
36. voidsessionClosed(IoSessionsession)throwsException;
38. /**
39. *Invokedwiththerelated{@linkIdleStatus}whenaconnectionbecomesidle.
40. *ThismethodisnotinvokedifthetransporttypeisUDP;it'saknownbug,
41. *andwillbefixedin2.0.
42. */
43. voidsessionIdle(IoSessionsession,IdleStatusstatus)throwsException;
45. /**
46. *Invokedwhenanyexceptionisthrownbyuser{@linkIoHandler}
47. *implementationorbyMINA.If<code>cause</code>isaninstanceof
48. *{@linkIOException},MINAwillclosetheconnectionautomatically.
49. */
50. voidexceptionCaught(IoSessionsession,Throwablecause)throwsException;
52. /**
53. *Invokedwhenamessageisreceived.
54. */
55. voidmessageReceived(IoSessionsession,Objectmessage)throwsException;
57. /**
58. *Invokedwhenamessagewrittenby{@linkIoSession#write(Object)}is
59. *sentout.
60. */
61. voidmessageSent(IoSessionsession,Objectmessage)throwsException;
62. }

Mina中IoHandler可供处理的事件回调

sessionCreate(IoSession)

IoSession对象被创建时的回调，一般用于进行会话初始化操作。注意：与sessionOpened(IoSession)不同，IoSession对象的创建并不意味着对应底层TCP连接的建立，而仅仅代表字面意思：一个IoSession对象被创建出来了。

sessionOpened(IoSession)

IoSession对象被打开时回调。在TCP中，该事件是在TCP连接建立时触发，一般可用于发起连接建立的握手、认证等操作。

sessionIdle(IoSession,IdleStatus)

IoSession对象超时时回调。当一个IoSession对象在指定的超时时常内没有读写事件发生，就会触发该事件，一般可用于通知服务器断开长时间闲置的连接等处理。具体的超时设置可由 IoService.setWriteIdleTime(int) ,IoService.setReadIdleTime(int) ,IoService.setBothIdleTime(int)设置。

messageReceived(IoSession,Object)

当接收到IoSession对Client发送的数据时回调。

messageSent(IoSession,Object)

当发送给IoSession对Client的数据发送成功时回调。

exceptionCaught(IoSession,Throwable)

当会话过程中出现异常时回调，通常用于错误处理。

session.write(Object)方法是一个异步方法，对该方法的调用并不会阻塞，而是向Mina投递一个异步的写操作，并返回一个可用于对已投递异步写操作进行控制的WriteFuture对象。例如：调用WriteFuture的await()或awaitUninterruptibly()，可由同步等待该异步操作的完成。

在I/O处理器中实现业务逻辑的时候，对于简单的情况，一般只需要在messageReceived中对传入的消息进行处理。如果需要写回数据到对等体，用IoSession.write()即可。

另外的情况，client和server的通信协议比较复杂，client是有状态变迁的，这时可用Mina提供的状态机实现，可使用IO处理器的实现更加简单。

androidpn中XmppIoHandler源代码：

Java代码

1. packageorg.androidpn.server.xmpp.net;
3. importjava.util.Map;
4. importjava.util.concurrent.ConcurrentHashMap;
6. importorg.androidpn.server.xmpp.XmppServer;
7. importorg.apache.commons.logging.Log;
8. importorg.apache.commons.logging.LogFactory;
9. importorg.apache.mina.core.service.IoHandler;
10. importorg.apache.mina.core.session.IdleStatus;
11. importorg.apache.mina.core.session.IoSession;
12. importorg.dom4j.io.XMPPPacketReader;
13. importorg.jivesoftware.openfire.net.MXParser;
14. importorg.jivesoftware.openfire.nio.XMLLightweightParser;
15. importorg.xmlpull.v1.XmlPullParserException;
16. importorg.xmlpull.v1.XmlPullParserFactory;
18. /**
19. *Thisclassistocreatenewsessions,destroysessionsanddeliver
20. *receivedXMLstanzastotheStanzaHandler.
21. *
22. *@authorSehwanNoh(devnoh@gmail.com)
23. */
24. publicclassXmppIoHandlerimplementsIoHandler{
26. privatestaticfinalLoglog=LogFactory.getLog(XmppIoHandler.class);
28. publicstaticfinalStringXML_PARSER="XML_PARSER";
30. privatestaticfinalStringCONNECTION="CONNECTION";
32. privatestaticfinalStringSTANZA_HANDLER="STANZA_HANDLER";
34. privateStringserverName;
36. privatestaticMap<Integer,XMPPPacketReader>parsers=newConcurrentHashMap<Integer,XMPPPacketReader>();
38. privatestaticXmlPullParserFactoryfactory=null;
40. static{
41. try{
42. factory=XmlPullParserFactory.newInstance(
43. MXParser.class.getName(),null);
44. factory.setNamespaceAware(true);
45. }catch(XmlPullParserExceptione){
46. log.error("Errorcreatingaparserfactory",e);
47. }
48. }
50. /**
51. *Constructor.Settheservernamefromserverinstance.
52. */
53. protectedXmppIoHandler(){
54. serverName=XmppServer.getInstance().getServerName();
55. }
57. /**
58. *InvokedfromanI/Oprocessorthreadwhenanewconnectionhasbeencreated.
59. */
60. publicvoidsessionCreated(IoSessionsession)throwsException{
61. log.debug("sessionCreated()...");
62. }
64. /**
65. *Invokedwhenaconnectionhasbeenopened.
66. */
67. publicvoidsessionOpened(IoSessionsession)throwsException{
68. log.debug("sessionOpened()...");
69. log.debug("remoteAddress="+session.getRemoteAddress());
70. //CreateanewXMLparser
71. XMLLightweightParserparser=newXMLLightweightParser("UTF-8");
72. session.setAttribute(XML_PARSER,parser);
73. //Createanewconnection
74. Connectionconnection=newConnection(session);
75. session.setAttribute(CONNECTION,connection);
76. session.setAttribute(STANZA_HANDLER,newStanzaHandler(serverName,
77. connection));
78. }
80. /**
81. *Invokedwhenaconnectionisclosed.
82. */
83. publicvoidsessionClosed(IoSessionsession)throwsException{
84. log.debug("sessionClosed()...");
85. Connectionconnection=(Connection)session.getAttribute(CONNECTION);
86. connection.close();
87. }
89. /**
90. *InvokedwiththerelatedIdleStatuswhenaconnectionbecomesidle.
91. */
92. publicvoidsessionIdle(IoSessionsession,IdleStatusstatus)
93. throwsException{
94. log.debug("sessionIdle()...");
95. Connectionconnection=(Connection)session.getAttribute(CONNECTION);
96. if(log.isDebugEnabled()){
97. log.debug("Closingconnectionthathasbeenidle:"+connection);
98. }
99. connection.close();
100. }
102. /**
103. *Invokedwhenanyexceptionisthrown.
104. */
105. publicvoidexceptionCaught(IoSessionsession,Throwablecause)
106. throwsException{
107. log.debug("exceptionCaught()...");
108. log.error(cause);
109. }
111. /**
112. *Invokedwhenamessageisreceived.
113. */
114. publicvoidmessageReceived(IoSessionsession,Objectmessage)
115. throwsException{
116. log.debug("messageReceived()...");
117. log.debug("RCVD:"+message);
119. //Getthestanzahandler
120. StanzaHandlerhandler=(StanzaHandler)session
121. .getAttribute(STANZA_HANDLER);
123. //GettheXMPPpacketparser
124. inthashCode=Thread.currentThread().hashCode();
125. XMPPPacketReaderparser=parsers.get(hashCode);
126. if(parser==null){
127. parser=newXMPPPacketReader();
128. parser.setXPPFactory(factory);
129. parsers.put(hashCode,parser);
130. }
132. //Thestanzahandlerprocessesthemessage
133. try{
134. handler.process((String)message,parser);
135. }catch(Exceptione){
136. log.error(
137. "Closingconnectionduetoerrorwhileprocessingmessage:"
138. +message,e);
139. Connectionconnection=(Connection)session
140. .getAttribute(CONNECTION);
141. connection.close();
142. }
143. }
145. /**
146. *InvokedwhenamessagewrittenbyIoSession.write(Object)issentout.
147. */
148. publicvoidmessageSent(IoSessionsession,Objectmessage)throwsException{
149. log.debug("messageSent()...");
150. }
152. }

XmppIoHandler在加载的时候创建相关的xml解析工厂。

sessionOpened：在连接打开时候创建相关的xml的解析器和Handler处理器。

sessionClosed：关闭相关的连接。

sessionIdle：关闭相关的连接。

messageReceived：获取相关的xml解析器和handler处理器处理相关的消息。