MyBatis代码分析资料

1、MyBatisBy:satan_0103基本配置：3 zrc-t* app+ L_ Main, j vf*莒 r dvipain :+ 0 User, javaUserMappiiiLg. KnlXj logback- semi禺 rnybitiE. KmlHi JKE System Library JavtSE-!. T 目Web A.pp Li br ar i es& WebContentD build:b D META-IHF -G> ffEB-IHFlogback-classj c_1s 0.7f j ar logbiek-core-l_ 0. 7. jar mybati

2、s3a L I. jar postjgresql9- 1902- jd'b|c4biii. j sl£4j-Api-1.7.2.眩S- & libarmybatis.xml<7xml versioE=P|!l, 0" encodi.ng= "JIFF-£" ?>DOCTYPE configuration PUBLIC "-/mybatis工g/DTD Config 3.0/EN"/rnybanrs erg/dtd/mybatis3-eenf1g dtdw> <confiouration

3、><typeAlia3es><tipp&AliLa5 匕匹亡 doiEarn E7占巴£" alias= nUser"/><71 ypeAliases>皂 nvi rc murent s default= Mdevel opmsn t ">< envi r nine nt i d= "dsvelopzEen cnranaacElcnManager type"<dataSouxGe 匸评启="PCLED1<prope 二匸y nariie= r/dri

4、ver " value= Marg postgrssq；! Dri verpp ><prDperty nane*MuriM valme*pljdhsr:pasturesql:/U70 0-1 rSdJ/Cpen1*?<prcpert；y name wusernanserr value* pppO5tgrres"/><prcipert；y name = ripassvordrr val.口皂="归国七孑芒合氐眸/></且日匸aSouree></environme口上 ></ envi r o nine

5、 nr s > |<inappers>CniApp-ftr reBouree"wdoBiain./t75*r2d.ppmg. xml W</rftappexs></C0 口壬：1甘口3：且匸1口11UserMappi ng.xml<?xnl version= '*1.On encodlng= "JTF-S'H ?><!DOCTYPE mapper PUBLIC "-/rnybatisaEg/DTD Mapper 30/EN" "http; /mybatis org/dtd/m

6、ybatis-3-inapper dtd*A<mapper namespace= ,rorg-«sybatisr exiupie BiogMppr*><reaultMap Jtype=,rCser,' id= *L7sexResu21*><id coluirmproperty=*id'f/><zesulv colunm=f,口EErnminu* praperty=,iJsernaiEC*/> </resuLtMap><select id= "seisctUser" parameter

7、Type= ifint" resul匸Typ= "sex'” select * from t_user where id = tid</select><insert id= insertUser" paramet;erType= irUsertl>inser匸 Inta t iser values (# id) * # usernarae)</in3&rt></niapper>User.javapackage domain;public class User Int id-l;Spring nsema

8、nie;public int getld()return id;public void 吕总匸Id(int id) tbis,id - id;public String getUsername) return lib&tnair.e:piibli void BetUsemame (String usernarte this p勻亡main亡 - username;Main .javapublic class Main * gpaLram args* throws Exception*/public static void main(String args) throws Except!

9、an String resource = llmyfciati.s xml啊；Reader reader Re?corees -resource);SqlSiss5ionFactory sqlMappex = 口居科 SqlSessionFactoryBuildex().build(zeadex); SqLSession session = sqlMapper.apenSessianO;User ujer new CJ亍皀r ();口iSer seld. (1);user set-Username (Ww丄d2 n):session insert("Ies皂工tUsern ruser

10、);代码分析一：建立SessionFactorypublic static void main( Stri ng args)throwsExcepti on /指向配置文件路径，格式为classpathStri ng resource ="mybatis.xml" ;/使用Mybatis的资源读取器获得reader对象Reader reader = Resources.getResourceAsReader (resource);/ 建立 SqlSessionFactorySqlSessi onF actory sqlMapper =new SqlSessi onF act

11、oryBuilder().build(reader);/创建一个会话SqlSessi on sessi on = sqlMapper.ope nSessi on();User user = new User();user.setld(1);user.setUsername( "satan_0103");/ 调用 sessionsessi on .i nsert("in sertUser",user);sessi on. commit();sessi on. close();分析Resources资源查询器：基本原理：使用 ClassLoader.getR

12、esourceAsStream(resource)方法实现而Resources 对象，使用ClassLoader 数组对象，进行遍历查询.分析：可以使用Resources的静态方法还获得对应输入输出流的对象public static Reader getReso口工：皂盒吕11皂且1 亡二(5匸工zing resource) throws IOException Reader reader;if (charset = null reader = new 工llfu匸5匸工亡mRe：己且皂工 (g巴匕Rpsdui?匚巴卫sBtTi&szE(工皂已口口工匚亡)； else <read

13、er = new 工口口tStTeaziReadersource) charset);return reader;调用 getResourceAsStream()方法.public static InpuuStream getResour ceAsStream (Class Loader loadeiji String r:皂 source) throw InpuSlureami in cl a ssLoj deirffr aippez" gr匸工 uA：3 5 匸工eaiu (工厚 口口工匚匕# loader);if (zn null) throw new IOException(

14、'Could not find resaurc皂 M + resource); return xn;)这里使用了 classLoaderWrapper这个静态对象，而这个对象包含了两个ClassLoader对象.分别为 systemClassLoader 和 defaultClassLoader对象.pnbllc class ClassLoaderWrapper ClassLoader defa'jltClasLo&der;ClaasLcader systeiaClasaLaader;ClasBLoaderWrapper()try ays匸吕日Lciadu= = Cla

15、ssLoader getSysteClafr(); eAteh (SecurityException ignored) / AccessContrclExcepion on Google App Engine继续跟进调用.这里使用了 getClassLoaders()这个方法来获得系统中存在的合理的类加载对象ClassLoader,注意这里的ClassLoader不止一个.public Input St re am getRes 口 uru 邑 Jk；3St工民却耳匸工九：!© rescuraer ClassLaa 且己工 classLca 且已 return getResQurce

16、AsStream(resaurcef g皂tClassLoaders(elassLcader);查看 getClassLoader()方法，返回一个ClassLoader数组对象.ClasaLoader；) genClassLaad&ra(ClaasLcader classLaader) return new ClassLoailer classLcader efaul-cClasaLoddz,Thread,Thread () . getConcexClassLcader ( rgerClass().gecClassLcader(), syflEercClassLaader>返回

17、上级进入调用getResourceAsStream()InpocStxeam gecReiourceAsSi&ream(Scrlg resource, ClaBslo&der(J alassLoader) for (CLassL口aid亡工 cl : classLoaderJ fif (null !* el) 查看到对资源(mtbatis.xml) 的.的加载，是通过对 ClassLoader数组的迭代查询来获得/ try ta find rhe resource as passedInputStream returnvalue = cl>getRsourceASrear

18、n(reso口ru亡)：ifnawj someloader« wanx his leadingso we * 11 add it and cry again(null = retuxnValue) ret 口亡 = 匚丄.get Res 口 uz匸巳工亡!azif 艸/*1 + resource);ifk(null != z皂turnValue) return returnValue;returnim 11;并且注意到，可以使用的路径表达式为1. org/sata n/mybatis.xml2. /org/sata n/mybatis.xml工厂类)代码:都可以.分析 SqlSess

19、ionFactoryBuilder(原理分析:通过 reader 获得 mybatis.xml配置文件，然后通过创建XMLCo nfigBuilder象来包含mybatis.xml中的内容，最后调用XMLConfigBuilder中parse() 方法，来获得一个 Configuration对象，来完成 SqlSessionFactory对象.类是包含了一组build() 方法，用来创建基本结构:SqlSessi onF actoryBuilderSqlSessionFactory对象的类.SqlSessi onFactoryEuiIder SllSessionFactcryBuilder 0

20、0 build (InputS trem) build dnputStr tan, 0 build (InputS tre Mb, build driputStrtan, 0 build (Re aderD build (Ke "er 0 build (Re ider, build (Rad:SqlSessi orJctoryString) SqlS&ssi orJ aeloryString, Properties) SqlS&ssi onFic Fr op «r ties) SiLessi »nf actcry :SqlSessionFictor

21、yStriy) 列止汕訂mF t hryString, FropertieEloriF&c tciryProperti ts) SqlSnssi .rJF d .：.fy Lniild (Ccnfi gurati on) : SqlSessi onFactc-i y各个方法的最终目的就是产生一个Configuration对象,然后使用build(C on figurati on)方法，来创建 SqlSessionFactory 对象.代码跟踪和分析下面的代码是进入了产生 ConfigurationXMLConfigBuilder 对象创建，和其对象方法parse() 调用对象，并且最后

22、调用build(Configuration)的过程.puullc SqlSessienFactQiy teuila(Reader readerr Spring enviranraeriLr Properties properties) try (XMLCnnfIgBuilder parser new XMLConfIgBuilder(reader, envircnnentr properties); return build (parses.parse()n catch (EMceptlon e) throw Excepticbuilding SqlSessiGn. n t e) j fina

23、lly (ErrorConcexc亠巴乞七占应卞巴)resec(;try <reader.close):* catch (IQExcept i n e) (H Intenclonally ignore Prefer previous errorreader 是指向mybatis.xml 对象的IO流.environment是显示指示使用那个environment配置环境，如果不指定，则使用default="some" 的环境.properties指定了替代属性的Key-Value ,$username进入 XMLConfigBuilder 过程.XMLCqnfigBi

24、iild皂工 parser = new XtQConf igBuilder (reader, envircmaent.f properties);首先创建一个XPathParser解析对象，这个对象是对 MybatisC on figurati on .xml对象的解析器，解析出一段Document格式的报文.还使用XMLMapperEntityResolver()对象来验证 mybatis.xml 使用的DTD约束对象是否正确.public XMLCDnfig3u.ild.er Reader readerf String enviresnment-r Prcpertiea praps) (t

25、hi a 1 new KPathEarser (leader, tms, props, new XMLMsapperEntityReaDiver ) r enTircnnse口匸尸 propa;对象.在this()自构造方法中，看到new 出一个 Configurationprivate XMLConfigBni.lciE：r IXTathPaLEBer parser, String envirarjnentf Frcperties props) | super(new Configuration() *:Em上orCanext;丄寰£D&iiue () resauree (

26、''SQL Eappe上 ConfigurationM) jtills configuracion».setVariablea (口工亡ps);tuift.paried falejthi 3- s e-nvizo iraent = environjuent:thiStparser = parsers而在Configuration构造方法中,是对typeAliasRegistry对象预先填充一些必要的别名,女口 JDBC,POOLED,UNPOOLED 等而其中VENDOR别名对象设置过程中启动了log,日志系统.public Cnfigua&ian t-ype

27、AliaRsgiscry?registerAlias (HJDBC',f# JcLbcTransationFactory-class.getName (): type Al iasRe gi s Er y 工电 gis：匚色:rliBLis ("KJJTASED" f ManagedT r ansact ± 口 gF县匕七口：:茁 口丄艮勻弓亠 §<5匸应呂上1段(); cypeSiliasRegiscry 工egisC-erAlias (pijNDItrf JndiDataScu.rceFact £y匚丄“国芳g色匸EJ皿亡(

28、r type Al lasRegi s " r y 工亡gi 日匚亡工？LL丄巴色("FOOLED PooledDataSourceFaccor y class 口亡 tNme：(); typeAllasRegistry,regiscerAlias(HUNFOO1EDWP UnpooledDaca5ourceFactory.class.getNane():type Al iasRegi 3 try Hegiis 匸丄工上LliaLm (氏 FiERFETHi工用, Perpet ualCache * class B getName *); cypeAliasRei3&quo

29、t;ry 工egiscerAlias ("FIFO", FlfaCache匚1盘宮审亡tNaL就(): cypeAiiasRegisry 上己qi.戟匕亡上岛丄丄己s ("LRUTr, LruCacfie.csl比乞合.gexWEme () J ;type Al issEle g i si; ry B xe gi s terAl i a s (H SOFT11ScltCche1«, clsiss«ijetNae ();CypeAliaBReg±st.ry 工egisterAlias (円百丘盘號卯# WeakCache .cfIk序孚

30、.gEtH且me ();cypeAliasRegis ry 工亡gi曹c亡工Rlin已：("NDOR"f VendorDatfibaseldProvlder .class(H值得注意的是 typeAliasRegistry在构造的时候自己也注册了一些别名org.apache.ibatis.mapp in g.Ve ndorDatabaseldProvider在ClassLoader 加载它的时候，执行如下代码为日志辅助类private staticfinal Log log = LogFactory.getLog (BaseExecutor.class );在LogFact

31、ory 中，看到static 代码，就是这段代码完成了对日志系统的初始化static tryTnLpleicentatian (new Runnable ()(public void run( LiseSlf 4jLogji.nj (;H;trylmpiemsntatioH(new Runnable() public void tliel ()wsKainianwSggf 蜩();；on (new Runnable ()public void run( ujsLoj4 JLogginj);八；trylnLplementirji sji (new Runnable (public void ru

32、n( 口 se JdkLogTng-();H;trylmpiementation(new Runnable() public void run()s i LqTWjrT cer * n/r / *回到原来的build() 方法,我们查看parser.parse()方法的执行查看到这个方法是对 mybatis.xml 中configuration标签的解析public Configuration parae () )if (parsea)(th row tiew BulldftEExeeptlDn rrEAe：h MApp-erConfiPArser can cnly be uafrd crne

33、-e 畤)： Jparsed true;parse Configurate 口 n (丘呂工 re：工亡 ¥赳1甘口£1 亡 C1 / eonf i gur a t id n，r) j return eanfigurat-ionj进入parseConfiguration()方法后，可以看到一些熟悉的字样，接下来就是对configuration标签的子元素进行解析，填充完一个Configuration象中的属性，返回这个Configuration对象给上级build().private void parseConfigura 匸丄口口(XNcidje root J try &

34、#163;propextiesElement (rootevalNod-e (tl-propex!txe5w) ) ;. is- til"? rs&d propercies firsttypeAliasesElemeiLt (root B evaINode ( "tpeSLlzases B);plsugiilE 1 ement (root eraLlNczcie ("pluginsrr)!);obj ectFaetoryE(root亡("objeccFactary):Obe吕(比口口匸它甘彳丄凶口日旨(用口：吕匚匸*芝冃泾口亡：扌3匸匸0工

35、65;1'1); settingsEleioent (root. eva3N 口 且£ (° settings1,1);芒口 viz a nme nt sE lenuei-t (roc 七 evalN 口:iis (trenvizonn.eiits11;diatafcaaeldPr口暫SditE丄匸 «：£匸亡廿nlNDd亡("datataselciPi：口誓久厲匕工11);te-EiandlerEleent (root 旨vbINid过它(ceHandl&is"):mapperE1 BJ&enc (root

36、evaXNQds (mappers11); catch (Exception e throw new aailderExcepticn("Err口:r parsing SQL Mapper CcnCiguratlcn Cause: <r + e);对properties标签解析：可以看到最后是在con figurati on中设置解析完成的properties.private void propertiesElenient (XNode caD&ex.) throws 'Exception if (contejtu nisLl Prcpexties defaul

37、ts = coBxext - gei&ChildrenllsPTopexties (;Serina resource 二 eontext,aetszrinQAetrlbute("resouree"):String url ® context . gets tri agAt tribute ("urlji jif (resource != nul丄 £.& url != 口丄 1).resQuxcfthrow new BuilderEx-cepion(The properties element cannot specify ba

38、th a URL and if (zeaDurce ? 口all) (defaults.putAll(Resonzces getSesourceAsPxcpertzes(resaurce);>-If (UZ1! != 7)1311 derfiulcs Pput All(Resources.gsturle i (urlH;IPrcpert ies vaszs = conf igu rat ion * get Vari abl e s (J ;if (vas != nail) idefaalca rputAll (vaxsj-;Ipasser u setVarxables(defaults)

39、;confionr(defaul);对typeAliases标签解析：privats voidtypeAliaseaElemer.iXl-Tode parent) if (parec != ncll> for (Xllade child : paren 匸.get Children () ) if ("packagen亡qUAla(ChildBgeCSame O)txasPackage = child>geS匸£|丄口0丸匸匸1|)且5匸它(耐孔期卄|；c nf igux at ion .gistTypTdiBiBRegjLtzzytJi 工 egisCerAl

40、iases (tn： eAlias Eac rage); else String alias = childg皀七号七匕工匸护七1：1：工扫11七已（叩ml工ms用）；String 七沖亡 - child try Class<?> clazz RescurcesIE taliks = ball typeAliasRegisicry工egisterAlias (clazz);卜 else (typeAliasRegistry .zeffisterAlias (aliaSj clazz|i: catch (Cla53tTci：FouEciEx.cepclon eJ fCause:thr

41、ow new EuxlderException (nError regi3terzng t1 as for 用 + alias +如果没有使用alias 元素，则直接把type类路径指向的类名作为alias 注册到Configuration对象中去.Cla35<?> clasz = Resources ,(te);if (alias = im 11) reAliasRegiBtry. regis匸芒工良丄且(clazz) * else typeAliasRegistry.registerAlias(alias f clazz);对objectFactory 标签解析：的 Objec

42、tFactory 属性中.把 factory对象注册至U configurationprivate void objecrFactoryElsment(XNade context) throws Exception < if (context != null SVriug type = can'text;. gev5CxiizvAttribute ( "T.ype ");Properties preperties = context. getCtiiLcireKAsPiepertiss );ObjecuEacrory faccary = (ObjecEFact

43、ory resolveClass-newlnstance (>factory setPrcpertiea(properties);confiijuxation,setObject-Factory (factoiy);对environments标签解析：可以看到参数evironment设置了启动哪个环境配置.如果没有制定，则使用default 指向的环境在配置evironment 过程中，总共配置了1. transactionManager（事务管理）2. dataSource（ 数据源） 两个内容.最后把配置完成的环境交给configuration对象.pr-ivate void env

44、liraELraentsEleme乃匸(:KMo吐比 esnLexT J tliFcwa ExeepEiDB if (context !* nzilll if (enviroTunent nnll> esivizon!匸 w cancEMt ijietS 匸工丄iigAtt工itoircit ( ttdefau 1 匸*);far (XlTode 亡hlJLd t eonEeKt .getChildreni () )String id 匸匚u (“丄日呼)：if (1 sSpecifiedEnvirarunent; (id) TxasaOTionEactury cxFaG&ory

45、 = t z anaccxa nManagexElerDe "匸 qatiild 巳v刊JL却口(1芒(Htxai!aactiQnHanagex") J; DacaSaurseEac匸口Ey dsFaccory - dacaSourceE 1 eoeIalilld»evaIKode (TldacaSource");DtCLSource tiatsSou rce - dsFa cto r y, ge t Data Soy r ce 0 -Environment. Builder environmentBuilder - new Environment rB

46、uilder (id)»txanaacLianFactDry cxfacr-oiy).daiaSaurce (da匸在巨口口工巴旦);eo nf Iguratien* setEnvlreironene (envi ronMHT.Biillder. t mid );tran sact ionMan ager(事务管理）:首先获得transactionManager的type 类型，接着用通过resolveClass(type)对象，获得合适的 TransactionFactory对象private TransaatianFactoxy traEsacuionHanagerEleme口匸

47、 KXNcidte context) throws Escepion if (context !- mail) String typ亡 = context; .亡匸宫匸工丄匚弓査匸丄士工匕口匕亡匸匕丫卞巴1'1,Proper 匸导 props = context匸Trans a at ion Fact dry f actDry (T rans a t i nF act r y) re salve Cl a asnewlnstance (J ;factory 3etFraperE(ie3 (props);return factary;)throw new Builder Ex cep 匸

48、 jldh (*'E；nvjL：cc:mne：:n:c decliar a cjldii requires a Trans ac tia nFa c 匸口 ry.11*);方法解析,从 configuration别名容器中把type设置为别名，调用resolveAlias（） 获取对应的Class<T>来实例化.protected Class<?> r皀solveClass(String alias) if (alias = im 11) return rm丄 1_：try <return reaolv&Alias(alias); catch (E

49、xception e) throw new BuilderException(r,Error resolving class . Cause: " + ef e);最后却是使用configuration中对typeAlias标签配置默认值进行解析alias,来获得一个合适的TransactionFactory对象的Class 对象.protected Cl«ss<?> resolveAlias(String Alias ret口cn cypeAliasRegiscryhusoI甘亡耳li社勻(alia勻)；dataSource( 数据源):数据源配置和事务配置类

50、似，通过别名来获得configuration容器中一个Class填充相应的属性就可以使用了private DaaSourceFaetfliy dataSaureeElement(XlJode eantexE) throws EKception if (contexE J - null> Spring= context哲亡匸SEringAiLEribute;ProperLues props = cont.exL.geLChjLlcLrenJLsPropertie3 (J ;De匸aSouro巳F<au匕口工y factory = (Da匸包巳E"rc匕口工y) resfll

51、veClasa (te) newlD3tance (); factory导皂xP上口左皂上匸丄亡si (preps;return factory;throw new Bui Ider Except ion ("'Environment; declaration requires a DataSourceFacTory.pr);对typeHandlers标签分析：也利用了 configuration中容器，把type作为别名解析.private void tiT-eHandlerElement(XNcde parent) throws Exception if (paxen匸!

52、= null) (for (XNode child : parent ,getChildren.() ) i f (irFac k已 ger, -B e (jiials (chil d g亡匸己皿巳 0 ) 5ltmg tfpeHaEdlerPackage = childg巳匸5tringAu匸ribute ( BnaaeH);zypeHandlerRegi5 tr y regLsuerz ypeHandler Package);)else String j avaTypeNaifte = cHildB get3-cxingAtribue ("javalype");Stri

53、ng jdfcaTpeName = child, gets匸工耳匸tritiiit：巳("jdfcuType：*);String handlerTyp皂Ne：nie = child 旺皂匸5匸1：兀11旺直£匸二:113口匸皂(口dl皂芷"1)；Clas3<?> javaTeClasa = resolveClass (javaTinpeNane);JdbcTiTe jdbcTe = resolveJdbcTirpe (jdbcTippeMazie);Cla33<?> Ei'peHa口d_l亡上亡 1且弓弓=TesclveClasj

54、(handle：rTeName;if (javaTypeClass !- null if (jdbcljT-e = null)(typeHandlerRegistry> register (javalypeClaaSi tipeHand 1 ezClas3); else 匸yF皂HandlerRegLstry. r皂gi_st：皂it (javaTiT皂二JL且导SdbcTiT皂 匸亡Handl皂工匚丄己53=); else eHandler Reg la 匚上 y 工匸建上(e ype Handl e r Class):其他标签的实现也是类是的方式现在回到build(Configura

55、tion),使用config创建了一个默认的SqISessionFactory对象.pilblic SqlSesBionFac'tory build f亡cmfigura匸丄on config) return new DefaulcSqlSessionFacory(config):可以发现整个 DefaultSqlSessio nFactory对象就包含了一个Con figuration对象public static void main -args) throws Exception String xesouzce： w niybatis auril1'1：Reader rea

56、dez = Hesn口工口巳却§芒匸貫艺序0112_口&卫占1?!5臼已三27 工巳!sou工口皀);SqlSessionFactory sqlMappex = new SqlSessionFacxciryBuilder () .build(reader):5qlSes51on -lessier User user n-ew Oa 口sez setId(1); usersetUsername(mgllrt 叩p er- Deful 皓评电si “rJ actory (i 4255)4 e coEtf pu- *ti &n= Confiiir b.ti on (i )到

57、此完成了对 SqISessionFactory 对象的创建資滩寻址转换XM报文为Dmu代n侧謀基本过程如下：1. 使用Resources中静态方法查询获得 reader 对象2. 通过XMLConfigBuilder 构造方法对reader 进行读取，具体的读取工作给XPathParser对象完成返回一份 Document对象，然后配置类的属性，完成构造过程.3. 通过XMLConfigBuilder对象的parse()方法对读取到的文档 (Document)进行解析对mybatis.xml中标签内容进行解析，设置到一个 Configuration对象中而这个过程中，多次利用到typeAlias标签对象的Configuration属性操作通过标签属性type转化为alias来查询容器中相应的Class对象.4. 最后new 出一个 DefaultSqlSessionFactory对象，而这个Factory属性中只是包含了 Configuration对象.的构造所以 XMLCo nfigBuild