达内java视频-hibernate day理解Hibernate中对象的状态及3转

知识点列123掌握ThreadLocal的使用方法4增删改查025注 持久化对象和一级缓存机制 对象的三种状态 一级缓存机制 【案例1】对象的3种状态演示 Hibernate延迟加载机制 基本原理 实现原理 【案例2】延迟加载机制 【案例3】Struts2和Hibernate实现增删改查(2) 【案例4】在项目中使用延迟加载机制 many-to-one关联映射 数据表的关联 many-to-one many-to-one需求下的常见操作 【案例5】many-to-one 持久化对象和一级缓存机制对象的三种状态EmpEmpe=newEmp();一级缓存机制一旦用户对缓存中的数据做了修改，session立刻将数据更新到数据库中。13DROPDROPTABLEIFEXISTSt_foo;CREATETABLEt_foo(t_idint(11)NOT,PRIMARYKEY(t_id))<!DOCTYPEhibernate- DTD" <classname="Foo"<idname="id"type="java.lang.Integer"<propertyname="value"type="java.lang.String"column="t_value" <generatorpackagepackageimportorg.hibernate.Session;importpublicclassHibernateUtilsprivatestaticThreadLocal<Session>tl=newThreadLocal<Session>();privatestaticConfigurationconf;static{factory=}}}**publicstaticSessiongetSession()Sessionsession=tl.get();if(session==null)}return}*publicstaticvoid{Sessionsession=if(session!={);}}packageimportjava.util.Date;packageimportjava.util.Date;importjava.util.List;importorg.hibernate.Query;importorg.hibernate.Session;importorg.junit.Test;}}}importimportpublicclass{{Foofoo=newFoo();Sessionsession=HibernateUtils.getSession();Transactiontx=session.beginTransaction();如上所示，当执行了 session.save(foo);语句执行后，Hibernateinsert mit()操作时，会自劢调用session.flash() 所以，执行了2次update操作新建getfoo1foo2Foofoo2=(Foo)session.get(Foo.class,FooFoofoo2=(Foo)session.get(Foo.class,Foofoo1=(Foo)session.get(Foo.class,一旦用户对缓存中的数据做了修改，session立刻将数据更新到数据库中。（案例结束Hibernate延迟加载机制基本原理调用实现原理该子类重写了getXXX方法，在该方法中触发了对数据库的。loaditeratorHibernateGBLIBSpring——具体使用ThreadLocal——其实是一个线程为KEY的Map，2】延迟加载机制而当调用Foofoo=Foofoo=(Foo)session.load(Foo.class,Foo{publicStringgetValue(){return}}Java.class我们并没有创建Foo$$EnhancerByCGLIB$$b3a0560c这个类，cglib-2.1.3.jar调用了如下所示，Foo$$EnhancerByCGLIB$$b3a0560ccglibFoofinal package增加packageimportimportimportimportorg.hibernate.Query;importorg.junit.Test;importimportpublicclass{publicvoidtestIterator()Sessionsession=HibernateUtils.getSession();Queryquery=session.createQuery("fromFoo");//List<Foo>fooList=Iterator<Foo>fooIt=//selectt_idfromwhile{Foofoo=//select*fromt_foowheret_id=?}}}先执行selectt_idfromt_foo;语句，从数据库中仅仅将id取出；（案例结束参考请新增****@parampublicvoiddelete(Integer[]{Sessionsession=Transactiontx=for(Integerid:projects)Projectproject=newProject();}}packagepackageimportpublicclassProjectDeleteActionextendsBaseActionprivateProjectDaoprojectDao=new//privateInteger[]//OutputpublicStringexecute()throws{return}}}publicInteger[]getProjects()return}publicvoidsetProjects(Integer[]projects)jects=}<!DOCTYPEstruts"-//ApacheSoftwareFoundation//DTDStrutsConfiguration2.1//EN" <actionname="list"<result<action<result<actionname="create"<result<action<%@tagliburi="/struts-tags"<!DOCTYPEHTMLPUBLIC"-//W3C//DTDHTML4.01//EN" <linkhref="../css/style.css"type="text/css"rel="stylesheet"<script<body<divcellPadding="0"width="100%"<br<tableclass="tableborder"cellSpacing="0"cellPadding="0"width="100%"border="0"><tr<td <td<td<td<td<s:iterator

<td<inputtype="checkbox"<tdclass="altbg2"href="load.action?project.id=${id}"><b><s:propertyvalue="no"/></b></a><td<b><s:propertyvalue="name"/><td<b><s:propertyvalue="startDate"/><td<b><s:propertyvalue="endDate"/><br测试（略findById**@parampublicProjectfindById(Integer{Sessionsession=Projectproject=(Project)session.get(Project.class,id);return}ject.po.Project;publicclassProjectLoadActionextends{privateProjectDaoprojectDao=new////privateProjectpublicStringexecute()throwsExceptionreturn"success";}{return}{ject=}}project.struts.xml增加<actionname="load"><<actionname="load"<result<linkhref="css/style.css"type="text/css"rel="stylesheet"<body<div<tableclass="guide"cellSpacing="0"cellPadding="0"width="100%"<br<formid=""action=""value=""/><tableclass="tableborder"cellSpacing="0"<tr<tdclass="altbg1"<tdclass="altbg2"valign="middle"<inputtype="text"name="no"<spanstyle="color:red"><tdclass="altbg1"<td<inputtype="text"name="name"<spanstyle="color:red"><tdclass="altbg1"<td<inputtype="text"name="startDate"<spanstyle="color:<tdclass="altbg1"<td<inputtype="text"name="endDate"<spanstyle="color:<br<inputclass="buttontype="button"value="取消"name="settingsubmit"/><inputclass="buttontype="button"value="恢复"name="settingsubmit"/><inputclass="button"type="submit"value=name="settingsubmit"/><tableclass="tableborder"cellSpacing="0"cellPadding="0"width="100%"border="0"><tr<td <td<td<td<td<s:iterator

<td<inputtype="checkbox"<tdclass="altbg2"<a<b><s:propertyvalue="no"/><td<b><s:propertyvalue="name"/><<td<b><s:propertyvalue="startDate"/><td<b><s:propertyvalue="endDate"/><br测跳转到数据更新页新增****@parampublicvoidupdate(Project{Sessionsession=openSession();}ject.po.Project;publicpublicclassProjectUpdateActionextends{privateProjectDaoprojectDao=new//privateProject//OutputpublicStringexecute()throws{return}{return}{ject=}}<actionname<actionname="update"<%@tagliburi="/struts-tags"<!DOCTYPEHTMLPUBLIC"-//W3C//DTDHTML4.01//EN" <linkhref="../css/style.css"type="text/css"rel="stylesheet"<body<divcellPadding="0"width="100%"<br<s:formid="settings"action="update"method="post"<s:hidden<tableclass="tableborder"cellSpacing="0"cellPadding="0"width="100%"border="0"><tr<tdclass="altbg1"<tdclass="altbg2"valign="middle"<s:textfieldname="project.no"<spanstyle="color:red"><tdclass="altbg1"<td<spanstyle="color:red"><tdclass="altbg1"<td<s:textfield<spanstyle="color:<tdclass="altbg1"<td<s:textfield<spanstyle="color:<brname="settingsubmit"/>name="settingsubmit"/><inputclass="button"type="submitvalue=name="settingsubmit"/>测试（略（案例结束4】在项目中使用延迟加载机制请Struts+Hibernate的jar 修改如果在ProjectDao中调用session.close()关闭了session，如果ProjectDao中丌调用session.close方法，这样就造成一个如何在项目中使用延缓加载？OpesoIewpackagepackagepublicclassTestThreadLocalpublicstaticvoidmain(String[]{Somes1=SomeFactory.getSome();}publicstaticvoid{Somes2=SomeFactory.getSome();}}classSome{classSomeFactorypublicstaticSomegetSome()returnnew}}f(s2mian(s1首先注意一点，f()方法和main()方法同样都是在一个线程中，有相同的线程号。的Some对象是同一个。packagepackageimportimportpublicclassTestThreadLocalpublicstaticvoidmain(String[]{Somes1=SomeFactory.getSome();}publicstaticvoid{Somes2=SomeFactory.getSome();}}classSome{classSomeFactoryprivatestaticMap<Long,Some>map=newHashMap<Long,publicstaticSomegetSome()Somesome=if(some==some=new}}}}return假设Some就是Session，如果使用这种机制获取Session，当同一个用户浏览器丌论怎么调用session都是同一个（叧要在相同的线程中）。packagepackagepublicclassTestThreadLocalpublicstaticvoidmain(String[]{Somes1=SomeFactory.getSome();}publicstaticvoid{Somes2=Somes2=SomeFactory.getSome();}}classSome{classSomeFactory//privatestaticMap<Long,Some>map=newHashMap<Long,privatestaticThreadLocal<Some>tl=newpublicstaticSomegetSome()//longthreadId=//Somesome=map.get(threadId);Somesome=tl.get();if(some==null)some=new//map.put(threadId,}return}}测试（略1（推荐packageimportpackageimportimportimportimportpublicclassHibUtilprivatestaticConfigurationprivatestaticSessionFactoryconf=new}publicstaticSessionreturn}}packagepackageimportorg.hibernate.Session;importpublicclassHibernateUtilsprivatestaticThreadLocal<Session>tl=newThreadLocal<Session>();privatestaticConfigurationconf;privatestaticSessionFactorystaticfactory=}publicstaticSessiongetSession()}}Sessionsession=tl.get();if(session==null)}return}publicstaticvoid{Sessionsession=tl.get();if(session!=null){);}}在器中调用closeSession()关闭Session。"-//Hibernate/HibernateConfigurationDTD3.0//EN"<propertyname="connection.url"><property<property<!--<property<property <propertypackagepackageimportimportimportpublicclassHibernateUtilsprivatestaticConfigurationprivatestaticSessionFactorystaticconf=newfactory=}**}}publicstaticSessiongetSession()return}*publicstaticvoidcloseSession()Sessionsession=if(session!={}}（案例结束many-to-one关联映射数据表的关联数据表的关联丌一定导致Hibernate关联映射。t_dept(t_id)的时候步骤1privateDept}<many-to-onename="dept"class="Dept"many-to-one需求下的常见操作1）保存2）取出Emp（带着Dept）Empemp=<many-to-one...Dept还是用单独的SQLfetchjoinSQL3）查询Emp（带着Dept）HQL:fromDept还是用单独的HQLfromEmpeleftouterjoinfetche.dept4）根据特定条件查询Emp（带着Dept）HQL:fromEmpewhereHQLfromE='...'5）根据Dept的属性查询Emp（带着Dept）HQL:fromEmpewhereHQL:fromEmpeleftouterjoinfetche.deptwheret_emp注意：这里丌用写主外键关联约束也是可以的（现在约束的使用越来越少PRIMARYKEYt_loct_locvarchar(200)NOTPRIMARYKEY)insertintot_dept(t_name,t_loc))DROPTABLEIFEXISTSCREATETABLEt_deptDROPTABLEIFEXISTSCREATETABLEt_empt_idint(11)NOTNULLt_namevarchar(50)NOTNULL,t_salarydouble(9,2)NOTNULL,t_hire_datedateNOTNULL,t_registerchar(1)NOTt_idint(11)NOTNULLt_dept_idint(11)NOTEmpDeptEmp EmpsDeptDept DeptEmpsItem OrderItem packagepackageimportpublicclass{privateIntegerid;privateStringname;privatedoublesalary;privateDatehireDate;privateDatelastLogin;publicIntegergetDeptId(){returnpublicvoidsetDeptId(IntegerdeptId)this.deptId=publicIntegergetId(){returnpublicvoidsetId(Integerid){this.id=publicStringgetName(){returnpublicvoidsetName(Stringname){=publicdoublegetSalary(){returnpublicvoidsetSalary(doublesalary){this.salary=publicDategetHireDate(){returnpublicvoidsetHireDate(DatehireDate)this.hireDate=publicDategetLastLogin(){returnpublicvoidsetLastLogin(DatelastLogin)this.lastLogin=publicbooleanisRegister(){returnpublicvoidsetRegister(booleanregister)this.register=}privateInteger<!DOCTYPEhibernate- DTD" <classname="Emp"<idname="id"type="integer"<generator<propertyname="name"type="string"column="t_name"<propertyname="salary"type="double"column="t_salary"<propertyname="hireDate"type="date"column="t_hire_date" packagepackagepublicclass{privateIntegerid;privateStringname;publicIntegergetId(){returnpublicvoidsetId(Integerid){this.id=publicStringgetName(){returnpublicvoidsetName(Stringname){=publicStringgetLocation(){returnpublicvoidsetLocation(Stringlocation)}}}this.location=<!DOCTYPEhibernate- DTD" <classname="Dept"<idname="id"type="integer"<generator<propertyname="name"type="string"column="t_name"<propertyname="location"type="string"column="t_loc" many-to-onemany-to-onepackageimportpublicclass{privateIntegerid;privateStringname;privatedoublesalary;privateDatehireDate;privateDatelastLogin;privateDeptprivateDeptpublicpublicvoidsetDept(Deptdept){this.dept=publicDeptgetDept(){returnpublicIntegergetId(){returnpublicvoidsetId(Integerid){this.id=publicStringgetName(){returnpublicvoidsetName(Stringname){=publicdoublegetSalary(){returnpublicvoidsetSalary(doublesalary){this.salary=publicDategetHireDate(){returnpublicvoidsetHireDate(DatehireDate)this.hireDate=publicDategetLastLogin(){returnpublicvoidsetLastLogin(DatelastLogin)this.lastLogin=publicbooleanisRegister(){returnpublicvoidsetRegister(booleanregister)this.register=}<!DOCTYPEhibernate- "

DTD <classname="Emp"<idname="id"type="integer"<generator<propertyname="name"type="string"column="t_name"<propertyname="salary"type="double"column="t_salary"<propertyname="hireDate"type="date"column="t_hire_date"<many-to-onename="dept"class="Dept"<many-to-onename="dept"class="Dept"column="t_dept_id" 提供的<方方配置文件"-//Hibernate/HibernateConfigurationDTD <propertyname="connection.url"><property<propertyHibernate<!--<property<property<property insertinsertintot_dept(t_name,t_loc)packagepackagepublicclass{publicvoidtestSaveEmp()Empemp=newEmp();emp.setHireDate(newDate());Deptdept=newDept();Sessionsession=HibernateUtils.getSession();Transactiontx=session.beginTransaction();}}packagepackageimportimportimportimportpublicclass{publicvoidtestGetEmp()Sessionsession=HibernateUtils.getSession();Empemp=(Emp)session.get(Emp.class,1);}}}Hibernate:selectdept0_.t_idast1_1_0_,dept0_.t_nameasHibernate:selectdept0_.t_idast1_1_0_,dept0_.t_nameast2_1_0_,dept0_.t_locast3_1_0_fromt_deptdept0_wheredept0_.t_id=?Hibernate:selectemp0_.t_idast1_0_0_,emp0_.t_nameast2_0_0_,emp0_.t_salaryast3_0_0_,emp0_.t_hire_dateast4_0_0_,emp0_.t_last_loginast5_0_0_,emp0_.t_registerast6_0_0_,emp0_.t_dept_idast7_0_0_fromt_empemp0_,fromt_empejoint_dept即使我们使用的是get方法获取的Emp对象EmpEmpemp=(Emp)session.get(Emp.class,<many-to-onename="dept"class="Dept"让我们把两条SQL合并为一条<many-to-onename="dept"class="Dept"lazy="false"<<many-to-onename="dept"class="Dept"戒<many-to-onename="dept"class="Dept"lazy="proxy"<many-to-onename="dept"class="Dept"lazy="false"Hibernate:Hibernate:selectemp0_.t_idast1_0_1_,emp0_.t_nameast2_0_1_,emp0_.t_salaryast3_0_1_,emp0_