介绍Hibernate使用UserType - 51CTO.COM

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介绍Hibernate使用UserType

2009-09-25 13:55 佚名 IT168 我要评论(0) 字号: T | T
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这里介绍Hibernate使用UserType,UserType就是用户自定义类型,这里的类型指的是除了Hibernate定义的那些类型之外的用户自己定义的。

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Hibernate有很多值得学习的地方,这里我们主要介绍Hibernate使用UserType,包括介绍UserType就是用户自定义类型等方面。

1、建立数据库的时候最好建立一个跟业务逻辑完全没有关系的id,这样的好处就是以后当数据量大的时候可以容易的建立索引,而且当业务逻辑变化的时候底层的数据结构不用变化很大。

2、代码的干净是非常非常的重要的,从现在开始尽量让自己的代码写的漂亮把!因为干净的代码不仅容易维护,而且容易发现bug,在Hibernate使用UserType是很好用的。举个经典的例子:

实现Hibernate使用UserType接口的email 类

比如 你需要在 TUSER 表中记录一个人的 email ,单独为其建立一张数据库表是很浪费资源的,一般的方法是将TUSER 一栏 varchar 的来记录email ,多个 email 之间用 " ; "号分开,我曾经做的项目中采取的方法是:取出一个记录着多条 email 的 string然后再来用 ; 号拆开,但是这样子就有个不好,在一堆整齐的 get 方法用出来一个有 bad smell 的代码。

有两个方法,一个是修改映射TUSER的 java 类在其中增加一个 getEmail 方法,返回一个 list ,该方法对原先的 getEmail 方法进行二次处理。第二个方法就是采用UserType 。

UserType就是用户自定义类型,这里的类型指的是除了Hibernate定义的那些类型之外的用户自己定义的。

一个实现Hibernate使用UserType接口的 email 类如下(里面的每个方法都是必须实现的接口方法,许多都可以复制粘贴的,不复杂):


  
  1. public class Email implements UserType  
  2. ...{  
  3.  
  4. // 表示本类型实例是否可变,一般是不可变  
  5. public boolean isMutable()  
  6. ...{  
  7. return false;  
  8. }  
  9.  
  10. //该类型对应的 sql 类型  
  11. public int[] sqlTypes()  
  12. ...{  
  13. return new int[]......{Types.VARCHAR};  
  14. }  
  15.  
  16. // 改类型对应的 java 类型  
  17. public Class returnedClass()  
  18. ...{  
  19. return List.class;  
  20. }  
  21.  
  22. // 完全复制的方法,由于是用户自己定义的类型
  23. //所以hibernate并不知道要如何来复制这个类,需要用户自己定义  
  24. public Object deepCopy(Object value)throws HibernateException  
  25. ...{  
  26. List source = (List)value;  
  27. List target = new ArrayList();  
  28. target.addAll(source);  
  29. return target;  
  30. }  
  31.  
  32. //equals方法,这个就不用多说了吧,肯定是要用户自定义的  
  33. public boolean equals(Object x,Object y) throws HibernateException  
  34. ...{  
  35. //这部分不写出来了,自己实现吧,这个不是我要讲的重点  
  36. }  
  37.  
  38. /** *//**//*  
  39. 这才是重头戏!nullSafeGet 和nullSafeSet 是核心所在,对数据的后期处理都在这两个方法里面  
  40. nullSafeGet 是读取的方法  
  41. owner 目前没用到过。  
  42. names 是对应的数据库列名,UserType是可以对应多个列的  
  43. */  
  44. public Object nullSafeGet(ResultSet rs,String[] names,Object owner)  throws HibernateException,SQLException  
  45. ...{  
  46. String value = (String)Hibernate.STRING.nullSafeGet(rs,names[0]);  
  47. if(value != null)  
  48. ...{  
  49. //把 string 拆开成 list 的代码放在这里  
  50. }  
  51. return resultList;//得到了拆开的 邮件列表  
  52. }  
  53.  
  54. /**//*  
  55. 保存的方法  
  56. index 是那个 PreparedStatement 的参数序号,一般来说不用管直接往下传  
  57. value 就是要保存的数据,在这边是一个保存着 email 列表的 List  
  58. */  
  59. public void nullSafeSet(PreparedStatement st,Object value,int index)  throws HibernateException,SQLException  
  60. ...{  
  61. if(value != null)  
  62. ...{  
  63. String email = assemble(value);//将 List 拼合成 String 的 Email 的方法  
  64. Hibernate.STRING.nullSafeSet(st,email,index);  
  65. }  
  66. else  
  67. ...{  
  68. Hibernate.STRING.nullSafeSet(st,value,index);  
  69. }  
  70. }  

在TUser.hbm.xml 中如此设置:


  
  1. <hibernate-mapping> 
  2. <class name="entity.TUser" table="T_USER"> 
  3. </class> 
  4. ..............  
  5. <property name = "emali"column = "email"type = "mytype.Email"/> 
  6. </hibernate-mapping> 

在TUser.java中如此设置


  
  1. public class TUser implement Serializable  
  2. ...{  
  3. private Integer id;  
  4. privarte Stirng name;  
  5. //看,这边的 email 可以大胆的使用 List 了  
  6. private List email;  
  7.  
  8. //下面是一些 getter 和 setter 了  

这样设置后你使用 TUser的时候要取出  email 直接 getEmail 出来的就是一个List 了,而且前台根本不知道后台干了什么,这样代码就简洁多了。

2025-06-06 16:30:36.012 ERROR 6348 --- [ main] o.s.boot.SpringApplication : Application run failed org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'entityManagerFactory' defined in class path resource [org/springframework/boot/autoconfigure/orm/jpa/HibernateJpaConfiguration.class]: Invocation of init method failed; nested exception is javax.persistence.PersistenceException: [PersistenceUnit: default] Unable to build Hibernate SessionFactory; nested exception is org.hibernate.MappingException: Could not determine type for: com.kucun.data.entity.Bancai, at table: jinhuo, for columns: [org.hibernate.mapping.Column(bancai)] at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1799) ~[spring-beans-5.2.15.RELEASE.jar:5.2.15.RELEASE] at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:594) ~[spring-beans-5.2.15.RELEASE.jar:5.2.15.RELEASE] at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:516) ~[spring-beans-5.2.15.RELEASE.jar:5.2.15.RELEASE] at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:324) ~[spring-beans-5.2.15.RELEASE.jar:5.2.15.RELEASE] at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) ~[spring-beans-5.2.15.RELEASE.jar:5.2.15.RELEASE] at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:322) ~[spring-beans-5.2.15.RELEASE.jar:5.2.15.RELEASE] at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202) ~[spring-beans-5.2.15.RELEASE.jar:5.2.15.RELEASE] at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1109) ~[spring-context-5.2.15.RELEASE.jar:5.2.15.RELEASE] at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:869) ~[spring-context-5.2.15.RELEASE.jar:5.2.15.RELEASE] at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:551) ~[spring-context-5.2.15.RELEASE.jar:5.2.15.RELEASE] at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:143) ~[spring-boot-2.3.12.RELEASE.jar:2.3.12.RELEASE] at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:755) ~[spring-boot-2.3.12.RELEASE.jar:2.3.12.RELEASE] at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:747) ~[spring-boot-2.3.12.RELEASE.jar:2.3.12.RELEASE] at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:402) ~[spring-boot-2.3.12.RELEASE.jar:2.3.12.RELEASE] at org.springframework.boot.SpringApplication.run(SpringApplication.java:312) ~[spring-boot-2.3.12.RELEASE.jar:2.3.12.RELEASE] at org.springframework.boot.web.servlet.support.SpringBootServletInitializer.run(SpringBootServletInitializer.java:173) [spring-boot-2.3.12.RELEASE.jar:2.3.12.RELEASE] at org.springframework.boot.web.servlet.support.SpringBootServletInitializer.createRootApplicationContext(SpringBootServletInitializer.java:153) [spring-boot-2.3.12.RELEASE.jar:2.3.12.RELEASE] at org.springframework.boot.web.servlet.support.SpringBootServletInitializer.onStartup(SpringBootServletInitializer.java:95) [spring-boot-2.3.12.RELEASE.jar:2.3.12.RELEASE] at org.springframework.web.SpringServletContainerInitializer.onStartup(SpringServletContainerInitializer.java:172) [spring-web-5.2.15.RELEASE.jar:5.2.15.RELEASE] at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5128) [catalina.jar:9.0.37] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183) [catalina.jar:9.0.37] at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:717) [catalina.jar:9.0.37] at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:690) [catalina.jar:9.0.37] at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:705) [catalina.jar:9.0.37] at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:1133) [catalina.jar:9.0.37] at org.apache.catalina.startup.HostConfig$DeployDirectory.run(HostConfig.java:1866) [catalina.jar:9.0.37] at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [na:1.8.0_331] at java.util.concurrent.FutureTask.run(FutureTask.java:266) [na:1.8.0_331] at org.apache.tomcat.util.threads.InlineExecutorService.execute(InlineExecutorService.java:75) [tomcat-util.jar:9.0.37] at java.util.concurrent.AbstractExecutorService.submit(AbstractExecutorService.java:112) [na:1.8.0_331] at org.apache.catalina.startup.HostConfig.deployDirectories(HostConfig.java:1045) [catalina.jar:9.0.37] at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:429) [catalina.jar:9.0.37] at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1576) [catalina.jar:9.0.37] at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:309) [catalina.jar:9.0.37] at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:123) [catalina.jar:9.0.37] at org.apache.catalina.util.LifecycleBase.setStateInternal(LifecycleBase.java:423) [catalina.jar:9.0.37] at org.apache.catalina.util.LifecycleBase.setState(LifecycleBase.java:366) [catalina.jar:9.0.37] at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:936) [catalina.jar:9.0.37] at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:841) [catalina.jar:9.0.37] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183) [catalina.jar:9.0.37] at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1384) [catalina.jar:9.0.37] at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1374) [catalina.jar:9.0.37] at java.util.concurrent.FutureTask.run(FutureTask.java:266) [na:1.8.0_331] at org.apache.tomcat.util.threads.InlineExecutorService.execute(InlineExecutorService.java:75) [tomcat-util.jar:9.0.37] at java.util.concurrent.AbstractExecutorService.submit(AbstractExecutorService.java:134) [na:1.8.0_331] at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:909) [catalina.jar:9.0.37] at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:262) [catalina.jar:9.0.37] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183) [catalina.jar:9.0.37] at org.apache.catalina.core.StandardService.startInternal(StandardService.java:421) [catalina.jar:9.0.37] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183) [catalina.jar:9.0.37] at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:930) [catalina.jar:9.0.37] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183) [catalina.jar:9.0.37] at org.apache.catalina.startup.Catalina.start(Catalina.java:738) [catalina.jar:9.0.37] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_331] at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_331] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_331] at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_331] at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:342) [bootstrap.jar:9.0.37] at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:473) [bootstrap.jar:9.0.37] Caused by: javax.persistence.PersistenceException: [PersistenceUnit: default] Unable to build Hibernate SessionFactory; nested exception is org.hibernate.MappingException: Could not determine type for: com.kucun.data.entity.Bancai, at table: jinhuo, for columns: [org.hibernate.mapping.Column(bancai)] at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.buildNativeEntityManagerFactory(AbstractEntityManagerFactoryBean.java:403) ~[spring-orm-5.2.15.RELEASE.jar:5.2.15.RELEASE] at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:378) ~[spring-orm-5.2.15.RELEASE.jar:5.2.15.RELEASE] at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.afterPropertiesSet(LocalContainerEntityManagerFactoryBean.java:341) ~[spring-orm-5.2.15.RELEASE.jar:5.2.15.RELEASE] at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1858) ~[spring-beans-5.2.15.RELEASE.jar:5.2.15.RELEASE] at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1795) ~[spring-beans-5.2.15.RELEASE.jar:5.2.15.RELEASE] ... 58 common frames omitted Caused by: org.hibernate.MappingException: Could not determine type for: com.kucun.data.entity.Bancai, at table: jinhuo, for columns: [org.hibernate.mapping.Column(bancai)] at org.hibernate.mapping.SimpleValue.getType(SimpleValue.java:499) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final] at org.hibernate.mapping.SimpleValue.isValid(SimpleValue.java:466) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final] at org.hibernate.mapping.Property.isValid(Property.java:227) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final] at org.hibernate.mapping.PersistentClass.validate(PersistentClass.java:624) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final] at org.hibernate.mapping.RootClass.validate(RootClass.java:267) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final] at org.hibernate.boot.internal.MetadataImpl.validate(MetadataImpl.java:354) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final] at org.hibernate.internal.SessionFactoryImpl.<init>(SessionFactoryImpl.java:298) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final] at org.hibernate.boot.internal.SessionFactoryBuilderImpl.build(SessionFactoryBuilderImpl.java:468) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final] at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:1259) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final] at org.springframework.orm.jpa.vendor.SpringHibernateJpaPersistenceProvider.createContainerEntityManagerFactory(SpringHibernateJpaPersistenceProvider.java:58) ~[spring-orm-5.2.15.RELEASE.jar:5.2.15.RELEASE] at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:365) ~[spring-orm-5.2.15.RELEASE.jar:5.2.15.RELEASE] at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.buildNativeEntityManagerFactory(AbstractEntityManagerFactoryBean.java:391) ~[spring-orm-5.2.15.RELEASE.jar:5.2.15.RELEASE] ... 62 common frames omitted
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