java – 对hibernate应用程序使用@Transactional注释导致错误
作者:互联网
我想在今天早上将春天与冬眠融为一体.我想使用spring transaction manager.但得到以下错误.该错误与@Trasactional Annotation有关.如果我删除注释,我能够从弹簧容器中获取bean.
Exception in thread "main" java.lang.ClassCastException: com.sun.proxy.$Proxy19 cannot be cast to com.hibernate.dao.EvntDAOImpl
at com.hibernate.action.HibernateAction.main(HibernateAction.java:17)
我粘贴在我的源代码下面.
的pom.xml
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>hibernate-tutorials</groupId>
<artifactId>hibernate-tutorials</artifactId>
<version>0.0.1-SNAPSHOT</version>
<build>
<sourceDirectory>src</sourceDirectory>
<plugins>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.1</version>
<configuration>
<source>1.6</source>
<target>1.6</target>
</configuration>
</plugin>
</plugins>
</build>
<properties>
<spring-framework.version>4.0.3.RELEASE</spring-framework.version>
<hibernate.version>4.3.5.Final</hibernate.version>
<slf4j.version>1.7.5</slf4j.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>${spring-framework.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-tx</artifactId>
<version>${spring-framework.version}</version>
</dependency>
<!-- Spring ORM support -->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-orm</artifactId>
<version>${spring-framework.version}</version>
</dependency>
<!-- Logging with SLF4J & LogBack -->
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>${slf4j.version}</version>
<scope>compile</scope>
</dependency>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-entitymanager</artifactId>
<version>${hibernate.version}</version>
</dependency>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-core</artifactId>
<version>${hibernate.version}</version>
</dependency>
<dependency>
<groupId>com.oracle</groupId>
<artifactId>ojdbc14</artifactId>
<version>10.2.0.2.0</version>
</dependency>
<dependency>
<groupId>commons-dbcp</groupId>
<artifactId>commons-dbcp</artifactId>
<version>1.4</version>
</dependency>
</dependencies>
休眠配置
<?xml version="1.0" encoding="UTF-8"?>
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.0.xsd
http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.xsd“>
<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource">
<property name="driverClassName" value="oracle.jdbc.driver.OracleDriver" />
<property name="url" value="${url}" />
<property name="username" value="${username}" />
<property name="password" value="${password}" />
</bean>
<bean id="sessionFactory"
class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">
<property name="dataSource" ref="dataSource" />
<property name="annotatedClasses">
<list>
<value>com.hibernate.model.Evnt</value>
</list>
</property>
<property name="hibernateProperties">
<props>
<prop key="hibernate.dialect">org.hibernate.dialect.Oracle10gDialect</prop>
<prop key="hibernate.show_sql">true</prop>
</props>
</property>
</bean>
<bean id="transactionManager"
class="org.springframework.orm.hibernatey.HibernateTransactionManager">
<property name="sessionFactory" ref="sessionFactory" />
</bean>
EvntDAOImpl.java
package com.hibernate.dao;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Repository;
import org.springframework.transaction.annotation.Transactional;
import com.hibernate.model.Evnt;
@Repository(value="evntDAO")
@Transactional
public class EvntDAOImpl implements EvntDAO {
@Autowired
private SessionFactory sessionFactory;
@Override
public void storeEvnt(Evnt evnt) {
sessionFactory.getCurrentSession().save(evnt);
}
}
HibernateAction.java
package com.hibernate.action;
import java.util.Date;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import com.hibernate.dao.EvntDAO;
import com.hibernate.dao.EvntDAOImpl;
import com.hibernate.model.Evnt;
public class HibernateAction {
public static void main(String[] args) {
ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
EvntDAOImpl evntDAO = (EvntDAOImpl) context.getBean("evntDAO");
Evnt evnt = new Evnt();
evnt.setTitle("first Event");
evnt.setDate(new Date());
evntDAO.storeEvnt(evnt);
}
}
提前致谢…
解决方法:
问题出在你注入EventDaoImpl的地方.
只需更换
@Autowired EventDaoImpl eventDaoImpl
同
@Autowired EventDao eventDao
无论你需要Spring,都要自动装配dao.
或者,如果要从applicationContext获取bean,请使用:
EvntDAO evntDAO =(EvntDAO)context.getBean(“evntDAO”);
问题是由于在dao的实现代码上使用@Transactional注释意味着Spring将为它创建一个JDK dynamic proxy,而不能将其强制转换为实现类. Here是Spring的AOP功能的完整文档(其中完整地解释了JDK动态代理和CGLib类代理的创建).
本质上意味着因为@Transactional,当你调用context.getBean(“evntDAO”)时,你没有得到你的EventDaoImpl(正如人们所期望的那样),但实际上你得到了一个类为java.lang的对象. .ref创建的.reflect.Proxy.该代理对象实现了EventDao(因此可以强制转换为它),但它的签名与EventDaoImpl无关(因此它不会扩展EventDaoImpl,因此也是ClassCastException).当在代理上调用方法时,在调用实际委托给EventDaoImpl之前和/或之后发生了各种事情(事件调用之前/之后或之后发生的事情是由Spring控制的,尽管是InvocationHandler的实现).
标签:spring-transactions,java,spring,hibernate 来源: https://codeday.me/bug/20190830/1768274.html