用Spring调用Hibernate时面临的问题

Question

package org.java.dao;

import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.java.spring.dataModel.Circle;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import org.springframework.stereotype.Repository;
@Repository
public class HibernateDao {
    @Autowired
    private SessionFactory sessionFactory;


    public SessionFactory getSessionFactory() {
        return sessionFactory;
    }


    public void setSessionFactory(SessionFactory sessionFactory) {
        this.sessionFactory = sessionFactory;
    }


    public int getCircleCount(){

        String hql="Select count(*) from circle";
        Query query=getSessionFactory().openSession().createQuery(hql);
     return ((Long)query.uniqueResult()).intValue();

    }

}

package org.java.Main;

import org.java.dao.HibernateDao;
import org.java.spring.dataModel.Circle;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class HibernateDemo {

    /**
     * @param args
     */
    public static void main(String[] args) {
        ApplicationContext ctx= new ClassPathXmlApplicationContext("spring.xml");
        HibernateDao dao=ctx.getBean("hibernateDao",HibernateDao.class);
        System.out.println("Circle is:"+dao.getCircleCount());


    }

}

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context-3.0.xsd">

    <context:annotation-config />
    <context:component-scan base-package="org.java.dao" />

    <bean id="dataSource"
        class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        <property name="driverClassName" value="org.postgresql.Driver"></property>
        <property name="url" value="jdbc:postgresql://localhost:5432/hibernatedb"></property>
        <property name="username" value="postgres"></property>
        <property name="password" value="****"></property>
        <!--
            <property name="initialSize" value="2"></property> <property
            name="maxActive" value="5"></property>
        -->
    </bean>

    <bean id="sessionFactory"
        class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">
        <property name="dataSource" ref="dataSource" />
        <property name="packagesToScan" value="org.java.dao" />
        <property name="hibernateProperties">
            <props>
                <prop key="dialect">org.hibernate.dialect.PostgreSQLDialect</prop>
            </props>
        </property>

    </bean>

    <bean id="transactionManager"
        class="org.springframework.orm.hibernate4.HibernateTransactionManager">
        <property name="sessionFactory" ref="sessionFactory" />
    </bean>


    </beans>

Answer 1

您编写的是HQL查询，而不是SQL查询。语法类似，但在HQL查询中使用映射类型。在本例中，由于映射的类型显然是circle，请尝试以下操作：

从循环c中选择计数(c)

正如异常所示，circle不是映射类型，这是有意义的。