Hibernate--根据实体类获得表名、主键名、字段名（与Spring集成）

标签：hibernate   spring   

本文参考自http://blog.csdn.net/fhwbj/article/details/3267787

在使用Hibernate时，我们有时可能需要根据实体类获得数据库表的信息，上面的那个链接的内容已经给出了模版，不过使用Hibernate4时，如果获得的PersistentClass一直为null，可以试着采用下面的方式初始化Configuration

if (configuration == null) {
	configuration = new Configuration().configure();
	configuration.buildSessionFactory();
}

HiberanteConfigurationUtil类 (映射工具类)

这里需要注意的是：

1.在取sessionFactory时要加上&号，原因可以看一下http://blog.csdn.net/zhangjk1993/article/details/40017583

2.这里采用的xml文件做的映射，要保证实体类名和对应的映射文件名一致

package util;

import java.util.Iterator;

import org.hibernate.cfg.Configuration;
import org.hibernate.mapping.Column;
import org.hibernate.mapping.PersistentClass;
import org.hibernate.mapping.Property;
import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.orm.hibernate4.LocalSessionFactoryBean;

/**
 * 根据实体类得到对应的表名、主键名、字段名（与Spring集成）
 * 这里使用xml文件配置的映射，需要保证实体类名与对应映射文件名一致，即User.java与User.hbm.xml 
 * </p>
 * 这里使用继承ApplicationContextAware的方式来获得ApplicationContext,
 * 因此需要在Spring配置文件中配置一下该类，才能自动注入ApplicationContext对象
 * 
 * <bean class="util.HibernateConfigurationUtil"/>
 */
public class HibernateConfigurationUtil implements ApplicationContextAware {

	private static ApplicationContext applicationContext;

	private static Configuration configuration;

	public static Configuration getConfiguration() {

		if (configuration == null) { 
			// 取sessionFactory的时候要加上&
			LocalSessionFactoryBean factory = (LocalSessionFactoryBean) applicationContext
					.getBean("&sessionFactory");
			configuration = factory.getConfiguration();
		}

		return configuration;
	}

	private static <T> PersistentClass getPersistentClass(Class<T> clazz) {
		synchronized (HibernateConfigurationUtil.class) {
			PersistentClass pc = getConfiguration().getClassMapping(
					clazz.getSimpleName());
			if (pc == null) {
				configuration = configuration.addClass(clazz);
				pc = configuration.getClassMapping(clazz.getName());
			}
			return pc;
		}
	}

	/**
	 * 获得实体类对应的表名
	 * 
	 * @param clazz
	 *            实体类的Class对象
	 * @return 表名
	 */
	public static <T> String getTableName(Class<T> clazz) {
		return getPersistentClass(clazz).getTable().getName();
	}

	/**
	 * 获得实体类对应表的主键字段名称
	 * 
	 * @param clazz
	 *            实体类的Class对象
	 * @return 主键字段名称
	 */
	public static <T> String getPKColumnName(Class<T> clazz) {
		return getPersistentClass(clazz).getTable().getPrimaryKey()
				.getColumn(0).getName();
	}

	/**
	 * 获得类属性对应的字段名
	 * 
	 * @param clazz
	 *            实体类的Class对象
	 * @param propertyName
	 *            实体类的属性名
	 * @return 属性对应的字段名
	 */
	public static <T> String getColumnName(Class<T> clazz, String propertyName) {
		String columnName = "";
		PersistentClass persistentClass = getPersistentClass(clazz);
		Property property = persistentClass.getProperty(propertyName);
		Iterator<?> iterator = property.getColumnIterator();
		if (iterator.hasNext()) {
			Column column = (Column) iterator.next();
			columnName += column.getName();
		}
		return columnName;
	}

	@Override
	public void setApplicationContext(ApplicationContext context)
			throws BeansException {
		applicationContext = context;
	}
}

<span style="white-space:pre">	</span><bean id="sessionFactory"
		class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">
		<property name="dataSource" ref="dataSource" />
		<property name="hibernateProperties">
			<props>
				<prop key="hibernate.hbm2ddl.auto">update</prop>
				<prop key="hibernate.show_sql">true</prop>
				<prop key="hibernate.format_sql">true</prop>
			</props>
		</property>
		<property name="mappingResources">
			<list>
				<value>bean/User.hbm.xml</value>
			</list>
		</property>
	</bean>
	<bean class="util.HibernateConfigurationUtil" />

package bean;

public class User {

	private int id;

	private String username;

	private String password;

	public int getId() {
		return id;
	}

	public void setId(int id) {
		this.id = id;
	}

	public String getUsername() {
		return username;
	}

	public void setUsername(String username) {
		this.username = username;
	}

	public String getPassword() {
		return password;
	}

	public void setPassword(String password) {
		this.password = password;
	}

}

<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
	<class name="bean.User" table="_user">
		<id name="id" type="int">
			<column name="id" />
			<generator class="increment" />
		</id>
		<property name="username" type="string">
			<column name="_username" />
		</property>
		<property name="password" type="string">
			<column name="_password" />
		</property>
	</class>
</hibernate-mapping>

new ClassPathXmlApplicationContext("applicationContext.xml");
System.out.println(HibernateConfigurationUtil.getTableName(User.class));
System.out.println(HibernateConfigurationUtil.getPKColumnName(User.class));
System.out.println(HibernateConfigurationUtil.getColumnName(User.class,"username"));

Hibernate--根据实体类获得表名、主键名、字段名（与Spring集成）

标签：hibernate   spring   

原文地址：http://blog.csdn.net/zhangjk1993/article/details/40020813