Hibernate--根据实体类获得表名、主键名、字段名（与Spring集成）(二)

在上一篇中，我们创建了HibernateConfigurationUtil类，可以通过它来获得实体类对应的表名、列名等相关信息，本篇我们会就借助于HibernateConfigurationUtil类以及Java反射，来实现一个JDBCUitl工具类，实现类似于Hibernate中Session.save(Object object)的功能

JDBCUtil类

package util;

import java.lang.reflect.Field;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.Timestamp;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;

public class JDBCUtil {

	/**
	 * 利用反射+JDBC实现类似于Session.save(Object object)的操作，适用于主键为单一自增主键
	 * 这里只是提供一种实现思路，可以根据需要进行扩展以及实现类似的update、delete、get操作
	 *
	 * @param connection 数据库连接
	 * @param entity 要保存的实体类
	 * @throws Exception
	 */
	public static <T> void save(Connection connection, T entity)
			throws Exception {
		Class<? extends Object> clazz = entity.getClass();
		Field[] fields = clazz.getDeclaredFields();
		StringBuilder builder = new StringBuilder();
		builder.append("insert into ");
		builder.append(HibernateConfigurationUtil.getTableName(clazz));
		builder.append(" (");

		List<Field> useFields = new ArrayList<Field>();
		Field field = null;

		for (int i = 0; i < fields.length; i++) {
			//设置字段可以被访问，如果不设置此选项就无法访问private字段
			field = fields[i];
			field.setAccessible(true);
			// 过滤不需要的属性,
			if ("id".equals(field.getName())) {
				continue;
			}
			useFields.add(field);
			builder.append(HibernateConfigurationUtil.getColumnName(clazz,
					field.getName()));
			if (i < fields.length - 1)
				builder.append(", ");
		}
		builder.append(") values (");
		for (int i = 0; i < useFields.size(); i++) {
			builder.append(" ?");
			if (i < useFields.size() - 1) {
				builder.append(", ");
			} else {
				builder.append(" )");
			}
		}
		PreparedStatement pstmt = connection.prepareStatement(builder
				.toString());
		Class<?> clazz2 = null;
		for (int i = 0; i < useFields.size(); i++) {
			field = useFields.get(i);
			// 根据字段的类型设置对应类型的值
			clazz2 = field.getType();
			if (clazz2 == String.class) {
				pstmt.setString(i + 1, field.get(entity).toString());
				continue;
			}
			if (clazz2 == Integer.class || clazz2 == int.class) {
				pstmt.setInt(i + 1, field.getInt(entity));
				continue;
			}
			if (clazz2 == Double.class || clazz2 == double.class) {
				pstmt.setDouble(i + 1, field.getDouble(entity));
				continue;
			}
			if (clazz2 == Date.class) {
				Date date = (Date) field.get(entity);
				pstmt.setTimestamp(i+1, new Timestamp(date.getTime()));
				continue;
			}
		}
		pstmt.executeUpdate();
	}
}

User类

package bean;

import java.util.Date;

public class User {

	private int id;

	private String username;

	private String password;

	private int intValue;

	private double doubleValue;

	private Date dateValue;

	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;
	}

	public int getIntValue() {
		return intValue;
	}

	public void setIntValue(int intValue) {
		this.intValue = intValue;
	}

	public double getDoubleValue() {
		return doubleValue;
	}

	public void setDoubleValue(double doubleValue) {
		this.doubleValue = doubleValue;
	}

	public Date getDateValue() {
		return dateValue;
	}

	public void setDateValue(Date dateValue) {
		this.dateValue = dateValue;
	}

}

User.hbm.xml

<?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="identity" />
		</id>
		<property name="username" type="string">
			<column name="_username" />
		</property>
		<property name="password" type="string">
			<column name="_password" />
		</property>
		<property name="intValue" type="int">
			<column name="_intValue" />
		</property>
		<property name="doubleValue" type="double">
			<column name="_doubleValue" />
		</property>
		<property name="dateValue" type="timestamp">
			<column name="_dateValue" />
		</property>
	</class>
</hibernate-mapping>

UserDao

package dao;

import bean.User;

public interface UserDao {
	public void addUser(User user);
}

UserDaoImpl

package dao.impl;

import java.sql.Connection;
import java.sql.SQLException;
import java.util.Date;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.jdbc.Work;

import util.JDBCUtil;
import bean.User;
import dao.UserDao;

public class UserDaoImpl implements UserDao {

	private SessionFactory sessionFactory;

	@Override
	public void addUser(final User user) {
		Session session = sessionFactory.getCurrentSession();
		session.doWork(new Work() {
			@Override
			public void execute(Connection connection) throws SQLException {

				try {
					JDBCUtil.save(connection, user);
				} catch (Exception e) {
					e.printStackTrace();
				}
			}
		});
	}

	public SessionFactory getSessionFactory() {
		return sessionFactory;
	}

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

}

applicationContext.xml

注意：在Hibernate4中必须要配置事务，否则上面的sessionFactory.getCurrentSession()将无法取到值

<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>

	<!-- 配置事务 -->
	<bean id="transactionManager"
		class="org.springframework.orm.hibernate4.HibernateTransactionManager">
		<property name="sessionFactory">
			<ref local="sessionFactory" />
		</property>
	</bean>

	<!-- 配置事务的传播特性 -->
	<tx:advice id="txAdvice" transaction-manager="transactionManager">
		<tx:attributes>
			<tx:method name="add*" propagation="REQUIRED" />
			<tx:method name="del*" propagation="REQUIRED" />
			<tx:method name="update*" propagation="REQUIRED" />
			<tx:method name="*" read-only="true" />
		</tx:attributes>
	</tx:advice>

	<!-- 配置参与事务的类和方法 -->
	<aop:config>
		<aop:pointcut expression="execution(* dao.impl.*.*(..))"
			id="allServiceMethod" />
		<aop:advisor advice-ref="txAdvice" pointcut-ref="allServiceMethod" />
	</aop:config>

	<bean id="userDao" class="dao.impl.UserDaoImpl">
		<property name="sessionFactory" ref="sessionFactory"/>
	</bean>
	

下面是测试代码：

package test;

import java.util.Date;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import bean.User;

import dao.UserDao;

public class TestJDBCUtil {
	@SuppressWarnings("resource")
	public static void main(String[] args) {

		ApplicationContext context =  new ClassPathXmlApplicationContext("applicationContext.xml");
		UserDao userDao = (UserDao) context.getBean("userDao");
		User user = new User();
		user.setUsername("name");
		user.setPassword("password");
		user.setIntValue(2);
		user.setDoubleValue(4.0);
		user.setDateValue(new Date());
		userDao.addUser(user);
	}
}

注：所使用的数据库为mysql，Hibernate版本为4.2.12.Final