????? 今天原打算研究一下Hibernate 1+N问题，却发现了一个Really Amazing的效率问题，问题如下，希望大牛可以解释一下：

1、简单描述一下测试中表结构（我用Mysql数据库），表结构如下图

?表名为Corporation，三个字段id、name、type，对应Mysql中表结构截图：

?

2、如下代码，简单调运JDBC测试插入10000条数据花费时间

public class DB {
	public static Connection getConn() {
		Connection conn = null;
		try {
			Class.forName("com.mysql.jdbc.Driver");
			conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/hibernate?user=root&password=root");	
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		} catch (SQLException e) {
			e.printStackTrace();
		}
		return conn;
	}
	public static Statement getStmt(Connection conn) {
		Statement stmt = null;
		try {
			if(conn != null) {
				stmt = conn.createStatement();
			}
		} catch (SQLException e) {
			e.printStackTrace();
		}
		return stmt;
	}
	public static void main(String[] args) throws SQLException {
		Statement stmt = getStmt(getConn());
		Date start = new Date();
		for(int i = 0 ; i < 10000 ; i ++) {
			String sql = "insert into corporation(name,type) value('Tibco','IT')";
			stmt.executeUpdate(sql);
		}
		System.out.println("Total spent " + (new Date().getTime() - start.getTime()));
	}
}

?

运行时间如下

Total spent 249531

?这个时间我觉得是比较合理的执行一条SQL花费25毫秒左右，之前有关效率方面的测试和这个结果差不多

?

3. 下面给出Hibernate中测试时间的代码，先给出Hibernate配置代码

3.1 Corporation对应的Annotation配置类

@Entity
public class Corporation {
	private int id;
	private String name;
	private String type;
	@Id
	@GeneratedValue
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getType() {
		return type;
	}
	public void setType(String type) {
		this.type = type;
	}
}

?3.2 hibernate.cfg.xml配置信息

<hibernate-configuration>
    <session-factory>
        <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="connection.url">jdbc:mysql://localhost/hibernate</property>
        <property name="connection.username">root</property>
        <property name="connection.password">root</property>
		<property name="connection.pool_size">1</property>
		<property name="current_session_context_class">thread</property>
        <property name="dialect">org.hibernate.dialect.MySQLDialect</property>
        <property name="cache.provider_class">org.hibernate.cache.NoCacheProvider</property>
        <property name="show_sql">true</property>
        <property name="format_sql">true</property>
        <property name="hbm2ddl.auto">update</property>
        <mapping class="com.kylin.test.Corporation"/>
    </session-factory>
</hibernate-configuration>

?3.3给出测试代码

package com.kylin.test;

import java.util.Date;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.AnnotationConfiguration;
import org.hibernate.tool.hbm2ddl.SchemaExport;
import org.junit.AfterClass;
import org.junit.BeforeClass;
import org.junit.Test;

public class AllTest {
	private static SessionFactory sessionFactory;
	@BeforeClass
	public static void beforeClass(){
		sessionFactory = new AnnotationConfiguration().configure().buildSessionFactory();
	} 
	@AfterClass
	public static void afterClass() {
		sessionFactory.close();
	}
	@Test
	public void testExportTable() {
		new SchemaExport(new AnnotationConfiguration().configure()).create(true, true);
	}
	@Test
	public void saveCorporation() {