JPA逆向生成数据库表

package com.ztesoft.zsmart.saas.test;
import java.util.HashMap;
import java.util.Map;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
/**
 * 用于由Hibernate，OR映射文件，生成表
 * @author Administrator
 *
 */
public class CreateDB {
 /**
  * 根据Hibernate配置文件、映射文件。在相应数据库中生成表。
  */
 public void createTable() {
  try {
   System.out.println("初始化数据开始......");
   Map<String,String> map = new HashMap<String,String>();
   map.put("hibernate.dialect", "org.hibernate.dialect.MySQL5Dialect");
   map.put("hibernate.connection.driver_class", "com.mysql.jdbc.Driver");
   map.put("hibernate.connection.url", "jdbc:mysql://localhost:3306/autocreate?useUnicode=true&characterEncoding=utf-8&&zeroDateTimeBehavior=convertToNull");
   map.put("hibernate.connection.username", "admin");
   map.put("hibernate.connection.password", "admin");
   map.put("hibernate.show_sql", "true");
   map.put("hibernate.hbm2ddl.auto", "create");
   EntityManagerFactory emf = Persistence.createEntityManagerFactory("SAAS_PU",map);
//	 /System.out.println(emf.getProperties());
   
   emf.close();
   System.out.println("初始化数据完成");
  } catch (Exception e) {
   e.printStackTrace();
  }
 }
 public static void main(String[] args) {
  CreateDB db = new CreateDB();
  db.createTable();
 }
}