一、批量插入(两种方式)
1,通过Hibernate缓存
如果这样写代码进行批量插入(初始设想):
- package com.anlw.util;
- import org.hibernate.Session;
- import org.hibernate.SessionFactory;
- import org.hibernate.Transaction;
- import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
- import org.hibernate.cfg.Configuration;
- import org.hibernate.service.ServiceRegistry;
- import com.anlw.entity.Student;
- public class SessionUtil {
- Configuration conf = null;
- ServiceRegistry st = null;
- SessionFactory sf = null;
- Session sess = null;
- Transaction tx = null;
- public void HIbernateTest() {
- conf = new Configuration().configure();
- st = new StandardServiceRegistryBuilder().applySettings(conf.getProperties()).build();
- sf = conf.buildSessionFactory(st);
- try {
- sess = sf.openSession();
- tx = sess.beginTransaction();
- for (int i = 0; i < 10; i++) {
- Student s = new Student();
- s.setAge(i + 1);
- s.setName("test");
- sess.save(s);
- }
- tx.commit();
- } catch (Exception e) {
- if (tx != null) {
- tx.rollback();
- }
- } finally {
- sess.close();
- sf.close();
- }
- }
- public static void main(String[] args) {
- new SessionUtil().HIbernateTest();
- }
- }
小知识:
(1).Hibernate一级缓存,对其容量没有限制,强制使用,由于所有的对象都被保存到这个缓存中,内存总会达到一定数目时出现内存溢出的情况;
(2).Hibernate二级缓存可以进行大小配置;
要解决内存溢出的问题,就应该定时的将Sessiion缓存中的数据刷到数据库,正确的批量插入方式:
(1).设置批量尺寸(博主至今还没有明白下面这个属性和flush()方法的区别)
<property name="hibernate.jdbc.batch_size">2</property>
配置这个参数的原因就是尽量少读数据库,该参数值越大,读数据库的次数越少,速度越快;上面这个配置,是Hibernate是等到程序积累了100个sql之后在批量提交;
(2).关闭二级缓存(这个博主也不是很明白)
<property name="hibernate.cache.use_second_level_cache">false</property>
除了Session级别的一级缓存,Hibernate还有一个SessionFactory级别的二级缓存,如果启用了二级缓存,从机制上来说,Hibernate为了维护二级缓存,在批量插入时,hibernate会将对象纳入二级缓存,性能上就会有很大损失,也可能引发异常,因此最好关闭SessionFactory级别的二级缓存;
(3).在一二设置完成的基础上,清空Session级别的一级缓存;
- package com.anlw.util;
- import org.hibernate.Session;
- import org.hibernate.SessionFactory;
- import org.hibernate.Transaction;
- import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
- import org.hibernate.cfg.Configuration;
- import org.hibernate.service.ServiceRegistry;
- import com.anlw.entity.Student;
- public class SessionUtil {
- Configuration conf = null;
- ServiceRegistry st = null;
- SessionFactory sf = null;
- Session sess = null;
- Transaction tx = null;
- public void HIbernateTest() {
- conf = new Configuration().configure();
- st = new StandardServiceRegistryBuilder().applySettings(conf.getProperties()).build();
- sf = conf.buildSessionFactory(st);
- try {
- sess = sf.openSession();
- tx = sess.beginTransaction();
- for (int i = 0; i < 10; i++) {
- Student s = new Student();
- s.setAge(i + 1);
- s.setName("test");
- sess.save(s);
- if(i%100 == 0){ //以每100个数据作为一个处理单元
- sess.flush(); //保持与数据库数据的同步
- sess.clear(); //清楚Session级别的一级缓存的全部数据,及时释放占用的内存
- }
- }
- tx.commit();
- } catch (Exception e) {
- if (tx != null) {
- tx.rollback();
- }
- } finally {
- sess.close();
- sf.close();
- }
- }
- public static void main(String[] args) {
- new SessionUtil().HIbernateTest();
- }
- }
2,绕过Hibernate,直接调用JDBC API
- package com.anlw.util;
- import java.sql.Connection;
- import java.sql.PreparedStatement;
- import java.sql.SQLException;
- import org.hibernate.Session;
- import org.hibernate.SessionFactory;
- import org.hibernate.Transaction;
- import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
- import org.hibernate.cfg.Configuration;
- import org.hibernate.jdbc.Work;
- import org.hibernate.service.ServiceRegistry;
- public class SessionUtil {
- Configuration conf = null;
- ServiceRegistry st = null;
- SessionFactory sf = null;
- Session sess = null;
- Transaction tx = null;
- public void HIbernateTest() {
- conf = new Configuration().configure();
- st = new StandardServiceRegistryBuilder().applySettings(conf.getProperties()).build();
- sf = conf.buildSessionFactory(st);
- try {
- sess = sf.openSession();
- tx = sess.beginTransaction();
- //执行Work对象指定的操作,即调用Work对象的execute()方法
- //Session会把当前使用的数据库连接传给execute()方法
- sess.doWork(new Work() {
- @Override
- public void execute(Connection arg0) throws SQLException {//需要注意的是,不需要调用close()方法关闭这个连接
- //通过JDBC API执行用于批量插入的sql语句
- String sql = "insert into student(name,age) values(?,?)";
- PreparedStatement ps = arg0.prepareStatement(sql);
- for(int i=0;i<10;i++){
- ps.setString(1, "kobe");
- ps.setInt(2,12);
- ps.addBatch();
- }
- ps.executeBatch();
- }
- });
- tx.commit();
- } catch (Exception e) {
- if (tx != null) {
- tx.rollback();
- }
- } finally {
- sess.close();
- sf.close();
- }
- }
- public static void main(String[] args) {
- new SessionUtil().HIbernateTest();
- }
- }