Hibernate的批量更新与删除（&&JDBC）

Love The Way You Lie 2022-09-22 03:38 308阅读 0赞

更新&&删除

语法格式：（HQL）

update  |     delete from? <ClassName> \[where where\_conditions\]

1>在from子句中，from关键字是可选的，即完全可以不写from关键字

2>在from子句中，只能有一个类名，可以在该类名后指定别名

3>不能在批量HQL语句中使用连接，显示或者隐式的都不行，但可以在where子句中使用子查询

4>整个where子句是可选的，where子句的语法sql语句中where子句的语法完全相同

5>Query.executeUpdate()方法返回一个整型值，该值是受此操作影响的记录数量，由于hibernate的底层操作实际上是由JDBC完成的，因此，如果有批量update或delete操作被转换成多条update或delete语句，(关联或者继承映射)，该方法只能返回最后一条sql语句影响的记录行数，不是所有的记录行数，需要注意；

一，批量更新(两种方式)

1，使用Hibernate直接进行批量更新

(1)方式1：(Hibernate的HQL直接支持update/delete的批量更新语法)

package com.anlw.util;
 
 import org.hibernate.Query;
 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;
 
 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();
 			//在HQL查询中使用update进行批量更新，下面的的语句是HQL语句，不是sql语句
 			Query query = sess.createQuery("update Student set name = 'www'");
 			query.executeUpdate();
 			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)方式2：(强烈不推荐)

package com.anlw.util;
 
 import java.sql.Connection;
 import java.sql.SQLException;
 import java.sql.Statement;
 
 import org.hibernate.CacheMode;
 import org.hibernate.Query;
 import org.hibernate.ScrollMode;
 import org.hibernate.ScrollableResults;
 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;
 
 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();
 			//查询表中的所有数据
 			ScrollableResults student = sess.createQuery("from Student")
 					.setCacheMode(CacheMode.IGNORE)
 					.scroll(ScrollMode.FORWARD_ONLY);
 			int count = 0;
 			while(student.next()){
 				Student s = (Student)student.get(0);
 				s.setName("haha");
 				if(++count%3 == 0){
 					sess.flush();
 					sess.clear();
 				}
 			}
 			tx.commit();
 		} catch (Exception e) {
 			if (tx != null) {
 				tx.rollback();
 			}
 		} finally {
 			sess.close();
 			sf.close();
 		}
 	}
 
 	public static void main(String[] args) {
 		new SessionUtil().HIbernateTest();
 	}
 }

通过这种方式，虽然可以执行批量更新，但效果非常不好，执行效率不高，需要先执行数据查询，然后再执行数据更新，而且这种更新将是逐行更新，即每更新一行记录，都要执行一条update语句，性能非常低；

2，绕过Hibernate，调用JDBC API

(1)方式1：

package com.anlw.util;
 
 import java.sql.Connection;
 import java.sql.PreparedStatement;
 import java.sql.SQLException;
 import java.sql.Statement;
 
 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
 					String sql = "update student set name = 'oracle'";
 					//创建一个Satement对象
 					Statement st = arg0.createStatement();
 					//调用JDBC的update进行批量更新
 					st.executeUpdate(sql);
 				}
 			});
 			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)方式2：

package com.anlw.util;
 
 import java.sql.Connection;
 import java.sql.PreparedStatement;
 import java.sql.SQLException;
 import java.sql.Statement;
 
 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
 					String sql = "update student set name = ? where name=?";
 					PreparedStatement ps = arg0.prepareStatement(sql);
 					for(int i=0;i<10;i++){
 						ps.setString(1,"tom");
 						ps.setString(2, "oracle");
 						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();
 	}
 }

二，批量删除(两种方式)

1，使用Hibernate直接进行批量删除

(1)方式1：(Hibernate的HQL直接支持update/delete的批量更新语法)

package com.anlw.util;
 
 import org.hibernate.Query;
 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;
 
 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();
 			//在HQL查询中使用delete进行批量删除，下面的的语句是HQL语句，不是sql
 			Query query = sess.createQuery("delete Student");//也可以是delete from，from关键字是可选的，可以不要，加条件的时候可以指定类的别名
 			query.executeUpdate();
 			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)方式2：(强烈不推荐)

package com.anlw.util;
 
 import java.sql.Connection;
 import java.sql.SQLException;
 import java.sql.Statement;
 
 import org.hibernate.CacheMode;
 import org.hibernate.Query;
 import org.hibernate.ScrollMode;
 import org.hibernate.ScrollableResults;
 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;
 
 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();
 			//查询表中的所有数据
 			ScrollableResults student = sess.createQuery("from Student")
 					.setCacheMode(CacheMode.IGNORE)
 					.scroll(ScrollMode.FORWARD_ONLY);
 			int count = 0;
 			while(student.next()){
 				Student s = (Student)student.get(0);
 				sess.delete(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();
 	}
 }

通过这种方式，虽然可以执行批量删除，但效果非常不好，执行效率不高，需要先执行数据查询，然后再执行数据删除，而且这种删除将是逐行删除，即每删除一行记录，都要执行一条delete语句，性能非常低；

2，绕过Hibernate，调用JDBC API

(1)方式1：

package com.anlw.util;
 
 import java.sql.Connection;
 import java.sql.SQLException;
 import java.sql.Statement;
 
 import org.hibernate.Query;
 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;
 
 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();
 			sess.doWork(new Work() {
 				
 				@Override
 				public void execute(Connection arg0) throws SQLException {
 					String sql = "delete from student where age > 5"; //mysql中删除语句不能省略from
 					Statement st = arg0.createStatement();
 					st.executeUpdate(sql);
 				}
 			});
 			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)方式2：

package com.anlw.util;
 
 import java.sql.Connection;
 import java.sql.PreparedStatement;
 import java.sql.SQLException;
 import java.sql.Statement;
 
 import org.hibernate.Query;
 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;
 
 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();
 			sess.doWork(new Work() {
 				
 				@Override
 				public void execute(Connection arg0) throws SQLException {
 					String sql = "delete from student where age = ?"; //mysql中删除语句不能省略from
 					PreparedStatement ps = arg0.prepareStatement(sql);
 					for(int i=0;i<10;i++){
 						if(i%2 == 0){
 							ps.setInt(1, i);
 							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();
 	}
 }