2018.11.13 Hibernate 中数据库查询中的Criteria查询实例

Criteria是面向对象的无语句查询

Demo.java

package com.legend.b_criteria;

import java.util.List;

import org.hibernate.Criteria;

import org.hibernate.Session;

import org.hibernate.Transaction;

import org.hibernate.criterion.Order;

import org.hibernate.criterion.Projections;

import org.hibernate.criterion.Restrictions;

import org.junit.jupiter.api.Test;

import com.legend.domain.Customer;

import com.legend.utils.HibernateUtils;

/**

 * 学习Criteria语法

 * @author qichunlin

 *

 */

public class Demo {

	//基本语法

	@Test

	public void fun1() {

		Session session = HibernateUtils.openSession();

		Transaction tx = session.beginTransaction();

		//--------------

		Criteria criteria = session.createCriteria(Customer.class);

		List<Customer> list = criteria.list();

		System.out.println(list);

		//--------------

		tx.commit();

		session.close();

	}

	//条件查询

	@Test

	public void fun2(){

		//

		Session session = HibernateUtils.openSession();

		Transaction tx = session.beginTransaction();

		//--------------

		//创建Criteria 对象

		Criteria criteria = session.createCriteria(Customer.class);

		//添加Criteria的查询参数

		criteria.add(Restrictions.eq("cust_id", 1l));

		//获取查询的结果

		Customer c = (Customer) criteria.uniqueResult();

		System.out.println(c);

		//--------------

		//事务的提交

		tx.commit();

		session.close();

	}

	//分页查询

	//(当前页数-1)*每页条数

	@Test

	public void fun3() {

		//

		Session session = HibernateUtils.openSession();

		Transaction tx = session.beginTransaction();

		//--------------

		//编写HQL语句

		Criteria criteria = session.createCriteria(Customer.class);

		criteria.setFirstResult(1);

		criteria.setMaxResults(2);

		List<Customer> list = criteria.list();

		System.out.println(list);

		//--------------

		tx.commit();

		session.close();

	}

	//排序检索

	@Test

	public void fun5() {

		//

		Session session = HibernateUtils.openSession();

		Transaction tx = session.beginTransaction();

		//--------------

		Criteria criteria = session.createCriteria(Customer.class);

		criteria.addOrder(Order.desc("cust_id"));

		List<Customer> list = criteria.list();

		System.out.println(list);

		//--------------

		tx.commit();

		session.close();

	}

	//统计查询

	@Test

	public void fun6() {

		//

		Session session = HibernateUtils.openSession();

		Transaction tx = session.beginTransaction();

		//--------------

		//编写HQL语句

		Criteria criteria = session.createCriteria(Customer.class);

		//设置查询目标

		criteria.setProjection(Projections.rowCount());

		//List list = query.list();

		List<Long> list = criteria.list();

		System.out.println(list);

		//--------------

		tx.commit();

		session.close();

	}

}

基本查询

统计查询

附上hibernate的额核心配置文件xml

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE hibernate-configuration PUBLIC

	"-//Hibernate/Hibernate Configuration DTD 3.0//EN"

	"http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">

<!-- 配置参数文件 -->

<hibernate-configuration>

	<session-factory>

		<!--

			#hibernate.dialect org.hibernate.dialect.MySQLDialect

			#hibernate.dialect org.hibernate.dialect.MySQLInnoDBDialect

			#hibernate.dialect org.hibernate.dialect.MySQLMyISAMDialect

			#hibernate.connection.driver_class com.mysql.jdbc.Driver

			#hibernate.connection.url jdbc:mysql:///test

			#hibernate.connection.username gavin

			#hibernate.connection.password

			配置mysql相关参数

		 -->

		<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>

		<property name="hibernate.connection.url">jdbc:mysql:///crm</property>

		<property name="hibernate.connection.username">root</property>

		<property name="hibernate.connection.password">123456</property>

		<!-- 配置mysql方言 -->

		<property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>

		<!--

			sql语句显示

			#hibernate.show_sql true

			# format SQL in log and console

			#hibernate.format_sql true

		 -->

		<property name="hibernate.format_sql">true</property>

		<property name="hibernate.show_sql">true</property>

		<!--

			## auto schema export

			#hibernate.hbm2ddl.auto create-drop

			#hibernate.hbm2ddl.auto create

			#hibernate.hbm2ddl.auto update

			#hibernate.hbm2ddl.auto validate

		 -->

		<property name="hibernate.hbm2ddl.auto">update</property>

		<!--

			设置数据库隔离级别

			## specify a JDBC isolation level

			#hibernate.connection.isolation 4

		 -->

		 <property name="hibernate.connection.isolation">4</property>

		<!-- 指定session与当前线程绑定 -->

		<property name="hibernate.current_session_context_class">thread</property>

		<!-- 配置映射文件加载 orm元数据 -->

		<mapping resource="com/legend/domain/Customer.hbm.xml"/>

		<mapping resource="com/legend/domain/LinkMan.hbm.xml" />

		<mapping resource="com/legend/domain/User.hbm.xml" />

		<mapping resource="com/legend/domain/Role.hbm.xml" />

	</session-factory>

</hibernate-configuration>

巴特西

2018.11.13 Hibernate 中数据库查询中的Criteria查询实例

Criteria是面向对象的无语句查询

Demo.java

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