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>  

传统的Criteria

离线的Criteria