Hibernate(十二)Criteria查询

一、简述

Criteria是一种比hql更面向对象的查询方式。Criteria 可使用 Criterion 和 Projection 设置查询条件。可以设置 FetchMode(联合查询抓取的模式 ) ，设置排序方式，Criteria 还可以设置 FlushModel （冲刷 Session 的方式）和 LockMode （数据库锁模式）。

Criteria本身只是查询的容器。Criteria查询又称对象查询

Criteria查询采用面向对象的方式封装查询条件。由Hibernater自动生成SQL查询语句

二、不带查询条件

建立数据表

create table login
(
       username   varchar2(32) primary key,
       password   varchar2(32) not null ,
       age         number(3)
);
insert into login
select '张三','123456',21 from dual union
select 'Tom','123123',34 from dual union
select 'Jack','12345678',34 from dual union
select '李四','qwerty',23 from dual;            
commit;

建立持久化类和配置文件

Hibernate.cfg.xml配置文件

<?xml version='1.0' encoding='UTF-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
          "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
          "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
 
    <session-factory>
        <property name="dialect">
            org.hibernate.dialect.Oracle9Dialect
        </property>
        <property name="connection.url">
            jdbc:oracle:thin:@localhost:1521:orcl
        </property>
        <property name="connection.username">root</property>
        <property name="connection.password">root</property>
        <property name="connection.driver_class">
            oracle.jdbc.OracleDriver
        </property>
        <property name="show_sql">true</property>
        <property name="format_sql">true</property>
        
        <mapping resource="entity/Login.hbm.xml" />
 
    </session-factory>
 
</hibernate-configuration>

持久化类和配置文件

package entity;
public class Login implements java.io.Serializable {
    // Fields
 
    /**
     * 
     */
    private static final long serialVersionUID = 1L;
    private String username;
    private String password;
    private int age;
    // Constructors
 
    /** default constructor */
    public Login() {
    }
    /** minimal constructor */
    public Login(String username, String password) {
        this.username = username;
        this.password = password;
    }
    /** full constructor */
    public Login(String username, String password, int age) {
        this.username = username;
        this.password = password;
        this.age = age;
    }
    // Property accessors
 
    public String getUsername() {
        return this.username;
    }
    public void setUsername(String username) {
        this.username = username;
    }
    public String getPassword() {
        return this.password;
    }
    public void setPassword(String password) {
        this.password = password;
    }
    public int getAge() {
        return this.age;
    }
    public void setAge(int age) {
        this.age = age;
    }
}

配置文件Login.hbm.xml

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
 
<hibernate-mapping>
    <class name="entity.Login" table="LOGIN" schema="ROOT">
        <id name="username" type="java.lang.String">
            <column name="USERNAME" length="32" />
            <generator class="assigned" />
        </id>
        <property name="password" type="java.lang.String">
            <column name="PASSWORD" length="32" not-null="true" />
        </property>
        <property name="age" type="java.lang.Integer">
            <column name="AGE" precision="3" scale="0" />
        </property>
    </class>
</hibernate-mapping>

测试类:

package demo;
import java.util.List;
import org.hibernate.Criteria;
import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
import entity.Login;
public class Demo1 {
    /**
     * Criteria无查询条件查询所有
     */
    public static void main(String[] args) {
        //声明一个集合用来接收结果
        List<Login> result=null;
        //声明SessionFactory
        SessionFactory factory=null;
        //声明Session
        Session session=null;
        //初始化以上对象
        try{
        factory=new Configuration().configure().buildSessionFactory();
        session=factory.openSession();
        //声明Criteria对象传入一个持久化类对象类型
        Criteria criteria=session.createCriteria(Login.class);
        //查询使用list方法
        result=criteria.list();
        }catch(HibernateException e){
            e.printStackTrace();
        }finally{
            session.close();
            factory.close();
        }
        //输出结果
        for (Login login : result) {
            System.out.println("用户名:"+login.getUsername()+"   密码："+login.getPassword()+"   年龄:"+login.getAge());
        }
        
        
    }
    
}

结果:

Hibernate: 
    select
        this_.USERNAME as USERNAME0_0_,
        this_.PASSWORD as PASSWORD0_0_,
        this_.AGE as AGE0_0_ 
    from
        ROOT.LOGIN this_
用户名:Jack   密码：12345678   年龄:34
用户名:Tom   密码：123123   年龄:34
用户名:李四   密码：qwerty   年龄:23
用户名:张三   密码：123456   年龄:21

三、添加查询条件

3.1、加入一个username的条件

    //声明Criteria对象传入一个持久化类对象类型
        Criteria criteria=session.createCriteria(Login.class);
        //添加查询条件 Restrictions.eq是等于的意思，2个参数，第一个为持久化类的属性，第2个为比较的参数值
        
        criteria.add(Restrictions.eq("username", "Tom"));
        //查询使用list方法
        result=criteria.list();

执行的SQL

    select
        this_.USERNAME as USERNAME0_0_,
        this_.PASSWORD as PASSWORD0_0_,
        this_.AGE as AGE0_0_ 
    from
        ROOT.LOGIN this_ 
    where
        this_.USERNAME=?

3.2、多个查询条件AND--between

//年龄在大于等于25
        criteria.add(Restrictions.le("age", 25));
        //年龄小于等于23
        criteria.add(Restrictions.ge("age", 23));

或者

//年年龄大于23小于25之间的记录
        criteria.add(Restrictions.between("age", 23, 25));

执行的SQL

 select
        this_.USERNAME as USERNAME0_0_,
        this_.PASSWORD as PASSWORD0_0_,
        this_.AGE as AGE0_0_ 
    from
        ROOT.LOGIN this_ 
    where
        this_.AGE<=? 
        and this_.AGE>=?

select
        this_.USERNAME as USERNAME0_0_,
        this_.PASSWORD as PASSWORD0_0_,
        this_.AGE as AGE0_0_ 
    from
        ROOT.LOGIN this_ 
    where
        this_.AGE between ? and ?

3.3、多个查询条件或者条件 or

criteria.add(Restrictions.or(Restrictions.eq("age", 23), Restrictions.like("username", "%李%")));
        //或者以下写法直接使用SQL语句
        criteria.add(Restrictions.sqlRestriction("age=20 or username like '%李%'"));

执行SQL

 select
        this_.USERNAME as USERNAME0_0_,
        this_.PASSWORD as PASSWORD0_0_,
        this_.AGE as AGE0_0_ 
    from
        ROOT.LOGIN this_ 
    where
        (
            this_.AGE=? 
            or this_.USERNAME like ?
        )

直接使用SQL的执行语句

 select
        this_.USERNAME as USERNAME0_0_,
        this_.PASSWORD as PASSWORD0_0_,
        this_.AGE as AGE0_0_ 
    from
        ROOT.LOGIN this_ 
    where
        age=20 
        or username like '%李%'

四、Restrictions常用方法

五、常用方法使用

package demo;
import java.util.List;
import org.hibernate.Criteria;
import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
import org.hibernate.criterion.Restrictions;
import entity.Login;
public class Demo1 {
    /**
     * Criteria无查询条件查询所有
     */
    public static void main(String[] args) {
        //声明一个集合用来接收结果
        List<Login> result=null;
        //声明SessionFactory
        SessionFactory factory=null;
        //声明Session
        Session session=null;
        //初始化以上对象
        try{
        factory=new Configuration().configure().buildSessionFactory();
        session=factory.openSession();
        //声明Criteria对象传入一个持久化类对象类型
        Criteria criteria=session.createCriteria(Login.class);
        //1.查询用户名为Tom的记录
        //criteria.add(Restrictions.eq("username", "Tom"));
        //2.查询年龄大于等于21同时小于等于25的记录
        //criteria.add(Restrictions.ge("age", 21));
        //criteria.add(Restrictions.le("age", 25));
        //between写法
        //criteria.add(Restrictions.between("age", 21, 25));
        //3.或者查询年龄=21或者名字中有李的记录
        //criteria.add(Restrictions.or(Restrictions.eq("age", 21), Restrictions.like("username", "%李%")));
        //sql写法
        //criteria.add(Restrictions.sqlRestriction("age=21 or username like '%李%'"));
        //4.年龄在21,23,25的记录
        //criteria.add(Restrictions.in("age", new Integer []{21,23,25}));
        //5.and用法
        criteria.add(Restrictions.and(Restrictions.ge("age", 23), Restrictions.like("username", "%T%")));
        
        //查询使用list方法
        result=criteria.list();
        }catch(HibernateException e){
            e.printStackTrace();
        }finally{
            session.close();
            factory.close();
        }
        System.out.println("==========");
        //输出结果
        for (Login login : result) {
            System.out.println("用户名:"+login.getUsername()+"   密码："+login.getPassword()+"   年龄:"+login.getAge());
        }
        
        
    }
    
}

六、对结果进行排序

使用Order关键字，进行排序

criteria.addOrder(Order.desc(属性名称));降序

criteria.addOrder(Order.asc（属性名称）);升序

//按年龄降序排序
criteria.addOrder(Order.desc("age"));
//按姓名升序排序
criteria.addOrder(Order.asc("username"));
//查询使用list方法
result=criteria.list();
//输出结果
        for (Login login : result) {
            System.out.println("用户名:"+login.getUsername()+"   密码："+login.getPassword()+"   年龄:"+login.getAge());
        }

七、示例查询

package demo;
import java.util.List;
import org.hibernate.Criteria;
import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
import org.hibernate.criterion.Example;
import org.hibernate.criterion.Order;
import org.hibernate.criterion.Restrictions;
import entity.Login;
public class Demo2 {
    /**
     * Criteria无查询条件查询所有
     */
    public static void main(String[] args) {
        //声明一个集合用来接收结果
        List<Login> result=null;
        //声明SessionFactory
        SessionFactory factory=null;
        //声明Session
        Session session=null;
        //声明一个Login对象，并赋值可以是多个 但不能是主键
        Login user=new Login();
        user.setAge(21);
        
        //初始化以上对象
        try{
        factory=new Configuration().configure().buildSessionFactory();
        session=factory.openSession();
        //声明Criteria对象传入一个持久化类对象类型
        Criteria criteria=session.createCriteria(Login.class);
        //加入查询条件
        criteria.add(Example.create(user));
        
        //查询使用list方法
        result=criteria.list();
        }catch(HibernateException e){
            e.printStackTrace();
        }finally{
            session.close();
            factory.close();
        }
        System.out.println("==========");
        //输出结果
        for (Login login : result) {
            System.out.println("用户名:"+login.getUsername()+"   密码："+login.getPassword()+"   年龄:"+login.getAge());
        }
        
        
    }
    
}

八、聚合函数

package demo;
import java.util.Iterator;
import java.util.List;
import org.hibernate.Criteria;
import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
import org.hibernate.criterion.ProjectionList;
import org.hibernate.criterion.Projections;
import entity.Login;
public class Demo3 {
    /**
     * Criteria无查询条件查询所有
     */
    public static void main(String[] args) {
        //声明一个集合用来接收结果
        List<Login> result=null;
        //声明SessionFactory
        SessionFactory factory=null;
        //声明Session
        Session session=null;
        
        //初始化以上对象
        try{
        factory=new Configuration().configure().buildSessionFactory();
        session=factory.openSession();
        //声明Criteria对象传入一个持久化类对象类型
        Criteria criteria=session.createCriteria(Login.class);
        //加入查询条件
        //总记录数
        //criteria.setProjection(Projections.rowCount());
        //平均年龄
        //criteria.setProjection(Projections.avg("age"));
        //分组
        criteria.setProjection(Projections.groupProperty("username"));
        //查询使用list方法
        result=criteria.list();
        //System.out.println("平均年龄："+result.iterator().next());
        //System.out.println("总记录数："+result.iterator().next());
        Iterator iterator=result.iterator();
        while(iterator.hasNext()){
            System.out.println(iterator.next());
        }
        }catch(HibernateException e){
            e.printStackTrace();
        }finally{
            session.close();
            factory.close();
        }
        
    }
    
}

分页

package demo;
import java.util.List;
import org.hibernate.Criteria;
import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
import org.hibernate.criterion.Order;
import org.hibernate.criterion.Restrictions;
import entity.Login;
public class Demo4 {
    /**
     * Criteria无查询条件查询所有
     */
    public static void main(String[] args) {
        //声明一个集合用来接收结果
        List<Login> result=null;
        //声明SessionFactory
        SessionFactory factory=null;
        //声明Session
        Session session=null;
        //当前页数第几页
        int pageIndex=1;
        //最大显示记录数
        int pageSize=2;
        //初始化以上对象
        try{
        factory=new Configuration().configure().buildSessionFactory();
        session=factory.openSession();
        //声明Criteria对象传入一个持久化类对象类型
        Criteria criteria=session.createCriteria(Login.class);
        //起始记录数
        criteria.setFirstResult((pageIndex-1)*pageSize);
        //每页显示最大记录数
        criteria.setMaxResults(pageSize);
        
        
        //查询使用list方法
        result=criteria.list();
        }catch(HibernateException e){
            e.printStackTrace();
        }finally{
            session.close();
            factory.close();
        }
        System.out.println("==========");
        //输出结果
        for (Login login : result) {
            System.out.println("用户名:"+login.getUsername()+"   密码："+login.getPassword()+"   年龄:"+login.getAge());
        }
    }
    
}