Hibernate(十一)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 loginselect '张三','123456',21 from dual unionselect 'Tom','123123',34 from dual unionselect 'Jack','12345678',34 from dual unionselect '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());        }    }    }