JavaWeb_(Hibernate框架)Hibernate中数据查询语句Criteria基本用法

2022-03-19 22:19:44

Criteria进行数据查询与HQL和SQL的区别是Criteria完全是面向对象的方式在进行数据查询，将不再看到有sql语句的痕迹，使用Criteria 查询数据包括以下步骤:

　　1. 通过session的createCriteria创建一个Criteria 对象

　　2. Criteria.add 增加约束。在本例中增加一个对name的模糊查询(like)

　　3. 调用list()方法返回查询结果的集合

　　本文展示四种基本的Criteria查询用法

1.Criteria基本查询

2.Criteria条件查询

3.Criteria查询总数

4.Criteria查询用户名中带有字符'a'的总人数

package com.Gary.dao;

import java.util.List;

import javax.persistence.criteria.CriteriaBuilder;

import javax.persistence.criteria.CriteriaQuery;

import javax.persistence.criteria.Root;

import org.hibernate.Criteria;

import org.hibernate.Session;

import org.hibernate.Transaction;

import org.hibernate.query.Query;

import com.Gary.domain.User;

import com.Gary.utils.HibernateUtils;

public class CriteriaDao {

    //Criteria基本查询

    public void search() {

        Session session = HibernateUtils.getSession();

        Transaction beginTransaction = session.beginTransaction();

        //模板：开始Criteria操作

        //操作    select * from user

        CriteriaBuilder criteriaBuilder = session.getCriteriaBuilder();

        //createQuery-->查询条件(首先需要知道查询什么类型数据)

        CriteriaQuery<User> createQuery = criteriaBuilder.createQuery(User.class);

        Root<User> from = createQuery.from(User.class);

        createQuery.select(from);

        List<User> resultList = session.createQuery(createQuery).getResultList();

        System.out.println(resultList);

        //模板：完成操作

        beginTransaction.commit();

        session.close();

    }

    //条件查询

    public void search2() {

        Session session = HibernateUtils.getSession();

        Transaction beginTransaction = session.beginTransaction();

        //模板：开始Criteria操作

        //操作    select * from user

        CriteriaBuilder criteriaBuilder = session.getCriteriaBuilder();

        //createQuery-->查询条件(首先需要知道查询什么类型数据)

        CriteriaQuery<User> criteria = criteriaBuilder.createQuery(User.class);

        Root<User> root = criteria.from(User.class);

        //查询到数据库中所有值

        criteria.select(root).where(root.get("id").in("1"));

        //执行查询

        List<User> resultList = session.createQuery(criteria).getResultList();

        //打印出查询出来的第1个用户

        System.out.println(resultList.get(0).getUsername());

        //模板：完成操作

        beginTransaction.commit();

        session.close();

    }

    //条件总数记录查询

    public void search3() {

        Session session = HibernateUtils.getSession();

        Transaction beginTransaction = session.beginTransaction();

        //模板：开始Criteria操作

        //操作    select count(*) from user

        CriteriaBuilder criteriaBuilder = session.getCriteriaBuilder();

        //createQuery-->查询条件(首先需要知道查询什么类型数据)(数Integer  Long)

        CriteriaQuery<Long> criteria = criteriaBuilder.createQuery(Long.class);

        //查找哪个表

        Root<User> root = criteria.from(User.class);

        criteria.select(criteriaBuilder.count(root));

        //执行查询

        Long count = session.createQuery(criteria).uniqueResult();

        //查询总数

        System.out.println(count);

        //模板：完成操作

        beginTransaction.commit();

        session.close();

    }

    //查询名字中带有a的人数总数  -- 2

    public void search4() {

        Session session = HibernateUtils.getSession();

        Transaction beginTransaction = session.beginTransaction();

        //模板：开始Criteria操作

        //操作    select count(*) from user where username like '%i%'

        CriteriaBuilder criteriaBuilder = session.getCriteriaBuilder();

        CriteriaQuery<Long> criteria = criteriaBuilder.createQuery(Long.class);

        Root<User> root = criteria.from(User.class);

        criteria.select(criteriaBuilder.count(root)).where(criteriaBuilder.like(root.get("username"),"%a%"));

        Long count = session.createQuery(criteria).uniqueResult();

        System.out.println(count);

        //模板：完成操作

        beginTransaction.commit();

        session.close();

    }

}

CriteriaDao.java

　　数据库user表

　　向数据库中添加假数据

1、Criteria基本查询

　　Root<User> from = createQuery.from(User.class);

　　createQuery.select(from);

　　CriteriaDao.java向数据库发起查询请求

//Criteria基本查询

    public void search() {

        Session session = HibernateUtils.getSession();

        Transaction beginTransaction = session.beginTransaction();

        //模板：开始Criteria操作

        //操作    select * from user

        CriteriaBuilder criteriaBuilder = session.getCriteriaBuilder();

        //createQuery-->查询条件(首先需要知道查询什么类型数据)

        CriteriaQuery<User> createQuery = criteriaBuilder.createQuery(User.class);

        Root<User> from = createQuery.from(User.class);

        createQuery.select(from);

        List<User> resultList = session.createQuery(createQuery).getResultList();

        System.out.println(resultList);

        //模板：完成操作

        beginTransaction.commit();

        session.close();

    }

package com.Gary.dao;

import java.util.List;

import javax.persistence.criteria.CriteriaBuilder;

import javax.persistence.criteria.CriteriaQuery;

import javax.persistence.criteria.Root;

import org.hibernate.Criteria;

import org.hibernate.Session;

import org.hibernate.Transaction;

import org.hibernate.query.Query;

import com.Gary.domain.User;

import com.Gary.utils.HibernateUtils;

public class CriteriaDao {

    //Criteria基本查询

    public void search() {

        Session session = HibernateUtils.getSession();

        Transaction beginTransaction = session.beginTransaction();

        //模板：开始Criteria操作

        //操作    select * from user

        CriteriaBuilder criteriaBuilder = session.getCriteriaBuilder();

        //createQuery-->查询条件(首先需要知道查询什么类型数据)

        CriteriaQuery<User> createQuery = criteriaBuilder.createQuery(User.class);

        Root<User> from = createQuery.from(User.class);

        createQuery.select(from);

        List<User> resultList = session.createQuery(createQuery).getResultList();

        System.out.println(resultList);

        //模板：完成操作

        beginTransaction.commit();

        session.close();

    }

}

CriteriaDao.java

2、Criteria条件查询

　　　　 //createQuery-->查询条件(首先需要知道查询什么类型数据)

        CriteriaQuery<User> criteria = criteriaBuilder.createQuery(User.class);

        Root<User> root = criteria.from(User.class);

        //查询到数据库中所有值

        criteria.select(root).where(root.get("id").in("1"));

        //执行查询

        List<User> resultList = session.createQuery(criteria).getResultList();

　　CriteriaDao.java向数据库发起查询请求

public void search2() {

        Session session = HibernateUtils.getSession();

        Transaction beginTransaction = session.beginTransaction();

        //模板：开始Criteria操作

        //操作    select * from user

        CriteriaBuilder criteriaBuilder = session.getCriteriaBuilder();

        //createQuery-->查询条件(首先需要知道查询什么类型数据)

        CriteriaQuery<User> criteria = criteriaBuilder.createQuery(User.class);

        Root<User> root = criteria.from(User.class);

        //查询到数据库中所有值

        criteria.select(root).where(root.get("id").in("1"));

        //执行查询

        List<User> resultList = session.createQuery(criteria).getResultList();

        //打印出查询出来的第1个用户

        System.out.println(resultList.get(0).getUsername());

        //模板：完成操作

        beginTransaction.commit();

        session.close();

    }

package com.Gary.dao;

import java.util.List;

import javax.persistence.criteria.CriteriaBuilder;

import javax.persistence.criteria.CriteriaQuery;

import javax.persistence.criteria.Root;

import org.hibernate.Criteria;

import org.hibernate.Session;

import org.hibernate.Transaction;

import org.hibernate.query.Query;

import com.Gary.domain.User;

import com.Gary.utils.HibernateUtils;

public class CriteriaDao {

    //Criteria基本查询

    public void search() {

        Session session = HibernateUtils.getSession();

        Transaction beginTransaction = session.beginTransaction();

        //模板：开始Criteria操作

        //操作    select * from user

        CriteriaBuilder criteriaBuilder = session.getCriteriaBuilder();

        //createQuery-->查询条件(首先需要知道查询什么类型数据)

        CriteriaQuery<User> createQuery = criteriaBuilder.createQuery(User.class);

        Root<User> from = createQuery.from(User.class);

        createQuery.select(from);

        List<User> resultList = session.createQuery(createQuery).getResultList();

        System.out.println(resultList);

        //模板：完成操作

        beginTransaction.commit();

        session.close();

    }

    public void search2() {

        Session session = HibernateUtils.getSession();

        Transaction beginTransaction = session.beginTransaction();

        //模板：开始Criteria操作

        //操作    select * from user

        CriteriaBuilder criteriaBuilder = session.getCriteriaBuilder();

        //createQuery-->查询条件(首先需要知道查询什么类型数据)

        CriteriaQuery<User> criteria = criteriaBuilder.createQuery(User.class);

        Root<User> root = criteria.from(User.class);

        //查询到数据库中所有值

        criteria.select(root).where(root.get("id").in("1"));

        //执行查询

        List<User> resultList = session.createQuery(criteria).getResultList();

        //打印出查询出来的第1个用户

        System.out.println(resultList.get(0).getUsername());

        //模板：完成操作

        beginTransaction.commit();

        session.close();

    }

}

CriteriaDao.java

3、Criteria查询总数

　　//createQuery-->查询条件(首先需要知道查询什么类型数据)(数Integer  Long)

　　CriteriaQuery<Long> criteria = criteriaBuilder.createQuery(Long.class);

　　//查找哪个表

　　Root<User> root = criteria.from(User.class);

　　criteria.select(criteriaBuilder.count(root));

　　//执行查询

　　Long count = session.createQuery(criteria).uniqueResult();

　　CriteriaDao.java向数据库发起查询请求

public void search3() {

        Session session = HibernateUtils.getSession();

        Transaction beginTransaction = session.beginTransaction();

        //模板：开始Criteria操作

        //操作    select count(*) from user

        CriteriaBuilder criteriaBuilder = session.getCriteriaBuilder();

        //createQuery-->查询条件(首先需要知道查询什么类型数据)(数Integer  Long)

        CriteriaQuery<Long> criteria = criteriaBuilder.createQuery(Long.class);

        //查找哪个表

        Root<User> root = criteria.from(User.class);

        criteria.select(criteriaBuilder.count(root));

        //执行查询

        Long count = session.createQuery(criteria).uniqueResult();

        //查询总数

        System.out.println(count);

        //模板：完成操作

        beginTransaction.commit();

        session.close();

    }

package com.Gary.dao;

import java.util.List;

import javax.persistence.criteria.CriteriaBuilder;

import javax.persistence.criteria.CriteriaQuery;

import javax.persistence.criteria.Root;

import org.hibernate.Criteria;

import org.hibernate.Session;

import org.hibernate.Transaction;

import org.hibernate.query.Query;

import com.Gary.domain.User;

import com.Gary.utils.HibernateUtils;

public class CriteriaDao {

    //Criteria基本查询

    public void search() {

        Session session = HibernateUtils.getSession();

        Transaction beginTransaction = session.beginTransaction();

        //模板：开始Criteria操作

        //操作    select * from user

        CriteriaBuilder criteriaBuilder = session.getCriteriaBuilder();

        //createQuery-->查询条件(首先需要知道查询什么类型数据)

        CriteriaQuery<User> createQuery = criteriaBuilder.createQuery(User.class);

        Root<User> from = createQuery.from(User.class);

        createQuery.select(from);

        List<User> resultList = session.createQuery(createQuery).getResultList();

        System.out.println(resultList);

        //模板：完成操作

        beginTransaction.commit();

        session.close();

    }

    //条件查询

    public void search2() {

        Session session = HibernateUtils.getSession();

        Transaction beginTransaction = session.beginTransaction();

        //模板：开始Criteria操作

        //操作    select * from user

        CriteriaBuilder criteriaBuilder = session.getCriteriaBuilder();

        //createQuery-->查询条件(首先需要知道查询什么类型数据)

        CriteriaQuery<User> criteria = criteriaBuilder.createQuery(User.class);

        Root<User> root = criteria.from(User.class);

        //查询到数据库中所有值

        criteria.select(root).where(root.get("id").in("1"));

        //执行查询

        List<User> resultList = session.createQuery(criteria).getResultList();

        //打印出查询出来的第1个用户

        System.out.println(resultList.get(0).getUsername());

        //模板：完成操作

        beginTransaction.commit();

        session.close();

    }

    //条件总数记录查询

    public void search3() {

        Session session = HibernateUtils.getSession();

        Transaction beginTransaction = session.beginTransaction();

        //模板：开始Criteria操作

        //操作    select count(*) from user

        CriteriaBuilder criteriaBuilder = session.getCriteriaBuilder();

        //createQuery-->查询条件(首先需要知道查询什么类型数据)(数Integer  Long)

        CriteriaQuery<Long> criteria = criteriaBuilder.createQuery(Long.class);

        //查找哪个表

        Root<User> root = criteria.from(User.class);

        criteria.select(criteriaBuilder.count(root));

        //执行查询

        Long count = session.createQuery(criteria).uniqueResult();

        //查询总数

        System.out.println(count);

        //模板：完成操作

        beginTransaction.commit();

        session.close();

    }

}

CriteriaDao.java

4、Criteria查询用户名中带有字符'a'的总人数

criteria.select(criteriaBuilder.count(root)).where(criteriaBuilder.like(root.get("username"),"%a%"));

　　CriteriaDao.java向数据库发起查询请求

    //查询名字中带有a的人数总数  -- 2

    public void search4() {

        Session session = HibernateUtils.getSession();

        Transaction beginTransaction = session.beginTransaction();

        //模板：开始Criteria操作

        //操作    select count(*) from user where username like '%i%'

        CriteriaBuilder criteriaBuilder = session.getCriteriaBuilder();

        CriteriaQuery<Long> criteria = criteriaBuilder.createQuery(Long.class);

        Root<User> root = criteria.from(User.class);

        criteria.select(criteriaBuilder.count(root)).where(criteriaBuilder.like(root.get("username"),"%a%"));

        Long count = session.createQuery(criteria).uniqueResult();

        System.out.println();

        //模板：完成操作

        beginTransaction.commit();

        session.close();

    }

package com.Gary.dao;

import java.util.List;

import javax.persistence.criteria.CriteriaBuilder;

import javax.persistence.criteria.CriteriaQuery;

import javax.persistence.criteria.Root;

import org.hibernate.Criteria;

import org.hibernate.Session;

import org.hibernate.Transaction;

import org.hibernate.query.Query;

import com.Gary.domain.User;

import com.Gary.utils.HibernateUtils;

public class CriteriaDao {

    //Criteria基本查询

    public void search() {

        Session session = HibernateUtils.getSession();

        Transaction beginTransaction = session.beginTransaction();

        //模板：开始Criteria操作

        //操作    select * from user

        CriteriaBuilder criteriaBuilder = session.getCriteriaBuilder();

        //createQuery-->查询条件(首先需要知道查询什么类型数据)

        CriteriaQuery<User> createQuery = criteriaBuilder.createQuery(User.class);

        Root<User> from = createQuery.from(User.class);

        createQuery.select(from);

        List<User> resultList = session.createQuery(createQuery).getResultList();

        System.out.println(resultList);

        //模板：完成操作

        beginTransaction.commit();

        session.close();

    }

    //条件查询

    public void search2() {

        Session session = HibernateUtils.getSession();

        Transaction beginTransaction = session.beginTransaction();

        //模板：开始Criteria操作

        //操作    select * from user

        CriteriaBuilder criteriaBuilder = session.getCriteriaBuilder();

        //createQuery-->查询条件(首先需要知道查询什么类型数据)

        CriteriaQuery<User> criteria = criteriaBuilder.createQuery(User.class);

        Root<User> root = criteria.from(User.class);

        //查询到数据库中所有值

        criteria.select(root).where(root.get("id").in("1"));

        //执行查询

        List<User> resultList = session.createQuery(criteria).getResultList();

        //打印出查询出来的第1个用户

        System.out.println(resultList.get(0).getUsername());

        //模板：完成操作

        beginTransaction.commit();

        session.close();

    }

    //条件总数记录查询

    public void search3() {

        Session session = HibernateUtils.getSession();

        Transaction beginTransaction = session.beginTransaction();

        //模板：开始Criteria操作

        //操作    select count(*) from user

        CriteriaBuilder criteriaBuilder = session.getCriteriaBuilder();

        //createQuery-->查询条件(首先需要知道查询什么类型数据)(数Integer  Long)

        CriteriaQuery<Long> criteria = criteriaBuilder.createQuery(Long.class);

        //查找哪个表

        Root<User> root = criteria.from(User.class);

        criteria.select(criteriaBuilder.count(root));

        //执行查询

        Long count = session.createQuery(criteria).uniqueResult();

        //查询总数

        System.out.println(count);

        //模板：完成操作

        beginTransaction.commit();

        session.close();

    }

    //查询名字中带有a的人数总数  -- 2

    public void search4() {

        Session session = HibernateUtils.getSession();

        Transaction beginTransaction = session.beginTransaction();

        //模板：开始Criteria操作

        //操作    select count(*) from user where username like '%i%'

        CriteriaBuilder criteriaBuilder = session.getCriteriaBuilder();

        CriteriaQuery<Long> criteria = criteriaBuilder.createQuery(Long.class);

        Root<User> root = criteria.from(User.class);

        criteria.select(criteriaBuilder.count(root)).where(criteriaBuilder.like(root.get("username"),"%a%"));

        Long count = session.createQuery(criteria).uniqueResult();

        System.out.println(count);

        //模板：完成操作

        beginTransaction.commit();

        session.close();

    }

}

CriteriaDao.java

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