JavaWeb_(Hibernate框架)Hibernate中数据查询语句Criteria基本用法
2024-09-03 13:45:10
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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