hibernate框架学习笔记7:HQL查询、Criteria查询…
2018-06-27 09:56:20来源:未知 阅读 ()
HQL查询:hibernate独有的查询语言
适用于不复杂的多表查询
示例:
实体类:
package domain; public class Customer { private Long cust_id; private String cust_name; private String cust_source; private String cust_industry; private String cust_level; private String cust_linkman; private String cust_phone; private String cust_mobile; public Long getCust_id() { return cust_id; } public void setCust_id(Long cust_id) { this.cust_id = cust_id; } public String getCust_name() { return cust_name; } public void setCust_name(String cust_name) { this.cust_name = cust_name; } public String getCust_source() { return cust_source; } public void setCust_source(String cust_source) { this.cust_source = cust_source; } public String getCust_industry() { return cust_industry; } public void setCust_industry(String cust_industry) { this.cust_industry = cust_industry; } public String getCust_level() { return cust_level; } public void setCust_level(String cust_level) { this.cust_level = cust_level; } public String getCust_linkman() { return cust_linkman; } public void setCust_linkman(String cust_linkman) { this.cust_linkman = cust_linkman; } public String getCust_phone() { return cust_phone; } public void setCust_phone(String cust_phone) { this.cust_phone = cust_phone; } public String getCust_mobile() { return cust_mobile; } public void setCust_mobile(String cust_mobile) { this.cust_mobile = cust_mobile; } @Override public String toString() { return "Customer [cust_id=" + cust_id + ", cust_name=" + cust_name + "]"; } }
自定义工具类:
package utils; import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.cfg.Configuration; public class HibernateUtils { private static SessionFactory sf; static{ //1 创建,调用空参构造 Configuration conf = new Configuration().configure(); //2 根据配置信息,创建 SessionFactory对象 sf = conf.buildSessionFactory(); } //获得session => 获得全新session public static Session openSession(){ //3 获得session Session session = sf.openSession(); return session; } //获得session => 获得与线程绑定的session public static Session getCurrentSession(){ //3 获得session Session session = sf.getCurrentSession(); return session; } }
测试类:
package hql; import java.util.List; import org.hibernate.Query; import org.hibernate.Session; import org.hibernate.Transaction; import org.junit.Test; import domain.Customer; import utils.HibernateUtils; //测试HQL语句 public class Demo { @Test //基本查询 public void fun1(){ //1 获得session Session session = HibernateUtils.openSession(); //2 控制事务 Transaction tx = session.beginTransaction(); //3执行操作 //------------------------------------------- //1> 书写HQL语句 //String hql = " from domain.Customer "; String hql = " from Customer "; // 如果查询所有Customer对象,可省略全名 //2> 根据HQL语句创建查询对象 Query query = session.createQuery(hql); //3> 根据查询对象获得查询结果 List<Customer> list = query.list(); // 返回list结果 //query.uniqueResult();//接收唯一的查询结果 System.out.println(list); //------------------------------------------- //4提交事务.关闭资源 tx.commit(); session.close(); } @Test //条件查询 //HQL语句中,不可能出现任何数据库相关的信息的 //不会出现数据库的表名类名字段名,使用的是实体类的属性名 public void fun2(){ //1 获得session Session session = HibernateUtils.openSession(); //2 控制事务 Transaction tx = session.beginTransaction(); //3执行操作 //------------------------------------------- //1> 书写HQL语句 String hql = " from Customer where cust_id = 1 "; // 查询所有Customer对象 //2> 根据HQL语句创建查询对象 Query query = session.createQuery(hql); //3> 根据查询对象获得查询结果 Customer c = (Customer) query.uniqueResult(); System.out.println(c); //------------------------------------------- //4提交事务.关闭资源 tx.commit(); session.close(); } @Test //条件查询 //问号占位符 public void fun3(){ //1 获得session Session session = HibernateUtils.openSession(); //2 控制事务 Transaction tx = session.beginTransaction(); //3执行操作 //------------------------------------------- //1> 书写HQL语句 String hql = " from Customer where cust_id = ? "; // 查询所有Customer对象 //2> 根据HQL语句创建查询对象 Query query = session.createQuery(hql); //设置参数 //query.setLong(0, 1l); query.setParameter(0, 1l); //3> 根据查询对象获得查询结果 Customer c = (Customer) query.uniqueResult(); System.out.println(c); //------------------------------------------- //4提交事务.关闭资源 tx.commit(); session.close(); } @Test //条件查询 //命名占位符 public void fun4(){ //1 获得session Session session = HibernateUtils.openSession(); //2 控制事务 Transaction tx = session.beginTransaction(); //3执行操作 //------------------------------------------- //1> 书写HQL语句 String hql = " from Customer where cust_id = :cust_id "; // 查询所有Customer对象 //2> 根据HQL语句创建查询对象 Query query = session.createQuery(hql); //设置参数 query.setParameter("cust_id", 1l); //3> 根据查询对象获得查询结果 Customer c = (Customer) query.uniqueResult(); System.out.println(c); //------------------------------------------- //4提交事务.关闭资源 tx.commit(); session.close(); } @Test //分页查询 public void fun5(){ //1 获得session Session session = HibernateUtils.openSession(); //2 控制事务 Transaction tx = session.beginTransaction(); //3执行操作 //------------------------------------------- //1> 书写HQL语句 String hql = " from Customer "; // 查询所有Customer对象 //2> 根据HQL语句创建查询对象 Query query = session.createQuery(hql); //设置分页信息 limit ?,? query.setFirstResult(0); query.setMaxResults(1); //3> 根据查询对象获得查询结果 List<Customer> list = query.list(); System.out.println(list); //------------------------------------------- //4提交事务.关闭资源 tx.commit(); session.close(); } }
Criteria查询:
hibernate独创的,无语句面向对象查询
适用于单表查询
示例:
package criteria; import java.util.List; import org.hibernate.Criteria; import org.hibernate.Query; import org.hibernate.Session; import org.hibernate.Transaction; import org.hibernate.criterion.Projections; import org.hibernate.criterion.Restrictions; import org.junit.Test; import domain.Customer; import utils.HibernateUtils; //测试Criteria查询 public class Demo { @Test //基本查询 public void fun1(){ //1 获得session Session session = HibernateUtils.openSession(); //2 控制事务 Transaction tx = session.beginTransaction(); //3执行操作 //------------------------------------------- //查询所有的Customer对象 Criteria criteria = session.createCriteria(Customer.class); List<Customer> list = criteria.list(); System.out.println(list); // Customer c = (Customer) criteria.uniqueResult(); //------------------------------------------- //4提交事务.关闭资源 tx.commit(); session.close(); } @Test //条件查询 //HQL语句中,不可能出现任何数据库相关的信息的 // > gt // >= ge // < lt // <= le // == eq // != ne // in in // between and between // like like // is not null isNotNull // is null isNull // or or // and and public void fun2(){ //1 获得session Session session = HibernateUtils.openSession(); //2 控制事务 Transaction tx = session.beginTransaction(); //3执行操作 //------------------------------------------- //创建criteria查询对象 Criteria criteria = session.createCriteria(Customer.class); //添加查询参数 => 查询cust_id为1的Customer对象 criteria.add(Restrictions.gt("cust_id", 1l)); //执行查询获得结果 Customer c = (Customer) criteria.uniqueResult(); System.out.println(c); //------------------------------------------- //4提交事务.关闭资源 tx.commit(); session.close(); } @Test //分页查询 public void fun3(){ //1 获得session Session session = HibernateUtils.openSession(); //2 控制事务 Transaction tx = session.beginTransaction(); //3执行操作 //------------------------------------------- //创建criteria查询对象 Criteria criteria = session.createCriteria(Customer.class); //设置分页信息 limit ?,? criteria.setFirstResult(1); criteria.setMaxResults(2); //执行查询 List<Customer> list = criteria.list(); System.out.println(list); //------------------------------------------- //4提交事务.关闭资源 tx.commit(); session.close(); } @Test //查询总记录数 public void fun4(){ //1 获得session Session session = HibernateUtils.openSession(); //2 控制事务 Transaction tx = session.beginTransaction(); //3执行操作 //------------------------------------------- //创建criteria查询对象 Criteria criteria = session.createCriteria(Customer.class); //设置查询的聚合函数 => 总行数 criteria.setProjection(Projections.rowCount()); //执行查询 Long count = (Long) criteria.uniqueResult(); System.out.println(count); //------------------------------------------- //4提交事务.关闭资源 tx.commit(); session.close(); } }
原生SQL查询:
适用于相当复杂的业务
package sql; import java.util.Arrays; import java.util.List; import org.hibernate.SQLQuery; import org.hibernate.Session; import org.hibernate.Transaction; import org.junit.Test; import domain.Customer; import utils.HibernateUtils; //测试原生SQL查询 public class Demo { @Test //基本查询 public void fun1(){ //1 获得session Session session = HibernateUtils.openSession(); //2 控制事务 Transaction tx = session.beginTransaction(); //3执行操作 //------------------------------------------- //1 书写sql语句 String sql = "select * from cst_customer"; //2 创建sql查询对象 SQLQuery query = session.createSQLQuery(sql); //3 调用方法查询结果 List<Object[]> list = query.list(); //query.uniqueResult(); for(Object[] objs : list){ System.out.println(Arrays.toString(objs)); } //------------------------------------------- //4提交事务.关闭资源 tx.commit(); session.close(); } @Test //基本查询 public void fun2(){ //1 获得session Session session = HibernateUtils.openSession(); //2 控制事务 Transaction tx = session.beginTransaction(); //3执行操作 //------------------------------------------- //1 书写sql语句 String sql = "select * from cst_customer"; //2 创建sql查询对象 SQLQuery query = session.createSQLQuery(sql); //指定将结果集封装到哪个对象中 query.addEntity(Customer.class); //3 调用方法查询结果 List<Customer> list = query.list(); System.out.println(list); //------------------------------------------- //4提交事务.关闭资源 tx.commit(); session.close(); } @Test //条件查询 public void fun3(){ //1 获得session Session session = HibernateUtils.openSession(); //2 控制事务 Transaction tx = session.beginTransaction(); //3执行操作 //------------------------------------------- //1 书写sql语句 String sql = "select * from cst_customer where cust_id = ? "; //2 创建sql查询对象 SQLQuery query = session.createSQLQuery(sql); query.setParameter(0, 1l); //指定将结果集封装到哪个对象中 query.addEntity(Customer.class); //3 调用方法查询结果 List<Customer> list = query.list(); System.out.println(list); //------------------------------------------- //4提交事务.关闭资源 tx.commit(); session.close(); } @Test //分页查询 public void fun4(){ //1 获得session Session session = HibernateUtils.openSession(); //2 控制事务 Transaction tx = session.beginTransaction(); //3执行操作 //------------------------------------------- //1 书写sql语句 String sql = "select * from cst_customer limit ?,? "; //2 创建sql查询对象 SQLQuery query = session.createSQLQuery(sql); query.setParameter(0, 0); query.setParameter(1, 1); //指定将结果集封装到哪个对象中 query.addEntity(Customer.class); //3 调用方法查询结果 List<Customer> list = query.list(); System.out.println(list); //------------------------------------------- //4提交事务.关闭资源 tx.commit(); session.close(); } }
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