Hibernate-HQL、Criteria、SQL实现查询对照以及增删改

最新推荐文章于 2022-12-08 15:51:22 发布

低调的洋仔

最新推荐文章于 2022-12-08 15:51:22 发布

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分类专栏： Hibernate曲径通幽文章标签： sql hql criteria hibernate

本文链接：https://blog.youkuaiyun.com/wangyang1354/article/details/50448484

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本文介绍 Hibernate 中三种查询方式：HQL、SQL 和 Criteria 的使用方法及特点，对比不同查询方式的实现思路，涵盖基本的增删改操作。

本文旨在为读者呈现不同的方式查询方式：HQL方式的查询、SQL原生态SQL方式的查询、以及Criteria方式的查询，拓展查询的不同实现思路，开阔视野、并涵盖了部分的Hibernate增删改的基本操作。

简单介绍一下HQL和Criteria:

HQL

HQL（Hibernate Query Language）提供更加丰富灵活、更为强大的查询能力；HQL更接近SQL语句查询语法；
[select/delete/update…][from…][where…][group by…][having…][order by…]

Criteria

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 Criterion 是 Criteria 的查询条件。

Criteria 提供了 add(Criterion criterion) 方法来添加查询条件。 Criterion 接口的主要实现包括： Example 、 Junction 和 SimpleExpression 。而Junction 的实际使用是它的两个子类 conjunction 和 disjunction ，分别是使用 AND 和 OR 操作符进行来联结查询条件集合。

Criterion 的实例可以通过 Restrictions 工具类来创建，Restrictions 提供了大量的静态方法，如 eq （等于）、 ge （大于等于）、 between 等来方法的创建 Criterion 查询条件（SimpleExpression 实例）。除此之外， Restrictions 还提供了方法来创建 conjunction 和disjunction 实例，通过往该实例的 add(Criteria) 方法来增加查询条件形成一个查询条件集合。

Example 的创建有所不同， Example 本身提供了一个静态方法 create(Objectentity) ，即根据一个对象（实际使用中一般是映射到数据库的对象）来创建。然后可以设置一些过滤条件：

Example exampleUser =Example.create(u)

.ignoreCase() // 忽略大小写

.enableLike(MatchMode.ANYWHERE); // 对 String 类型的属性，无论在那里值在那里都匹配。相当于 %value%

Project 主要是让 Criteria 能够进行报表查询，并可以实现分组。 Project 主要有SimpleProjection 、ProjectionList 和 Property 三个实现。其中SimpleProjection 和ProjectionList 的实例化是由内建的Projections 来完成，如提供的 avg 、count 、max 、min 、sum 可以让开发者很容易对某个字段进行统计查询。

Property 是对某个字段进行查询条件的设置，如通过Porperty.forName(“color”). in(new String[]{“black”,”red”,”write”}); 则可以创建一个 Project 实例。通过criteria 的 add(Project) 方法加入到查询条件中去。

准备工作

jar包以及项目的结构

User.java

package com.siti.domain;

public class User {

	private Long userId;
	private String userName;
	private String password;
	
	public Long getUserId() {
		return userId;
	}
	public void setUserId(Long userId) {
		this.userId = userId;
	}
	public String getUserName() {
		return userName;
	}
	public void setUserName(String userName) {
		this.userName = userName;
	}
	public String getPassword() {
		return password;
	}
	public void setPassword(String password) {
		this.password = password;
	}
	@Override
	public String toString() {
		return "User [userId=" + userId + ", userName=" + userName
				+ ", password=" + password + "]";
	}
	
}

User.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 package="com.siti.domain">
	<class name = "User" table="user">
		<id name = "userId" type = "java.lang.Long" column = "id">
			<generator class="native"></generator>
		</id>
		<property name="userName" type = "string" column = "userName" length = "20"></property>
		<property name="password" type = "string" column = "password"  length = "20"></property>
	</class>
</hibernate-mapping>

hibernate.cfg.xml

<!DOCTYPE hibernate-configuration PUBLIC
	"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
	"http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">

<!-- Generated by MyEclipse Hibernate Tools.                   -->
<hibernate-configuration>
<session-factory>
	<property name="hibernate.connection.driver_class">
		com.mysql.jdbc.Driver
	</property>
	<property name="hibernate.connection.url">
		jdbc:mysql://localhost:3306/hiber
	</property>
	<property name="hibernate.connection.username">root</property>
	<property name="hibernate.connection.password">root</property>
	<property name="dialect">
		org.hibernate.dialect.MySQLDialect
	</property>
	<property name="connection.pool_size">1</property>
	<property name="show_sql">true</property>
	<property name="hibernate.hbm2ddl.auto">update</property>
	<mapping resource="com/siti/domain/User.hbm.xml" />
</session-factory>

</hibernate-configuration>

对照代码

package com.siti.test;

import java.util.List;

import org.hibernate.SQLQuery;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
import org.hibernate.criterion.Criterion;
import org.hibernate.criterion.Projection;
import org.hibernate.criterion.Projections;
import org.hibernate.criterion.Restrictions;

import com.siti.domain.User;

public class HiberTest {

	static SessionFactory sessionFactory = null;
	static {
		sessionFactory = new Configuration()
		.configure()
		.buildSessionFactory();
	}
	public static void main(String[] args) {
	
		testCriteriaSelectProjectUser();
	}
	
	/**
	 * 7. Criteria 方式投影分组查询
	 * Hibernate: select this_.userName as y0_, count(this_.password) as y1_ from user this_ group by this_.userName
	 * 
	 * [[Ljava.lang.Object;@1f44ec7, [Ljava.lang.Object;@602b6b, [Ljava.lang.Object;@1c297a3, [Ljava.lang.Object;@717323, [Ljava.lang.Object;@3e1bc8]
	 * 
	 * 从这几个例子我们不难发现，如果没有指定select语句（没有投影），那么将返回表中的所有字段，返回结果会被封装到Entity实体对象User中，一但提供select语句（投影）后，
	 * 返回的结果类型，将不再封装到User对象，而是根据投影的实际类型返回，这就是投影对结果封装策略的影响。 
	 */
	public static void testCriteriaSelectProjectUser(){
		Session session = sessionFactory.openSession();
		List<Object> userList = session.createCriteria(User.class)//
				.setProjection(
						Projections.projectionList()
						.add(Projections.groupProperty("userName"))
						.add(Projections.count("password"))
					)
				.list();
		System.out.println(userList);
		session.close();
	}
	
	
	/**
	 * 6. SQL 方式测试查询附加条件id>?
	 * Hibernate: select * from user where id > 5 // 注意这里用的是id>5而不是userId
	 * 
	 * [User [userId=11, userName=zhangsan, password=zs]]
	 * 
	 */
	public static void testSQLSelectUser(){
		Session session = sessionFactory.openSession();
		List<User> userList = session.createSQLQuery("select * from user where id > 5")//
				.addEntity(User.class)//
				.list();
		System.out.println(userList);
		session.close();
	}
	/**
	 * 6. HQL 方式测试查询附加条件id>?
	 * Hibernate: select user0_.id as id0_, user0_.userName as userName0_, user0_.password as password0_ from user user0_ where user0_.id>5
	 * 
	 * [User [userId=11, userName=zhangsan, password=zs]]
	 * 
	 */
	public static void testHQLSelectUser(){
		Session session = sessionFactory.openSession();
		List<User> userList = session.createQuery("from User user where user.userId > 5")
				.list();
		System.out.println(userList);
		session.close();
	}
	/**
	 * 6. Criteria 方式测试查询附加条件id>?
	 * Hibernate: select this_.id as id0_0_, this_.userName as userName0_0_, this_.password as password0_0_ from user this_ where this_.id>?
	 * 
	 * [User [userId=11, userName=zhangsan, password=zs]]
	 * 
	 */
	public static void testCriteriaSelectUser(){
		Session session = sessionFactory.openSession();
		List<User> userList = session.createCriteria(User.class)//
				.add(Restrictions.gt("userId", 5L))//
				.list();
		System.out.println(userList);
		session.close();
	}
	
	/**
	 * 5. SQL 方式测试查询like附加条件
	 * Hibernate: select * from user where userName like 'zhan%'
	 * 
	 * [User [userId=11, userName=zhangsan, password=zs]]
	 * 
	 */
	public static void testSQLSelectPartUser(){
		Session session = sessionFactory.openSession();
		List<User> userList = session.createSQLQuery("select * from user where userName like 'zhan%'")
				.addEntity(User.class)
				.list();
		System.out.println(userList);
		session.close();
	}
	/**
	 * 5. HQL 方式测试查询like附加条件
	 * Hibernate: select user0_.id as id0_, user0_.userName as userName0_, user0_.password as password0_ from user user0_ where user0_.userName like 'zhan%'
	 * 
	 * [User [userId=11, userName=zhangsan, password=zs]]
	 * 
	 */
	public static void testHQLSelectPartUser(){
		Session session = sessionFactory.openSession();
		List<User> userList = session.createQuery("from User user where user.userName like 'zhan%'")
				.list();
		System.out.println(userList);
		session.close();
	}
	
	/**
	 * 5. Criteria 方式测试查询like附加条件
	 * Hibernate: select this_.id as id0_0_, this_.userName as userName0_0_, this_.password as password0_0_ from user this_ where this_.userName like ?
	 * 
	 * [User [userId=11, userName=zhangsan, password=zs]]
	 * 
	 */
	public static void testCriteriaSelectPartUser(){
		Session session = sessionFactory.openSession();
		List<User> userList = session.createCriteria(User.class)
				.add(Restrictions.like("userName", "zhan%"))
				.list();
		System.out.println(userList);
		session.close();
	}
	
	/**
	 * 4. SQL 方式测试查询所有的user数据
	 * Hibernate: select * from user
	 * 
	 * [User [userId=1, userName=wy, password=1234], 
	 * User [userId=2, userName=yy, password=123], 
	 * User [userId=3, userName=sd, password=12], 
	 * User [userId=4, userName=test, password=sffs], 
	 * User [userId=11, userName=zhangsan, password=zs]]
	 */
	public static void testSQLSelectAllUser(){
		Session session = sessionFactory.openSession();
		List<User> userList = session.createSQLQuery("select * from user").addEntity(User.class).list();
		System.out.println(userList);
		session.close();
	}
	/**
	 * 4. HQL 方式测试查询所有的user数据
	 * Hibernate: select user0_.id as id0_, user0_.userName as userName0_, user0_.password as password0_ from user user0_
	 * 
	 * [User [userId=1, userName=wy, password=1234], 
	 * User [userId=2, userName=yy, password=123], 
	 * User [userId=3, userName=sd, password=12], 
	 * User [userId=4, userName=test, password=sffs], 
	 * User [userId=11, userName=zhangsan, password=zs]]
	 */
	public static void testHQLSelectAllUser(){
		Session session = sessionFactory.openSession();
		List<User> userList = session.createQuery("from User").list();
		System.out.println(userList);
		session.close();
	}
	/**
	 * 4. Criteria 方式测试查询所有的user数据
	 * Hibernate: select this_.id as id0_0_, this_.userName as userName0_0_, this_.password as password0_0_ from user this_
	 * 
	 * [User [userId=1, userName=wy, password=1234], 
	 * User [userId=2, userName=yy, password=123], 
	 * User [userId=3, userName=sd, password=12], 
	 * User [userId=4, userName=test, password=sffs], 
	 * User [userId=11, userName=zhangsan, password=zs]]
	 */
	public static void testCriteriaSelectAllUser(){
		Session session = sessionFactory.openSession();
		List<User> userList = session.createCriteria(User.class).list();
		System.out.println(userList);
		session.close();
	}
	
	/**
	 * 3. 删除用户
	 * Hibernate: delete from user where id=?
	 */
	public static void testDeleteUser(){
		User user = new User();
		user.setUserId(5L);
		user.setUserName("zhanan");
		user.setPassword("zb");
		Session session = sessionFactory.openSession();
		session.beginTransaction(); // 开启事务
		session.delete(user);
		session.getTransaction().commit();// 提交事务
		session.close();
	}
	
	/**
	 * 2. 更新用户
	 * Hibernate: update user set userName=?, password=? where id=?
	 */
	public static void testUpdateUser(){
		User user = new User();
		user.setUserId(5L);
		user.setUserName("zhanan");
		user.setPassword("zb");
		Session session = sessionFactory.openSession();
		session.beginTransaction(); // 开启事务
		session.update(user);
		session.getTransaction().commit();// 提交事务
		session.close();
	}
	
	/**
	 * 1. 添加用户
	 * Hibernate: insert into user (userName, password) values (?, ?)
	 */
	public static void testInsertUser(){
		User user = new User();
		user.setUserId(5L);
		user.setUserName("zhangsan");
		user.setPassword("zs");
		Session session = sessionFactory.openSession();
		session.beginTransaction(); // 开启事务
		session.save(user);
		session.getTransaction().commit();// 提交事务
		session.close();
	}
	

}

代码下载： Hibernate_Hql/Criteria/Sql代码