Hibernate-HQL、Criteria、SQL实现查询对照以及增删改

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();
     }


 }