hibernate HQL的简单使用一

编程技术  /  houtizong 发布于 3年前   48

Hibernate中的HQL使用
1、 建立相应的关系表
Category类：

package com.edu.hpu;import javax.persistence.Entity;import javax.persistence.GeneratedValue;import javax.persistence.Id;@Entitypublic class Category {private int id;private String name;@Id@GeneratedValuepublic int getId() {return id;}public void setId(int id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}}

Topic类：

package com.edu.hpu;import java.util.Date;import javax.persistence.Entity;import javax.persistence.FetchType;import javax.persistence.GeneratedValue;import javax.persistence.Id;import javax.persistence.JoinColumn;import javax.persistence.ManyToOne;@Entitypublic class Topic {private int id;private String title;private Date date;private Category category;@Id@GeneratedValuepublic int getId() {return id;}public void setId(int id) {this.id = id;}public String getTitle() {return title;}public void setTitle(String title) {this.title = title;}public Date getDate() {return date;}public void setDate(Date date) {this.date = date;}@ManyToOne(fetch=FetchType.LAZY)@JoinColumn(name="category_ID")public Category getCategory() {return category;}public void setCategory(Category category) {this.category = category;}}

Msg类：

package com.edu.hpu;import javax.persistence.Entity;import javax.persistence.GeneratedValue;import javax.persistence.Id;import javax.persistence.JoinColumn;import javax.persistence.ManyToOne;@Entitypublic class Msg {private int id;private String cont;private Topic topic;@Id@GeneratedValuepublic int getId() {return id;}public void setId(int id) {this.id = id;}public String getCont() {return cont;}public void setCont(String cont) {this.cont = cont;}@ManyToOne@JoinColumn(name="topic_ID")public Topic getTopic() {return topic;}public void setTopic(Topic topic) {this.topic = topic;}}

第12个查询用到的MsgInfo类：

package com.edu.hpu;public class MsgInfo {private int id;private String cont;private String topicName;private String categoryName;public MsgInfo(int id, String cont, String topicName, String categoryName) {super();this.id = id;this.cont = cont;this.topicName = topicName;this.categoryName = categoryName;}public int getId() {return id;}public void setId(int id) {this.id = id;}public String getCont() {return cont;}public void setCont(String cont) {this.cont = cont;}public String getTopicName() {return topicName;}public void setTopicName(String topicName) {this.topicName = topicName;}public String getCategoryName() {return categoryName;}public void setCategoryName(String categoryName) {this.categoryName = categoryName;}}

Hibernate.cfg.xml配置信息：

<?xml version='1.0' encoding='utf-8'?><!DOCTYPE hibernate-configuration PUBLIC        "-//Hibernate/Hibernate Configuration DTD 3.0//EN"        "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd"><hibernate-configuration>    <session-factory>        <!-- Database connection settings -->        <property name="connection.driver_class">com.mysql.jdbc.Driver</property>        <property name="connection.url">jdbc:mysql://localhost:3306/hibernate</property>        <property name="connection.username">root</property>        <property name="connection.password">r</property>        <!-- JDBC connection pool (use the built-in) -->        <property name="connection.pool_size">1</property>        <!-- SQL dialect -->        <property name="dialect">org.hibernate.dialect.MySQL5Dialect</property>        <!-- Enable Hibernate's automatic session context management -->        <property name="current_session_context_class">thread</property>        <!-- Disable the second-level cache  -->        <property name="cache.provider_class">org.hibernate.cache.internal.NoCacheProvider</property>        <!-- Echo all executed SQL to stdout -->        <property name="show_sql">true</property>                <property name="format_sql">true</property>        <!-- Drop and re-create the database schema on startup -->        <!--<property name="hbm2ddl.auto">update</property>-->        <!--<mapping resource="org/hibernate/tutorial/domain/Event.hbm.xml"/>-->                <!--<mapping resource="com/edu/hpu/Husband.hbm.xml" />-->        <!--        <mapping resource="com/edu/hpu/Teacher.hbm.xml" />        <mapping resource="com/edu/hpu/Student.hbm.xml" />        -->        <mapping class="com.edu.hpu.Category" />        <mapping class="com.edu.hpu.Topic" />        <mapping class="com.edu.hpu.Msg" />                    </session-factory></hibernate-configuration>

简单的HQL测试类：

package com.edu.hpu;import java.util.List;import org.hibernate.Query;import org.hibernate.Session;import org.hibernate.SessionFactory;import org.hibernate.cfg.Configuration;import org.hibernate.service.ServiceRegistry;import org.hibernate.service.ServiceRegistryBuilder;import org.hibernate.tool.hbm2ddl.SchemaExport;import org.junit.AfterClass;import org.junit.BeforeClass;import org.junit.Test;public class TestClass {private static SessionFactory sf = null;@BeforeClasspublic static void beforeClass() {Configuration conf = new Configuration().configure();ServiceRegistry sr = new ServiceRegistryBuilder().applySettings(conf.getProperties()).buildServiceRegistry();sf = conf.buildSessionFactory(sr);}@Testpublic void testExport() {new SchemaExport(new Configuration().configure()).create(true ,true);}@Testpublic void testSave() {Session session = sf.openSession();session.beginTransaction();for(int i = 0; i < 10; i++) {Category c = new Category();c.setName("c" + i);session.save(c);}for(int i = 0; i < 10; i++) {Category c = new Category();c.setId(1);Topic t = new Topic();t.setTitle("t" + i);t.setCategory(c);session.save(t);}for(int i = 0; i < 10; i++) {Topic t = new Topic();t.setId(1);Msg m = new Msg();m.setTopic(t);m.setCont("m" + i);session.save(m);}session.getTransaction().commit();session.close();}@Testpublic void testHQL_1() {Session session = sf.getCurrentSession();session.beginTransaction();Query query = session.createQuery("from Category");List<Category> categories = (List<Category>)query.list();for(Category category : categories) {System.out.println(category.getName());}session.getTransaction().commit();}@Testpublic void testHQL_2() {Session session = sf.getCurrentSession();session.beginTransaction();Query query = session.createQuery("from Category c where c.name > 'c5'");List<Category> categories = (List<Category>)query.list();for(Category c : categories) {System.out.println(c.getName());}session.getTransaction().commit();}@Testpublic void testHQL_3() {Session s = sf.getCurrentSession();s.beginTransaction();Query query = s.createQuery("from Category c order by c.name desc");List<Category> cs = query.list();for(Category c : cs) {System.out.println(c.getName());}s.getTransaction().commit();}@Testpublic void testHQL_4() {Session session = sf.getCurrentSession();session.beginTransaction();Query q = session.createQuery("select distinct c from Category c order by c.name desc");List<Category> cs = (List<Category>)q.list();for(Category c : cs) {System.out.println(c.getName());}session.getTransaction().commit();}@Testpublic void testHQL_5() {Session session = sf.getCurrentSession();session.beginTransaction();Query q = session.createQuery("from Category c where c.id > :min and c.id < :max");/*q.setParameter("min", 2);q.setParameter("max", 8);*/q.setInteger("min", 2);q.setInteger("max", 8);List<Category> cs = (List<Category>)q.list();for(Category c : cs) {System.out.println(c.getId() + "-" + c.getName());}session.getTransaction().commit();}@Testpublic void testHQL_6() {Session s = sf.getCurrentSession();s.beginTransaction();Query q = s.createQuery("from Category c where c.id > ? and c.id < ?")   .setInteger(0, 2).setInteger(1, 8);List<Category> cs = (List<Category>)q.list();for(Category c : cs) {System.out.println(c.getId() + " - " + c.getName());}s.getTransaction().commit();}@Testpublic void testHQL_7() {Session s = sf.getCurrentSession();s.beginTransaction();Query q = s.createQuery("from Category c order by c.id desc");q.setMaxResults(4);q.setFirstResult(0);List<Category> cs = (List<Category>)q.list();for(Category c : cs) {System.out.println(c.getId() + " - " + c.getName());}s.getTransaction().commit();}@Testpublic void testHQL_8() {Session s = sf.getCurrentSession();s.beginTransaction();Query q = s.createQuery("select c.id , c.name from Category c order by c.id desc");List<Object[]> cs = (List<Object[]>)q.list();for(Object[] c : cs) {System.out.println(c[0] + " - " + c[1]);}s.getTransaction().commit();}//把Topic的FetchType调成LAZY的时候，没有有第二条查询语句@Testpublic void testHQL_9() {Session s = sf.getCurrentSession();s.beginTransaction();Query q = s.createQuery("from Topic t where t.category.id = 1");List<Topic> ts = (List<Topic>)q.list();for(Topic t : ts) {System.out.println(t.getId());}s.getTransaction().commit();}@Testpublic void testHQL_10() {Session s = sf.getCurrentSession();s.beginTransaction();Query q = s.createQuery("from Topic t where t.category.id = 1");List<Topic> ts = (List<Topic>)q.list();for(Topic t : ts) {System.out.println(t.getId() + " = " + t.getCategory().getName());}s.getTransaction().commit();}@Testpublic void testHQL_11() {Session s = sf.getCurrentSession();s.beginTransaction();Query q = s.createQuery("from Msg m where m.topic.category.id = 1");List<Msg> ms = (List<Msg>)q.list();for(Msg m : ms) {System.out.println(m.getCont());}s.getTransaction().commit();}//VO Value Object//DTO Data Transfer Object@Testpublic void testHQL_12() {Session s = sf.getCurrentSession();s.beginTransaction();Query q = s.createQuery("select new com.edu.hpu.MsgInfo(m.id , m.cont, m.topic.title , m.topic.category.name) from Msg m");List<MsgInfo> ms = (List<MsgInfo>)q.list();for(MsgInfo m : ms ) {System.out.println(m.getCont() + " = " + m.getTopicName() + " = " + m.getCategoryName());}s.getTransaction().commit();}//必须写成t.category,必须指定使用哪个变量做的连接@Testpublic void testHQL_13() {Session s = sf.getCurrentSession();s.beginTransaction();Query q = s.createQuery("select t.title , c.name from Topic t join t.category c");List<Object[]> cs = (List<Object[]>)q.list();for(Object[] c : cs) {System.out.println(c[0] + " = " + c[1]);}s.getTransaction().commit();}@Testpublic void testHQL_14() {Session s = sf.getCurrentSession();s.beginTransaction();Query q = s.createQuery("from Category c where c = :CInfo");Category c = new Category();c.setId(1);q.setParameter("CInfo", c);Category cs = (Category)q.uniqueResult();System.out.println(cs.getName());s.getTransaction().commit();}@Testpublic void testHQL_15() {Session s = sf.getCurrentSession();s.beginTransaction();Query q = s.createQuery("select count(*) from Category");long count = (Long)q.uniqueResult();System.out.println(count);s.getTransaction().commit();}@Testpublic void testHQL_16() {Session s = sf.getCurrentSession();s.beginTransaction();Query q = s.createQuery("from Category c where c.id between 3 and 5");List<Category> cs = (List<Category>)q.list();for(Category c : cs) {System.out.println(c.getId() + " - " + c.getName());}s.getTransaction().commit();}@Testpublic void testHQL_17() {Session s = sf.getCurrentSession();s.beginTransaction();Query q = s.createQuery("from Category c where c.id in (1,3,5)");List<Category> cs = (List<Category>)q.list();for(Category c : cs) {System.out.println(c.getId() + " - " + c.getName());}s.getTransaction().commit();}@Testpublic void testHQL_18() {Session s = sf.getCurrentSession();s.beginTransaction();Query q = s.createQuery("from Msg m where m.cont is not null");List<Msg> cs = (List<Msg>)q.list();for(Msg c : cs) {System.out.println(c.getId() + " - " + c.getCont());}s.getTransaction().commit();}@AfterClasspublic static void afterClass() {sf.close();}}