Hibernate中Criteria查询简单例子新手上路第一案例

使用Hibernate中的Criteria来写一个简单的例子，例子中有三个类，分别是Student、Teacher、JavaTest三了类，其中teacher和student是一对多的关系。

首先列出需要的Jar文件：

然后是最基础的hibernate.cfg.xml配置文件：

<?xml version='1.0' encoding='utf-8'?><!DOCTYPE hibernate-configuration PUBLIC        "-//Hibernate/Hibernate Configuration DTD 3.0//EN"        "http://hibernate.sourceforge.net/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/magic</property>        <property name="connection.username">root</property>        <property name="connection.password">root</property>        <!-- SQL 方言 -->        <property name="dialect">org.hibernate.dialect.MySQLDialect</property>        <!-- 显示SQL语句 -->        <property name="show_sql">true</property>        <!-- 使用本地事物（JDBC事物） -->        <property name="current_session_context_class">thread</property>        <!-- 自动生成表 -->        <property name="hbm2ddl.auto">update</property>        <!-- 配置实体类的映射 -->        <mapping class="com.model.Student"/>        <mapping class="com.model.Teacher"/>    </session-factory></hibernate-configuration>

我写了一个HibernateUtil工具类,该工具类主要用于创建Session :

public class HibernateUtil {    private static final SessionFactory sessionFactory = buildSessionFactory();    private static SessionFactory buildSessionFactory(){        try{            Configuration config = new Configuration().configure();            ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder().applySettings(config.getProperties()).build();            return config.buildSessionFactory(serviceRegistry);        }catch (Throwable ex) {            System.err.println("Initial SessionFactory creation failed." + ex);            throw new ExceptionInInitializerError(ex);        }    }    // 该方法获取的是一个Session工厂    public static SessionFactory getSessionFactory() {        return sessionFactory;    }    // 该方法过去的是一个Session    public static Session getSession(){        return sessionFactory.getCurrentSession();    }}

下面是两个实体类的代码:

package com.model;import javax.persistence.*;@Entity@Table(name = "t_student")public class Student {    @Id    @GeneratedValue(strategy = GenerationType.IDENTITY)    private int id;    private String stuName;    @ManyToOne(cascade = CascadeType.ALL)    @JoinColumn(name = "teacherId")    private Teacher myTeacher; // 在学生类中持有老师的对象,即many方只有one方的对象;    // 省略 getter和setter}

package com.model;import org.hibernate.annotations.Fetch;import javax.persistence.*;import java.util.List;@Entity@Table(name = "t_teacher")public class Teacher {    @Id    @GeneratedValue(strategy = GenerationType.IDENTITY)    private  int id;    private String tchName;    //@OneToMany(mapped=“由One的一方指向Many的一方，并且，这个属性应该等于Many的一方中含有One类的属性的属性名，否则会出错啦 ”)    @OneToMany(cascade = CascadeType.ALL,mappedBy = "myTeacher" )    private List<Student> students;  // 老师类中持有学生类的集合 , 即one方持有many方的集合    // 省略 getter和setter}

最后就是测试类了:

package com.text;import com.model.MyUser;import com.model.Student;import com.model.Teacher;import com.util.HibernateUtil;import org.hibernate.Criteria;import org.hibernate.Session;import org.hibernate.Transaction;import org.hibernate.criterion.Restrictions;import java.util.Iterator;import java.util.List;public class JavaTest {    public static void main(String[] args) throws Exception{        save();//      getStudents();//      getStudentsByName();    }    public static void save(){        Session session = HibernateUtil.getSession();        Transaction tx = session.beginTransaction();        Teacher t = new Teacher();        t.setTchName("guangTouQiang");        Student s1 = new Student();        s1.setStuName("xiongDa");        s1.setTeacher(t);        session.save(s1);        Student s2 = new Student();        s2.setStuName("xiongEr");        s2.setTeacher(t);        session.save(s2);        tx.commit();    }    public static void getStudents(){        Session session = HibernateUtil.getSession();        session.beginTransaction();        Criteria criteria = session.createCriteria(Student.class,"s");        List list = criteria.list();        Iterator<Student> iterator = list.iterator();        while(iterator.hasNext()){            Student s  = iterator.next();            System.out.println( s.getId()+"***"+ s.getStuName()+"***"+s.getTeacher().getTchName());        }    }    public static void getStudentsByName(){        Session session = HibernateUtil.getSession();        session.beginTransaction();        Criteria criteria = session.createCriteria(Student.class);        // 精准查询        List list = criteria.add(Restrictions.eq("stuName","xiongDa")).list();        //模糊查询      //List list = criteria.add(Restrictions.like("stuName","xiong%")).list();        Iterator<Student> iterator = list.iterator();        while(iterator.hasNext()){            Student s  = iterator.next();            System.out.println( s.getId()+"***"+ s.getStuName()+"***"+s.getTeacher().getTchName());        }    }}

关于更过Criteria高级查询用法，请参见：http://blog.csdn.net/qq_28082757/article/details/68938941

踏实一些，不要着急，你想要的，岁月都会给你。