hibernate之CRUD操作

CRUD是指在做计算处理时的增加(Create)、读取(Retrieve)（重新得到数据）、更新(Update)和删除(Delete)几个单词的首字母简写.

下面列举实例来讲解这几个操作：

实体类：

package com.oumyye.model;

public class Student {

    private long id;

    private String name;

    private Class c;

    public long getId() {

        return id;

    }

    public void setId(long id) {

        this.id = id;

    }

    public String getName() {

        return name;

    }

    public void setName(String name) {

        this.name = name;

    }

    public Class getC() {

        return c;

    }

    public void setC(Class c) {

        this.c = c;

    }

    @Override

    public String toString() {

        return "Student [id=" + id + ", name=" + name + "]";

    }

}

package com.oumyye.model;

import java.util.HashSet;

import java.util.Set;

public class Class {

    private long id;

    private String name;

    private Set<Student> students=new HashSet<Student>();

    public long getId() {

        return id;

    }

    public void setId(long id) {

        this.id = id;

    }

    public String getName() {

        return name;

    }

    public void setName(String name) {

        this.name = name;

    }

    public Set<Student> getStudents() {

        return students;

    }

    public void setStudents(Set<Student> students) {

        this.students = students;

    }

}

映射文件：

Student.hbm.xml

<?xml version="1.0"?>

<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"

                                   "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="com.oumyye.model">

 <class name="Student" table="t_student">

  <id column="stuId" name="id">

   <generator class="native"/>

  </id>

  <property column="stuName" generated="never" lazy="false" name="name"/>

  <many-to-one cascade="save-update" class="com.oumyye.model.Class"

   column="classId" name="c"/>

 </class>

</hibernate-mapping>

Class.hbm.xml

<?xml version="1.0"?>

<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"

                                   "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="com.oumyye.model">

 <class name="Class" table="t_class">

  <id column="classId" name="id">

   <generator class="native"/>

  </id>

  <property column="className" generated="never" lazy="false" name="name"/>

  <set cascade="delete" inverse="true" name="students" sort="unsorted">

   <key column="classId"/>

   <one-to-many class="com.oumyye.model.Student"/>

  </set>

 </class>

</hibernate-mapping>

工具类：可以有myeclipse生成

package com.oumyye.util;

import org.hibernate.HibernateException;

import org.hibernate.Session;

import org.hibernate.cfg.Configuration;

import org.hibernate.cfg.AnnotationConfiguration;

/**

 * Configures and provides access to Hibernate sessions, tied to the

 * current thread of execution.  Follows the Thread Local Session

 * pattern, see {@link http://hibernate.org/42.html }.

 */

public class HibernateSessionFactory {

    /**

     * Location of hibernate.cfg.xml file.

     * Location should be on the classpath as Hibernate uses

     * #resourceAsStream style lookup for its configuration file.

     * The default classpath location of the hibernate config file is

     * in the default package. Use #setConfigFile() to update

     * the location of the configuration file for the current session.

     */

    private static final ThreadLocal<Session> threadLocal = new ThreadLocal<Session>();

    private static org.hibernate.SessionFactory sessionFactory;

    private static Configuration configuration = new AnnotationConfiguration();    private static String CONFIG_FILE_LOCATION = "/hibernate.cfg.xml";

    private static String configFile = CONFIG_FILE_LOCATION;

    static {

        try {

            configuration.configure(configFile);

            sessionFactory = configuration.buildSessionFactory();

        } catch (Exception e) {

            System.err.println("%%%% Error Creating SessionFactory %%%%");

            e.printStackTrace();

        }

    }

    private HibernateSessionFactory() {

    }

    /**

     * Returns the ThreadLocal Session instance.  Lazy initialize

     * the <code>SessionFactory</code> if needed.

     *

     *  @return Session

     *  @throws HibernateException

     */

    public static Session getSession() throws HibernateException {

        Session session = (Session) threadLocal.get();

        if (session == null || !session.isOpen()) {

            if (sessionFactory == null) {

                rebuildSessionFactory();

            }

            session = (sessionFactory != null) ? sessionFactory.openSession()

                    : null;

            threadLocal.set(session);

        }

        return session;

    }

    /**

     *  Rebuild hibernate session factory

     *

     */

    public static void rebuildSessionFactory() {

        try {

            configuration.configure(configFile);

            sessionFactory = configuration.buildSessionFactory();

        } catch (Exception e) {

            System.err.println("%%%% Error Creating SessionFactory %%%%");

            e.printStackTrace();

        }

    }

    /**

     *  Close the single hibernate session instance.

     *

     *  @throws HibernateException

     */

    public static void closeSession() throws HibernateException {

        Session session = (Session) threadLocal.get();

        threadLocal.set(null);

        if (session != null) {

            session.close();

        }

    }

    /**

     *  return session factory

     *

     */

    public static org.hibernate.SessionFactory getSessionFactory() {

        return sessionFactory;

    }

    /**

     *  return session factory

     *

     *    session factory will be rebuilded in the next call

     */

    public static void setConfigFile(String configFile) {

        HibernateSessionFactory.configFile = configFile;

        sessionFactory = null;

    }

    /**

     *  return hibernate configuration

     *

     */

    public static Configuration getConfiguration() {

        return configuration;

    }

}

配置文件hibernate.cfg.xml

<?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>

    <!--数据库连接设置 -->

    <property name="connection.driver_class">

        com.mysql.jdbc.Driver

    </property>

    <property name="connection.url">

        jdbc:mysql://localhost:3306/mytest

    </property>

    <property name="connection.username">root</property>

    <property name="connection.password">root</property>

    <!-- 方言 -->

    <property name="dialect">

        org.hibernate.dialect.MySQL5Dialect

    </property>

    <!-- 控制台显示SQL -->

    <property name="show_sql">true</property>

    <!-- 自动更新表结构 -->

    <property name="hbm2ddl.auto">update</property>

    <mapping resource="com/oumyye/model/Class.hbm.xml" />

    <mapping resource="com/oumyye/model/Student.hbm.xml" />

</session-factory>

</hibernate-configuration>

测试类

package com.oumyye.service;

import java.util.Iterator;

import java.util.Set;

import org.hibernate.Session;

import org.hibernate.SessionFactory;

import org.junit.After;

import org.junit.Before;

import org.junit.Test;

import com.oumyye.model.Class;

import com.oumyye.model.Student;

import com.oumyye.util.HibernateSessionFactory;

public class StudentTest {

    private SessionFactory sessionFactory=HibernateSessionFactory.getSessionFactory();

    private Session session;

    @Before

    public void setUp() throws Exception {

        session=sessionFactory.openSession(); // 生成一个session

        session.beginTransaction(); // 开启事务

    }

    @After

    public void tearDown() throws Exception {

         session.getTransaction().commit(); // 提交事务

         session.close(); // 关闭session

    }

    @Test

    public void testSaveClassAndStudent() {

        Class c=new Class();

        c.setName("08计本");

        Student s1=new Student();

        s1.setName("张三");

        s1.setC(c);

        Student s2=new Student();

        s2.setName("李四");

        s2.setC(c);

        session.save(s1);

        session.save(s2);

    }

    @Test

    public void testLoadClass(){

        // Class c=(Class)session.load(Class.class, Long.valueOf(2));

        Class c=(Class)session.load(Class.class, Long.valueOf());

        System.out.println(c.getStudents());

    }

    @Test

    public void testGetClass(){

        // Class c=(Class)session.get(Class.class, Long.valueOf(2));

        Class c=(Class)session.get(Class.class, Long.valueOf());

        System.out.println(c.getStudents());

    }

    @Test

    public void testUpdateClass(){

        Session session1=sessionFactory.openSession();

        session1.beginTransaction();

        Class c=(Class)session1.get(Class.class, Long.valueOf());

        session1.getTransaction().commit(); // 提交事务

        session1.close();

        Session session2=sessionFactory.openSession();

        session2.beginTransaction();

        c.setName("08计算机本科2");

        session2.update(c);

        session2.getTransaction().commit(); // 提交事务

        session2.close();

    }

    <!--更新-->

    @Test

    public void testSaveOrUpdateClass(){

        Session session1=sessionFactory.openSession();

        session1.beginTransaction();

        Class c=(Class)session1.get(Class.class, Long.valueOf());

        session1.getTransaction().commit(); // 提交事务

        session1.close();

        Session session2=sessionFactory.openSession();

        session2.beginTransaction();

        c.setName("08计算机本科3");

        Class c2=new Class();

        c2.setName("09计算机本科3");

        session2.saveOrUpdate(c);

        session2.saveOrUpdate(c2);

        session2.getTransaction().commit(); // 提交事务

        session2.close();

    }

    @Test

    public void testMergeClass(){

        Session session1=sessionFactory.openSession();

        session1.beginTransaction();

        Class c=(Class)session1.get(Class.class, Long.valueOf());

        session1.getTransaction().commit(); // 提交事务

        session1.close();

        Session session2=sessionFactory.openSession();

        session2.beginTransaction();

        Class c2=(Class)session2.get(Class.class, Long.valueOf());

        c.setName("08计算机本科4");

        session2.merge(c);

        session2.getTransaction().commit(); // 提交事务

        session2.close();

    }

    <!--删除-->

    @Test

    public void testDeleteStudent(){

        Student student=(Student)session.load(Student.class, Long.valueOf());

        session.delete(student);

    }

}

package com.oumyye.service;

import java.util.Iterator;

import java.util.Set;

import org.hibernate.Session;

import org.hibernate.SessionFactory;

import org.junit.After;

import org.junit.Before;

import org.junit.Test;

import com.oumyye.model.Class;

import com.oumyye.model.Student;

import com.oumyye.util.HibernateSessionFactory;

public class StudentTest {

    private SessionFactory sessionFactory=HibernateSessionFactory.getSessionFactory();

    private Session session;

    @Before

    public void setUp() throws Exception {

        session=sessionFactory.openSession(); // 生成一个session

        session.beginTransaction(); // 开启事务

    }

    @After

    public void tearDown() throws Exception {

         session.getTransaction().commit(); // 提交事务

         session.close(); // 关闭session

    }

    @Test

    public void testSaveClassAndStudent() {

        Class c=new Class();

        c.setName("08计本");

        Student s1=new Student();

        s1.setName("张三");

        s1.setC(c);

        Student s2=new Student();

        s2.setName("李四");

        s2.setC(c);

        session.save(s1);

        session.save(s2);

    }

    @Test

    public void testLoadClass(){

        // Class c=(Class)session.load(Class.class, Long.valueOf(2));

        Class c=(Class)session.load(Class.class, Long.valueOf());

        System.out.println(c.getStudents());

    }

    @Test

    public void testGetClass(){

        // Class c=(Class)session.get(Class.class, Long.valueOf(2));

        Class c=(Class)session.get(Class.class, Long.valueOf());

        System.out.println(c.getStudents());

    }

    @Test

    public void testUpdateClass(){

        Session session1=sessionFactory.openSession();

        session1.beginTransaction();

        Class c=(Class)session1.get(Class.class, Long.valueOf());

        session1.getTransaction().commit(); // 提交事务

        session1.close();

        Session session2=sessionFactory.openSession();

        session2.beginTransaction();

        c.setName("08计算机本科2");

        session2.update(c);

        session2.getTransaction().commit(); // 提交事务

        session2.close();

    }

    <!--更新-->

    @Test

    public void testSaveOrUpdateClass(){

        Session session1=sessionFactory.openSession();

        session1.beginTransaction();

        Class c=(Class)session1.get(Class.class, Long.valueOf());

        session1.getTransaction().commit(); // 提交事务

        session1.close();

        Session session2=sessionFactory.openSession();

        session2.beginTransaction();

        c.setName("08计算机本科3");

        Class c2=new Class();

        c2.setName("09计算机本科3");

        session2.saveOrUpdate(c);

        session2.saveOrUpdate(c2);

        session2.getTransaction().commit(); // 提交事务

        session2.close();

    }

    @Test

    public void testMergeClass(){

        Session session1=sessionFactory.openSession();

        session1.beginTransaction();

        Class c=(Class)session1.get(Class.class, Long.valueOf());

        session1.getTransaction().commit(); // 提交事务

        session1.close();

        Session session2=sessionFactory.openSession();

        session2.beginTransaction();

        Class c2=(Class)session2.get(Class.class, Long.valueOf());

        c.setName("08计算机本科4");

        session2.merge(c);

        session2.getTransaction().commit(); // 提交事务

        session2.close();

    }

    <!--删除-->

    @Test

    public void testDeleteStudent(){

        Student student=(Student)session.load(Student.class, Long.valueOf());

        session.delete(student);

    }

}

Session的入门常用方法

Query query = session.createQuery(hql)：利用hql查询语句查询；
Criteria critera = session.createCriteria(Class clazz);
(3)Transaction tx = session.beginTransaction(); //开始事务；tx.commit()提交事务；
session.close();//关闭Session，此后被session管理的持久化对象变为脱管状态；
session.save(Object obj); //添加
session.update(Object obj); //更新
session.delete(Object obj); //删除
Object obj = session.get(Class clazz,Serialiazble id); //根据主键查找记录并返回；
Object obj = session.load(Class clazz,Serializable id); //和get方法效果一样，但是是懒加载，即在不使用他之前他不会返回对象；

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