Hibernate学习总结

Hibernate学习总结----

一、搭建Hibernate环境

使用Hibernate必须要导入3个jar包在pom.xml中的<dependencies> </dependencies>中插入jar包

 1 <dependency>
 2       <groupId>org.hibernate</groupId>
 3       <artifactId>hibernate-core</artifactId>
 4       <version>3.5.0-Final</version>
 5     </dependency>
 6 
 7 
 8     <dependency>
 9       <groupId>org.slf4j</groupId>
10       <artifactId>slf4j-log4j12</artifactId>
11       <version>1.5.8</version>
12     </dependency>
13 
14 
15     <dependency>
16       <groupId>org.javassist</groupId>
17       <artifactId>javassist</artifactId>
18       <version>3.13.0-GA</version>
19     </dependency>

1.在src目录下创建hibernate.cfg.xml配置文件没有数据库的话要创建数据库，表会自动建

PS:文件的名字不能改！

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <!DOCTYPE hibernate-configuration
 3         PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
 4         "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
 5 <hibernate-configuration>
 6     <session-factory>
 7         <property name="hbm2ddl.auto">update</property><!--自动生成数据库表-->
 8         <property name="dialect">org.hibernate.dialect.MySQLDialect</property><!--数据库方言-->
 9         <property name="connection.url">jdbc:mysql://localhost:3306/hibernate</property>
10         <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
11         <property name="connection.username">root</property>
12         <property name="connection.password">1234</property>
13         <!--设置输出sql语句 若为true，表示在程序运行时，将在控制台输出SQL语句默认false-->
14         <property name="show_sql">true</property>
15         <mapping resource="hbm/user.hbm.xml"/><!--加载映射文件-->
16     </session-factory>
17 </hibernate-configuration>

2. 编写实体类，以User类为例

 1 package cn.yunhe.entity;
 2 
 3 import java.util.Date;
 4 
 5 /**
 6  * Created by Administrator on 2017/7/4.
 7  */
 8 public class User {
 9     private int userid;//用户id
10     private String uname;//用户名
11     private String upwd;//密码
12     private int age;//年龄
13     private Date hiredate;//注册日期
14 
15     public Date getHiredate() {
16         return hiredate;
17     }
18 
19     public void setHiredate(Date hiredate) {
20         this.hiredate = hiredate;
21     }
22 
23     public int getUserid() {
24         return userid;
25     }
26 
27     public void setUserid(int userid) {
28         this.userid = userid;
29     }
30 
31     public String getUname() {
32         return uname;
33     }
34 
35     public void setUname(String uname) {
36         this.uname = uname;
37     }
38 
39     public String getUpwd() {
40         return upwd;
41     }
42 
43     public void setUpwd(String upwd) {
44         this.upwd = upwd;
45     }
46 
47     public int getAge() {
48         return age;
49     }
50 
51     public void setAge(int age) {
52         this.age = age;
53     }
54 }

3.创建映射文件 hbm/user.hbm.xml

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <!DOCTYPE hibernate-mapping PUBLIC
 3         "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
 4         "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
 5 <!--映射文件-->
 6 <hibernate-mapping>
 7     <class name="cn.yunhe.entity.User" table="t_user">
 8         <id name="userid" type="java.lang.Integer">
 9             <column name="userid"/>
10             <!--mysql用identity -->
11             <generator class="identity"/>
12             <!--oracle用sequence-->
13            <!-- <generator class="sequence">
14                 <param name="sequence">SEQ_ID</param>
15             </generator>-->
16             <!--不知道是mysql还是Oracle就用native 如果是Oracle它会自动创建序列，如果是mysql它也能用-->
17             <!--<generator class="native"/>-->
18         </id>
19         <property name="uname" type="java.lang.String">
20             <column name="uname" length="20"/>
21         </property>
22         <property name="upwd" type="java.lang.String">
23             <column name="upwd" length="20"/>
24         </property>
25         <property name="age" type="java.lang.Integer">
26             <column name="age"/>
27         </property>
28         <property name="hiredate" type="java.util.Date">
29             <column name="hiredate"/>
30         </property>
31      </class>
32 </hibernate-mapping>

4.创建测试类Demo

 1 import cn.yunhe.entity.User;
 2 import org.hibernate.Session;
 3 import org.hibernate.SessionFactory;
 4 import org.hibernate.Transaction;
 5 import org.hibernate.cfg.Configuration;
 6 import org.junit.After;
 7 import org.junit.Before;
 8 import org.junit.Test;
 9 
10 import java.util.Date;
11 
12 /**
13  * 测试类
14  * Created by Administrator on 2017/7/4.
15  */
16 public class demo  {
17     Session session=null;//Session接口：负责保存、更新、删除、加载以及查询对象
18     Transaction tr=null;//管理事务 执行增删改操作后要 tr.comment()；
19 
20     @Before
21     //目标方法前的方法  用与获得session
22     public void setUp() throws Exception{
23         //获得Hibernate配置管理接口Configuration
24         Configuration configuration=new Configuration().configure();
25         //根据Configuration实例创建session的工厂类SessionFactory
26         SessionFactory factory=configuration.buildSessionFactory();
27         //通过session工厂获得session实例
28         session=factory.openSession();
29     }
30 
31     @Test
32     //添加用户
33     public void testSave(){
34         tr=session.beginTransaction();//在单元测试的setUp()方法中获得session对象，开启事务
35         User user=new User();
36         user.setUname("弗拉基米尔");
37         user.setUpwd("1234");
38         user.setAge(1000);
39         user.setHiredate(new Date());
40         session.save(user);//执行添加功能，会自动建表
41         tr.commit();//提交事务
42     }
43     @Test
44     //查询用户
45     public void testFindById(){
46         //get里第一个参数是实体类，第二个参数是所要查询的用户id
47         User user=(User) session.get(User.class,new Integer(2));
48         System.out.println("用户id："+user.getUserid());
49         System.out.println("用户名："+user.getUname());
50         System.out.println("密码："+user.getUpwd());
51         System.out.println("年龄："+user.getAge());
52         System.out.println("注册日期："+user.getHiredate());
53         //查询不用提交事务  tearDown会关闭session
54     }
55 
56     @Test
57     //修改用户  实际上是根据id查，改了再修改
58     public void testModify(){
59         tr=session.beginTransaction();///在单元测试的setUp()方法中获得session对象
60         //先根据id查询出来要修改的数据
61         User user=(User) session.get(User.class,new Integer(2));
62         //把要修改的内容放入 user中
63         user.setAge(600);
64         session.update(user); //可以省略
65         tr.commit();//提交事务
66     }
67 
68     @Test
69     //删除用户
70     public void testDel(){
71         tr=session.beginTransaction();
72         //根据id查出来，然后再删除
73         User user=(User)session.get(User.class,2);
74         session.delete(user);
75         tr.commit();
76     }
77 
78     @After
79     //目标方法后的方法 用于关闭sesseion 对象
80     public void tearDown() throws Exception{
81         session.close();
82     }
83 }

二、主键生成策略

identity：使用数据库的自动增长策略，不是所有数据库都支持，比如oracle就不支持。

sequence：在 DB2，PostgreSQL，Oracle，SAP DB，McKoi 中使用序列（sequence）在使用Oracle数据库时可以使用这一个。

hilo:使用高低位算法生成主键值。只需要一张额外表，所有的数据都支持。

native:根据底层数据库的能力选择 identity、sequence 或者 hilo中的一个。

assigned：手工指定主键值。

uuid：由Hibernate自动生成UUID并指定为主键值。

三、Hibernate映射关系配置

1.一对一映射（以主键关联作为示例）User与IdCard（有外键方）的XML配置：

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<!-- 
    Mapping file autogenerated by MyEclipse Persistence Tools
-->
<hibernate-mapping package="test.Hibernate.model">
    <class name="User" table="user">
        <id name="id" type="int" column="id">
            <generator class="native"></generator>
        </id>
        
        <property name="name" type="string" column="name"/>        
        
         <set name="address" table="address">    
            <key column="userId"></key>
            <element column="address" type="string"></element>
        </set>
        
        <one-to-one name="idCard" class="IdCard" cascade="all"></one-to-one>     
    </class>
</hibernate-mapping>

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<!-- 
    Mapping file autogenerated by MyEclipse Persistence Tools
-->
<hibernate-mapping package="test.Hibernate.model">
    <class name="IdCard" table="idCard">
        <id name="id" type="int" column="id">
            <generator class="foreign">
                <param name="property">user</param>
            </generator>
        </id>
        <property name="number" type="string" column="number"/>        
        <one-to-one name="user" class="User" constrained="true"></one-to-one>
        
    </class>
</hibernate-mapping>

2.一对多，多对一（以qx(区县)和jd(街道)为例）外键要设置可以为空，不然不能进行插入数据

（1）Jd.hbm.xml

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <!DOCTYPE hibernate-mapping PUBLIC
 3         "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
 4         "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
 5 <hibernate-mapping>
 6     <class name="cn.yunhe.model.Jd" table="jd">
 7         <id name="jdid" column="jdid" type="java.lang.Integer">
 8             <generator class="native"/>
 9         </id>
10         <property name="jdname" column="jdname" type="java.lang.String"/>
11 
12         <!--多对一-->
13         <many-to-one name="qx" class="cn.yunhe.model.Qx" column="qxid"/>
14 
15     </class>
16 </hibernate-mapping>

(2) Qx.hbm.xml

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <!DOCTYPE hibernate-mapping PUBLIC
 3         "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
 4         "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
 5 <hibernate-mapping>
 6     <class name="cn.yunhe.model.Qx" table="qx">
 7         <id name="qxid" column="qxid" type="java.lang.Integer">
 8             <generator class="native"/>
 9         </id>
10         <property name="qxname" column="qxname"/>
11 
12         <set name="jds" inverse="false" cascade="all">   <!--反转-->
13             <key column="qxid"/>
14             <one-to-many class="cn.yunhe.model.Jd"/>
15         </set>
16 
17     </class>
18 
19 </hibernate-mapping>

(3) Demo

  1 import cn.yunhe.model.Jd;
  2 import cn.yunhe.model.Qx;
  3 import org.hibernate.Session;
  4 import org.hibernate.SessionFactory;
  5 import org.hibernate.Transaction;
  6 import org.hibernate.cfg.Configuration;
  7 import org.junit.After;
  8 import org.junit.Before;
  9 import org.junit.Test;
 10 
 11 import java.util.Iterator;
 12 
 13 /**
 14  * Created by Administrator on 2017/7/5.
 15  */
 16 public class Demo {
 17 
 18     Session session=null;
 19     Transaction tr=null;
 20 
 21     @Before
 22     public void setUp(){
 23         //获得session
 24         Configuration config=new Configuration().configure();
 25         SessionFactory factory=config.buildSessionFactory();
 26         session=factory.openSession();
 27         tr=session.beginTransaction();
 28     }
 29 
 30     @Test
 31     //多对一查询
 32     public void manyToOne(){
 33         //查询出街道以及对应的区县
 34         Jd jd = (Jd) session.get(Jd.class,1);
 35         String qxname = jd.getQx().getQxname();
 36 
 37         System.out.println("街道：" + jd.getJdname() + "所在的区县是：" + qxname);
 38 
 39     }
 40 
 41     @Test
 42     //一对多查询
 43     public void oneToMany(){
 44         //查询出一个区县下的所有街道
 45         Qx qx=(Qx)session.get(Qx.class,1);//查出区县
 46         System.out.println("区县"+qx.getQxname()+"下有:");
 47         //遍历输出qx的属性jds中所有的jd对象
 48         Iterator<Jd> it =qx.getJds().iterator();
 49         while (it.hasNext()){
 50             Jd jd=it.next();
 51             System.out.println(jd.getJdname());
 52         }
 53     }
 54 
 55     @Test
 56     //在one一方添加数据 增加一个区县：黄河区
 57     public void testAddOne(){
 58         Qx qx=new Qx();
 59         qx.setQxname("黄河区");
 60         session.save(qx);
 61         tr.commit();
 62     }
 63 
 64     @Test
 65     //在many一方添加数据 增加山南区下属的三个街道：“和平路”、“八一路”和“五四大道”
 66     //有一点要注意，应设置外键可以为null
 67     public void testAddMany(){
 68         //保存多的一方
 69         Jd jd1=new Jd();
 70         jd1.setJdname("和平路");
 71         Jd jd2=new Jd();
 72         jd2.setJdname("八一路");
 73         Jd jd3=new Jd();
 74         jd3.setJdname("五四大道");
 75         session.save(jd1);
 76         session.save(jd2);
 77         session.save(jd3);
 78         //保存一的一方
 79         Qx qx=new Qx();
 80         qx.setQxname("南山区");
 81         qx.getJds().add(jd1);
 82         qx.getJds().add(jd2);
 83         qx.getJds().add(jd3);
 84 
 85         session.save(qx);
 86         tr.commit();
 87     }
 88 
 89     @Test
 90     //在many一方删除数据
 91     //给配置文件中set属性增加inverse属性，设为false
 92     public void delMany(){
 93         //获取被删除的对象
 94         Jd jd=(Jd) session.get(Jd.class,41);
 95         Qx qx=(Qx) session.get(Qx.class,jd.getQx().getQxid());
 96         //先在一的一方的集合中把删除的对象删除
 97         qx.getJds().remove(jd);
 98         //再使用session的delete删除
 99         session.delete(jd);
100         tr.commit();
101     }
102 
103     @Test
104     //在one的一方删除数据
105     public void delOne(){
106         Qx qx=(Qx)session.get(Qx.class,5);
107         session.delete(qx);
108         tr.commit();
109     }
110 
111     @After
112     public void tearDown(){
113         //关闭session
114         session.close();
115     }
116 }

(4) Qx.java(区县实体类)

 1 package cn.yunhe.model;
 2 
 3 import java.util.HashSet;
 4 import java.util.Set;
 5 
 6 /**
 7  * Created by Administrator on 2017/7/5.
 8  */
 9 public class Qx {//区县
10     private int qxid;
11     private String qxname;
12     private Set<Jd> jds =new HashSet<Jd>();//街道集合
13 
14     public int getQxid() {
15         return qxid;
16     }
17 
18     public void setQxid(int qxid) {
19         this.qxid = qxid;
20     }
21 
22     public String getQxname() {
23         return qxname;
24     }
25 
26     public void setQxname(String qxname) {
27         this.qxname = qxname;
28     }
29 
30     public Set<Jd> getJds() {
31         return jds;
32     }
33 
34     public void setJds(Set<Jd> jds) {
35         this.jds = jds;
36     }
37 }

（5）Jd.java(街道实体类)

 1 package cn.yunhe.model;
 2 
 3 /**
 4  * Created by Administrator on 2017/7/5.
 5  */
 6 public class Jd {//街道
 7     private int jdid;
 8     private String jdname;
 9     private Qx qx;//区县
10 
11     public int getJdid() {
12         return jdid;
13     }
14 
15     public void setJdid(int jdid) {
16         this.jdid = jdid;
17     }
18 
19     public String getJdname() {
20         return jdname;
21     }
22 
23     public void setJdname(String jdname) {
24         this.jdname = jdname;
25     }
26 
27     public Qx getQx() {
28         return qx;
29     }
30 
31     public void setQx(Qx qx) {
32         this.qx = qx;
33     }
34 }

3.多对多（以Student和Teacher为例）

PS:有一方的set集合要标明inverse=true（后面会讲）

表： student(id name) teacher( id name ) 中间表： student_teacher(列：studentid (fk) teacherid(fk))

(1) Student.hbm.xml

 1 <?xml version="1.0" encoding="utf-8"?>
 2 <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
 3         "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
 4 <hibernate-mapping package="cn.yunhe.model">
 5     <class name="Student" table="student">
 6         <id name="id" column="id" type="java.lang.Integer">
 7             <generator class="native"/>
 8         </id>
 9         <property name="name" column="name" type="java.lang.String"/>
10 
11         <set name="teachers" table="student_teacher" inverse="false">
12             <key column="studentid"></key>
13             <many-to-many class="Teacher" column="teacherid"></many-to-many>
14         </set>
15     </class>
16 </hibernate-mapping>

(2)Teacher.hbm.xml

 1 <?xml version="1.0" encoding="utf-8"?>
 2 <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
 3         "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
 4 <hibernate-mapping package="cn.yunhe.model">
 5     <class name="Teacher" table="teacher">
 6         <id name="id" column="id" type="java.lang.Integer">
 7             <generator class="native"/>
 8         </id>
 9         <property name="name" column="name" type="java.lang.String"/>
10 
11         <set name="students" table="student_teacher" inverse="true" cascade="all">
12             <key column="teacherid"></key>
13             <many-to-many class="Student"  column="studentid"></many-to-many>
14         </set>
15     </class>
16 </hibernate-mapping>

(3 ) 实体类Student

 1 package cn.yunhe.model;
 2 
 3 import java.util.HashSet;
 4 import java.util.Set;
 5 
 6 /**
 7  * Created by Administrator on 2017/7/5.
 8  */
 9 public class Student
10 {
11     private int id;
12     private String name;
13     private Set<Teacher> teachers =new HashSet<Teacher>();
14 
15     public int getId() {
16         return id;
17     }
18 
19     public void setId(int id) {
20         this.id = id;
21     }
22 
23     public String getName() {
24         return name;
25     }
26 
27     public void setName(String name) {
28         this.name = name;
29     }
30 
31     public Set<Teacher> getTeachers() {
32         return teachers;
33     }
34 
35     public void setTeachers(Set<Teacher> teachers) {
36         this.teachers = teachers;
37     }
38 }

(4) 实体类Teacher

 1 package cn.yunhe.model;
 2 
 3 import java.util.HashSet;
 4 import java.util.Set;
 5 
 6 /**
 7  * Created by Administrator on 2017/7/5.
 8  */
 9 public class Teacher {
10     private int id;
11     private String name;
12     private Set<Student> students=new HashSet<Student>();
13 
14     public int getId() {
15         return id;
16     }
17 
18     public void setId(int id) {
19         this.id = id;
20     }
21 
22     public String getName() {
23         return name;
24     }
25 
26     public void setName(String name) {
27         this.name = name;
28     }
29 
30     public Set<Student> getStudents() {
31         return students;
32     }
33 
34     public void setStudents(Set<Student> students) {
35         this.students = students;
36     }
37 }

(5) 测试类 Demo2

 1 import cn.yunhe.model.Student;
 2 import cn.yunhe.model.Teacher;
 3 import org.hibernate.Session;
 4 import org.hibernate.SessionFactory;
 5 import org.hibernate.Transaction;
 6 import org.hibernate.cfg.Configuration;
 7 import org.junit.After;
 8 import org.junit.Before;
 9 import org.junit.Test;
10 
11 
12 /**
13  * Created by Administrator on 2017/7/5.
14  */
15 public class Demo2 {
16     Session session=null;
17     Transaction tr=null;
18 
19     @Before
20     public void setUp(){
21         //获得session
22         Configuration config=new Configuration().configure();
23         SessionFactory factory=config.buildSessionFactory();
24         session=factory.openSession();
25         tr=session.beginTransaction();
26     }
27 
28     @Test
29     public void manyToMany(){
30         Teacher teacher1=new Teacher();
31         Teacher teacher2=new Teacher();
32         Teacher teacher3=new Teacher();
33         teacher1.setName("刘备");
34         teacher2.setName("曹操");
35         teacher3.setName("孙权");
36         session.save(teacher1);
37         session.save(teacher2);
38         session.save(teacher3);
39         Student student1=new Student();
40         Student student2=new Student();
41         Student student3=new Student();
42         student1.setName("诸葛亮");
43         student2.setName("司马懿");
44         student3.setName("陆逊");
45         student1.getTeachers().add(teacher1);
46         student1.getTeachers().add(teacher3);
47         student2.getTeachers().add(teacher2);
48         student2.getTeachers().add(teacher3);
49         student3.getTeachers().add(teacher1);
50         student3.getTeachers().add(teacher2);
51 
52         session.save(student1);
53         session.save(student2);
54         session.save(student3);
55         tr.commit();
56     }
57 
58     @After
59     public void tearDown(){
60         //关闭session
61         session.close();
62     }
63 }

四、inverse和cascade的区别（个人总结，有不对还望指正）

1.inverse=false 在many一方删除数据时给配置文件中set属性增加inverse属性，设为false （由many一方负责维护关联）

2.set节点之cascade属性：

all : 对所有操作都进行级联

none : 对所有操作都不进行级联

save-update : 执行更新操作时级联 delete 执行删除操作时级联

3.many to many的时候由一方维护，所以一方要设置inverse=false，但是inverse=true的另一方直接删除会出错，这个时候可以用casecade完成级联删除

4.inverse=false只用于set等集合属性，在one to one关系中可以用casecade完成级联删除

五、使用C3P0连接池

1.需要额外导入3个jar包

2.在hibernate.cfg.xml中加入C3P0配置信息

        <!-- C3P0连接池设定-->
        <!-- 使用c3p0连接池  配置连接池提供的供应商-->
        <property name="connection.provider_class">org.hibernate.connection.C3P0ConnectionProvider</property>
        <!--在连接池中可用的数据库连接的最少数目 -->
        <property name="c3p0.min_size">5</property>
        <!--在连接池中所有数据库连接的最大数目  -->
        <property name="c3p0.max_size">20</property>
        <!--设定数据库连接的过期时间,以秒为单位,
        如果连接池中的某个数据库连接处于空闲状态的时间超过了timeout时间,就会从连接池中清除 -->
        <property name="c3p0.timeout">120</property>
         <!--每3000秒检查所有连接池中的空闲连接 以秒为单位-->
        <property name="c3p0.idle_test_period">3000</property>

六、HQL语句

@Test
    public void HQLSearch(){
        Session session = SessionFactory.getSession();
        Transaction tr = session.beginTransaction();
        //-----------------------------------------
        
        //common search with where
//        String hql= "select e.id,e.name from User e where e.id>=5 and e.id<=9";
//        Query query = session.createQuery(hql);
//        List list = query.list();        
//        for(Object o : list){            
//            System.out.println(Arrays.toString((Object[])o));
//        }
        
        //paging search
//        String hql= "select e.id,e.name from User e";
//        Query query = session.createQuery(hql);
//        query.setFirstResult(0);
//        query.setMaxResults(10);
//        List list = query.list();        
//        for(Object o : list){            
//            System.out.println(Arrays.toString((Object[])o));
//        }
        
        //search with parameters
//        String hql= "select e.id,e.name from User e where id>=? and id<=?";
//        Query query = session.createQuery(hql)
//                .setParameter(0, 1)
//                .setParameter(1, 3);
//        List list = query.list();        
//        for(Object o : list){            
//            System.out.println(Arrays.toString((Object[])o));
//        }
        
        //search with parameters whose type is collection
//        String hql= "select e.id,e.name from User e where id in (:ids)";
//        Query query = session.createQuery(hql)
//                .setParameterList("ids",new Object[]{1,2,3,8} );
//        List list = query.list();    
//        for(Object o : list){            
//            System.out.println(Arrays.toString((Object[])o));
//        }
        
        
        //-----------------------------------------
        tr.commit();
        SessionFactory.closeSession();
    }

七、DML语句

@Test
    public void DML(){
        Session session = SessionFactory.getSession();
        Transaction tr = session.beginTransaction();
        //-----------------------------------------
        User u = (User)session.get(User.class, 11);
        
        String sql = "update User set name=? where id>?";
        int result = session.createQuery(sql)
                .setParameter(0, "updated")
                .setParameter(1, 10)
                .executeUpdate();
        System.out.println("count of update:"+result);
        
        //the object's status in session was not updated when the object in database have been changed,so if you want
        //to get the updated object in session,you should use method "refresh".
        session.refresh(u);
        
        System.out.println(u);
        
        //-----------------------------------------
        tr.commit();
        SessionFactory.closeSession();
    }

八、开启二级缓存

1. 需要导入以下jar包

2.在hibernate.cfg.xml中加入以下配置

        <!-- 使用二级缓存，默认是未打开的。 -->
        <!-- 指定要使用的缓存的提供商，这也就打开了二级缓存--> 
        <property name="hibernate.cache.use_second_level_cache">true</property>  
        <property name="hibernate.cache.region.factory_class">org.hibernate.cache.ehcache.EhCacheRegionFactory</property>
        <!-- 开启使用查询缓存 -->
        <property name="cache.use_query_cache">true</property>
        <!-- 指定要使用二级缓存的实体类 -->
        <class-cache usage="read-write" class="test.Hibernate.model.Person" />

九、Hibernate对象状态及转化

相关阅读:
javascript-jquery对象的事件处理
 javascript-jquery对象的动画处理
 vue.config.js配置移动端配置自适应rem响应
 vue封装axios
js工具类
 git解决空文件夹无法提交
 vue的axios
vue中axios跨域问题
 全局控制vue的依赖
 linux搭建php环境
原文地址：https://www.cnblogs.com/liuyingke/p/7115264.html