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  • 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

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  • 原文地址:https://www.cnblogs.com/liuyingke/p/7115264.html
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