Hibernate高级配置

1. 配置数据库连接池

反问数据库，需要不断的创建和释放连接，假如访问量大的话，效率比较低级，服务器消耗大；
使用数据库连接池，我们可以根据实际项目的情况，定义连接池的连接个数，从而可以实现从连接池获取连接，用户放回到连接池。从而有效的提高的系统的执行效率；
Hibernate自带的连接池不是很好，有bug；
推荐使用C3P0,proxool等；

新建项目Hibernate11

导入C3P0 jar包，右键buildPath

c3p0-0.9.2.1.jar
hibernate-c3p0-4.3.5.Final.jar
mchange-commons-java-0.2.3.4.jar

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/hibernate4</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>
        <!-- 最小连接数 --> 
        <property name="c3p0.min_size">7</property> 
        <!-- 最大连接数 -->   
        <property name="c3p0.max_size">42</property> 
        <!-- 获得连接的超时时间,如果超过这个时间,会抛出异常，单位毫秒 -->  
        <property name="c3p0.timeout">1800</property> 
        <!-- 最大的PreparedStatement的数量 -->   
        <property name="c3p0.max_statements">50</property>
        <!-- Mapper -->
        <mapping resource="com/andrew/model/Student.hbm.xml"/>
    </session-factory>
</hibernate-configuration>

HibernateUtil.java

package com.andrew.util;
import org.hibernate.SessionFactory;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
public class HibernateUtil {
    private static final SessionFactory sessionFactory = buildSessionFactory();
    private static SessionFactory buildSessionFactory() {
        // 1. 实例化配置文件
        Configuration configuration = new Configuration().configure();
        // 2. 实例化服务登记
        ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder()
                .applySettings(configuration.getProperties()).build();
        // 3. 获取Session工厂
        return configuration.buildSessionFactory(serviceRegistry);
    }
    public static SessionFactory getSessionFactory() {
        return sessionFactory;
    }
}

Student.java

package com.andrew.model;
public class Student {
    private int id;
    private String name;
    private int age;
    public 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;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    @Override
    public String toString() {
        return "Student [id=" + id + ", name=" + name + ", age=" + age + "]";
    }
}

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.andrew.model">
    <class name="Student" table="t_student">
        <id name="id" column="stuId">
            <generator class="native"></generator>
        </id>
        <property name="name" column="stuName"></property>
        <property name="age" column="stuAge"></property>
    </class>
</hibernate-mapping>

StudentTest.java

package com.andrew.service;
import java.util.Iterator;
import java.util.List;
import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
import com.andrew.model.Student;
import com.andrew.util.HibernateUtil;
public class StudentTest {
    private SessionFactory sessionFactory = HibernateUtil.getSessionFactory();
    private Session session;
    @Before
    public void setUp() throws Exception {
        session = sessionFactory.openSession(); // 1. 生成一个session
        session.beginTransaction(); // 2. 开启事务
    }
    @After
    public void tearDown() throws Exception {
        session.getTransaction().commit(); // 3. 提交事务
        session.close(); // 4. 关闭session
    }
    @Test
    public void testSQLQuery() {
        String sql = "select * from t_student";
        Query query = session.createSQLQuery(sql).addEntity(Student.class);
        List studentList = query.list();
        Iterator it = studentList.iterator();
        while (it.hasNext()) {
            Student s = (Student)it.next();
            System.out.println(s);
        }        
    }
}

运行结果：
Hibernate: select * from t_student
Student [id=1, name=张三, age=10]
Student [id=2, name=李四, age=15]
Student [id=3, name=王五, age=13]

2.  配置日志框架Log4J

Log4J作为一个开源的优秀日志框架，被广泛使用，Hibernate4必须包中直接支持Log4J日志框架；我们只需要引入Log4jjar包，即可使用；

导入log4j jar包，邮件buildPath

log4j-1.2.17.jar

log4j.properties

log4j.rootLogger=info,appender1,appender2
log4j.appender.appender1=org.apache.log4j.ConsoleAppender 
log4j.appender.appender2=org.apache.log4j.FileAppender 
log4j.appender.appender2.File=E:/hibernate4_logFile.txt
log4j.appender.appender1.layout=org.apache.log4j.TTCCLayout
log4j.appender.appender2.layout=org.apache.log4j.TTCCLayout  

StudentTest.java

private Logger logger = Logger.getLogger(StudentTest.class);
@Test
public void testSQLQuery() {
    String sql = "select * from t_student";
    Query query = session.createSQLQuery(sql).addEntity(Student.class);
    List studentList = query.list();
    Iterator it = studentList.iterator();
    while (it.hasNext()) {
        Student s = (Student)it.next();
        System.out.println(s);
    }
    logger.debug("这是一个debug信息");
    logger.info("这是一个info信息");
    logger.error("这是一个错误信息");
}

运行结果：
Hibernate: select * from t_student
Student [id=1, name=张三, age=10]
Student [id=2, name=李四, age=15]
Student [id=3, name=王五, age=13]
[main] INFO com.andrew.service.StudentTest - 这是一个info信息
[main] ERROR com.andrew.service.StudentTest - 这是一个错误信息
生成文件：
hibernate4_logFile.txt

3. 配置Hibernate二级缓存

新建项目Hibernate11-02

3.1) 缓存的概念

缓存是介于物理数据源与应用程序之间，是对数据库中的数据复制一份临时放在内存或者硬盘中的容器，其作用是为了减少应用程序对物理数据源访问的次数，从而提高了应用程序的运行性能。Hibernate在进行读取数据的时候，根据缓存机制在相应的缓存中查询，如果在缓存中找到了需要的数据(我们把这称做"缓存命中")，则就直接把命中的数据作为结果加以利用，避免了大量发送SQL语句到数据库查询的性能损耗。

3.2) Hibernate缓存的分类

3.2.1) Session缓存(又称作事务缓存)：Hibernate内置的，不能卸除。

缓存范围：缓存只能被当前Session对象访问。缓存的生命周期依赖于Session的生命周期，当Session被关闭后，缓存也就结束生命周期。

3.2.2) SessionFactory缓存(又称作应用缓存)：使用第三方插件，可插拔。

缓存范围：缓存被应用范围内的所有session共享,不同的Session可以共享。这些session有可能是并发访问缓存，因此必须对缓存进行更新。缓存的生命周期依赖于应用的生命周期，应用结束时，缓存也就结束了生命周期，二级缓存存在于应用程序范围。

3.3) 二级缓存策略提供商

提供了HashTable缓存，EHCache，OSCache，SwarmCache，jBossCathe2，这些缓存机制，其中EHCache，OSCache是不能用于集群环境(ClusterSafe)的，而SwarmCache，jBossCathe2是可以的。HashTable缓存主要是用来测试的，只能把对象放在内存中，EHCache，OSCache可以把对象放在内存(memory)中，也可以把对象放在硬盘(disk)上。

3.4) 什么数据适合放二级缓存中

(1) 经常被访问
(2) 改动不大
(3) 数量有限
(4) 不是很重要的数据，允许出现偶尔并发的数据。
比如组织机构代码，列表信息等；

4) 配置EHCache二级缓存

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/hibernate4</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>
        <!-- Mapper -->
        <mapping resource="com/andrew/model/Student.hbm.xml"/>
        <mapping resource="com/andrew/model/Class.hbm.xml"/>
    </session-factory>
</hibernate-configuration>

HibernateUtil.java

package com.andrew.util;
import org.hibernate.SessionFactory;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
public class HibernateUtil {
    private static final SessionFactory sessionFactory = buildSessionFactory();
    private static SessionFactory buildSessionFactory() {
        // 1. 实例化配置文件
        Configuration configuration = new Configuration().configure();
        // 2. 实例化服务登记
        ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder()
                .applySettings(configuration.getProperties()).build();
        // 3. 获取Session工厂
        return configuration.buildSessionFactory(serviceRegistry);
    }
    public static SessionFactory getSessionFactory() {
        return sessionFactory;
    }
}

Class.java

package com.andrew.model;
public class Class {
    private long id;
    private String name;
    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;
    }
}

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.andrew.model">
    <class name="Class" table="t_class">
        <id name="id" column="classId">
            <generator class="native"></generator>
        </id>
        <property name="name" column="className"></property>
    </class>
</hibernate-mapping>

Student.java

package com.andrew.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 + "]";
    }
}

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.andrew.model">
    <class name="Student" table="t_student">
        <id name="id" column="stuId">
            <generator class="native"></generator>
        </id>
        <property name="name" column="stuName"></property>
        <many-to-one name="c" column="classId" class="com.andrew.model.Class" cascade="save-update"></many-to-one>
    </class>
</hibernate-mapping>

insert into t_class values(1, '10级1班');

StudentTest.java

package com.andrew.service;
import java.util.Iterator;
import java.util.List;
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.andrew.model.Class;
import com.andrew.model.Student;
import com.andrew.util.HibernateUtil;
public class StudentTest {
    private SessionFactory sessionFactory = HibernateUtil.getSessionFactory();
    private Session session;
    @Before
    public void setUp() throws Exception {
        session = sessionFactory.openSession(); // 1. 生成一个session
        session.beginTransaction(); // 2. 开启事务
    }
    @After
    public void tearDown() throws Exception {
        session.getTransaction().commit(); // 3. 提交事务
        session.close(); // 4. 关闭session
    }
    @Test
    public void testCache1() {
        Class c1 = (Class)session.get(Class.class, Long.valueOf(1));
        System.out.println(c1.getName());
        Class c2 = (Class)session.get(Class.class, Long.valueOf(1));
        System.out.println(c2.getName());
        System.out.println(c1==c2);
    }
    
    @Test
    public void testCache2(){
        Session session1 = sessionFactory.openSession();
        session1.beginTransaction();
        Class c1 = (Class)session1.get(Class.class, Long.valueOf(1));
        System.out.println(c1.getName());
        session1.getTransaction().commit();
        session1.close();
        
        Session session2 = sessionFactory.openSession();
        session2.beginTransaction();
        Class c2 = (Class)session2.get(Class.class, Long.valueOf(1));
        System.out.println(c2.getName());
        session2.getTransaction().commit();
        session2.close();
        
        System.out.println(c1==c2);
    }
}

运行结果：
Hibernate: select class0_.classId as classId1_0_0_, class0_.className as classNam2_0_0_ from t_class class0_ where class0_.classId=?
10级1班
10级1班
true
运行结果：
Hibernate: select class0_.classId as classId1_0_0_, class0_.className as classNam2_0_0_ from t_class class0_ where class0_.classId=?
10级1班
Hibernate: select class0_.classId as classId1_0_0_, class0_.className as classNam2_0_0_ from t_class class0_ where class0_.classId=?
10级1班
false

5) 配置二级缓存

新建项目Hibernate12-02

导入ehcache jar包，右键buildPath

ehcache-core-2.4.3.jar
hibernate-ehcache-4.3.5.Final.jar
slf4j-api-1.6.1.jar

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/hibernate4</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>
        <!-- 启用二级缓存 -->
        <property name="cache.use_second_level_cache">true</property>
        <!-- 配置使用的二级缓存的产品 -->
        <property name="hibernate.cache.region.factory_class">org.hibernate.cache.ehcache.EhCacheRegionFactory</property>
        <!-- 配置启用查询缓存 -->
        <property name="cache.use_query_cache">true</property>
        <!-- Mapper -->
        <mapping resource="com/andrew/model/Class.hbm.xml"/>
    </session-factory>
</hibernate-configuration>

ehcache.xml

<ehcache>
    <!-- 指定一个文件目录，当EHCache把数据写到硬盘上时，将把数据写到这个目录下 -->
    <diskStore path="e:\\ehcache"/>
    <!--  
        设置缓存的默认数据过期策略 
    -->    
    <defaultCache
        maxElementsInMemory="10000"
        eternal="false"
        timeToIdleSeconds="120"
        timeToLiveSeconds="120"
        overflowToDisk="true"
        />
    <!-- 
        name 设置缓存的名字，他的取值为类的完整名字或者类的集合的名字；
        maxElementsInMemory 设置基于内存的缓存可存放的对象的最大数目
        eternal 如果为true，表示对象永远不会过期，此时会忽略timeToIdleSeconds和timeToLiveSeconds，默认为false;
        timeToIdleSeconds 设定允许对象处于空闲状态的最长时间，以秒为单位；
        timeToLiveSeconds 设定对象允许存在于缓存中的最长时间，以秒为单位；
        overflowToDisk 如果为true,表示当基于内存的缓存中的对象数目达到maxElementsInMemory界限，会把溢出的对象写到基于硬盘的缓存中；
     -->
    <!-- 设定具体的第二级缓存的数据过期策略 -->
    <cache name="com.andrew.model.Class"
        maxElementsInMemory="1"
        eternal="false"
        timeToIdleSeconds="300"
        timeToLiveSeconds="600"
        overflowToDisk="true"
        />
</ehcache>

HibernateUtil.java

package com.andrew.util;
import org.hibernate.SessionFactory;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
public class HibernateUtil {
    private static final SessionFactory sessionFactory = buildSessionFactory();
    private static SessionFactory buildSessionFactory() {
        // 1. 实例化配置文件
        Configuration configuration = new Configuration().configure();
        // 2. 实例化服务登记
        ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder()
                .applySettings(configuration.getProperties()).build();
        // 3. 获取Session工厂
        return configuration.buildSessionFactory(serviceRegistry);
    }
    public static SessionFactory getSessionFactory() {
        return sessionFactory;
    }
}

Class.java

package com.andrew.model;
public class Class {
    private long id;
    private String name;
    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;
    }
}

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.andrew.model">
    <class name="Class" table="t_class">
        <cache usage="read-only"/>
        <id name="id" column="classId">
            <generator class="native"></generator>
        </id>
        <property name="name" column="className"></property>
    </class>
</hibernate-mapping>

StudentTest.java

package com.andrew.service;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.junit.Test;
import com.andrew.model.Class;
import com.andrew.util.HibernateUtil;
public class StudentTest {
    private SessionFactory sessionFactory = HibernateUtil.getSessionFactory();
    private Session session;    
    @Test
    public void testCache() {
        Session session1 = sessionFactory.openSession();
        session1.beginTransaction();
        Class c1 = (Class)session1.get(Class.class, Long.valueOf(1));
        System.out.println(c1.getName());
        session1.getTransaction().commit();
        session1.close();
        
        Session session2 = sessionFactory.openSession();
        session2.beginTransaction();
        Class c2 = (Class)session2.get(Class.class, Long.valueOf(1));
        System.out.println(c2.getName());
        session2.getTransaction().commit();
        session2.close();
        
        System.out.println(c1==c2);
    }
}

运行结果：
Hibernate: select class0_.classId as classId1_0_0_, class0_.className as classNam2_0_0_ from t_class class0_ where class0_.classId=?
10级1班
10级1班
false