在Spring+Hibernate集成环境中使用EhCache缓存

柔情只为你懂 2022-06-07 10:16 241阅读 0赞

**\#缓存的配置**

在applicationContext.xml加入使用缓存的属性

<prop key="hibernate.cache.use_query_cache">true</prop>
                    
                    <prop key="hibernate.cache.use_second_level_cache">true</prop>
                    
                    <prop key="hibernate.cache.provider_class">org.hibernate.cache.EhCacheProvider</prop>
                    
                    <prop key="hibernate.cache.provider_configuration_file_resource_path">ehcache.xml</prop>

整体的applicationContext.xml如下:

<?xml version="1.0" encoding="UTF-8"?>
    <beans
    	xmlns="http://www.springframework.org/schema/beans"
    	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    	xmlns:p="http://www.springframework.org/schema/p"
    	xmlns:context="http://www.springframework.org/schema/context"
    	xmlns:aop="http://www.springframework.org/schema/aop"
    	xmlns:tx="http://www.springframework.org/schema/tx"
    	xsi:schemaLocation="http://www.springframework.org/schema/beans
    	                    http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
                            http://www.springframework.org/schema/context 
                            http://www.springframework.org/schema/context/spring-context-3.0.xsd
                            http://www.springframework.org/schema/tx
                            http://www.springframework.org/schema/tx/spring-tx-3.0.xsd
                            http://www.springframework.org/schema/aop
                            http://www.springframework.org/schema/aop/spring-aop-3.0.xsd">
                            
        
        <context:property-placeholder location="classpath:db.properties"/>
        
        
        
        <context:component-scan base-package="com.sunline">
        </context:component-scan>
    	<bean id="dataSource"
    		class="org.apache.commons.dbcp.BasicDataSource">
    		<property name="driverClassName"
    			value="${driverClassName}">
    		</property>
    		<property name="url"
    			value="${url}">
    		</property>
    		<property name="username" value="${username}"></property>
    		<property name="password" value="${password}"></property>
    	</bean>
    	<bean id="sessionFactory"
    		class="org.springframework.orm.hibernate3.LocalSessionFactoryBean">
    		<property name="dataSource">
    			<ref bean="dataSource" />
    		</property>
    		<property name="hibernateProperties">
    			<props>
    				<prop key="hibernate.dialect">
    					org.hibernate.dialect.MySQLDialect
    				</prop>
    				<prop key="dialect">
    				    org.hibernate.dialect.MySQLDialect
    				</prop>
                    <prop key="hibernate.hbm2ddl.auto">true</prop>
                    <prop key="hibernate.show_sql">true</prop> 
                    
                    
                    <prop key="hibernate.cache.use_query_cache">true</prop>
                    
                    <prop key="hibernate.cache.use_second_level_cache">true</prop>
                    
                    <prop key="hibernate.cache.provider_class">org.hibernate.cache.EhCacheProvider</prop>
                    
                    <prop key="hibernate.cache.provider_configuration_file_resource_path">ehcache.xml</prop>
    			</props>
    		</property>
    		<property name="mappingResources">
    			<list>
    				<value>com/sunline/entity/User.hbm.xml</value>
    			</list>
    		</property>
      </bean>
       
       	
    	<bean id="transactionManager" class="org.springframework.orm.hibernate3.HibernateTransactionManager">
            <property name="sessionFactory" ref="sessionFactory" />
        </bean>
       
        
    	<tx:annotation-driven transaction-manager="transactionManager"/>
    </beans>

完成ehcache.xml的配置

在数据模型层User.hbm.xml映射文件Cache配置的class节点下，加入类似如下格式信息

**\#数据模型层**

package com.sunline.entity;
    
    
    
    /**
     * User entity. @author MyEclipse Persistence Tools
     */
    
    public class User  implements java.io.Serializable {
    
    
        // Fields    
    
         private Integer id;
         private String userName;
         private String userPassword;
         private String userInfo;
    
    
        // Constructors
    
        /** default constructor */
        public User() {
        }
    
        
        /** full constructor */
        public User(String userName, String userPassword, String userInfo) {
            this.userName = userName;
            this.userPassword = userPassword;
            this.userInfo = userInfo;
        }
    
       
        // Property accessors
    
        public Integer getId() {
            return this.id;
        }
        
        public void setId(Integer id) {
            this.id = id;
        }
    
        public String getUserName() {
            return this.userName;
        }
        
        public void setUserName(String userName) {
            this.userName = userName;
        }
    
        public String getUserPassword() {
            return this.userPassword;
        }
        
        public void setUserPassword(String userPassword) {
            this.userPassword = userPassword;
        }
    
        public String getUserInfo() {
            return this.userInfo;
        }
        
        public void setUserInfo(String userInfo) {
            this.userInfo = userInfo;
        }
    }

<?xml version="1.0" encoding="utf-8"?>
    <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
    "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
    
    <hibernate-mapping>
        <class name="com.sunline.entity.User" table="user" catalog="association">
        <cache usage="read-write" region="Cache"/>
            <id name="id" type="java.lang.Integer">
                <column name="id" />
                <generator class="increment"></generator>
            </id>
            <property name="userName" type="java.lang.String">
                <column name="user_name" length="200" not-null="true" />
            </property>
            <property name="userPassword" type="java.lang.String">
                <column name="user_password" length="50" not-null="true" />
            </property>
            <property name="userInfo" type="java.lang.String">
                <column name="user_info" length="60" not-null="true" />
            </property>
        </class>
    </hibernate-mapping>

**\#数据访问层**

package com.sunline.dao;
    
    import java.util.List;
    
    import javax.annotation.Resource;
    
    import org.hibernate.SessionFactory;
    import org.springframework.orm.hibernate3.support.HibernateDaoSupport;
    import org.springframework.stereotype.Repository;
    
    import com.sunline.entity.User;
    
    @Repository(value="userDao")
    public class UserDao extends HibernateDaoSupport {
    	
    	/*
    	 * 使用注解必须添加以下方式
    	 */
        @Resource  
        public void setSessionFacotry(SessionFactory sessionFacotry) {  
            super.setSessionFactory(sessionFacotry);  
        }  
        
    	/*
    	 * 查找所有用户
    	 */
    	@SuppressWarnings("unchecked")
    	public List<User> findAll(){
    		String sql="from User";
    		getHibernateTemplate().setCacheQueries(true);
    		getHibernateTemplate().setQueryCacheRegion(sql);               //这行可省略
    		List<User> list=this.getHibernateTemplate().find(sql);
    		getHibernateTemplate().setCacheQueries(false);                //避免出现N+1情况
    		return list;
    	}
    	
    }

**\#业务逻辑层**

package com.sunline.biz;
    
    import java.util.List;
    
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.beans.factory.annotation.Qualifier;
    import org.springframework.stereotype.Service;
    
    import com.sunline.dao.UserDao;
    import com.sunline.entity.User;
    
    @Service(value="userBiz")
    public class UserBiz {
    
    	@Autowired
    	@Qualifier("userDao")            //使用@Qualifier注解来说明使用哪一个实现类
        UserDao userDao;
    	
    	/*
    	 * 查找所有用户
    	 */
    	public List<User> findAll(){
           return userDao.findAll();
    	}
    	
    }

**\#测试类**

package com.sunline.test;
    
    import java.util.List;
    
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.support.ClassPathXmlApplicationContext;
    import org.springframework.transaction.annotation.Propagation;
    import org.springframework.transaction.annotation.Transactional;
    
    import com.sunline.biz.UserBiz;
    import com.sunline.entity.User;
    
    @Transactional(propagation=Propagation.REQUIRED)
    public class Test {
    
    	/**
    	 * @param args
    	 */
    	@Transactional(propagation=Propagation.REQUIRED)        //用事务管理做双重保障
    	public static void main(String[] args) {
    		// TODO Auto-generated method stub
            ApplicationContext ctx = new ClassPathXmlApplicationContext("applicationContext.xml");
            UserBiz userBiz = (UserBiz) ctx.getBean("userBiz");
            
            System.out.println("第一次开始获取");        //获取数据库中的数据
            List<User> list = userBiz.findAll();    
            for(User user : list){
            	System.out.println("你的个人信息为: "+user.getUserName()+" "+user.getUserPassword()+" "+user.getUserInfo());
            }
            
            try {
            	System.out.println("请关闭数据库");     
    			Thread.sleep(1000*40);              //线程休眠40秒,手动关闭数据库服务.测试缓存数据
    		} catch (InterruptedException e) {
    			// TODO Auto-generated catch block
    			e.printStackTrace();
    		}
            
            System.out.println("第二次开始获取");         //获取的是缓存数据
            List<User> list2 = userBiz.findAll();
            for(User user : list2){
            	System.out.println("你的个人信息为: "+user.getUserName()+" "+user.getUserPassword()+" "+user.getUserInfo());
            }
    	}
    
    }

**\#结果:**

1.缓存保存在D:\\ehcache下,运行后出现

![Center][]

2.运行结果:

![Center 1][]

**\#总结:**

发现在线程休眠,手动关闭数据库服务后,仍能读取出数据,说明读取的是缓存的数据,并非数据库中的数据.

**\#注意:**

使用ehcache，打印sql语句是正常的，因为query cache设置为true将会创建两个缓存区域：一个用于保存查询结果集 (org.hibernate.cache.StandardQueryCache)； 另一个则用于保存最近查询的一系列表的时间戳(org.hibernate.cache.UpdateTimestampsCache)。请注意：在查询缓存中，它并不缓存结果集中所包含的实体的确切状态；它只缓存这些实体的标识符属性的值、以及各值类型的结果。**需要将打印sql语句与最近的cache内 容相比较，将不同之处修改到cache中，所以查询缓存通常会和二级缓存一起使用。**

[Center]: /images/20220607/dc6aa3a1a37d496bbea6edfc4329fc61.png
[Center 1]: /images/20220607/a9816b01149b4d65a894c023d0cf14ac.png