mybatis详解-(22)整合第三方缓存Ehcache

落日映苍穹つ 2022-06-03 07:13 212阅读 0赞

前面几篇文章剖析了mybatis的缓存原理，发现mybatis提供的缓存是非常简陋的，用HashMap进行存储。  
有专业做缓存的，那么就使用专业的缓存框架吧，这里使用Ehcache来作为mybatis的缓存。

# 1.引入jar #

<dependency>
        <groupId>net.sf.ehcache</groupId>
        <artifactId>ehcache-core</artifactId>
        <version>2.6.10</version>
    </dependency>
    
    
    <dependency>
         <groupId>org.mybatis</groupId>
         <artifactId>mybatis-ehcache</artifactId>
         <version>1.0.0</version>
       </dependency>
    
    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-api</artifactId>
        <version>1.7.12</version>
    </dependency>
    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-log4j12</artifactId>
        <version>1.7.6</version>
    </dependency>
    <dependency>
        <groupId>log4j</groupId>
        <artifactId>log4j</artifactId>
        <version>1.2.17</version>
    </dependency>

# 2.引入ehcache.xml文件 #

添加ehcache.xml

<?xml version="1.0" encoding="UTF-8"?>
    <ehcache xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../config/ehcache.xsd">     
    
    <diskStore path="D:\mybatis\ehcache"/>     
    
            
            
       <defaultCache maxElementsInMemory="10" eternal="false" timeToIdleSeconds="120" timeToLiveSeconds="120" overflowToDisk="true" maxElementsOnDisk="10000000" diskPersistent="false" diskExpiryThreadIntervalSeconds="120" memoryStoreEvictionPolicy="LRU" />     
    </ehcache>

# 3.创建示例 #

package org.mybatis.cache3ehcache;
    
    public class Employee { 
        private Integer id;
        private String lastName;
        private String email;
        private String gender;
    
        public Employee() {
    
        }
    
        public Employee(Integer id, String lastName, String email, String gender) {
            this.id = id;
            this.lastName = lastName;
            this.email = email;
            this.gender = gender;
        }
    
        public Integer getId() {
            return id;
        }
        public void setId(Integer id) {
            this.id = id;
        }
        public String getLastName() {
            return lastName;
        }
        public void setLastName(String lastName) {
            this.lastName = lastName;
        }
        public String getEmail() {
            return email;
        }
        public void setEmail(String email) {
            this.email = email;
        }
        public String getGender() {
            return gender;
        }
        public void setGender(String gender) {
            this.gender = gender;
        }
        public String toString() {
            return "Employee [id=" + id + ", lastName=" + lastName + ", email="
                    + email + ", gender=" + gender + "]";
        }
    
    }

package org.mybatis.cache3ehcache;
    
    public interface EmployeeMapper { 
    
        public Employee getEmpById(Integer id);
    
    }

<?xml version="1.0" encoding="UTF-8" ?>
    <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
    
    <mapper namespace="org.mybatis.cache3ehcache.EmployeeMapper">
    
        
        <cache type="org.mybatis.caches.ehcache.EhcacheCache"></cache>
    
        <select id="getEmpById" resultType="org.mybatis.cache3ehcache.Employee" useCache="true">
            select * from mybatis_employee me where me.id = #{id}
        </select>
    </mapper>

<?xml version="1.0" encoding="UTF-8" ?>
    <!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd">
    <configuration>
    
        <properties resource="db.properties"></properties>
    
        <settings>
            <setting name="mapUnderscoreToCamelCase" value="true"/>
            <setting name="lazyLoadingEnabled" value="true" />
            <setting name="aggressiveLazyLoading" value="false"/>
            
            <setting name="cacheEnabled" value="true"/>
        </settings>
    
        <typeAliases>
            
            <package name="org.mybatis.cache3ehcache"/>
        </typeAliases>
    
    
        
        <environments default="dev_mysql">
            <environment id="dev_mysql">
                <transactionManager type="JDBC" />
                <dataSource type="POOLED">
                    <property name="driver" value="${mysql.driver}" />
                    <property name="url" value="${mysql.url}" />
                    <property name="username" value="${mysql.username}" />
                    <property name="password" value="${mysql.password}" />
                </dataSource>
            </environment>
    
            <environment id="test_mysql">
                <transactionManager type="JDBC"></transactionManager>
                <dataSource type="POOLED">
                    <property name="driver" value="${mysql.drivertest}" />
                    <property name="url" value="${mysql.urltest}" />
                    <property name="username" value="${mysql.usernametest}" />
                    <property name="password" value="${mysql.passwordtest}" />
                </dataSource>
            </environment>
    
        </environments>
    
        <mappers>
            <mapper resource="mapper/cache3ehcachemapper.xml"/>
        </mappers>
    
    </configuration>

测试类：

package org.mybatis.cache3ehcache;
    
    import java.io.IOException;
    import java.io.InputStream;
    
    import org.apache.ibatis.io.Resources;
    import org.apache.ibatis.session.SqlSession;
    import org.apache.ibatis.session.SqlSessionFactory;
    import org.apache.ibatis.session.SqlSessionFactoryBuilder;
    import org.junit.Test;
    
    /** * 整个Ehcache * @author Tang */
    public class MybatisTest { 
    
        @Test
        public void testMybatis() {
            String resource = "mybatis-config-cache3ehcache.xml";//全局配置文件
    
            InputStream inputStream = null;
            SqlSessionFactory sqlSessionFactory = null;
    
            try {
                inputStream = Resources.getResourceAsStream(resource);
                sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
    
                SqlSession sqlSession1 = sqlSessionFactory.openSession();
                EmployeeMapper mapper1 = sqlSession1.getMapper(EmployeeMapper.class);
                Employee emp1 = mapper1.getEmpById(2);
                System.out.println(emp1);
                sqlSession1.close();
    
                System.out.println("`######");
    
                SqlSession sqlSession2 = sqlSessionFactory.openSession();
                EmployeeMapper mapper2 = sqlSession2.getMapper(EmployeeMapper.class);
                Employee emp2 = mapper2.getEmpById(2);
                System.out.println(emp2);
                sqlSession2.close();
    
                System.out.println(emp1 == emp2);
    
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
    
            }
        }
    }

运行结果：  
![这里写图片描述][SouthEast]  
两个不同的sqlSession，发送了一个sql查询，说明缓存已经生效。

[SouthEast]: /images/20220603/ec6416a73bed40818d6f595aaa116bb0.png