10、JPA-二级缓存

2021-12-11 22:11:19

pom.xml

<?xml version="1.0" encoding="UTF-8"?>

<project xmlns="http://maven.apache.org/POM/4.0.0"

         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">

    <modelVersion>4.0.0</modelVersion>

    <groupId>com</groupId>

    <artifactId>jpa</artifactId>

    <version>1.0-SNAPSHOT</version>

    <dependencies>

        <dependency>

            <groupId>mysql</groupId>

            <artifactId>mysql-connector-java</artifactId>

            <version>8.0.14</version>

        </dependency>

        <dependency>

            <groupId>org.hibernate</groupId>

            <artifactId>hibernate-core</artifactId>

            <version>5.4.1.Final</version>

        </dependency>

        <dependency>

            <groupId>org.hibernate</groupId>

            <artifactId>hibernate-jpamodelgen</artifactId>

            <version>5.4.1.Final</version>

            <scope>provided</scope>

        </dependency>

        <dependency>

            <groupId>junit</groupId>

            <artifactId>junit</artifactId>

            <version>4.12</version>

            <scope>test</scope>

        </dependency>

    </dependencies>

    <build>

        <plugins>

            <!-- 指定jdk -->

            <plugin>

                <groupId>org.apache.maven.plugins</groupId>

                <artifactId>maven-compiler-plugin</artifactId>

                <configuration>

                    <source>1.8</source>

                    <target>1.8</target>

                </configuration>

            </plugin>

        </plugins>

    </build>

</project>

persistence.xml

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>

<persistence xmlns="http://xmlns.jcp.org/xml/ns/persistence"

             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

             xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence http://xmlns.jcp.org/xml/ns/persistence/persistence_2_2.xsd"

             version="2.2">

    <persistence-unit name="jpaname">

        <!-- 实体类 -->

        <class>com.jpa.yingshe.Customer</class>

        <properties>

            <!-- 数据库信息 -->

            <property name="javax.persistence.jdbc.driver" value="com.mysql.cj.jdbc.Driver"/>

            <property name="javax.persistence.jdbc.url" value="jdbc:mysql://192.168.8.136/jpa?useSSL=false"/>

            <property name="javax.persistence.jdbc.user" value="root"/>

            <property name="javax.persistence.jdbc.password" value="root"/>

            <!-- 配置 hibernate 属性 -->

            <property name="hibernate.format_sql" value="true"/>

            <property name="hibernate.show_sql" value="true"/>

            <property name="hibernate.hbm2ddl.auto" value="update"/>

        </properties>

    </persistence-unit>

</persistence>

Customer

package com.jpa.yingshe;

import javax.persistence.*;

@Table(name = "JPA_CUTOMERS")

@Entity

public class Customer {

    private Integer id;

    private String lastName;

    private String email;

    public Customer() {

    }

    public Customer(String lastName) {

        this.lastName = lastName;

    }

    @GeneratedValue(strategy = GenerationType.AUTO)

    @Id

    public Integer getId() {

        return id;

    }

    public void setId(Integer id) {

        this.id = id;

    }

    @Column(name = "LAST_NAME", length = 50, nullable = false)

    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;

    }

}

测试

先看JPA自带的一级缓存

package jpa.test;

import com.jpa.yingshe.Customer;

import org.junit.After;

import org.junit.Before;

import org.junit.Test;

import javax.persistence.EntityManager;

import javax.persistence.EntityManagerFactory;

import javax.persistence.EntityTransaction;

import javax.persistence.Persistence;

public class JPAyingshe {

    private EntityManagerFactory entityManagerFactory;

    private EntityManager entityManager;

    private EntityTransaction transaction;

    @Before

    public void init() {

        entityManagerFactory = Persistence.createEntityManagerFactory("jpaname");

        entityManager = entityManagerFactory.createEntityManager();

        transaction = entityManager.getTransaction();

        transaction.begin();

    }

    @After

    public void destroy() {

        transaction.commit();

        entityManager.close();

        entityManagerFactory.close();

    }

    @Test

    public void testFirstLevelCache() {

        Customer customer1 = entityManager.find(Customer.class, 1);

        Customer customer2 = entityManager.find(Customer.class, 1);

    }

}

中间关闭会话再试试

@Test

public void testFirstLevelCache() {

    Customer customer1 = entityManager.find(Customer.class, 1);

    transaction.commit();

    entityManager.close();

    entityManager = entityManagerFactory.createEntityManager();

    transaction = entityManager.getTransaction();

    transaction.begin();

    Customer customer2 = entityManager.find(Customer.class, 1);

}

配置二级缓存，让关闭会话后也只发送一次查询

添加 ehcache 依赖

<dependency>

    <groupId>org.hibernate</groupId>

    <artifactId>hibernate-ehcache</artifactId>

    <version>5.4.1.Final</version>

</dependency>

<dependency>

    <groupId>org.ehcache</groupId>

    <artifactId>ehcache</artifactId>

    <version>3.6.3</version>

</dependency>

添加 ehcache.xml 配置

<ehcache>

    <diskStore path="./target/tmp"/>

    <defaultCache

        maxElementsInMemory="10000"

        eternal="false"

        timeToIdleSeconds="120"

        timeToLiveSeconds="120"

        overflowToDisk="true"

        />

    <cache name="sampleCache1"

        maxElementsInMemory="10000"

        eternal="false"

        timeToIdleSeconds="300"

        timeToLiveSeconds="600"

        overflowToDisk="true"

        />

    <cache name="sampleCache2"

        maxElementsInMemory="1000"

        eternal="true"

        timeToIdleSeconds="0"

        timeToLiveSeconds="0"

        overflowToDisk="false"

        /> -->

</ehcache>

修改 persistence.xml 配置

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>

<persistence xmlns="http://xmlns.jcp.org/xml/ns/persistence"

             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

             xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence http://xmlns.jcp.org/xml/ns/persistence/persistence_2_2.xsd"

             version="2.2">

    <persistence-unit name="jpaname" transaction-type="RESOURCE_LOCAL">

        <!-- 配置使用什么 ORM 产品来作为 JPA 的实现 -->

        <provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>

        <!-- 实体类 -->

        <class>com.jpa.yingshe.Customer</class>

        <!--

        配置二级缓存的策略

        ALL：所有的实体类都被缓存

        NONE：所有的实体类都不被缓存.

        ENABLE_SELECTIVE：标识 @Cacheable(true) 注解的实体类将被缓存

        DISABLE_SELECTIVE：缓存除标识 @Cacheable(false) 以外的所有实体类

        UNSPECIFIED：默认值，JPA 产品默认值将被使用

        -->

        <shared-cache-mode>ENABLE_SELECTIVE</shared-cache-mode>

        <properties>

            <!-- 数据库信息 -->

            <property name="javax.persistence.jdbc.driver" value="com.mysql.cj.jdbc.Driver"/>

            <property name="javax.persistence.jdbc.url" value="jdbc:mysql://192.168.8.136/jpa?useSSL=false"/>

            <property name="javax.persistence.jdbc.user" value="root"/>

            <property name="javax.persistence.jdbc.password" value="root"/>

            <!-- 配置 hibernate 属性 -->

            <property name="hibernate.format_sql" value="true"/>

            <property name="hibernate.show_sql" value="true"/>

            <property name="hibernate.hbm2ddl.auto" value="update"/>

            <!-- 二级缓存相关 -->

            <property name="hibernate.cache.use_second_level_cache" value="true"/>

            <property name="hibernate.cache.region.factory_class" value="org.hibernate.cache.ehcache.internal.EhcacheRegionFactory"/>

            <property name="hibernate.cache.use_query_cache" value="true"/>

        </properties>

    </persistence-unit>

</persistence>

修改实体类，添加缓存注解

@Cacheable

@Table(name = "JPA_CUTOMERS")

@Entity

public class Customer {

    private Integer id;

查询

@Test

public void testSecondLevelCache() {

    Customer customer1 = entityManager.find(Customer.class, 1);

    transaction.commit();

    entityManager.close();

    entityManager = entityManagerFactory.createEntityManager();

    transaction = entityManager.getTransaction();

    transaction.begin();

    Customer customer2 = entityManager.find(Customer.class, 1);

}

项目结构

码农公寓

10、JPA-二级缓存

pom.xml

persistence.xml

Customer

测试

先看JPA自带的一级缓存

配置二级缓存，让关闭会话后也只发送一次查询

官方文档

码农公寓

pom.xml

persistence.xml

Customer

测试

先看JPA自带的一级缓存

配置二级缓存，让关闭会话后也只发送一次查询

官方文档

相关文章