引子
我门知道一个程序的瓶颈在于数据库，我门也知道内存的速度是大大快于硬盘的速度的。当我门需要重复的获取相同的数据的时候，我门一次又一次的请求数据库或者远程服务，导致大量的时间耗费在数据库查询或者远程方法的调用上，导致程序性能的恶化，这更是数据缓存要解决的问题。
spring 缓存支持
spring定义了 org.springframework.cache.CacheManager和org.springframework.cache.Cache接口来统一不同的缓存技术。其中，CacheManager是Spring提供的各种缓存技术抽象接口，Cache接口包含了缓存的各种操作（增加、删除获得缓存，我门一般不会直接和此接口打交道）
spring 支持的CacheManager
针对不同的缓存技术，需要实现不同的CacheManager ,spring 定义了如下表的CacheManager实现。
实现任意一种CacheManager 的时候，需要注册实现CacheManager的bean，当然每种缓存技术都有很多额外的配置，但配置CacheManager 是必不可少的。
声明式缓存注解
spring提供了4个注解来声明缓存规则（又是使用注解式的AOP的一个生动例子），如表。
开启声明式缓存
开启声明式缓存支持非常简单，只需要在配置类上使用@EnabelCaching 注解即可。
springBoot 的支持
在spring中国年使用缓存技术的关键是配置CacheManager 而springbok 为我门自动配置了多个CacheManager的实现。在spring boot 环境下，使用缓存技术只需要在项目中导入相关缓存技术的依赖包，并配置类使用@EnabelCaching开启缓存支持即可。
小例子
小例子是使用 springboot+jpa ＋cache 实现的。
实例步骤目录
1.创建maven项目
新建maven 项目pom.xml文件如下内容如下：
<?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.us</groupId> <artifactId>springboot-Cache</artifactId> <version>1.0-SNAPSHOT</version> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>1.3.0.RELEASE</version> </parent> <properties> <start-class>com.us.Application</start-class> <maven.compiler.target>1.8</maven.compiler.target> <maven.compiler.source>1.8</maven.compiler.source> </properties> <!-- Add typical dependencies for a web application --> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-cache</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-jpa</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>net.sf.ehcache</groupId> <artifactId>ehcache</artifactId> </dependency> <!--db--> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>6.0.5</version> </dependency> <dependency> <groupId>com.mchange</groupId> <artifactId>c3p0</artifactId> <version>0.9.5.2</version> <exclusions> <exclusion> <groupId>commons-logging</groupId> <artifactId>commons-logging</artifactId> </exclusion> </exclusions> </dependency> </dependencies></project>
2.数据库配置
在src/main/esouces目录下新建application.properties 文件，内容为数据库连接信息，如下：
application.properties
ms.db.driverClassName=com.mysql.jdbc.Driverms.db.url=jdbc:mysql://localhost:3306/cache?prepStmtCacheSize=517&cachePrepStmts=true&autoReconnect=true&useUnicode=true&characterEncoding=utf-8&useSSL=false&allowMultiQueries=truems.db.username=rootms.db.password=xxxxxxms.db.maxActive=500
新建DBConfig.java 配置文件，配置数据源
package com.us.example.config;/** * Created by yangyibo on 17/1/13. */import java.beans.PropertyVetoException;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Configuration;import org.springframework.core.env.Environment;import com.mchange.v2.c3p0.ComboPooledDataSource;@Configurationpublic class DBConfig { @Autowired private Environment env; @Bean(name="dataSource") public ComboPooledDataSource dataSource() throws PropertyVetoException { ComboPooledDataSource dataSource = new ComboPooledDataSource(); dataSource.setDriverClass(env.getProperty("ms.db.driverClassName")); dataSource.setJdbcUrl(env.getProperty("ms.db.url")); dataSource.setUser(env.getProperty("ms.db.username")); dataSource.setPassword(env.getProperty("ms.db.password")); dataSource.setMaxPoolSize(20); dataSource.setMinPoolSize(5); dataSource.setInitialPoolSize(10); dataSource.setMaxIdleTime(300); dataSource.setAcquireIncrement(5); dataSource.setIdleConnectionTestPeriod(60); return dataSource; }}数据库设计，数据库只有一张Person表，设计如下：
3.jpa配置
spring－data－ jpa 配置文件如下：
package com.us.example.config;import java.util.HashMap;import java.util.Map;import javax.persistence.EntityManagerFactory;import javax.sql.DataSource;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.ComponentScan;import org.springframework.context.annotation.Configuration;import org.springframework.data.jpa.repository.config.EnableJpaRepositories;import org.springframework.orm.jpa.JpaTransactionManager;import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;import org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter;import org.springframework.transaction.PlatformTransactionManager;import org.springframework.transaction.annotation.EnableTransactionManagement;/** * Created by yangyibo on 17/1/13. */@Configuration@EnableJpaRepositories("com.us.example.dao")@EnableTransactionManagement@ComponentScanpublic class JpaConfig { @Autowired private DataSource dataSource; @Bean public EntityManagerFactory entityManagerFactory() { HibernateJpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter(); LocalContainerEntityManagerFactoryBean factory = new LocalContainerEntityManagerFactoryBean(); factory.setJpaVendorAdapter(vendorAdapter); factory.setPackagesToScan("com.us.example.bean"); factory.setDataSource(dataSource); Map<String, Object> jpaProperties = new HashMap<>(); jpaProperties.put("hibernate.ejb.naming_strategy","org.hibernate.cfg.ImprovedNamingStrategy"); jpaProperties.put("hibernate.jdbc.batch_size",50); factory.setJpaPropertyMap(jpaProperties); factory.afterPropertiesSet(); return factory.getObject(); } @Bean public PlatformTransactionManager transactionManager() { JpaTransactionManager txManager = new JpaTransactionManager(); txManager.setEntityManagerFactory(entityManagerFactory()); return txManager; }}4.编写bean 和dao层
实体类 Person.java
package com.us.example.bean;import javax.persistence.Entity;import javax.persistence.GeneratedValue;import javax.persistence.Id;import javax.persistence.Table;/** * Created by yangyibo on 17/1/13. */@Entity@Table(name = "Person")public class Person { @Id @GeneratedValue private Long id; private String name; private Integer age; private String address; public Person() { super(); } public Person(Long id, String name, Integer age, String address) { super(); this.id = id; this.name = name; this.age = age; this.address = address; } 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 Integer getAge() { return age; } public void setAge(Integer age) { this.age = age; } public String getAddress() { return address; } public void setAddress(String address) { this.address = address; }}dao层，PersonRepository.java
package com.us.example.dao;import com.us.example.bean.Person;import org.springframework.data.jpa.repository.JpaRepository;/** * Created by yangyibo on 17/1/13. */public interface PersonRepository extends JpaRepository<Person, Long> {}5.编写service层
service 接口
package com.us.example.service;import com.us.example.bean.Person;/** * Created by yangyibo on 17/1/13. */public interface DemoService { public Person save(Person person); public void remove(Long id); public Person findOne(Person person);}实现：(重点，此处加缓存)
package com.us.example.service.Impl;import com.us.example.bean.Person;import com.us.example.dao.PersonRepository;import com.us.example.service.DemoService;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.cache.annotation.CacheEvict;import org.springframework.cache.annotation.CachePut;import org.springframework.cache.annotation.Cacheable;import org.springframework.stereotype.Service;/** * Created by yangyibo on 17/1/13. */@Servicepublic class DemoServiceImpl implements DemoService { @Autowired private PersonRepository personRepository; @Override //@CachePut缓存新增的或更新的数据到缓存,其中缓存名字是 people 。数据的key是person的id @CachePut(value = "people", key = "#person.id") public Person save(Person person) { Person p = personRepository.save(person); System.out.println("为id、key为:"+p.getId()+"数据做了缓存"); return p; } @Override //@CacheEvict 从缓存people中删除key为id 的数据 @CacheEvict(value = "people") public void remove(Long id) { System.out.println("删除了id、key为"+id+"的数据缓存"); //这里不做实际删除操作 } @Override //@Cacheable缓存key为person 的id 数据到缓存people 中,如果没有指定key则方法参数作为key保存到缓存中。 @Cacheable(value = "people", key = "#person.id") public Person findOne(Person person) { Person p = personRepository.findOne(person.getId()); System.out.println("为id、key为:"+p.getId()+"数据做了缓存"); return p; }}6.编写controller
为了测试方便请求方式都用了get
package com.us.example.controller;import com.us.example.bean.Person;import com.us.example.service.DemoService;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.stereotype.Controller;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.ResponseBody;import org.springframework.web.bind.annotation.RestController;/** * Created by yangyibo on 17/1/13. */@RestControllerpublic class CacheController { @Autowired private DemoService demoService; //http://localhost:8080/put?name=abel&age=23&address=shanghai @RequestMapping("/put") public Person put(Person person){ return demoService.save(person); } //http://localhost:8080/able?id=1 @RequestMapping("/able") @ResponseBody public Person cacheable(Person person){ return demoService.findOne(person); } //http://localhost:8080/evit?id=1 @RequestMapping("/evit") public String evit(Long id){ demoService.remove(id); return "ok"; }}7.启动cache
启动类中要记得开启缓存配置。
package com.us.example;import org.springframework.boot.autoconfigure.SpringBootApplication;import org.springframework.cache.annotation.EnableCaching;import org.springframework.context.ConfigurableApplicationContext;import org.springframework.context.annotation.ComponentScan;import static org.springframework.boot.SpringApplication.*;/** * Created by yangyibo on 17/1/13. */@ComponentScan(basePackages ="com.us.example")@SpringBootApplication@EnableCachingpublic class Application { public static void main(String[] args) { ConfigurableApplicationContext run = run(Application.class, args); }}8.测试校验检验able：
启动Application 类，启动后在浏览器输入：http://localhost:8080/able?id=1（首先要在数据库中初始化几条数据。）
控制台输出：
“为id、key为:1数据做了缓存“ 此时已经为此次查询做了缓存，再次查询该条数据将不会出现此条语句，也就是不查询数据库了。
检验put
在浏览器输入：http://localhost:8080/put?name=abel&age=23&address=shanghai（向数据库插入一条数据，并将数据放入缓存。）
此时控制台输出为该条记录做了缓存：
然后再次调用able 方法，查询该条数据，将不再查询数据库，直接从缓存中读取数据。
测试evit
在浏览器输入：http://localhost:8080/evit?id=1（将该条记录从缓存中清楚，清除后，在次访问该条记录，将会重新将该记录放入缓存。）
控制台输出：
切换缓存
1.切换为EhCache作为缓存
pom.xml 文件中添加依赖
<dependency> <groupId>net.sf.ehcache</groupId> <artifactId>ehcache</artifactId> </dependency>
在resource 文件夹下新建ehcache的配置文件ehcache.xml 内容如下，此文件spring boot 会自动扫描
<?xml version="1.0" encoding="UTF-8"?><ehcache> <!--切换为ehcache 缓存时使用--><cache name="people" maxElementsInMemory="1000" /></ehcache>
2.切换为Guava作为缓存
只需要在pom中添加依赖
<dependency> <groupId>com.google.guava</groupId> <artifactId>guava</artifactId> <version>18.0</version> </dependency>
3.切换为redis作为缓存
请看下篇博客
本文参考：《JavaEE开发的颠覆者：Spring Boot实战 》
本文源代码：https://github.com/527515025/springBoot.git
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持武林网。