springboot学习笔记(九) spring cache

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springboot学习笔记(九)

开启缓存spring cache

导入 pom 依赖

<parent>    <groupId>org.springframework.boot</groupId>    <artifactId>spring-boot-starter-parent</artifactId>    <version>1.5.7.RELEASE</version></parent><dependencies>    <dependency>        <groupId>org.springframework.boot</groupId>        <artifactId>spring-boot-starter</artifactId>    </dependency>    <dependency>        <groupId>org.springframework.boot</groupId>        <artifactId>spring-boot-starter-test</artifactId>    </dependency>    <dependency>        <groupId>org.springframework.boot</groupId>        <artifactId>spring-boot-starter-cache</artifactId>    </dependency></dependencies>

构建一个程序入口

@SpringBootApplicationpublic class CacheApp {    public static void main(String[] args) {        SpringApplication.run(CacheApp.class, args);    }}

application.yml 文件如下
```
server:   port: 8089
```

构建一个数据访问层

@Repositorypublic class UserDaoImpl implements UserDao{    @Override    public User getById(Integer id) {        System.out.println("get user " + id + " in repo");        dosomething();        return new User(id);    }    private void dosomething(){        try {            Thread.sleep(2000);        } catch (InterruptedException e) {            e.printStackTrace();        }    }}

编写测试类

@Componentpublic class AppRunner implements CommandLineRunner {    private static final Logger logger = LoggerFactory.getLogger(AppRunner.class);    private final UserDao userDaoImpl;    public AppRunner(UserDao userDaoImpl) {        this.userDaoImpl = userDaoImpl;    }    @Override    public void run(String... args) throws Exception {        logger.info("Fetching users...");        logger.info("" + userDaoImpl.getById(1));        logger.info("" + userDaoImpl.getById(2));        logger.info("" + userDaoImpl.getById(1));        logger.info("" + userDaoImpl.getById(2));        logger.info("" + userDaoImpl.getById(1));        logger.info("" + userDaoImpl.getById(1));        System.out.println();    }}

启动程序,控制台打印如下:

可以看见每一次都执行了数据访问层的方法,此时并没有开启缓存技术

开启缓存技术

在程序的入口中加入@ EnableCaching开启缓存技术：

@SpringBootApplication@EnableCachingpublic class CacheApp {    public static void main(String[] args) {        SpringApplication.run(CacheApp.class, args);    }}

在需要缓存的地方加入@Cacheable注解，比如在 getById() 方法上加入@Cacheable(“users”)，这个方法就开启了缓存策略，当缓存有这个数据的时候，会直接返回数据，不会等待去查询数据库。

@Repositorypublic class UserDaoImpl implements UserDao{    @Override    @Cacheable("users")    public User getById(Integer id) {        System.out.println("get user " + id + " in repo");        dosomething();        return new User(id);    }    private void dosomething(){        try {            Thread.sleep(2000);        } catch (InterruptedException e) {            e.printStackTrace();        }    }}

此时启动程序,控制台打印如下:

只有前面两个数据被打印了,说明此时缓存起作用了

个人学习springboot博客地址:http://blog.csdn.net/forezp/article/details/70341818http://blog.didispace.com/Spring-Boot%E5%9F%BA%E7%A1%80%E6%95%99%E7%A8%8B/

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