Spring Boot 2 和 ehcache 3 示例 · HowToDoInJava 中文系列教程

# Spring Boot 2 和 ehcache 3 示例 > 原文： [https://howtodoinjava.com/spring-boot2/ehcache3-config-example/](https://howtodoinjava.com/spring-boot2/ehcache3-config-example/) 学习使用 **ehcache 3.x** 在 [spring boot](https://howtodoinjava.com/spring-boot-tutorials/) 应用程序中配置缓存。学习使用 [**基于注解的缓存配置**](https://howtodoinjava.com/spring-boot2/spring-boot-cache-example/) ，以及使用[`CacheManager`](https://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/cache/CacheManager.html)手动更新缓存。 ## 1\. Maven 依赖在此示例中，我们使用的是 Spring 运行版本`2.1.6.RELEASE`。较早的 spring boot 版本支持`net.sf.ehcache`软件包下的`ehcache 2.x`。 Spring Boot 支持`ehcache 3.x`的新版本可在`org.ehcache`软件包下获得。 Ehcache 版本 3 是 [JSR-107](https://www.jcp.org/en/jsr/detail?id=107) 缓存管理器的实现。我们需要以下依赖项来添加缓存功能。 * `spring-boot-starter-cache` * **ehcache** （`org.ehcache`） * **缓存 API** （`javax.cache`） `pom.xml` ```java <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.company</groupId> <artifactId>SpringBootEhcache</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>jar</packaging> <name>SpringBootEhcache</name> <url>http://maven.apache.org</url> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.1.6.RELEASE</version> <relativePath /> </parent> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding> <java.version>1.8</java.version> <skipTests>true</skipTests> </properties> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-cache</artifactId> </dependency> <dependency> <groupId>org.ehcache</groupId> <artifactId>ehcache</artifactId> </dependency> <dependency> <groupId>javax.cache</groupId> <artifactId>cache-api</artifactId> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build> </project> ``` ## 2\. `application.properties` Spring 的自动配置可以找到 Ehcache 的 JSR-107 实现。但是，默认情况下不会创建任何缓存，因为 Spring 和 Ehcache 都不会寻找默认的`ehcache.xml`文件。我们必须专门提供必须使用的 ehcache 配置文件路径。 `application.properties` ```java spring.cache.jcache.config=classpath:ehcache.xml ``` ## 3\. `ehcache.xml` 在`ehcache.xml`文件中，配置缓存名称及其属性。在[ ehcache 文档](https://www.ehcache.org/documentation/3.0/107.html#supplement-jsr-107-configurations)中找到属性的完整列表。 `ehcache.xml` ```java <config xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' xmlns='http://www.ehcache.org/v3' xmlns:jsr107='http://www.ehcache.org/v3/jsr107'> <service> <jsr107:defaults enable-statistics="true"/> </service> <cache alias="employeeCache"> <key-type>java.lang.Long</key-type> <value-type>com.company.Employee</value-type> <expiry> <ttl unit="seconds">10000</ttl> </expiry> <listeners> <listener> <class>com.company.CustomCacheEventLogger</class> <event-firing-mode>ASYNCHRONOUS</event-firing-mode> <event-ordering-mode>UNORDERED</event-ordering-mode> <events-to-fire-on>CREATED</events-to-fire-on> <events-to-fire-on>UPDATED</events-to-fire-on> <events-to-fire-on>EXPIRED</events-to-fire-on> <events-to-fire-on>REMOVED</events-to-fire-on> <events-to-fire-on>EVICTED</events-to-fire-on> </listener> </listeners> <resources> <heap unit="entries">2000</heap> <offheap unit="MB">100</offheap> </resources> </cache> </config> ``` ## 4\. `CacheEventListener` 我们还使用了事件监听器，该事件监听器将在创建，删除或更新缓存条目时记录缓存事件。 `CustomCacheEventLogger.java` ```java package com.company; import org.ehcache.event.CacheEvent; import org.ehcache.event.CacheEventListener; import org.slf4j.Logger; import org.slf4j.LoggerFactory; public class CustomCacheEventLogger implements CacheEventListener<Object, Object> { private static final Logger LOG = LoggerFactory.getLogger(CustomCacheEventLogger.class); @Override public void onEvent(CacheEvent cacheEvent) { LOG.info("Cache event = {}, Key = {}, Old value = {}, New value = {}", cacheEvent.getType(), cacheEvent.getKey(), cacheEvent.getOldValue(), cacheEvent.getNewValue()); } } ``` ## 5\. `@EnableCaching` 它启用 Spring 的注解驱动的缓存管理功能，并在调用[`@Cacheable`](https://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/cache/annotation/Cacheable.html)注解方法时启用对代理拦截器的支持。 `CacheConfig.java` ```java import org.springframework.cache.annotation.EnableCaching; import org.springframework.context.annotation.Configuration; @Configuration @EnableCaching public class CacheConfig { } ``` ## 6\. `@Cacheable`注解要缓存从方法调用返回的数据，我们可以在方法上使用`@Cacheable`注解。使用其属性`cacheNames`和`key`来指代缓存和缓存条目的键属性。 `EmployeeManager.java` ```java import java.util.HashMap; import org.springframework.cache.annotation.Cacheable; import org.springframework.stereotype.Service; @Service public class EmployeeManager { static HashMap<Long, Employee> db = new HashMap<>(); static { db.put(1L, new Employee(1L, "Alex", "Gussin")); db.put(2L, new Employee(2L, "Brian", "Schultz")); } @Cacheable(cacheNames="employeeCache", key="#id") public Employee getEmployeeById(Long id) { System.out.println("Getting employee from DB"); return db.get(id); } } ``` ## 7\. Spring `CacheManager` API 有时，在使用注解似乎不是完美解决方案的情况下，我们可能需要使用缓存。在这种情况下，我们可以使用`org.springframework.cache.CacheManager`和`org.springframework.cache.Cache`抽象来访问并利用 ehcache 添加和访问缓存条目。要使用`CacheManager`，我们必须首先自动装配到 spring 组件中，并使用它的`getCache(name)`方法来按名称获取缓存实例。访问缓存后，我们可以使用其`get()`和`put()`方法来添加和访问缓存条目。 ```java //1 @Autowired private CacheManager cacheManager; //2 Cache cache = cacheManager.getCache("myCache"); cache.put(3L, "Hello"); String value = cache.get(3L).get(); ``` ## 8\. Spring Boot ehcache 3 示例 – 演示我正在创建一个模型类`Employee`，其实例将被缓存。 `Employee.java` ```java import java.io.Serializable; public class Employee implements Serializable { private static final long serialVersionUID = 5517244812959569947L; private Long id; private String firstName; private String lastName; public Employee() { super(); } public Employee(Long id, String firstName, String lastName) { super(); this.id = id; this.firstName = firstName; this.lastName = lastName; } //Getters and setters @Override public String toString() { return "Employee [id=" + id + ", firstName=" + firstName + ", lastName=" + lastName + "]"; } } ``` 现在在演示应用程序类中，我正在使用`@Cacheable`注解测试基于注解的缓存访问，并使用`CacheManager`进行手动缓存访问。 `Application.java` ```java import org.springframework.beans.factory.annotation.Autowired; import org.springframework.boot.CommandLineRunner; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.cache.Cache; import org.springframework.cache.CacheManager; import org.springframework.context.ApplicationContext; import org.springframework.context.annotation.Bean; @SpringBootApplication public class Application { @Autowired private CacheManager cacheManager; @Autowired private EmployeeManager employeeManager; public static void main(String[] args) { SpringApplication.run(Application.class, args); } @Bean public CommandLineRunner commandLineRunner(ApplicationContext ctx) { return args -> { //This will hit the database System.out.println(employeeManager.getEmployeeById(1L)); //This will hit the cache - verify the message in console output System.out.println(employeeManager.getEmployeeById(1L)); //Access cache instance by name Cache cache = cacheManager.getCache("employeeCache"); //Add entry to cache cache.put(3L, new Employee(3L, "Charles", "Dave")); //Get entry from cache System.out.println(cache.get(3L).get()); }; } } ``` 程序输出。 `Console` ```java //First hit to "employeeManager.getEmployeeById(1L)" Getting employee from DB Employee [id=1, firstName=Alex, lastName=Gussin] 2019-07-10 15:42:32.371 INFO 11956 --- [e [_default_]-0] com.company.CustomCacheEventLogger : Cache event = CREATED, Key = 1, Old value = null, New value = Employee [id=1, firstName=Alex, lastName=Gussin] //Second hit to "employeeManager.getEmployeeById(1L)" Employee [id=1, firstName=Alex, lastName=Gussin] //cache.put(3L, new Employee(3L, "Charles", "Dave")); 2019-07-10 15:42:32.399 INFO 11956 --- [e [_default_]-0] com.company.CustomCacheEventLogger : Cache event = CREATED, Key = 3, Old value = null, New value = Employee [id=3, firstName=Charles, lastName=Dave] //System.out.println(cache.get(3L).get()); Employee [id=3, firstName=Charles, lastName=Dave] ``` 请在评论中使用 ehcache 3 将有关此 **spring boot 2** 缓存示例的问题交给我。学习愉快！ [下载源码](https://howtodoinjava.com/wp-content/downloads/SpringBootCacheDemo-ehcache2.zip)