Spring @Configuration和FactoryBean

考慮使用FactoryBean通過Spring配置檔案定義緩存：

<cache:annotation-driven />
 <context:component-scan base-package='org.bk.samples.cachexml'></context:component-scan>
 
 <bean id='cacheManager' class='org.springframework.cache.support.SimpleCacheManager'>
  <property name='caches'>
   <set>
    <ref bean='defaultCache'/>
   </set>
  </property>
 </bean>
 
 <bean name='defaultCache' class='org.springframework.cache.concurrent.ConcurrentMapCacheFactoryBean'>
  <property name='name' value='default'/>
 </bean>
           

工廠bean ConcurrentMapCacheFactoryBean是一個依次負責建立Cache bean的bean。

我第一次嘗試将此設定轉換為@Configuration樣式：

@Bean
public SimpleCacheManager cacheManager(){
 SimpleCacheManager cacheManager = new SimpleCacheManager();
 List<Cache> caches = new ArrayList<Cache>();
 ConcurrentMapCacheFactoryBean cacheFactoryBean = new ConcurrentMapCacheFactoryBean();
 cacheFactoryBean.setName('default');
 caches.add(cacheFactoryBean.getObject());
 cacheManager.setCaches(caches );
 return cacheManager;
}
           

但是，這沒有用，原因是我在這裡完全繞過了一些Spring bean生命周期機制。 事實證明，ConcurrentMapCacheFactoryBean還實作了InitializingBean接口，并在InitializingBean的'afterPropertiesSet'方法中對緩存進行了急切的初始化。 現在，通過直接調用factoryBean.getObject（），我完全繞過了afterPropertiesSet方法。

有兩種可能的解決方案：

1.以與在XML中定義的相同方式定義FactoryBean：

@Bean
public SimpleCacheManager cacheManager(){
 SimpleCacheManager cacheManager = new SimpleCacheManager();
 List<Cache> caches = new ArrayList<Cache>();
 caches.add(cacheBean().getObject());
 cacheManager.setCaches(caches );
 return cacheManager;
}

@Bean
public ConcurrentMapCacheFactoryBean cacheBean(){
 ConcurrentMapCacheFactoryBean cacheFactoryBean = new ConcurrentMapCacheFactoryBean();
 cacheFactoryBean.setName('default');
 return cacheFactoryBean;
}
           

在這種情況下，從@Bean方法傳回一個顯式的FactoryBean，Spring将負責在此bean上調用生命周期方法。

2.複制相關生命周期方法中的行為，在此特定執行個體中，我知道FactoryBean在afterPropertiesSet方法中執行個體化ConcurrentMapCache，我可以通過以下方式直接複制此行為：

@Bean
public SimpleCacheManager cacheManager(){
 SimpleCacheManager cacheManager = new SimpleCacheManager();
 List<Cache> caches = new ArrayList<Cache>();
 caches.add(cacheBean());
 cacheManager.setCaches(caches );
 return cacheManager;
}

@Bean
public Cache  cacheBean(){
 Cache  cache = new ConcurrentMapCache('default');
 return cache;
}
           

将FactoryBean從xml轉換為@Configuration時要記住的一點。

注意：

可以根據需要進行一頁有效的測試：

package org.bk.samples.cache;
 
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.equalTo;
 
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Random;
 
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.cache.Cache;
 import org.springframework.cache.annotation.Cacheable;
 import org.springframework.cache.annotation.EnableCaching;
 import org.springframework.cache.concurrent.ConcurrentMapCacheFactoryBean;
 import org.springframework.cache.support.SimpleCacheManager;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.ComponentScan;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.stereotype.Component;
 import org.springframework.test.context.ContextConfiguration;
 import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
 
 @RunWith(SpringJUnit4ClassRunner.class)
 @ContextConfiguration(classes={TestSpringCache.TestConfiguration.class})
 public class TestSpringCache {
 
  @Autowired TestService testService;
 
  @Test
  public void testCache() {
   String response1 = testService.cachedMethod('param1', 'param2');
   String response2 = testService.cachedMethod('param1', 'param2');
   assertThat(response2, equalTo(response1));
  }
 
 
  @Configuration
  @EnableCaching
  @ComponentScan('org.bk.samples.cache')
  public static class TestConfiguration{
 
   @Bean
   public SimpleCacheManager cacheManager(){
    SimpleCacheManager cacheManager = new SimpleCacheManager();
    List<Cache> caches = new ArrayList<Cache>();
    caches.add(cacheBean().getObject());
    cacheManager.setCaches(caches );
    return cacheManager;
   }
 
   @Bean
   public ConcurrentMapCacheFactoryBean cacheBean(){
    ConcurrentMapCacheFactoryBean cacheFactoryBean = new ConcurrentMapCacheFactoryBean();
    cacheFactoryBean.setName('default');
    return cacheFactoryBean;
   }
  }
 
 }
 
 interface TestService{
  String cachedMethod(String param1,String param2);
 }
 
 @Component
 class TestServiceImpl implements TestService{
 
  @Cacheable(value='default', key='#p0.concat('-').concat(#p1)')
  public String cachedMethod(String param1, String param2){
   return 'response ' + new Random().nextInt();
  }
 }
           

參考： all和其他部落格中來自我們JCG合作夥伴 Biju Kunjummen的Spring @Configuration和FactoryBean 。

翻譯自: https://www.javacodegeeks.com/2012/08/spring-configuration-and-factorybean.html