SpringBoot中注入ApplicationContext物件的三種方式
阿新 • • 發佈:2019-02-01
在專案中,我們可能需要手動獲取spring中的bean物件,這時就需要通過 ApplicationContext 去操作一波了!
1、直接注入(Autowired)
@Component
public class User {
@Autowired
private ApplicationContext applicationContext;
}
2、構造器方法注入
@Component
public class User{
private ApplicationContext applicationContext;
public User (ApplicationContext applicationContext) {
this.applicationContext = applicationContext;
}
}
3、手動構建類實現介面
/**
* Spring的ApplicationContext的持有者,可以用靜態方法的方式獲取spring容器中的bean
*
* @author yj
* @date 2018年5月27日 下午6:32:11
*/
@Component
public class SpringContextHolder implements ApplicationContextAware {
private static ApplicationContext applicationContext;
@Override
public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
SpringContextHolder.applicationContext = applicationContext;
}
public static ApplicationContext getApplicationContext () {
assertApplicationContext();
return applicationContext;
}
@SuppressWarnings("unchecked")
public static <T> T getBean(String beanName) {
assertApplicationContext();
return (T) applicationContext.getBean(beanName);
}
public static <T> T getBean(Class<T> requiredType) {
assertApplicationContext();
return applicationContext.getBean(requiredType);
}
private static void assertApplicationContext() {
if (SpringContextHolder.applicationContext == null) {
throw new RuntimeException("applicaitonContext屬性為null,請檢查是否注入了SpringContextHolder!");
}
}
}
注:在使用該類靜態方法時必須保證spring載入順序正確!
可以在使用類上新增 @DependsOn(“springContextHolder”),確保在此之前 SpringContextHolder 類已載入!