第一种：在初始化时保存ApplicationContext对象
ApplicationContext ac = new FileSystemXmlApplicationContext("applicationContext.xml");
ac.getBean("beanId");
说明：这种方式适用于采用Spring框架的独立应用程序，需要程序通过配置文件手工初始化Spring。
第二种：通过Spring提供的工具类获取ApplicationContext对象
ApplicationContext ac1 = WebApplicationContextUtils.getRequiredWebApplicationContext(ServletContext sc);
ac1.getBean("beanId");
ApplicationContext ac2 = WebApplicationContextUtils.getWebApplicationContext(ServletContext sc);
ac2.getBean("beanId");
说明：
1. 这两种方式适合于采用Spring框架的B/S系统，通过ServletContext对象获取ApplicationContext对象，然后在通过它获取需要的类实例；
2. 第一种方式在获取失败时抛出异常，第二种方式返回null.
第三种：继承自抽象类ApplicationObjectSupport
说明：通过抽象类ApplicationObjectSupport提供的getApplicationContext()方法可以方便的获取到ApplicationContext实例，进而获取Spring容器中的bean。Spring初始化时，会通过该抽象类的setApplicationContext(ApplicationContext context)方法将ApplicationContext 对象注入。
第四种：继承自抽象类WebApplicationObjectSupport
说明：和上面方法类似，通过调用getWebApplicationContext()获取WebApplicationContext实例；
第五种：实现接口ApplicationContextAware
说明：实现该接口的setApplicationContext(ApplicationContext context)方法，并保存ApplicationContext对象。Spring初始化时，会通过该方法将ApplicationContext对象注入。
虽然Spring提供了后三种方法可以实现在普通的类中继承或实现相应的类或接口来获取Spring的ApplicationContext对象，但是在使用时一定要注意继承或实现这些抽象类或接口的普通java类一定要在Spring的配置文件（即application-context.xml文件）中进行配置，否则获取的ApplicationContext对象将为null。
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
public class ApplicationContextHolderimplements ApplicationContextAware {
private static final Loggerlog = LoggerFactory.getLogger(ApplicationContextHolder.class);
private static ApplicationContextapplicationContext;
public void setApplicationContext(ApplicationContext context)throws BeansException {
if (applicationContext !=null) {
throw new IllegalStateException("ApplicationContextHolder already holded 'applicationContext'.");
}
applicationContext = context;
log.info("holded applicationContext,displayName:" +applicationContext.getDisplayName());
}
public static ApplicationContext getApplicationContext() {
if (applicationContext ==null)
throw new IllegalStateException("'applicationContext' property is null,ApplicationContextHolder not yet init.");
return applicationContext;
}
public static T getBean(String beanName) {
return (T)getApplicationContext().getBean(beanName);
}
}
applicationContext.xml配置文件需添加如下配置：
<bean id="ApplicationContextHolder" class="com.dragonsoft.is2.sys.utils.ApplicationContextHolder"></bean>
还有一种方法
WebApplicationContext wac = ContextLoader.getCurrentWebApplicationContext();
EhCacheCacheManager cacheManager = (EhCacheCacheManager)wac.getBean(“cacheManager”);
```
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
public class ApplicationContextHolderimplements ApplicationContextAware {
private static final Loggerlog = LoggerFactory.getLogger(ApplicationContextHolder.class);
private static ApplicationContextapplicationContext;
public void setApplicationContext(ApplicationContext context)throws BeansException {
if (applicationContext !=null) {
throw new IllegalStateException("ApplicationContextHolder already holded 'applicationContext'.");
}
applicationContext = context;
log.info("holded applicationContext,displayName:" +applicationContext.getDisplayName());
}
public static ApplicationContext getApplicationContext() {
if (applicationContext ==null)
throw new IllegalStateException("'applicationContext' property is null,ApplicationContextHolder not yet init.");
return applicationContext;
}
public static T getBean(String beanName) {
return (T)getApplicationContext().getBean(beanName);
}
}
```
