不加载，手动实例化Service

最新推荐文章于 2024-07-07 03:48:12 发布

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本文介绍了一种在Java应用中使用Spring框架进行Bean实例化的策略。通过定义BeanService和BeanUtil两个工具类，实现了按需加载Spring上下文中定义的Beans，并缓存已加载的Bean实例以提高后续获取Bean实例的效率。

//调用方法
private static IEntityService entityService=(IEntityService) BeanService.getBean("entityService");

BeanService里面的方法
private static Map<String, Object> beans;
static {
beans = new HashMap<String, Object>();
}
public static Object getBean(String beanName) {
if (beans.containsKey(beanName) && beans.get(beanName) != null) {
return beans.get(beanName);
}
Object bean = BeanUtil.getBean(beanName);
if (bean != null) {
beans.put(beanName, bean);
}
return bean;
}

BeanUtil里面的方法

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.springframework.util.StringUtils;
public class BeanUtil {
private static ClassPathXmlApplicationContext context;
private static String flagInit = "0";
/**
* 获取spring上下文
* 
* @return 上下文容器
*/
private static ApplicationContext getContext() {
synchronized (flagInit) {
if ("0".equals(flagInit)) {
if (context == null) {
ClassPathXmlApplicationContext context1 = new ClassPathXmlApplicationContext("spring-config.xml", "spring-mvc.xml");//分别是Spring和MVC的配置文件
context = context1;
context.start();
}
flagInit = "1";
}
}
return context;

}

static {
getContext();
}

/**
* 获取bean
* 
* @param beanName
* @return
*/
public static Object getBean(String beanName) {
if (StringUtils.isEmpty(beanName)) {
return null;
}
if (getContext() == null) {
return null;
}

return getContext().getBean(beanName);
}
}