Spring中 FactoryBean和bean
Spring中 FactoryBean和bean
1.整合spring+hibernate中,让spring接管hibernate的session工厂有一段代码
- <bean id="sFactory" class="org.springframework.orm.hibernate3.LocalSessionFactoryBean">
- public class LocalSessionFactoryBean extends AbstractSessionFactoryBean implements BeanClassLoaderAware
- public abstract class AbstractSessionFactoryBean
- implements FactoryBean<SessionFactory>, InitializingBean, DisposableBean, PersistenceExceptionTranslator
发现了实现了一个factoryBean<T>,里面给了个泛型(SeesionFactory).
注:这个bean和其他的bean不一样,spring中有两种bean.
普通bean和bean工厂,即FactoryBean. FactoryBean 返回的不是这个类的实例,其返回的是该工厂Bean的getObject()方法所返回的对象
普通的Bean直接返回指定类(配置中的class属性的值)的一个实例.
一个小例子:
- package org.ymm.entity;
- import org.springframework.beans.factory.FactoryBean;
- /**
- * TestBean 类实现了FactoryBean<T>
- * @author witho_000
- *
- */
- public class TestBean implements FactoryBean<Object>{
- public Object getObject() throws Exception {
- // TODO Auto-generated method stub
- return "string类型";
- }
- @Override
- public Class<?> getObjectType() {
- // TODO Auto-generated method stub
- return null;
- }
- @Override
- public boolean isSingleton() {
- // TODO Auto-generated method stub
- return false;
- }
- }
- <?xml version="1.0" encoding="UTF-8"?>
- <beans xmlns="http://www.springframework.org/schema/beans"
- xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
- xmlns:context="http://www.springframework.org/schema/context"
- xsi:schemaLocation="http://www.springframework.org/schema/beans
- http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
- http://www.springframework.org/schema/context
- http://www.sprinsgframework.org/schema/context/spring-context-3.0.xsd">
- <!-- 测试factorybean -->
- <bean id="factorybean1" class="org.ymm.entity.TestBean" />
- </beans>
- package org.ym.test;
- import org.springframework.context.ApplicationContext;
- import org.springframework.context.support.ClassPathXmlApplicationContext;
- import org.ymm.entity.TestBean;
- /**
- * Tester测试类
- * @author witho_000
- *
- */
- public class Tester {
- public static void main(String[] args) {
- ApplicationContext cont=new ClassPathXmlApplicationContext("beans.xml");
- String s= cont.getBean("&factorybean1",String.class);
- System.out.println(s.getClass());
- }
- }
网上找到的小技巧:
String s= cont.getBean("&factorybean1",String.class);
bean的id前加个&得到的就是TestBean
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