模拟Spring框架

BeanFactory

package com.bjsxt.spring;

public interface BeanFactory {
    public Object getBean(String name);
}

ClassPathXmlApplicationContext

package com.bjsxt.spring;

import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.jdom.Document;
import org.jdom.Element;
import org.jdom.input.SAXBuilder;

public class ClassPathXmlApplicationContext implements BeanFactory{
    private Map<String, Object> beans = new HashMap<String, Object>();
    
    public ClassPathXmlApplicationContext() throws Exception{
        SAXBuilder sb = new SAXBuilder();
        Document doc = sb.build(this.getClass().getClassLoader().getResourceAsStream("beans.xml"));
        Element root = doc.getRootElement();//获取根元素
        List list = root.getChildren("bean");//取名字为bean的所有元素
        for(int i=0; i<list.size(); i++){
            Element element = (Element) list.get(i);
            String id = element.getAttributeValue("id");
            String clazz = element.getAttributeValue("class");
            System.out.println(id + ":" + clazz);
            Object o = Class.forName(clazz).newInstance();
            beans.put(id, o);
            
            for(Element propertyElement : (List<Element>)element.getChildren("property")){
                String name = propertyElement.getAttributeValue("name");//userDAO
                String bean = propertyElement.getAttributeValue("bean");//u
                Object beanObject = beans.get(bean);//UserDAOImpl instance
                
                String methodName = "set" + name.substring(0, 1).toUpperCase() + name.substring(1);
                System.out.println("method name = " + methodName);
                
                Method m = o.getClass().getMethod(methodName, beanObject.getClass().getInterfaces()[0]);
                m.invoke(o, beanObject);    
            }
        }
    }

    public Object getBean(String name) {
        return beans.get(name);
    }
    
}

beans.xml

<beans>
    <bean id="u" class="com.bjsxt.dao.impl.UserDAOImpl"></bean>
    <bean id="userService" class="com.bjsxt.service.UserService">
        <property name="userDAO" bean="u"></property>
    </bean>
</beans>

UserDAO

package com.bjsxt.dao;

import com.bjsxt.model.User;

public interface UserDAO {
    public void save(User u);
}

UserDAOImpl

package com.bjsxt.dao.impl;

import com.bjsxt.dao.UserDAO;
import com.bjsxt.model.User;

public class UserDAOImpl implements UserDAO{

    public void save(User u) {
        System.out.println("a user saved!");
    }

}

测试类：

package com.bjsxt.service;

import org.junit.Test;

import com.bjsxt.model.User;
import com.bjsxt.spring.BeanFactory;
import com.bjsxt.spring.ClassPathXmlApplicationContext;

public class UserServiceTest {

    @Test
    public void testAddUser() throws Exception {
        BeanFactory factory = new ClassPathXmlApplicationContext();
        
        UserService service = (UserService)factory.getBean("userService");
        User u = new User();
        service.addUser(u);
    }

}

代码链接: http://pan.baidu.com/s/1eSoYu8i 密码: gtj2

所需jar包：

　　junit链接: http://pan.baidu.com/s/1kVFS8lx 密码: mkh3

　　jdom链接: http://pan.baidu.com/s/1c1X15Xu 密码: 9vpi