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