模拟Spring框架

Posted 2020-09-18 流年如水~烟雨随风

BeanFactory

1 package com.bjsxt.spring;
2 
3 public interface BeanFactory {
4     public Object getBean(String name);
5 }

ClassPathXmlApplicationContext

 1 package com.bjsxt.spring;
 2 
 3 import java.lang.reflect.Method;
 4 import java.util.HashMap;
 5 import java.util.List;
 6 import java.util.Map;
 7 
 8 import org.jdom.Document;
 9 import org.jdom.Element;
10 import org.jdom.input.SAXBuilder;
11 
12 public class ClassPathXmlApplicationContext implements BeanFactory{
13     private Map<String, Object> beans = new HashMap<String, Object>();
14     
15     public ClassPathXmlApplicationContext() throws Exception{
16         SAXBuilder sb = new SAXBuilder();
17         Document doc = sb.build(this.getClass().getClassLoader().getResourceAsStream("beans.xml"));
18         Element root = doc.getRootElement();//获取根元素
19         List list = root.getChildren("bean");//取名字为bean的所有元素
20         for(int i=0; i<list.size(); i++){
21             Element element = (Element) list.get(i);
22             String id = element.getAttributeValue("id");
23             String clazz = element.getAttributeValue("class");
24             System.out.println(id + ":" + clazz);
25             Object o = Class.forName(clazz).newInstance();
26             beans.put(id, o);
27             
28             for(Element propertyElement : (List<Element>)element.getChildren("property")){
29                 String name = propertyElement.getAttributeValue("name");//userDAO
30                 String bean = propertyElement.getAttributeValue("bean");//u
31                 Object beanObject = beans.get(bean);//UserDAOImpl instance
32                 
33                 String methodName = "set" + name.substring(0, 1).toUpperCase() + name.substring(1);
34                 System.out.println("method name = " + methodName);
35                 
36                 Method m = o.getClass().getMethod(methodName, beanObject.getClass().getInterfaces()[0]);
37                 m.invoke(o, beanObject);    
38             }
39         }
40     }
41 
42     public Object getBean(String name) {
43         return beans.get(name);
44     }
45     
46 }

beans.xml

1 <beans>
2     <bean id="u" class="com.bjsxt.dao.impl.UserDAOImpl"></bean>
3     <bean id="userService" class="com.bjsxt.service.UserService">
4         <property name="userDAO" bean="u"></property>
5     </bean>
6 </beans>

UserDAO

1 package com.bjsxt.dao;
2 
3 import com.bjsxt.model.User;
4 
5 public interface UserDAO {
6     public void save(User u);
7 }

UserDAOImpl

 1 package com.bjsxt.dao.impl;
 2 
 3 import com.bjsxt.dao.UserDAO;
 4 import com.bjsxt.model.User;
 5 
 6 public class UserDAOImpl implements UserDAO{
 7 
 8     public void save(User u) {
 9         System.out.println("a user saved!");
10     }
11 
12 }

测试类：

 1 package com.bjsxt.service;
 2 
 3 import org.junit.Test;
 4 
 5 import com.bjsxt.model.User;
 6 import com.bjsxt.spring.BeanFactory;
 7 import com.bjsxt.spring.ClassPathXmlApplicationContext;
 8 
 9 public class UserServiceTest {
10 
11     @Test
12     public void testAddUser() throws Exception {
13         BeanFactory factory = new ClassPathXmlApplicationContext();
14         
15         UserService service = (UserService)factory.getBean("userService");
16         User u = new User();
17         service.addUser(u);
18     }
19 
20 }

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