java模拟spring与aop

写在前面：这篇文章是按照尚学堂马士兵老师的讲解总结的。

1，搭架构

 

对每个类进行代码的编写

UserDao.class

package com.bjsxt.dao; import com.bjsxt.model.User; public interface UserDAO {     public void save(User user);     public void delete(); }

UserDaoImpl.class

package com.bjsxt.dao.impl; import com.bjsxt.dao.UserDAO; import com.bjsxt.model.User; public class UserDAOImpl implements UserDAO {     public void save(User user) {                 //Hibernate         //JDBC         //XML         //NetWork         System.out.println("user saved!");     }     public void delete() {         System.out.println("user deteleted");             } }

User.class

package com.bjsxt.model; public class User {     private String username;     private String password;     public String getUsername() {         return username;     }     public void setUsername(String username) {         this.username = username;     }     public String getPassword() {         return password;     }     public void setPassword(String password) {         this.password = password;     } }

UserService

package com.bjsxt.service; import com.bjsxt.dao.UserDAO; import com.bjsxt.model.User; public class UserService {     private UserDAO userDAO;      public void add(User user) {         userDAO.save(user);     }     public UserDAO getUserDAO() {         return userDAO;     }     public void setUserDAO(UserDAO userDAO) {         this.userDAO = userDAO;     } }

BeanFactory.class

package com.bjsxt.spring; public interface BeanFactory {     public Object getBean(String id); }

ClassPathXmlApplicationContext.class

 

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>();             //IOC Inverse of Control DI Dependency Injection     public ClassPathXmlApplicationContext() throws Exception {         SAXBuilder sb=new SAXBuilder();                 Document doc=sb.build(this.getClass().getClassLoader().getResourceAsStream("beans.xml")); //构造文档对象         Element root=doc.getRootElement(); //获取根元素HD         List list=root.getChildren("bean");//取名字为disk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");            Object o = Class.forName(clazz).newInstance();            System.out.println(id);            System.out.println(clazz);            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 id) {         return beans.get(id);     } }

模拟SpringAop

加入LogIterceptor

 

package com.bjsxt.aop; import java.lang.reflect.InvocationHandler; import java.lang.reflect.Method; public class LogInterceptor implements InvocationHandler {     private Object target;         public Object getTarget() {         return target;     }     public void setTarget(Object target) {         this.target = target;     }     public void beforeMethod(Method m) {                 System.out.println(m.getName() + " start");     }     public Object invoke(Object proxy, Method m, Object[] args)             throws Throwable {         beforeMethod(m);         m.invoke(target, args);         return null;     } }

接下来是测试类

 

package com.bjsxt.service; import java.lang.reflect.Proxy; import org.junit.Test; import com.bjsxt.aop.LogInterceptor; import com.bjsxt.dao.UserDAO; import com.bjsxt.dao.impl.UserDAOImpl; import com.bjsxt.model.User; import com.bjsxt.spring.BeanFactory; import com.bjsxt.spring.ClassPathXmlApplicationContext; public class UserServiceTest {     @Test     public void testAdd() throws Exception {         BeanFactory applicationContext = new ClassPathXmlApplicationContext();                         UserService service = (UserService)applicationContext.getBean("userService");                             User u = new User();         u.setUsername("zhangsan");         u.setPassword("zhangsan");         service.add(u);     }         @Test     public void testProxy() {         UserDAO userDAO = new UserDAOImpl();         LogInterceptor li = new LogInterceptor();         li.setTarget(userDAO);         UserDAO userDAOProxy = (UserDAO)Proxy.newProxyInstance(userDAO.getClass().getClassLoader(), userDAO.getClass().getInterfaces(), li);         //System.out.println(userDAOProxy.getClass());         userDAOProxy.delete();         userDAOProxy.save(new User());             }         /*class $Proxy4 implements UserDAO      * {      *     save(User u) {      *     Method m = UserDAO.getclass.getmethod      * li.invoke(this, m, u)      * }      * }      */ }   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"/>  </bean>   </beans> 附 test.xml <?xml version="1.0" encoding="UTF-8"?> <HD>   <disk name="C">     <capacity>8G</capacity>     <directories>200</directories>     <files>1580</files>   </disk>   <disk name="D">     <capacity>10G</capacity>     <directories>500</directories>     <files>3000</files>   </disk> </HD>