Simulate spring functions
1. Create User.java with the following content:
package net.model; /** * @项目名:spring2.5 * @包名:net.model * @文件名:User.java * @日期:Jun 22, 2011 4:31:22 PM * @备注: * @作者:apple */ 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; } }
2. Create UserDao.java with the following content:
package net.dao; import net.model.User; /** * @项目名:spring2.5 * @包名:net.dao * @文件名:UserDao.java * @日期:Jun 22, 2011 4:12:42 PM * @备注: * @作者:apple */ public interface UserDao { public void save(User u); }
3. Create UserDaoImpl.java with the following content:
package net.dao.impl; import net.dao.UserDao; import net.model.User; /** * @项目名:spring2.5 * @包名:net.dao.impl * @文件名:UserDaoImpl.java * @日期:Jun 22, 2011 4:13:45 PM * @备注: * @作者:apple */ public class UserDaoImpl implements UserDao { public void save(User u) { // TODO Auto-generated method stub System.out.println("user save..."); } }
4. Create UserService.java with the following content:
package net.service; import net.dao.UserDao; import net.dao.impl.UserDaoImpl; import net.model.User; /** * @项目名:spring2.5 * @包名:net.service * @文件名:UserService.java * @日期:Jun 22, 2011 4:15:47 PM * @备注: * @作者:apple */ public class UserService { private UserDao userDao ; public UserDao getUserDao() { return userDao; } public void setUserDao(UserDao userDao) { this.userDao = userDao; } public void add(User u){ userDao.save(u); }//这里可以调用任务实现了UserDao接口的save方法了。 }
5. Create BeanFactory.java with the following content:
package net.factory; /** * @项目名:spring2.5 * @包名:net.factory * @文件名:BeanFactory.java * @日期:Jun 22, 2011 4:37:08 PM * @备注: * @作者:apple */ public interface BeanFactory { public Object getBean(String name); }
6. Create ClassPathXmlApplicationContext.java with the following content:
package net.util; import java.lang.reflect.Method; import java.util.HashMap; import java.util.List; import java.util.Map; import net.dao.UserDao; import net.factory.BeanFactory; import net.model.User; import net.service.UserService; import org.jdom.Document; import org.jdom.Element; import org.jdom.input.SAXBuilder; /** * @项目名:spring2.5 * @包名:net.util * @文件名:ClassPathXmlApplicationContext.java * @日期:Jun 22, 2011 4:19:35 PM * @备注: * @作者:apple */ public class ClassPathXmlApplicationContext implements BeanFactory{ private Map<String,Object> beans = new HashMap<String, Object>(); public ClassPathXmlApplicationContext() throws Exception{ SAXBuilder sb=new SAXBuilder();//创建一个SAXBuilder对象 Document doc=sb.build(ClassPathXmlApplicationContext.class.getClassLoader().getResourceAsStream("beans.xml")); //构造文档对象 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); //* 以下for循环是实现模拟spring自动装配(注入)功能 //一开始列出此bean的所有property子元素 for (Element propertyElement : (List<Element>)element.getChildren("property")){ //获取property子元素中 属性为name的值(也就是需要注入的参数名称) String name = propertyElement.getAttributeValue("name"); //获取property子元素中 属性为bean的值 (需要注入参数的类型),此处的bean值是已经在上面初始化好了的bean的ID了。 String bean = propertyElement.getAttributeValue("bean"); //因此此处获取指定ID的bean Object beanObject = beans.get(bean); //组成set方法名称:set + 第一个字母大写 + 其它的字母 String methodName = "set" + name.substring(0,1).toUpperCase() + name.substring(1); System.out.println("methodName = " + methodName); //获取bean的set方法,参数(方法名,参数:此参数的类型) Method m = o.getClass().getMethod(methodName, beanObject.getClass().getInterfaces()[0]); //使用反映机制,执行method方法,从而实现注入功能 m.invoke(o, beanObject); } } } public Object getBean(String name){ return beans.get(name); } public static void main(String[] args){ BeanFactory factory=null; try { factory = new ClassPathXmlApplicationContext(); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } UserService service = (UserService)factory.getBean("userService"); User u = new User(); service.add(u); } }
7. Create beans.xml with the following content:
<?xml version="1.0" encoding="UTF-8"?> <beans> <bean id="u" class="net.dao.impl.UserDaoImpl"> </bean> <bean id="userService" class="net.service.UserService"> <property name="userDao" bean="u"/> </bean> </beans>

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