dom4j实现模拟Spring读取配置文件 注入

1.

beans.xml

<?xml version="1.0" encoding="UTF-8" ?><beans><bean id="u" class="com.bjsxt.impl.UserDAOImpl" /><bean id="userService" class="com.bjsxt.service.UserService"><property name="userDAO" ref="u"></property></bean></beans>

 

2.UserDao代码

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

3.

package com.bjsxt.impl;import com.bjsxt.dao.UserDAO;import com.bjsxt.model.User;public class UserDAOImpl implements UserDAO{@Overridepublic void save(User user) {System.out.println("a user save !");}}

4.User类

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;}}

5.UserService类

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

6.BeanFactory接口

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

7.读取XML文件代码也是最重要的代码

package com.bjsxt.spring;import java.lang.reflect.Method;import java.util.HashMap;import java.util.List;import java.util.Map;import org.dom4j.Document;import org.dom4j.Element;import com.bjsxt.util.XMLUtils;public class ClassPathXmlApplicationContext implements BeanFactory{private Map<String,Object> beans = new HashMap<String,Object>();@SuppressWarnings("unchecked")public ClassPathXmlApplicationContext() throws Exception {Document document = XMLUtils.readXML();//List<Element> list = document.selectNodes("/beans/bean");Element root = document.getRootElement();List<Element> list = root.elements();for(Element element : list){String id = element.attributeValue("id");String clazz = element.attributeValue("class");Object o = Class.forName(clazz).newInstance();beans.put(id, o);List<Element> propertyList = element.elements();for(Element propertyElement : propertyList){String name = propertyElement.attributeValue("name"); //方法名String methodName = "set" + name.substring(0,1).toUpperCase() + name.substring(1);String ref = propertyElement.attributeValue("ref"); // uObject obj = beans.get(ref); //得到参考的对象//o 代表 com.bjsxt.service.UserService 类 //参数 setUserDAO,UserDAO接口Method m = o.getClass().getMethod(methodName, obj.getClass().getInterfaces()[0]); m.invoke(o, obj); //userService.setUserDAO()}}}public Object getBean(String name){return beans.get(name);}public static void main(String[] args) throws Exception {new ClassPathXmlApplicationContext();}}

8.工具类

package com.bjsxt.util;import org.dom4j.Document;import org.dom4j.DocumentException;import org.dom4j.io.SAXReader;public class XMLUtils {public static Document readXML() {Document document = null;try {document = new SAXReader().read(XMLUtils.class.getResourceAsStream("beans.xml"));return document;} catch (DocumentException e) {e.printStackTrace();}return document;}public static void main(String[] args) {Document document = readXML();System.out.println(document);}}

 

测试类：

(在工程中创建一个SourceFolder文件夹(取名为test)

在UserService.java上右键创建一个Junit Test Case  会得到一个UserServiceTest.java文件 再将它移到test文件夹下)

package com.bjsxt.service;import org.junit.Test;import com.bjsxt.dao.UserDAO;import com.bjsxt.model.User;import com.bjsxt.spring.BeanFactory;import com.bjsxt.spring.ClassPathXmlApplicationContext;public class UserServiceTest {@Testpublic void testAdd() {try {BeanFactory beanFactory = new ClassPathXmlApplicationContext();//通过配置文件得到UserDAOImpl对象UserDAO userDAO = (UserDAO) beanFactory.getBean("u");UserService userService = (UserService) beanFactory.getBean("userService");//userService.setUserDAO(userDAO); //不用写,ClassPathXmlApplicationContext中用反射setUserDAO了userService.add(new User());} catch (Exception e) {e.printStackTrace();}}}

 

右键UserServiceTest.java

Run as-->Junit Test

 

 

2011-1-16