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{

@Override
public 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"); // u
Object 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 {

@Test
public 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