\(^)/ 模拟Spring的IoC

参考：http://blog.****.net/lyq8479/article/category/1366622

参考：http://neversky.iteye.com/blog/1956018

参考：http://www.cnblogs.com/txw1958/

参考：http://justsee.iteye.com/blog/1298861

参考：http://xiaoye4188.iteye.com/blog/846822

参考：http://josephmok.iteye.com/blog/763653

参考：http://lgd-java2eye.iteye.com/blog/756599

参考：http://byd1200479.iteye.com/blog/1599365

参考：http://jim8757.iteye.com/blog/2059999

参考：http://chenzehe.iteye.com/blog/1488781

参考：http://dyygusi.iteye.com/blog/1997231

参考：http://lgd-java2eye.iteye.com/blog/759878

参考：http://ewf-momo.iteye.com/blog/1693723

Bean元素封装

package spring.mock;

import java.util.ArrayList;
import java.util.List;

/**
 * Xml文件中<bean/>元素的对象
 */
public class BeanDefinition {
	private String id;
	private String clazz;
	private List<PropertyDefinition> propertyDefinition = new ArrayList<PropertyDefinition>();

	public BeanDefinition(String id, String clazz) {
		super();
		this.id = id;
		this.clazz = clazz;
	}

	public String getId() {
		return id;
	}

	public void setId(String id) {
		this.id = id;
	}

	public String getClazz() {
		return clazz;
	}

	public void setClazz(String clazz) {
		this.clazz = clazz;
	}

	public List<PropertyDefinition> getPropertyDefinition() {
		return propertyDefinition;
	}

	public void setPropertyDefinition(List<PropertyDefinition> propertyDefinition) {
		this.propertyDefinition = propertyDefinition;
	}

}

Bean中的Property元素封装

package spring.mock;

/**
 * Xml元素中<bean>元素中的property元素
 */
public class PropertyDefinition {
	private String name;
	private String ref;
	private String value;

	public PropertyDefinition(String name, String ref, String value) {
		super();
		this.name = name;
		this.ref = ref;
		this.value = value;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public String getRef() {
		return ref;
	}

	public void setRef(String ref) {
		this.ref = ref;
	}

	public String getValue() {
		return value;
	}

	public void setValue(String value) {
		this.value = value;
	}

}

ApplicationContext模拟

package spring.mock;

import java.beans.IntrospectionException;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.net.URL;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.apache.commons.beanutils.ConvertUtils;
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.XPath;
import org.dom4j.io.SAXReader;

public class MockSpringXmlApplicationContext {
	private List<BeanDefinition> beanDefinitions = new ArrayList<BeanDefinition>();
	private Map<String, Object> singletons = new HashMap<String, Object>();
	
	public MockSpringXmlApplicationContext(String fileName){
		try{
			this.readXML(fileName);
			this.instanceBean();
			this.injectObject();
		}catch(Exception e){
			e.printStackTrace();
		}
	}

	private void readXML(String fileName) throws DocumentException {
		SAXReader saxReader = new SAXReader();
		Document document = null;
		URL xmlPath = this.getClass().getClassLoader().getResource(fileName);
		document = saxReader.read(xmlPath);
		XPath beanPath = document.createXPath("//ns:beans/ns:bean");
		Map<String, String> nsMap = new HashMap<String, String>();
		nsMap.put("ns", "http://www.springframework.org/schema/beans");
		beanPath.setNamespaceURIs(nsMap);
		List<Element> beans = beanPath.selectNodes(document);
		for (Element element : beans) {
			String id = element.attributeValue("id");
			String clazz = element.attributeValue("class");
			BeanDefinition beanDefinition = new BeanDefinition(id, clazz);
			XPath propertyPath = element.createXPath("ns:property");
			propertyPath.setNamespaceURIs(nsMap);
			List<Element> properties = propertyPath.selectNodes(element);
			for (Element propElement : properties) {
				String name = propElement.attributeValue("name");
				String ref = propElement.attributeValue("ref");
				String value = propElement.attributeValue("value");
				PropertyDefinition propertyDefinition = new PropertyDefinition(name, ref, value);
				beanDefinition.getPropertyDefinition().add(propertyDefinition);
			}
			beanDefinitions.add(beanDefinition);
		}
	}

	private void instanceBean() throws InstantiationException, IllegalAccessException, ClassNotFoundException {
		for (BeanDefinition beanDefinition : beanDefinitions) {
			if (beanDefinition.getClass() != null && !"".equals(beanDefinition.getClass())) {
				singletons.put(beanDefinition.getId(), Class.forName(beanDefinition.getClazz()).newInstance());
			}
		}
	}

	private void injectObject() throws IntrospectionException, IllegalArgumentException, IllegalAccessException, InvocationTargetException {
		for (BeanDefinition beanDefinition : beanDefinitions) {
			Object bean = singletons.get(beanDefinition.getId());
			if (bean != null) {
				PropertyDescriptor[] ps = Introspector.getBeanInfo(bean.getClass()).getPropertyDescriptors();
				for (PropertyDefinition propertyDefinition : beanDefinition.getPropertyDefinition()) {
					for(PropertyDescriptor propertyDescriptor:ps){
						if(propertyDefinition.getName().equals(propertyDescriptor.getName())){
							Method setterMethod = propertyDescriptor.getWriteMethod();
							if(setterMethod!=null){
								Object temp = null;
								if(propertyDefinition.getRef()!=null&&!"".equals(propertyDefinition.getRef().trim())){
									temp = singletons.get(propertyDefinition.getRef());
								}else if(propertyDefinition.getValue()!=null&&!"".equals(propertyDefinition.getValue().trim())){
									temp = ConvertUtils.convert(propertyDefinition.getValue(), propertyDescriptor.getPropertyType());
								}
								setterMethod.setAccessible(true);
								setterMethod.invoke(bean, temp);
							}
							break;
						}
					}
				}
			}
		}
	}
	
	public Object getBean(String beanName){
		return this.singletons.get(beanName);
	}
}

测试DAO

package spring.mock;

public class UserDAO {
	private String id;

	public String getId() {
		return id;
	}

	public void setId(String id) {
		this.id = id;
	}

	@Override
	public String toString() {
		return "UserDAO [id=" + id + "]";
	}

}

测试Service

package spring.mock;

public class UserService {
	private String id;
	private String name;
	private int age;
	private UserDAO userDAO;
	public String getId() {
		return id;
	}
	public void setId(String id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public int getAge() {
		return age;
	}
	public void setAge(int age) {
		this.age = age;
	}
	public UserDAO getUserDAO() {
		return userDAO;
	}
	public void setUserDAO(UserDAO userDAO) {
		this.userDAO = userDAO;
	}
	@Override
	public String toString() {
		return "UserService [id=" + id + ", name=" + name + ", age=" + age + ", userDAO=" + userDAO + "]";
	}
}

beans.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://www.springframework.org/schema/beans
           http://www.springframework.org/schema/beans/spring-beans-2.5.xsd">
	<bean id="userDAO" class="spring.mock.UserDAO">
		<property name="id" value="userDAO_id_001" />
	</bean>
	<bean id="userService" class="spring.mock.UserService">
		<property name="id" value="userService_id_001" />
		<property name="name" value="userName_test" />
		<property name="age" value="23" />
		<property name="userDAO" ref="userDAO" />
	</bean>
</beans>

测试类

package spring.mock;

public class Test {
	public static void main(String[] args) {
		
		MockSpringXmlApplicationContext context = new MockSpringXmlApplicationContext("beans.xml");
		UserService userService = (UserService)context.getBean("userService");
		System.out.println(userService.toString());
	}
}