java模拟spring ioc

 

<?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="personDao" class="junit.test12.PersonDaoBean"/>
          <bean id="personService" class="junit.test12.PersonServiceBean">
           	<property name="id" value="24"/>
          	<property name="name" value="zyj"/>
          	<!--  <property name="personDao" ref="personDao"/> -->
          </bean>
</beans>

 

package junit.test12;

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

/**
 * xml中的<bean/>的定义
 * @author Administrator
 *
 */
public class BeanDefinition {
	private String id;
	private String clazz;
	private List<PropertyDefinition> propertyDefinitions=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> getPropertyDefinitions() {
		return propertyDefinitions;
	}
	public void setPropertyDefinitions(List<PropertyDefinition> propertyDefinitions) {
		this.propertyDefinitions = propertyDefinitions;
	}
	

	
	
} 

 

 

package junit.test12;

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;
	}
	
	
	
	
	
	
}

 

 

 

package junit.test12;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.FIELD,ElementType.METHOD})
public @interface UserDefinedResource {
	public String name() default "";
}

 

//使用dom4j读取spring配置文件

package junit.test12;

import java.beans.IntrospectionException;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.lang.reflect.Field;
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 junit.test12.BeanDefinition;

import org.apache.commons.beanutils.ConvertUtils;
import org.apache.commons.beanutils.Converter;
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.XPath;
import org.dom4j.io.SAXReader;
/**
 * 自定义容器
 * @author Administrator
 *
 */
public class UserDefinedClassPathXMLApplicationContext {
	private List<BeanDefinition> beanDefinitions=new ArrayList<BeanDefinition>();
	private Map<String, Object> sigletons=new HashMap<String, Object>();
	
	public UserDefinedClassPathXMLApplicationContext(String filename){
		this.readXML(filename);
		this.instanceBeans();
		this.annotationInject();
		this.injectObject();
	}
	


	/**
	 * 读取xml配置文件
	 * @param filename
	 */
	private void readXML(String filename){
		SAXReader saxReader=new SAXReader();
		Document document=null;
		try {
			URL xmlPath=this.getClass().getClassLoader().getResource(filename);
			document=saxReader.read(xmlPath);
			XPath xPath=document.createXPath("//ns:beans/ns:bean");//创建beans/bean查询路径。从根路径开始
			Map<String, String> nsMap=new HashMap<String, String>();
			nsMap.put("ns", "http://www.springframework.org/schema/beans");//加入命名空间
			xPath.setNamespaceURIs(nsMap);//设置命名空间
			List<Element> beans=xPath.selectNodes(document);//获取文档下所有bean节点 
			for (Element element : beans) {
				String id=element.attributeValue("id");
				String clazz=element.attributeValue("class");
				BeanDefinition beanDefinition=new BeanDefinition(id, clazz);
				XPath xPath2=element.createXPath("ns:property");//从相对路径开始
				xPath2.setNamespaceURIs(nsMap);
				List<Element> propertys=xPath2.selectNodes(element);
				for (Element element2 : propertys) {
					String name=element2.attributeValue("name");
					String ref=element2.attributeValue("ref");
					String value=element2.attributeValue("value");
					PropertyDefinition propertyDefinition=new PropertyDefinition(name, ref,value);
					beanDefinition.getPropertyDefinitions().add(propertyDefinition);
				}
				beanDefinitions.add(beanDefinition);
			}	
		} catch (DocumentException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
	}	
	/**
	 * 完成bean的实例化
	 */
	private void instanceBeans(){
		try {
			for (BeanDefinition beanDefinition : beanDefinitions) {
				if (beanDefinition.getClazz()!=null&&!"".equals(beanDefinition.getClazz().trim())) {
					sigletons.put(beanDefinition.getId(), Class.forName(beanDefinition.getClazz()).newInstance());
				}
			}
		} catch (ClassNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (InstantiationException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IllegalAccessException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
	
	/**
	 * 为bean对象的属性注入值
	 * @throws IntrospectionException 
	 * @throws InvocationTargetException 
	 * @throws IllegalAccessException 
	 * @throws IllegalArgumentException 
	 */
	private void injectObject()  {
		try {
			for (BeanDefinition beanDefinition : beanDefinitions) {
				Object bean=sigletons.get(beanDefinition.getId());
				if (bean!=null) {
					PropertyDescriptor[] ps=Introspector.getBeanInfo(bean.getClass()).getPropertyDescriptors();
					for(PropertyDefinition propertyDefinition:beanDefinition.getPropertyDefinitions()){
					for (PropertyDescriptor propertyDescriptor : ps) {
						if (propertyDefinition.getName().equals(propertyDescriptor.getName())) {
							Method setterMethod=propertyDescriptor.getWriteMethod();//获取属性的setter方法
							if (setterMethod!=null) {
								Object temp=null;
								if (propertyDefinition.getRef()!=null&&!"".equals(propertyDefinition.getRef().trim())) {
									temp=sigletons.get(propertyDefinition.getRef());
								}else if (propertyDefinition.getValue()!=null&&!"".equals(propertyDefinition.getValue().trim())) {
									temp=ConvertUtils.convert(propertyDefinition.getValue(), propertyDescriptor.getPropertyType());
								}
							setterMethod.setAccessible(true);//防止setter方法为private
							setterMethod.invoke(bean, temp);//把引用对象注入到属性
							}
							break;
						}
					}
					}
				}
				
			}
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
	
	/**
	 * 通过注解实现注入依赖对象
	 * @throws IntrospectionException 
	 * @throws InvocationTargetException 
	 * @throws IllegalAccessException 
	 * @throws IllegalArgumentException 
	 */
	private void annotationInject(){
		try {
			for (String beanName : sigletons.keySet()) {
				Object bean=sigletons.get(beanName);
				if (bean!=null) {
					PropertyDescriptor[] ps=Introspector.getBeanInfo(bean.getClass()).getPropertyDescriptors();
					for (PropertyDescriptor propertyDescriptor : ps) {
					Method setterMethod=propertyDescriptor.getWriteMethod();
					if (setterMethod!=null&&setterMethod.isAnnotationPresent(UserDefinedResource.class)) {
						UserDefinedResource userDefinedResource=setterMethod.getAnnotation(UserDefinedResource.class);
						Object temp = null;
						if(userDefinedResource.name()!=null && !"".equals(userDefinedResource.name())){
							//一旦指定了name属性，就只能按名称装配了
							temp = sigletons.get(userDefinedResource.name());
						}else{
							temp = sigletons.get(propertyDescriptor.getName());
							if(temp==null){
								for(String key : sigletons.keySet()){
									if(propertyDescriptor.getPropertyType().isAssignableFrom(sigletons.get(key).getClass())){
										temp = sigletons.get(key);
										break;
									}
								}
							}								
						}
						setterMethod.setAccessible(true);
						setterMethod.invoke(bean, temp);//把引用对象注入到属性
					}
					}
					
					Field[] fields = bean.getClass().getDeclaredFields();
					for(Field field : fields){
						if(field.isAnnotationPresent(UserDefinedResource.class)){
							UserDefinedResource userDefinedResource = field.getAnnotation(UserDefinedResource.class);
							Object temp = null;
							if(userDefinedResource.name()!=null && !"".equals(userDefinedResource.name())){
								temp = sigletons.get(userDefinedResource.name());
							}else{
								temp = sigletons.get(field.getName());
								if(temp==null){
									for(String key : sigletons.keySet()){
										if(field.getType().isAssignableFrom(sigletons.get(key).getClass())){
											temp = sigletons.get(key);
											break;
										}
									}
								}								
							}
							field.setAccessible(true);//允许访问private字段
							field.set(bean, temp);
						}
					}
					
				}
			}
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} 
	}
	
	
	/**
	 * 获取bean实例
	 * @param beanName
	 * @return
	 */
	public Object getBean(String beanName){
		return this.sigletons.get(beanName);
	}
	
}

 

 

package junit.test12;

import static org.junit.Assert.*;
import junit.test12.PersonService;
import junit.test12.UserDefinedClassPathXMLApplicationContext;

import org.junit.Test;

public class SpringTest {

	@Test
	public void instanceSpring() {
		UserDefinedClassPathXMLApplicationContext applicationContext=new UserDefinedClassPathXMLApplicationContext("beans.xml");
		PersonService personService=(PersonService) applicationContext.getBean("personService");
		personService.save();
	}

}