Spring之Bean装配原理

package com.zznode.bean;import java.beans.Introspector;import java.beans.PropertyDescriptor;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.Element;import org.dom4j.XPath;import org.dom4j.io.SAXReader;public class ClassPathXMlApplicationContext {private List<BeanDefinition> beanDefines = new ArrayList<BeanDefinition>();private Map<String, Object> sigletons = new HashMap<String, Object>();public ClassPathXMlApplicationContext(String filename) {this.readXMl(filename);this.instanceBeans();this.injectObject();}/** * 为Bean对象的属性注入值 */private void injectObject() {for (BeanDefinition beanDefinition : beanDefines) {Object bean = sigletons.get(beanDefinition.getId());if (bean != null) {try {PropertyDescriptor[] ps = Introspector.getBeanInfo(bean.getClass()).getPropertyDescriptors();for (PropertyDefinition propertyDefinition : beanDefinition.getPropertys()) {for (PropertyDescriptor propertyDescriptor : ps) {if (propertyDefinition.getName().equals(propertyDescriptor.getName())) {Method setter = propertyDescriptor.getWriteMethod();// 获取属性的setter方法if (setter != null) {Object value = null;if (propertyDefinition.getRef() != null&& !"".equals(propertyDefinition.getRef().trim())) {value = sigletons.get(propertyDefinition.getRef());} else {value = ConvertUtils.convert(propertyDefinition.getValue(),propertyDescriptor.getPropertyType());}setter.setAccessible(true);setter.invoke(bean, value);// 把引用对象注入到属性}break;}}}} catch (Exception e) {e.printStackTrace();}}}}/** * 实例化Bean */private void instanceBeans() {try {for (BeanDefinition beanDefinition : beanDefines) {if (beanDefinition.getClassName() != null&& !"".equals(beanDefinition.getClassName().trim())) {sigletons.put(beanDefinition.getId(), Class.forName(beanDefinition.getClassName()).newInstance());}}} catch (Exception e) {e.printStackTrace();}}/** * 读取XML配置文件 */private void readXMl(String filename) {SAXReader reader = new SAXReader();Document document = null;try {URL xmlpath = this.getClass().getClassLoader().getResource(filename);document = reader.read(xmlpath);Map<String, String> nsMap = new HashMap<String, String>();nsMap.put("ns", "http://www.springframework.org/schema/beans");// 加入命名空间XPath xsub = document.createXPath("//ns:beans/ns:bean");// 创建beans/bean查询路径xsub.setNamespaceURIs(nsMap);// 设置命名空间List<Element> beans = xsub.selectNodes(document);for (Element element : beans) {String id = element.attributeValue("id");String clazz = element.attributeValue("class");BeanDefinition beanDefine = new BeanDefinition(id, clazz);XPath propertysub = document.createXPath("ns:property");propertysub.setNamespaceURIs(nsMap);List<Element> properties = propertysub.selectNodes(element);for (Element property : properties) {String propertyName = property.attributeValue("name");String propertyref = property.attributeValue("ref");String propertyValue = property.attributeValue("value");PropertyDefinition propertyDefinition = new PropertyDefinition(propertyName, propertyref, propertyValue);beanDefine.getPropertys().add(propertyDefinition);}beanDefines.add(beanDefine);}} catch (Exception e) {e.printStackTrace();}}/** * 获得Bean对象 * @param beanName * @return */public Object getBean(String beanName) {return sigletons.get(beanName);}}

 

 <?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xmlns:context="http://www.springframework.org/schema/context"xmlns:aop="http://www.springframework.org/schema/aop"xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-2.5.xsdhttp://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.5.xsd"><aop:aspectj-autoproxy /><bean id="siteDao" class="com.zznode.services.impl.SiteDao"/><bean id="siteService" class="com.zznode.services.impl.SiteService" > <property name="siteDao" ref="siteDao"></property> <property name="name" value="arron"></property> <property name="id" value="88"></property></bean></beans>

package com.zznode.proxy;import com.zznode.bean.ClassPathXMlApplicationContext;import com.zznode.services.ISiteService;public class Util {public static void main(String[] args) {ClassPathXMlApplicationContext cxt = new ClassPathXMlApplicationContext("beans.xml");ISiteService service = (ISiteService) cxt.getBean("siteService");service.handler("Alex");}}

public class SiteDao implements ISiteDao{public void handler(String name) {System.out.println(name+" is doing some things！");}}

public interface ISiteDao {public void handler(String name);}

public class SiteService implements ISiteService {private ISiteDao siteDao;private Integer id;private String name;public String getName() {return name;}public void setName(String name) {this.name = name;}public Integer getId() {return id;}public void setId(Integer id) {this.id = id;}public SiteService() {}public ISiteDao getSiteDao() {return siteDao;}public void setSiteDao(ISiteDao siteDao) {this.siteDao = siteDao;}public void handler(String name) {System.out.println("id="+id+",name="+this.getName());siteDao.handler(name);}}

public interface ISiteService {public void handler(String name);}