Spring2.5学习2.2_编码剖析Spring依赖注入原理
为了便于理解Spring属性注入,这里来模拟Spring容器是如何实现将PersonDaoBean注入到PersonServiceBean的。
所需jar包:下载地址http://download.csdn.net/detail/jeofey/8747927
PersonDaoBean.java
- package xjj.dao.impl;
- import xjj.dao.PersonDao;
- public class PersonDaoBean implements PersonDao {
- public void add(){
- System.out.println("执行PersonDaoBean中的add()方法");
- }
- }
- package xjj.dao;
- public interface PersonDao {
- public void add();
- }
- package xjj.service.impl;
- import xjj.dao.PersonDao;
- import xjj.service.PersonService;
- public class PersonServiceBean implements PersonService {
- private PersonDao personDao;
- public PersonDao getPersonDao() {
- return personDao;
- }
- public void setPersonDao(PersonDao personDao) {
- this.personDao = personDao;
- }
- public void save(){
- personDao.add();
- }
- }
- package xjj.service;
- public interface PersonService {
- public void save();
- }
BeanDefinition.java
- package junit.test;
- import java.util.ArrayList;
- import java.util.List;
- public class BeanDefinition {
- private String id;
- private String className;
- private List<PropertyDefinition> propertys = new ArrayList<PropertyDefinition>();
- public BeanDefinition(String id, String className) {
- this.id = id;
- this.className = className;
- }
- public String getId() {
- return id;
- }
- public void setId(String id) {
- this.id = id;
- }
- public String getClassName() {
- return className;
- }
- public void setClassName(String className) {
- this.className = className;
- }
- public List<PropertyDefinition> getPropertys() {
- return propertys;
- }
- public void setPropertys(List<PropertyDefinition> propertys) {
- this.propertys = propertys;
- }
- }
- package junit.test;
- public class PropertyDefinition {
- private String name;
- private String ref;
- public PropertyDefinition(String name, String ref) {
- this.name = name;
- this.ref = ref;
- }
- 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;
- }
- }
XjjClassPathXMLApplicationContext.java
- package junit.test;
- 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.dom4j.Document;
- import org.dom4j.Element;
- import org.dom4j.XPath;
- import org.dom4j.io.SAXReader;
- /**
- * 传智传客版容器
- *
- */
- public class XjjClassPathXMLApplicationContext {
- private List<BeanDefinition> beanDefines = new ArrayList<BeanDefinition>();
- private Map<String, Object> sigletons = new HashMap<String, Object>();
- public XjjClassPathXMLApplicationContext(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 properdesc : ps){
- if(propertyDefinition.getName().equals(properdesc.getName())){
- Method setter = properdesc.getWriteMethod();//获取属性的setter方法 ,private
- if(setter!=null){
- Object value = sigletons.get(propertyDefinition.getRef());
- setter.setAccessible(true);
- setter.invoke(bean, value);//把引用对象注入到属性
- }
- break;
- }
- }
- }
- } catch (Exception e) {
- }
- }
- }
- }
- /**
- * 完成bean的实例化
- */
- private void instanceBeans() {
- for(BeanDefinition beanDefinition : beanDefines){
- try {
- 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
- * @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);
- 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);//获取文档下所有bean节点
- for(Element element: beans){
- String id = element.attributeValue("id");//获取id属性值
- String clazz = element.attributeValue("class"); //获取class属性值
- BeanDefinition beanDefine = new BeanDefinition(id, clazz);
- XPath propertysub = element.createXPath("ns:property");
- propertysub.setNamespaceURIs(nsMap);//设置命名空间
- List<Element> propertys = propertysub.selectNodes(element);
- for(Element property : propertys){
- String propertyName = property.attributeValue("name");
- String propertyref = property.attributeValue("ref");
- PropertyDefinition propertyDefinition = new PropertyDefinition(propertyName, propertyref);
- beanDefine.getPropertys().add(propertyDefinition);
- }
- beanDefines.add(beanDefine);
- }
- }catch(Exception e){
- e.printStackTrace();
- }
- }
- /**
- * 获取bean实例
- * @param beanName
- * @return
- */
- public Object getBean(String beanName){
- return this.sigletons.get(beanName);
- }
- }
- package junit.test;
- import org.junit.BeforeClass;
- import org.junit.Test;
- import xjj.service.PersonService;
- public class SpringTest {
- @BeforeClass
- public static void setUpBeforeClass() throws Exception {
- }
- @Test public void instanceSpring(){
- XjjClassPathXMLApplicationContext ctx = new XjjClassPathXMLApplicationContext("beans.xml");
- PersonService personService = (PersonService)ctx.getBean("personService");
- personService.save();
- }
- }
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="personDao" class="xjj.dao.impl.PersonDaoBean"></bean>
- <bean id="personService" class="xjj.service.impl.PersonServiceBean">
- <property name="personDao" ref="personDao"></property>
- </bean>
- </beans>
结果:
原csdn博客地址:http://write.blog.csdn.net/postlist