这个我是参见了别人的一些东西，不是原创！
定义一些抽象的方法：
package com.huxin.springinject.dao;
public interface Person {
public void save();
public void useAxe();
}
package com.huxin.springinject.dao;
public interface Axe {
public void chop();
}
实现的一些方法：
package com.huxin.springinject.dao.impl;
import com.huxin.springinject.dao.Axe;
import com.huxin.springinject.dao.Person;
public class Chinese implements Person {
private Axe axe;
public Axe getAxe() {
return axe;
}
public void setAxe(Axe axe) {
this.axe = axe;
}
public void save() {
System.out.println("保存人的方法");
}
public void useAxe(){
axe.chop();
}
}
package com.huxin.springinject.dao.impl;
import com.huxin.springinject.dao.Axe;
public class StoneAxe implements Axe {
@Override
public void chop() {
System.out.println("铁斧头砍柴真慢");
}
}
这里是关键spring框架模拟的实现的一些原理！！！
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.apache.commons.beanutils.ConvertUtils;
import org.dom4j.Document;
import org.dom4j.Element;
import org.dom4j.XPath;
import org.dom4j.io.SAXReader;
public class ApplicationContext {
List<BeanInformation> beansInformation = new ArrayList<BeanInformation>();
Map<String,Object> singleton = new HashMap<String,Object>();
public ApplicationContext(){};
public ApplicationContext(String filename){
readXml(filename);
initBean();
this.injectObject();
}
public void readXml(String filename){
SAXReader saxReader = new SAXReader();
Document document = null;
try{
//使用反射机制,通过文件名加载文件路径
URL xmlPath = this.getClass().getClassLoader().getResource(filename);
//通过文件路径获得这个文件的document对象
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
//获得所有路径下的节点
List<Element> beans = xsub.selectNodes(document);//获取文档下所有bean节点
for(Element element : beans){
System.out.println(element.attributeValue("id"));
System.out.println(element.attributeValue("class"));
BeanInformation beanInformation = new BeanInformation();
beanInformation.setId(element.attributeValue("id"));
beanInformation.setName(element.attributeValue("class"));
XPath xref = element.createXPath("ns:property");//创建properties查询路径
xref.setNamespaceURIs(nsMap);//设置命名空间
List<Element> propertys = xref.selectNodes(element);
for(Element property : propertys){
PropertyInformation propertyInformation = new PropertyInformation();
propertyInformation.setName(property.attributeValue("name"));
propertyInformation.setRef(property.attributeValue("ref"));
propertyInformation.setValue(property.attributeValue("value"));
beanInformation.getPropertyInformation().add(propertyInformation);
}
beansInformation.add(beanInformation);
}
} catch(Exception e){
e.printStackTrace();
}
}
public void initBean(){
for(BeanInformation beanInformation: beansInformation){
if(beanInformation.getName()!=null && !"".equals(beanInformation.getName())){
//通过反射机制，根据名字初始化这个类
try {
singleton.put(beanInformation.getId(), Class.forName(beanInformation.getName()).newInstance());
} catch (Exception e) {
e.printStackTrace();
}
}
}
}
/**
* 关于注入的实现
*/
private void injectObject() {
for(BeanInformation beanInformation : beansInformation){
Object bean = singleton.get(beanInformation.getId());
if(bean!=null){
try {
PropertyDescriptor[] ps = Introspector.getBeanInfo(bean.getClass()).getPropertyDescriptors();
for(PropertyInformation propertyInformation : beanInformation.getPropertyInformation()){
for(PropertyDescriptor properdesc : ps){
if(propertyInformation.getName().equals(properdesc.getName())){
Method setter = properdesc.getWriteMethod();//获取属性的setter方法 ,private
if(setter!=null){
Object value = null;
if(propertyInformation.getRef()!=null && !"".equals(propertyInformation.getRef().trim())){
value = singleton.get(propertyInformation.getRef());
}else{
value = ConvertUtils.convert(propertyInformation.getValue(), properdesc.getPropertyType());
}
setter.setAccessible(true);
setter.invoke(bean, value);//把引用对象注入到属性
}
break;
}
}
}
} catch (Exception e) {
}
}
}
}
public Object getBean(String id){
return this.singleton.get(id);
}
}
package junit.test;
import java.util.HashSet;
import java.util.Set;
public class BeanInformation {
private String id;
private String name;
private Set<PropertyInformation> propertyInformation = new HashSet<PropertyInformation>();
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 Set<PropertyInformation> getPropertyInformation() {
return propertyInformation;
}
public void setPropertyInformation(Set<PropertyInformation> propertyInformation) {
this.propertyInformation = propertyInformation;
}
}
package junit.test;
public class PropertyInformation {
private String name;
private String ref;
private String 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;
}
}
测试类：
package junit.test;
import com.huxin.springinject.dao.Person;
public class Test {
public static void main(String[] args) {
ApplicationContext ac = new ApplicationContext("applicationContext.xml");
Person person = (Person)ac.getBean("chinese");
person.save();
person.useAxe();
}
}
<?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"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-3.0.xsd">
<bean id="chinese" class="com.huxin.springinject.dao.impl.Chinese">
<property name="axe" ref="stoneAxe"/>
</bean>
<bean id="stoneAxe" class="com.huxin.springinject.dao.impl.StoneAxe"/>
</beans>
补充说明： 需要导入dom4j相应的辅助包和junit辅助包！