模拟ClasspathXmlApplication：
package junit.test; import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.io.File;
import java.lang.reflect.Field;
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.io.SAXReader; public class ItcastClassPathXmlApplicationContext {
private ArrayList<BeanDefinition> beanDefinitions=new ArrayList<BeanDefinition>();
private Map<String,Object> sigletons=new HashMap<String,Object>(); public ItcastClassPathXmlApplicationContext(String filename){
this.readXml(filename);
this.instanceBeans();
this.annotationInject();
this.injectObject();
}
/**
* 注解方式装载对象
*/
private void annotationInject() {
for(String beanName :sigletons.keySet()){
Object bean=sigletons.get(beanName);
if(bean!=null){
try{
/*
* 查找方法上的注解
*/
PropertyDescriptor[] ps=Introspector.getBeanInfo(bean.getClass()).getPropertyDescriptors();
for(PropertyDescriptor properdesc:ps){
Method setter=properdesc.getWriteMethod();
if(setter!=null && setter.isAnnotationPresent(ItcastResource.class)){
ItcastResource itcastResource=setter.getAnnotation(ItcastResource.class);
Object value=null;
if(itcastResource.name()!=null && !"".equals(itcastResource.name())){
value=sigletons.get(itcastResource.name());
}else{
value=sigletons.get(properdesc.getName());
if(value==null){
for(String key:sigletons.keySet()){
if(properdesc.getPropertyType().isAssignableFrom(sigletons.get(key).getClass())){
value=sigletons.get(key);
break;
}
}
}
}
setter.setAccessible(true);
setter.invoke(bean, value);
}
} /**
* 查找字段上的注解
*/
Field[] fields=bean.getClass().getDeclaredFields();
for(Field field:fields){
if(field.isAnnotationPresent(ItcastResource.class)){
ItcastResource resource=field.getAnnotation(ItcastResource.class);
Object value=null;
if(resource.name()!=null && !"".equals(resource.name())){
value=sigletons.get(resource.name());
}else{
value=sigletons.get(field.getName());
if(value==null){
for(String key:sigletons.keySet()){
if(field.getType().isAssignableFrom(sigletons.get(key).getClass())){
value=sigletons.get(key);
break;
}
}
}
}
String methodName="set"+field.getName().substring(,).toUpperCase()+field.getName().substring();
Method setter=bean.getClass().getMethod(methodName, field.getType());
setter.setAccessible(true);
setter.invoke(bean, value);
}
}
}catch(Exception e){
e.printStackTrace();
}
}
}
} /**
* 为bean对象的属性注入值
*/
private void injectObject() {
for(BeanDefinition beanDefinition: beanDefinitions){
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
if(setter!=null){
Object value=null;
if(propertyDefinition.getRef()!=null &&!"".equals(propertyDefinition.getRef())){
value=sigletons.get(propertyDefinition.getRef());
}else{
value=ConvertUtils.convert(propertyDefinition.getValue(), properdesc.getPropertyType());
}
setter.setAccessible(true);
setter.invoke(bean, value); }
break; }
}
}
} catch (Exception e) {
e.printStackTrace();
} }
}
}
/**
* 完成bean的实例化
*/
private void instanceBeans(){
for(BeanDefinition bd:beanDefinitions){
try {
if(bd.getClassName()!=null && !"".equals(bd.getClassName().trim()))
sigletons.put(bd.getId(), Class.forName(bd.getClassName()).newInstance());
} catch (Exception e) {
e.printStackTrace();
}
}
}
/**
* 解析xml文件
* @param fileName
*/
private void readXml(String fileName) {
File inputXml=new File(fileName);
URL url=this.getClass().getClassLoader().getResource(fileName);
SAXReader saxReader=new SAXReader();
try {
Document document=saxReader.read(url);
Element root=document.getRootElement();
@SuppressWarnings("unchecked")
List<Element> beans=root.elements("bean"); for(Element bean:beans){
String id= bean.attributeValue("id");
String className=bean.attributeValue("class");
BeanDefinition bd=new BeanDefinition(id,className);
@SuppressWarnings("unchecked")
List<Element> propertys=bean.elements("property");
for(Element property:propertys){
String propertyName = property.attributeValue("name");
String propertyRef = property.attributeValue("ref");
String propertyValue=property.attributeValue("value");
PropertyDefinition pd=new PropertyDefinition(propertyName, propertyRef,propertyValue);
bd.getPropertys().add(pd);
}
beanDefinitions.add(bd);
} } catch (DocumentException e) {
e.printStackTrace();
}
} public Object getBean(String beanName){
return this.sigletons.get(beanName);
}
}
存放bean信息的类：
package junit.test; import java.util.ArrayList;
import java.util.List; /**
* 存放读取到的bean的信息
* @author Administrator
*
*/
public class BeanDefinition {
private String id;
private String className;
private List<PropertyDefinition> propertys=new ArrayList<PropertyDefinition>(); public BeanDefinition() {
super();
} public BeanDefinition(String id, String className) {
super();
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 void setPropertys(List<PropertyDefinition> propertys) {
this.propertys = propertys;
} public List<PropertyDefinition> getPropertys() {
return propertys;
} }
存放bean中属性信息的类：
package junit.test;
/**
* 属性的定义类
* @author Administrator
*
*/
public class PropertyDefinition { private String name;
private String ref;
private String value;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public PropertyDefinition(String name, String ref,String value) {
super();
this.name = name;
this.ref = ref;
this.value=value;
}
public PropertyDefinition() {
super();
}
public String getRef() {
return ref;
}
public void setRef(String ref) {
this.ref = ref;
}
public void setValue(String value) {
this.value = value;
}
public String getValue() {
return value;
} }
对应Resource注解：
package junit.test; 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 ItcastResource {
public String name() default "";
}