package app;
import java.io.InputStream;
import java.lang.reflect.InvocationTargetException;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.apache.commons.beanutils.PropertyUtils;
import org.dom4j.Document;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;
public class ApplicationContext {
private Map<String, BeanDefinition> beans=new HashMap<String, BeanDefinition>();
/**
* 初始化beanMap
* @param string
* @throws Exception
*/
public ApplicationContext(String config) throws Exception {
//1.读取config对应的xml文件,把读取到的所有的bean节点封装为对应的beanDefinition，并将其放入beans中
init(config);
//2.创建对应的bean实例，并且把bean实例放入beanMap中
initBean();
//3.为由property节点的bean的属性赋值
initBeanProperties();
}
/**
* 初始化bean的实例
* @throws Exception
* @throws InvocationTargetException
* @throws IllegalAccessException
*/
private void initBeanProperties() throws Exception {
for(BeanDefinition bd:beans.values()){
List<PropertyDefinition> pds=bd.getPropertyDefinition();
if(pds.size()>0){
for(PropertyDefinition pd:pds){
String propertyName=pd.getName();
String ref=pd.getRef();
Object propertyValue=beanMap.get(ref);
PropertyUtils.setProperty(beanMap.get(bd.getId()), propertyName, propertyValue);
}
}
}
}
/**
* 创建bean实例
* @throws Exception
* @throws IllegalAccessException
* @throws InstantiationException
*/
private void initBean() throws Exception {
for(BeanDefinition bd:beans.values()){
String clazz=bd.getClazz();
String id=bd.getId();
Object obj=Class.forName(clazz).newInstance();
beanMap.put(id, obj);
}
}
/**
* 读取配置文件
* @param config
* @throws Exception
*/
private void init(String config) throws Exception {
SAXReader reader=new SAXReader();
InputStream is=getClass().getClassLoader().getResourceAsStream(config);
Document doc=reader.read(is);
Element root=doc.getRootElement();
List<Element> eles=root.elements("bean");
for(Element ele:eles){
String id=ele.attributeValue("id");
String clazz=ele.attributeValue("class");
BeanDefinition bd=new BeanDefinition(id, clazz);
beans.put(id, bd);
List<Element> props=ele.elements("property");
for(Element prop:props){
String name=prop.attributeValue("name");
String ref=prop.attributeValue("ref");
PropertyDefinition pd=new PropertyDefinition(name, ref);
bd.getPropertyDefinition().add(pd);
}
}
}
private Map<String, Object> beanMap=new HashMap<String, Object>();
/**
* 根据传入的beanName，从beanMap中获取对应的Bean对象
* @param beanName
* @return
*/
public Object getBean(String beanName){
return beanMap.get(beanName);
}
}
