package lianxi;

import org.w3c.dom.*;
import javax.xml.parsers.*;
import java.lang.reflect.*;
import java.util.*;
import org.com.gather.*;

public class ConfigTest{
	private Properties pro = null;
	private static String key = "abc";
	private Document doc = null;
	private static ConfigTest instance = null;
	
	private ConfigTest(Properties pro){
		this.pro = pro;
	}

	public static ConfigTest getInstance(Properties pro){
		if(instance == null){
			synchronized(key){
				if(instance == null){
					instance = new ConfigTest(pro);
					instance.init(pro.getProperty("xmlPath"));
				}
			}
		}
		return instance;
	}

	public void init(String xmlPath){
		try{
			DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
			DocumentBuilder db = dbf.newDocumentBuilder();
			doc = db.parse(xmlPath);
		}catch(Exception e){
			e.printStackTrace();
		}
	}

	public DB getDB(){
		return (DB)loadClass("db");
	}

	public Object loadClass(String nodeName){
		Properties pro = getNodeProperties("db");

		String single = pro.getProperty("single");
		String methodName = pro.getProperty("methodName");
		
		if(single.equals("true")){
			return ClassLoaderFactory.loadClassByMethod(methodName,pro);
		}else{
			return ClassLoaderFactory.loadClassByConstructor(pro);
		}
	}

	public Properties getNodeProperties(String nodeName){
		Properties pro = new Properties();

		Node fatherNode = doc.getElementsByTagName(nodeName).item(0);

		NamedNodeMap attributes = fatherNode.getAttributes();

		for(int i = 0; i < attributes.getLength(); i++){
			Node an = attributes.item(i);

			String attribute_name = an.getNodeName();
			String attribute_value = an.getNodeValue();

			pro.setProperty(attribute_name,attribute_value);
		}

		NodeList childList = fatherNode.getChildNodes();

		for(int i = 0; i < childList.getLength(); i++){
			Node cn = childList.item(i);
			if(cn instanceof Element){
				String childNodeName = cn.getNodeName();
				String childNodeValue = cn.getFirstChild().getNodeValue();

				pro.setProperty(childNodeName,childNodeValue);
			}
		}

		System.out.println("Properties is <--->"+pro);

		return pro;
	}
}

class ClassLoaderFactory{
	public static Object loadClassByMethod(String methodName,Properties pro){
		try{
			ClassLoader cl = ClassLoader.getSystemClassLoader();
			String className = pro.getProperty("className");
			Class c = cl.loadClass(className);
			Method method = c.getMethod(methodName,new Class[]{Properties.class});
			return method.invoke(c,new Object[]{pro});
		}catch(Exception e){
			e.printStackTrace();
			return null;
		}
	}

	public static Object loadClassByConstructor(Properties pro){
		try{
			ClassLoader cl = ClassLoader.getSystemClassLoader();

			String className = pro.getProperty("className");

			Class c = cl.loadClass(className);
			Constructor ct = c.getConstructor(new Class[]{Properties.class});

			return ct.newInstance(new Object[]{pro});

		}catch(Exception e){
			e.printStackTrace();
			return null;
		}
	}
}