通过JAVA反射机制与DOM4J来实现持久化JAVA对象

一个接口ReadWriteInt ，一个实现类ReadWriteIntImp ，代码如下：

package com.netunit.workbench.util;

import java.io.IOException;
import java.util.List;

/**
 * 读写XML接口
 * @author Ming.He
 *
 * @Data 2009-12-21
 */
public interface ReadWriteInt {

	/**
	 * 把数据写入xml文件
	 * @param list
	 * @param cls
	 * @throws IOException
	 */
	public void writeXML(List list, Class cls) throws IOException;
	
	/**
	 * 把数据重xml读出来
	 * @param cls
	 * @return
	 * @throws Exception
	 */
	public List readXML(Class cls) throws Exception;
}

package com.netunit.workbench.util;

import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import org.dom4j.Document;
import org.dom4j.DocumentHelper;
import org.dom4j.Element;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.SAXReader;
import org.dom4j.io.XMLWriter;

/**
 * 读写XML的实现
 * @author Ming.He
 *
 * @Data 2009-12-21
 */
public class ReadWriteIntImp implements ReadWriteInt {

	/**
	 * 文件名
	 */
	private File file ;
	/**
	 * 设置编码
	 */
	private String encoding = "GBK";
	
	private String roots = "root";
	
	public ReadWriteIntImp(File file) {
		this.file = file;
	}
	
	public void writeXML(List list, Class cls) throws IOException{
		String className = cls.getName();	//类名包含包名
		String classes = className.substring(className.lastIndexOf(".")+1,className.length());//类名
		XMLWriter writer = null; 		// 声明写XML的对象
		OutputFormat format = OutputFormat.createPrettyPrint();
		format.setEncoding(encoding); 	// 设置XML文件的编码格式
		Document document = DocumentHelper.createDocument();
		Element root = document.addElement(roots);//根节点
		Element two = root.addElement(classes+"s");
		two.addAttribute("class", className);
		Element three = null;
		for (int i=0;i<list.size();i++){
			three = two.addElement(classes);
			insert(three,list.get(i),cls);
		}
		writer = new XMLWriter(new FileWriter(file), format);
		writer.write(document);
		writer.close();
	}
	
	private void insert(Element three,Object object,Class cls){
		Element tem  = null;
		String name = null;
		Field[] field = cls.getDeclaredFields();	//所有字段
		for (int i=0;i<field.length;i++){
			name = field[i].getName();
			tem = three.addElement(name);
			try {
				Method methodTitle = cls.getMethod(getOnetoUpperCase(name));//查找这个字段的get方法
				tem.setText(methodTitle.invoke(object)+"");		//执行get方法
			} catch (Exception e) {
				e.printStackTrace();
			}
		}
	}
	/**
	 * 生成get方法
	 * @param str
	 * @return
	 */
	private String getOnetoUpperCase(String str){
		return "get"+ firsttoUpperCase(str);
	}
	
	/**
	 * 生成set方法
	 * @param str
	 * @return
	 */
	private String setOnetoUpperCase(String str){
		return "set"+ firsttoUpperCase(str);
	}
	/**
	 * 第一个字母大写
	 * @param str
	 * @return
	 */
	private String firsttoUpperCase(String str){
		return Character.toUpperCase(str.charAt(0)) + str.substring(1);
	}

	public List readXML(Class cls) throws Exception{
		List list = new ArrayList();
		String className = cls.getName();//类名包含包名
		String classes = className.substring(className.lastIndexOf(".")+1,className.length());//类名
		// 取文件
		SAXReader sr = new SAXReader();
		Document doc = sr.read(file);
		// 取根节点
		Element root = doc.getRootElement();
		// 跌带跟节点.
		Iterator it = root.elementIterator();
		while (it.hasNext()) {
			Element two = (Element) it.next();
			// 当根节点等于datas时
			if (two.getName().equalsIgnoreCase(classes+"s")) {
				for (Iterator i = two.elementIterator(); i.hasNext();) {
					Element three = (Element) i.next();
					Object object = cls.newInstance(); //创建对象
					Element element  = null ; 
					Field[] field ;
					for (Iterator y = three.elementIterator(); y.hasNext();){	
						element = (Element) y.next();				
						field = cls.getDeclaredFields();	//所有字段
						for (int tem=0;tem<field.length;tem++){
							if (field[tem].getName().equals(element.getName())){
								field[tem].setAccessible(true);   //设置属性可以修改
								setObject(field[tem],object,element);
							}
						}
					}
					list.add(object);
				}
			}
		}
		return list;
	}
	
	private void setObject(Field field,Object object,Element element){
		try {
			if (field.getType().toString().equals("int"))
				field.set(object, new Integer(element.getTextTrim()));
			else if (field.getType().toString().equals("double"))
				field.set(object, new Double(element.getTextTrim()));
			else if (field.getType().toString().equals("long"))
				field.set(object, new Long(element.getTextTrim()));
			else
				field.set(object, element.getTextTrim());
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
}

效率：1W两秒，10W溢出

评论

2 楼 ＷＩＮ 2009-12-27  

yunzhu 写道

  好东西，学习了

我帖上来的只是一点原理，自己可以试着扩展和优化

1 楼 yunzhu 2009-12-26  

  好东西，学习了