forum.java

这是一个简单的基于Ajax和DWR实现的无刷新在线实时聊天程序

package com.lan.Forum;

import java.io.File;
import java.io.FileInputStream;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;

import javax.servlet.Servlet;
import javax.servlet.ServletConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletRequest;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.jsp.PageContext;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerConfigurationException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NodeList;

public class Forum {
	
	DocumentBuilderFactory dbf=null;
	DocumentBuilder db=null;
	Document doc=null;
	String file="d://Forum.xml";
	public Forum(){
	dbf=DocumentBuilderFactory.newInstance();
	try {
		db=dbf.newDocumentBuilder();
		doc=db.parse(new FileInputStream(file));
	} catch (Exception e) {
		// TODO 自动生成 catch 块
		e.printStackTrace();
	}
	}
	
	public void writexml(String username,String content){
		Element forums;
		Element forum;
		Element name;
		Element con;
		Element date;
		forums=(Element) doc.getElementsByTagName("Forums").item(0);
		forum=doc.createElement("Forum");
		name=doc.createElement("UserName");
		name.appendChild(doc.createTextNode(username));
		con=doc.createElement("Content");
		con.appendChild(doc.createTextNode(content));
		date=doc.createElement("DateTime");
		date.appendChild(doc.createTextNode(new Date().toString()));
		forum.appendChild(name);
		forum.appendChild(con);
		forum.appendChild(date);
		forums.appendChild(forum);
		TransformerFactory tf=TransformerFactory.newInstance();
		try {
			Transformer trans=tf.newTransformer();
			trans.transform(new DOMSource(doc),new StreamResult(new File(file)));
		} catch (Exception e) {
			// TODO 自动生成 catch 块
			e.printStackTrace();
		}
		
	}
	public ArrayList<Forumbean> getxml(){
		ArrayList<Forumbean> list=new ArrayList<Forumbean>();
		NodeList n1=doc.getElementsByTagName("Forum");
		for(int i=0;i<n1.getLength();i++){
			Element n=(Element) n1.item(i);
			NodeList u=n.getElementsByTagName("UserName");
			NodeList c=n.getElementsByTagName("Content");
			NodeList d=n.getElementsByTagName("DateTime");
			String username=u.item(0).getFirstChild().getNodeValue();
			String content=c.item(0).getFirstChild().getNodeValue();
			String datetime=d.item(0).getFirstChild().getNodeValue();
			Forumbean bean=new Forumbean();
			bean.setUsername(username);
			bean.setContent(content);
			bean.setDatetime(datetime);
			list.add(bean);
		}
		return list;
	}

	public String formatedate(String date){
		String style="yyyy-MM-dd:HH:mm:ss";
		SimpleDateFormat df=new SimpleDateFormat(style);
		return df.format(date);
	}
	
}