一个jsp+AJAX评论系统第1/2页

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这是一个简单的评论系统,使用了JDOM(这边使用Jdom-b9),实例使用JSP作为视图,结合使用AJAX(用到prototype-1.4),Servlet和JavaBean作为后台处理，使用xml文件存储数据。
1.应用目录结构如下:
data
 |--comment.xml
js
 |--prototype.js
 |--ufo.js(UTF-8格式)
css
 |--ufo.css
images
 |--loading.gif
ufo.jsp(UTF-8格式)
WEB-INF
 |-lib
 |-jdom.jar
 |-classes
 ...
 |-web.xml

/*********************************************
*Author:Java619
*Time:2007-02-14
**********************************************/

2.后台JavaBean CommentBean.java

/** *//**
* 外星人是否存在评论系统
* @author ceun
* 联系作者: 
* <a href="mailto:[email protected]">ceun</a> 
* @version 1.0 2007-01-30 实现基本功能 
* CommentBean.java
* Created on Jan 30, 2007 9:39:19 AM
*/
package com.ceun.bean;

import java.io.FileWriter;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
import java.util.Random;

import org.jdom.CDATA;
import org.jdom.Document;
import org.jdom.Element;
import org.jdom.JDOMException;
import org.jdom.Text;
import org.jdom.input.SAXBuilder;
import org.jdom.output.XMLOutputter;

/** *//**
* 封装对XML的操作
* @author ceun
* 联系作者: 
* <a href="mailto:[email protected]">ceun</a> 
* @version 1.0 2007-01-30 实现基本功能 
*/
public class CommentBean ...{
 private String filepath;

 private SAXBuilder builder = null;

 private Document doc = null;

 public CommentBean() ...{

 }
/** *//**
* 初始化XML文件路径,加载文件
* */
 public CommentBean(String path) ...{
 this.filepath = path;
 builder = new SAXBuilder();
 try ...{
 doc = builder.build(filepath);
 } catch (JDOMException e) ...{
 System.out.print("找不到指定的XML文件");
 e.printStackTrace();
 } catch (IOException e) ...{
 System.out.print("找不到指定的文件");
 e.printStackTrace();
 }
 }
/** *//**
 * 添加评论
 * @param nikename 评论者昵称
 * @param comment 评论内容
 * @param attitude 评论者的结论(yes-存在,no-不存在)
 * */
 public String addComment(String nikename, String comment, String attitude) ...{
 Element root = doc.getRootElement();

 Element el = new Element("comment");
 Random rand = new Random();
 int id = rand.nextInt(10000);
 el.setAttribute("id", "comment_" + id);
 el.setAttribute("attitude", attitude);

 Element name = new Element("nikename");
 CDATA cname = new CDATA(nikename);
 name.addContent(cname);

 Element data = new Element("data");
 CDATA ctext = new CDATA(comment);
 data.addContent(ctext);

 SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
 Date date = new Date();
 Text tdate = new Text(format.format(date));
 Element pubdate = new Element("pubdate");
 pubdate.addContent(tdate);

 el.addContent(name);
 el.addContent(data);
 el.addContent(pubdate);
 root.addContent(el);
 XMLOutputter outputter = new XMLOutputter(" ", true, "GB2312");
 // 清除comment元素间的空格
 outputter.setTrimAllWhite(true);
 try ...{
 outputter.output(doc, new FileWriter(filepath));
 } catch (IOException e) ...{
 System.out.println("指定路径有错");
 e.printStackTrace();
 }
 return tdate.getText();
 }
/** *//**
* 删除指定ID的评论
* @param commentId 评论ID
* @return 返回操作结果字符串(成功或失败)
* */
 public String removeComment(String commentId) ...{
 Element root = doc.getRootElement();
 List comments = root.getChildren();
 int size = comments.size();
 Element dist = null;
 for (int i = 0; i < size; i++) ...{
 Element comment = (Element) comments.get(i);
 String id = comment.getAttributeValue("id");
 if (id.equals(commentId)) ...{
 dist = comment;
 break;
 }
 }
 if (dist != null) ...{
 root.removeContent(dist);
 XMLOutputter outputter = new XMLOutputter(" ", true, "GB2312");
 // 清除comment元素间的空格
 outputter.setTrimAllWhite(true);
 try ...{
 outputter.output(doc, new FileWriter(filepath));
 } catch (IOException e) ...{
 System.out.println("重写文件有出错");
 e.printStackTrace();
 }
 return "成功删除指定元素!";
 } else
 return "指定元素不存在!";
 }
/** *//**
* 批量删除评论
* @param commentIdArgs 评论ID数组
* @return 返回操作结果字符串(成功或失败)
* */
 public String removeComments(String[] commentIdArgs) ...{
 Element root = doc.getRootElement();
 List comments = root.getChildren();
 int size = comments.size();
 int len = commentIdArgs.length;
 List<Element> dist = new ArrayList<Element>();
 outer:for (int i = 0; i < size; i++) ...{
 Element comment = (Element) comments.get(i);
 String id = comment.getAttributeValue("id");

 for (int j = 0; j < len; j++)
 if (id.equals(commentIdArgs[j])) ...{
 dist.add(comment);
 continue outer;
 }
 }
 int dist_size=dist.size();
 if (dist_size != 0) ...{
 for (int i = 0; i < dist_size; i++)
 root.removeContent(dist.get(i));
 XMLOutputter outputter = new XMLOutputter(" ", true, "GB2312");
 // 清除comment元素间的空格
 outputter.setTrimAllWhite(true);
 try ...{
 outputter.output(doc, new FileWriter(filepath));
 } catch (IOException e) ...{
 System.out.println("重写文件有出错");
 e.printStackTrace();
 }
 return "成功删除指定的元素集合!";
 } else
 return "指定元素集合的不存在!";
 }

 /** *//**
 * @return the filepath
 */
 public String getFilepath() ...{
 return filepath;
 }

 /** *//**
 * @param filepath
 * the filepath to set
 */
 public void setFilepath(String filepath) ...{
 this.filepath = filepath;
 }

 /** *//**
 * @return the builder
 */
 public SAXBuilder getBuilder() ...{
 return builder;
 }

 /** *//**
 * @param builder
 * the builder to set
 */
 public void setBuilder(SAXBuilder builder) ...{
 this.builder = builder;
 }
}

3.处理AJAX请求的Servlet AddCommentServlet.java

package com.ceun.servlet;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.ceun.bean.CommentBean;
/** *//**
* 后台处理Servlet
*2007-01-30
* * @author ceun
* 联系作者: 
* <a href="mailto:[email protected]">ceun</a> 
* @version 1.0 2007-01-30 实现基本功能 
* */
public class AddCommentServlet extends HttpServlet ...{

 /** *//**
 * serialVersionUID long
 */
 private static final long serialVersionUID = 1L;

 /** *//**
 * The doGet method of the servlet. 
 *
 * This method is called when a form has its tag value method equals to get.
 *
 * @param request
 * the request send by the client to the server
 * @param response
 * the response send by the server to the client
 * @throws ServletException
 * if an error occurred
 * @throws IOException
 * if an error occurred
 */
 public void doGet(HttpServletRequest request, HttpServletResponse response)
 throws ServletException, IOException ...{
 request.setCharacterEncoding("UTF-8");
 response.setContentType("text/html;charset=UTF-8");
 response.setHeader("Cache-Control", "no-cache");

 PrintWriter out = response.getWriter();
 String nikename = request.getParameter("nn");

 String comment = request.getParameter("rsn");
 String attitude = request.getParameter("atti");
 String filepath = request.getSession().getServletContext().getRealPath(
 "data/comment.xml");
 CommentBean bean = new CommentBean(filepath);
 String str = bean.addComment(nikename, comment, attitude);
 out.println(str);
 }

 /** *//**
 * The doPost method of the servlet. 
 *
 * This method is called when a form has its tag value method equals to
 * post.
 *
 * @param request
 * the request send by the client to the server
 * @param response
 * the response send by the server to the client
 * @throws ServletException
 * if an error occurred
 * @throws IOException
 * if an error occurred
 */
 public void doPost(HttpServletRequest request, HttpServletResponse response)
 throws ServletException, IOException ...{

 doGet(request, response);
 }

}

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