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JavaBeanCommentBean.java

/***//**
*<P>外星人是否存在评论系统</p>
*@authorceun
*联系作者:<br>
*<ahref="mailto:ceun@163.com">ceun</a><br>
*@version1.02007-01-30实现基本功能<br>
*CommentBean.java
*CreatedonJan30,20079:39:19AM
*/
packagecom.ceun.bean;

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

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

/***//**
*<p>封装对XML的操作</p>
*@authorceun
*联系作者:<br>
*<ahref="mailto:ceun@163.com">ceun</a><br>
*@version1.02007-01-30实现基本功能<br>
*/
publicclassCommentBean...{
privateStringfilepath;

privateSAXBuilderbuilder=null;

privateDocumentdoc=null;

publicCommentBean()...{

}
/***//**
*初始化XML文件路径,加载文件
**/
publicCommentBean(Stringpath)...{
this.filepath=path;
builder=newSAXBuilder();
try...{
doc=builder.build(filepath);
}catch(JDOMExceptione)...{
System.out.print("找不到指定的XML文件");
e.printStackTrace();
}catch(IOExceptione)...{
System.out.print("找不到指定的文件");
e.printStackTrace();
}
}
/***//**
*添加评论
*@paramnikename评论者昵称
*@paramcomment评论内容
*@paramattitude评论者的结论(yes-存在,no-不存在)
**/
publicStringaddComment(Stringnikename,Stringcomment,Stringattitude)...{
Elementroot=doc.getRootElement();

Elementel=newElement("comment");
Randomrand=newRandom();
intid=rand.nextInt(10000);
el.setAttribute("id","comment_"+id);
el.setAttribute("attitude",attitude);

Elementname=newElement("nikename");
CDATAcname=newCDATA(nikename);
name.addContent(cname);

Elementdata=newElement("data");
CDATActext=newCDATA(comment);
data.addContent(ctext);

SimpleDateFormatformat=newSimpleDateFormat("yyyy-MM-ddHH:mm:ss");
Datedate=newDate();
Texttdate=newText(format.format(date));
Elementpubdate=newElement("pubdate");
pubdate.addContent(tdate);

el.addContent(name);
el.addContent(data);
el.addContent(pubdate);
root.addContent(el);
XMLOutputteroutputter=newXMLOutputter("",true,"GB2312");
//清除comment元素间的空格
outputter.setTrimAllWhite(true);
try...{
outputter.output(doc,newFileWriter(filepath));
}catch(IOExceptione)...{
System.out.println("指定路径有错");
e.printStackTrace();
}
returntdate.getText();
}
/***//**
*删除指定ID的评论
*@paramcommentId评论ID
*@return返回操作结果字符串(成功或失败)
**/
publicStringremoveComment(StringcommentId)...{
Elementroot=doc.getRootElement();
Listcomments=root.getChildren();
intsize=comments.size();
Elementdist=null;
for(inti=0;i<size;i++)...{
Elementcomment=(Element)comments.get(i);
Stringid=comment.getAttributeValue("id");
if(id.equals(commentId))...{
dist=comment;
break;
}
}
if(dist!=null)...{
root.removeContent(dist);
XMLOutputteroutputter=newXMLOutputter("",true,"GB2312");
//清除comment元素间的空格
outputter.setTrimAllWhite(true);
try...{
outputter.output(doc,newFileWriter(filepath));
}catch(IOExceptione)...{
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
*@paramcommentIdArgs评论ID数组
*@return返回操作结果字符串(成功或失败)
**/
publicStringremoveComments(String[]commentIdArgs)...{
Elementroot=doc.getRootElement();
Listcomments=root.getChildren();
intsize=comments.size();
intlen=commentIdArgs.length;
List<Element>dist=newArrayList<Element>();
outer:for(inti=0;i<size;i++)...{
Elementcomment=(Element)comments.get(i);
Stringid=comment.getAttributeValue("id");

for(intj=0;j<len;j++)
if(id.equals(commentIdArgs[j]))...{
dist.add(comment);
continueouter;
}
}
intdist_size=dist.size();
if(dist_size!=0)...{
for(inti=0;i<dist_size;i++)
root.removeContent(dist.get(i));
XMLOutputteroutputter=newXMLOutputter("",true,"GB2312");
//清除comment元素间的空格
outputter.setTrimAllWhite(true);
try...{
outputter.output(doc,newFileWriter(filepath));
}catch(IOExceptione)...{
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!";
}

/***//**
*@returnthefilepath
*/
publicStringgetFilepath()...{
returnfilepath;
}

/***//**
*@paramfilepath
*thefilepathtoset
*/
publicvoidsetFilepath(Stringfilepath)...{
this.filepath=filepath;
}

/***//**
*@returnthebuilder
*/
publicSAXBuildergetBuilder()...{
returnbuilder;
}

/***//**
*@parambuilder
*thebuildertoset
*/
publicvoidsetBuilder(SAXBuilderbuilder)...{
this.builder=builder;
}
}

3.处理AJAX请求的ServletAddCommentServlet.java

packagecom.ceun.servlet;

importjava.io.IOException;
importjava.io.PrintWriter;

importjavax.servlet.ServletException;
importjavax.servlet.http.HttpServlet;
importjavax.servlet.http.HttpServletRequest;
importjavax.servlet.http.HttpServletResponse;

importcom.ceun.bean.CommentBean;
/***//**
*<p>后台处理Servlet</p>
*2007-01-30
**@authorceun
*联系作者:<br>
*<ahref="mailto:ceun@163.com">ceun</a><br>
*@version1.02007-01-30实现基本功能<br>
**/
publicclassAddCommentServletextendsHttpServlet...{

/***//**
*serialVersionUIDlong
*/
privatestaticfinallongserialVersionUID=1L;

/***//**
*ThedoGetmethodoftheservlet.<br>
*
*Thismethodiscalledwhenaformhasitstagvaluemethodequalstoget.
*
*@paramrequest
*therequestsendbytheclienttotheserver
*@paramresponse
*theresponsesendbytheservertotheclient
*@throwsServletException
*ifanerroroccurred
*@throwsIOException
*ifanerroroccurred
*/
publicvoiddoGet(HttpServletRequestrequest,HttpServletResponseresponse)
throwsServletException,IOException...{
request.setCharacterEncoding("UTF-8");
response.setContentType("text/html;charset=UTF-8");
response.setHeader("Cache-Control","no-cache");

PrintWriterout=response.getWriter();
Stringnikename=request.getParameter("nn");

Stringcomment=request.getParameter("rsn");
Stringattitude=request.getParameter("atti");
Stringfilepath=request.getSession().getServletContext().getRealPath(
"data/comment.xml");
CommentBeanbean=newCommentBean(filepath);
Stringstr=bean.addComment(nikename,comment,attitude);
out.println(str);
}

/***//**
*ThedoPostmethodoftheservlet.<br>
*
*Thismethodiscalledwhenaformhasitstagvaluemethodequalsto
*post.
*
*@paramrequest
*therequestsendbytheclienttotheserver
*@paramresponse
*theresponsesendbytheservertotheclient
*@throwsServletException
*ifanerroroccurred
*@throwsIOException
*ifanerroroccurred
*/
publicvoiddoPost(HttpServletRequestrequest,HttpServletResponseresponse)
throwsServletException,IOException...{

doGet(request,response);
}

}
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