学步园

1.利用application内置对象,进行I/O操作.
  (1)利用表单输入文件名及文件内容,通过文件名及文件的内容来创建文件.
  (2)查看文件所在文件夹的信息.
  (3)将该文件的内容显示在网页上.

以下源码分别是app1.jsp；app2.jsp；app3.jsp；app4.jsp.

<%@page contentType="text/html;charset=GBK"%>
<style type="text/css">
<!--
.STYLE1 {
	font-family: "宋体";
	font-size: large;
	font-weight: bold;
}
-->
</style>

<form action="app2.jsp"method="post">
	<div align="center" class="STYLE1">输入文件名称：
	  <input type="text" name="filename">
	  <br>
	输入文件内容：
	<textarea name="content"></textarea>
	<br>
	<input type="submit"value="提交">
    </div>
</form>

<%@page contentType="text/html;charset=GBK"%>
<%@page import="java.io.*"%>
<h1>文件写入成功</h1>
<%
	request.setCharacterEncoding("GBK");
	String fileName=this.getServletContext().getRealPath("/")+"mars"+File.separator+request.getParameter("filename");
	String content=request.getParameter("content").replaceAll("\r\n","<br>");
	PrintStream ps=new PrintStream(new FileOutputStream(new File(fileName)));
	ps.println(content);
	ps.close();
%>

<%@page contentType="text/html;charset=GBK"%>
<%@page import="java.io.*"%>
<h1></h1>
<%
	request.setCharacterEncoding("GBK");
	String fileName=this.getServletContext().getRealPath("/")+"mars";
	File f = new File(fileName);
	String files[] = f.list();
	for(int i=0;i<files.length;i++){
	%>
	<h3><a href="app4.jsp?filename=<%=files[i]%>"><%=files[i]%></a></h3>
	<%
	}
%>

<%@ page contentType="text/html;charset=GBK"%>
<%@ page import="java.io.*"%>

<%
	request.setCharacterEncoding("GBK") ;
	String fileName = this.getServletContext().getRealPath("/") + "mars" + File.separator + request.getParameter("filename") ;
	File f = new File(fileName) ;
	BufferedReader buf = new BufferedReader(new InputStreamReader(new FileInputStream(f))) ;
	String str = buf.readLine() ;	// 读取内容
%>
	<h3><%=str%></h3>
<%
	buf.close() ;	// 关闭
%>

2.制作网页计数器.

<%@page contentType="text/html;charset=GBK"%>
<%
	  if(application.getAttribute("count")==null) {
		application.setAttribute("count","1");
	  }
	  else {
		String str=application.getAttribute("count").toString();
		int ncount=Integer.valueOf(str).intValue()+1;
		application.setAttribute("count",""+ncount);
	  }
%>
  
 欢迎光临本网站，您是第 <%=application.getAttribute("count")%>位访问者