JAVA WEB_JSP的初步(9)

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