本文实例讲述了JSP实现快速上传文件的方法。分享给大家供大家参考。具体如下：
这里演示JSP不使用第三方库，实现快速上传文件的功能
1. FileUpload.java：
"C://";
public FileUpload()
{
fpath="C://";
in=null;
}
public void setInputStream(ServletInputStream in)
{
this.in=in;
}
public void setFpath(String p)
{
this.fpath=p;
}
public String getFpath()
{
return fpath;
}
public String getParameter()
{
String r=null;
try
{
r=getParameter(in);
}
catch (Exception e)
{
e.printStackTrace();
}
return r;
}
public long getFileUpload()
{
long r=-1;
try
{
r=getFileUpload(in,fpath);
}
catch (Exception e)
{
e.printStackTrace();
}
return r;
}
public String getParameter(ServletInputStream in)// 只能按顺序提取
throws Exception
{
int l = 0;
byte[] b = new byte[1024];
l = in.readLine(b, 0, b.length);// 依次是读取属性的开始符、名称、属性值的类型、属性的值
String si = new String(b);
if (si.startsWith("----------------------------"))
{// 表示是从开始符开始读，否则应为刚读取文件后的一个属性，此时应少读一次
l = in.readLine(b, 0, b.length);
}
l = in.readLine(b, 0, b.length);
l = in.readLine(b, 0, b.length);
String value = new String(b, 0, l);
return value;
}
public long getFileUpload(ServletInputStream in, String fpath)// 需要提供输入流和存储路径
throws Exception
{
// out.println("文件信息:<br>");
long begin = System.currentTimeMillis();// 传送时间计时开始
int l = 0;
byte[] b = new byte[1024];
l = in.readLine(b, 0, b.length);
String sign = new String(b, 0, l);// eg.-----------------------------7d9dd29630a34
l = in.readLine(b, 0, b.length);
String info = new String(b, 0, l);// eg.Content-Disposition:form-data;
// name="file";
l = in.readLine(b, 0, b.length);
// String type=new
// String(b,0,l);//eg.Content-Type:application/octet-stream(程序文件)
l = in.readLine(b, 0, b.length);
// String nulll=new String(b,0,l);//此值应为空
int nIndex = info.toLowerCase().indexOf("filename=\"");
int nLastIndex = info.toLowerCase().indexOf("\"", nIndex + 10);
String filepath = info.substring(nIndex + 10, nLastIndex);
int na = filepath.lastIndexOf("\\");
String filename = filepath.substring(na + 1);
// out.println("文件绝对路径："+filepath+"<br>");
// out.println("文件名："+filename+"<br><br>");
String path=fpath + filename;
File fi = new File(path);// 建立目标文件
if (!fi.exists()&&!fi.createNewFile())
return -2;
BufferedOutputStream f = new BufferedOutputStream(new FileOutputStream(
fi));
while ((l = in.readLine(b, 0, b.length)) > 0)
{
if (l == sign.length())
{
String sign1 = new String(b, 0, sign.length());
// out.println(sign1+"<br>");
if (sign1.startsWith(sign))// 比对是否文件已传完
break;
}
f.write(b, 0, l);
f.flush();
}
f.flush();
f.close();
long end = System.currentTimeMillis();// 传送时间计时结束
// out.println("上传文件用时："+(end-begin)+"毫秒<br>");
return end - begin;
}
}
2. submitFile.jsp：
"java" import="java.util.*" pageEncoding="GB18030"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme() + "://"
+ request.getServerName() + ":" + request.getServerPort()
+ path + "/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP 'submitFile.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
<script language="javascript">
function check()
{
if (document.form2.name.value==""){
alert("姓名不能为空！！");
document.form2.name.focus();
return false;
}
if (document.form2.file.value==""){
alert("文件不能为空！！");
return false;
}
return true;
}
</script>
</head>
<body>
<br>
<form method="post" name="form2" enctype="MULTIPART/FORM-DATA"
action="AnswerFile.jsp">
<br>
<p align="center">
<br>
</p>
<table width="530" border="1" bgcolor="#c0c0c0" align="center"
height="91">
<tbody>
<tr>
<td valign="top" align="right">
姓名
<br>
</td>
<td valign="top">
<input type="text" name="name">
</td>
</tr>
<tr>
<td align="right">
文件
</td>
<td align="left">
<input type="file" name="file">
</td>
</tr>
<tr>
<td valign="top" align="right">
文件类型
<br>
</td>
<td valign="top" align="left">
<select size="1" name="leixing">
<option selected value="作业">
作业
</option>
<option value="课程设计">
课程设计
</option>
<option value="论文">
论文
</option>
</select>
</td>
</tr>
<tr>
<td align="right">
<input type="Submit" value="上传" name="button2" onclick="return(check());">
</td>
<td align="left">
<input type="reset" value="重置" name="button3">
</td>
</tr>
</tbody>
</table>
<p>
<br>
<br>
</p>
</form>
</body>
</html>
3. AnswerFile.jsp：
"htmlcode">
<%@ page language="java" import="java.util.*,java.io.*"
pageEncoding="GB18030"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme() + "://"
+ request.getServerName() + ":" + request.getServerPort()
+ path + "/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP 'AnswerFile.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</head>
<body>
<jsp:useBean id="upload" scope="session" class="FileUpload.FileUpload"/>
<jsp:setProperty name="upload" value="C://" property="fpath"/>
<%
ServletInputStream in = request.getInputStream();
upload.setInputStream(in);
String nam = upload.getParameter();
out.println("姓名:" + nam + "<br><br>");
long time = upload.getFileUpload();
out.println("文件上传完毕，总共耗时：" + time + "毫秒<br>");
String leixing = upload.getParameter();
out.println("文件类型：" + leixing + "<br>");
in.close();
%>
<br>
<div align="right">
<a href="index.jsp">回到首页</a>
</div>
</body>
</html>
希望本文所述对大家的JSP程序设计有所帮助。