UploadExample.jsp
<%@ page contentType="text/html;charset=gb2312"%>
<html>
<title><%=
application.getServerInfo()
%></title>
<body>
上传文件程序应用示例
<form action="doUpload.jsp" method="post" enctype="multipart/form-data">
<%-- 类型enctype用multipart/form-data，这样可以把文件中的数据作为流式数据上传，不管是什么文件类型，均可上传。--%>
请选择要上传的文件<input type="file" name="upfile"
size="50">
<input type="submit"
value="提交">
</form>
</body>
</html>
doUpload.jsp
<%@ page contentType="text/html; charset=GBK"
%>
<%@ page import="java.io.*"%>
<%@ page import="java.util.*"%>
<%@ page
import="javax.servlet.*"%>
<%@ page
import="javax.servlet.http.*"%>
<html><head><title>upFile</title></head>
<body bgcolor="#ffffff">
<%
//定义上载文件的最大字节
int MAX_SIZE = 102400 * 102400;
// 创建根路径的保存变量
String rootPath;
//声明文件读入类
DataInputStream in = null;
FileOutputStream fileOut = null;
//取得客户端的网络地址
String remoteAddr = request.getRemoteAddr();
//获得服务器的名字
String serverName = request.getServerName();
//取得互联网程序的绝对地址
String realPath = request.getRealPath(serverName);
realPath = realPath.substring(0,realPath.lastIndexOf("\"));
//创建文件的保存目录
rootPath = realPath + "\upload\";
//取得客户端上传的数据类型
String contentType = request.getContentType();
try{
if(contentType.indexOf("multipart/form-data") >=
0){
//读入上传的数据
in = new DataInputStream(request.getInputStream());
int formDataLength = request.getContentLength();
if(formDataLength > MAX_SIZE){
out.println("<P>上传的文件字节数不可以超过" +
MAX_SIZE + "</p>");
return;
}
//保存上传文件的数据
byte dataBytes[] = new byte[formDataLength];
int byteRead = 0;
int totalBytesRead = 0;
//上传的数据保存在byte数组
while(totalBytesRead < formDataLength){
byteRead = in.read(dataBytes,totalBytesRead,formDataLength);
totalBytesRead += byteRead;
}
//根据byte数组创建字符串
String file = new String(dataBytes);
//out.println(file);
//取得上传的数据的文件名
String saveFile = file.substring(file.indexOf("filename="") +
10);
saveFile = saveFile.substring(0,saveFile.indexOf("
"));
saveFile = saveFile.substring(saveFile.lastIndexOf("\") +
1,saveFile.indexOf("""));
int lastIndex = contentType.lastIndexOf("=");
//取得数据的分隔字符串
String boundary = contentType.substring(lastIndex +
1,contentType.length());
//创建保存路径的文件名
String fileName = rootPath + saveFile;
//out.print(fileName);
int pos;
pos = file.indexOf("filename="");
pos = file.indexOf("
",pos) + 1;
pos = file.indexOf("
",pos) + 1;
pos = file.indexOf("
",pos) + 1;
int boundaryLocation = file.indexOf(boundary,pos) - 4;
//out.println(boundaryLocation);
//取得文件数据的开始的位置
int startPos = ((file.substring(0,pos)).getBytes()).length;
//out.println(startPos);
//取得文件数据的结束的位置
int endPos =
((file.substring(0,boundaryLocation)).getBytes()).length;
//out.println(endPos);
//检查上载文件是否存在
File checkFile = new File(fileName);
if(checkFile.exists()){
out.println("<p>" + saveFile +
"文件已经存在.</p>");
}
//检查上载文件的目录是否存在
File fileDir = new File(rootPath);
if(!fileDir.exists()){
fileDir.mkdirs();
}
//创建文件的写出类
fileOut = new FileOutputStream(fileName);
//保存文件的数据
fileOut.write(dataBytes,startPos,(endPos - startPos));
fileOut.close();
out.println(saveFile +
"文件成功上载.</p>");
}else{
String content = request.getContentType();
out.println("<p>上传的数据类型不是multipart/form-data</p>");
}
}catch(Exception ex){
throw new ServletException(ex.getMessage());
}
%>
</body>
</html>
运行方法，将这两个JSP文件放在同一路径下，运行UploadExample.jsp即可。