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File Upload
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(Continued from previous part...)
UploadSave.jsp - Saving Uploaded Files
As you can see from the previous section, dumping uploaded files back to the
browser is easy. But saving uploaded files on the server machine correctly
is not so easy. I wrote the following JSP program, UploadSave.jsp, that scans
the HTTP request body and saves uploaded files if there are any:
<?xml version="1.0"?>
<jsp:root xmlns:jsp="http://java.sun.com/JSP/Page" version="1.2">
<!--
- UploadSave.jsp
- Copyright (c) 2004 by Dr. Herong Yang. All rights reserved.
-->
<jsp:directive.page contentType="text/html"/>
<jsp:directive.page import="java.io.*"/>
<html><body>
<p>
<jsp:scriptlet><![CDATA[
out.println("<pre>");
ServletInputStream in = request.getInputStream();
byte[] line = new byte[128];
byte[] crlf = {(byte) 0x0D, (byte) 0x0A}; // \r\n
String sLine = null;
String enctype = null;
String boundary = null;
String status = null;
String fName = null;
FileOutputStream file = null;
int i = in.readLine(line, 0, 128);
boolean holdNewLine = false;
while (i != -1) {
boolean hasNewLine = i>=2 && line[i-1]==crlf[1]
&& line[i-2]== crlf[0];
if (hasNewLine) i = i-2;
sLine = new String(line, 0, i);
if (enctype==null) {
// try to determine the encryption type
if (i>3 && sLine.startsWith("--")) {
enctype = "form-data";
boundary = sLine;
status = "boundary";
} else {
enctype = "x-www-form-urlencoded";
}
out.println(sLine);
} else if (enctype.equals("x-www-form-urlencoded")) {
out.println(sLine);
} else if (enctype.equals("form-data")) {
// Calculating the status of the current line
if (status.equals("boundary")) {
// Expecting the "Content-Disposition:" line
status = "disposition";
} else if (status.equals("disposition")) {
// Expecting the "Content-Type:" line or a blank line
if (sLine.startsWith("Content-Type:")) {
status = "type";
} else {
status = "blank";
}
} else if (status.equals("type")) {
// Expecting a blank line
status = "blank";
} else if (status.equals("blank")||status.equals("data")) {
// Expecting the data or boundary
if (sLine.startsWith(boundary)) {
status = "boundary";
} else {
status = "data";
}
}
// Now "status" is updated. Let's do the saving and echoing
if (status.equals("disposition")) {
// Getting the file name and open a file for saving
int l = sLine.indexOf("filename=");
if (l>=0) {
fName = sLine.substring(l+9);
fName = fName.replaceAll("\"","");
l = fName.lastIndexOf("\\");
if (l>=0) fName = fName.substring(l+1);
if (fName.length()>0)
file = new FileOutputStream("\\var\\"+fName);
}
} else if (status.equals("boundary")) {
fName = null;
if (file!=null) {
file.close();
file = null;
}
}
if (status.equals("data")) {
if (file!=null) {
if (holdNewLine) file.write(crlf);
file.write(line,0,i);
holdNewLine = hasNewLine;
} else {
out.println(status+": "+fName+": "+sLine);
holdNewLine = false;
}
} else {
out.println(status+": "+fName+": "+sLine);
holdNewLine = false;
}
}
i = in.readLine(line, 0, 128);
}
out.println("</pre>");
]]></jsp:scriptlet>
</p>
</body></html>
</jsp:root>
I repeated my previous upload test with UploadSave.jsp by using the UploadInit.html
page:
File Upload Test Settings:
File upload handler: [UploadSave.jsp]
Submit method: [post]
Encryption type: [multipart/form-data ]
Submit
(Continued on next part...)
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