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Overview of the org.apache.commons.fileupload component
A component for handling HTML file uploads as specified by
RFC 1867.
This component provides support for uploads within both servlets (JSR 53)
and portlets (JSR 168).
While this package provides the generic functionality for file uploads,
these classes are not typically used directly. Instead, normal usage
involves one of the provided extensions of
{@link org.apache.commons.fileupload.FileUpload FileUpload} such as
{@link org.apache.commons.fileupload.servlet.ServletFileUpload ServletFileUpload}
or
{@link org.apache.commons.fileupload.portlet.PortletFileUpload PortletFileUpload},
together with a factory for
{@link org.apache.commons.fileupload.FileItem FileItem} instances,
such as
{@link org.apache.commons.fileupload.disk.DiskFileItemFactory DiskFileItemFactory}.
The following is a brief example of typical usage in a servlet, storing
the uploaded files on disk.
public void doPost(HttpServletRequest req, HttpServletResponse res) {
DiskFileItemFactory factory = new DiskFileItemFactory();
// maximum size that will be stored in memory
factory.setSizeThreshold(4096);
// the location for saving data that is larger than getSizeThreshold()
factory.setRepository(new File("/tmp"));
ServletFileUpload upload = new ServletFileUpload(factory);
// maximum size before a FileUploadException will be thrown
upload.setSizeMax(1000000);
List fileItems = upload.parseRequest(req);
// assume we know there are two files. The first file is a small
// text file, the second is unknown and is written to a file on
// the server
Iterator i = fileItems.iterator();
String comment = ((FileItem)i.next()).getString();
FileItem fi = (FileItem)i.next();
// filename on the client
String fileName = fi.getName();
// save comment and filename to database
...
// write the file
fi.write(new File("/www/uploads/", fileName));
}
In the example above, the first file is loaded into memory as a
String. Before calling the getString method,
the data may have been in memory or on disk depending on its size. The
second file we assume it will be large and therefore never explicitly
load it into memory, though if it is less than 4096 bytes it will be
in memory before it is written to its final location. When writing to
the final location, if the data is larger than the threshold, an attempt
is made to rename the temporary file to the given location. If it cannot
be renamed, it is streamed to the new location.
Please see the FileUpload
User Guide
for further details and examples of how to use this package.
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