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JSP - File Uploading

A JSP can be used with an HTML form tag to allow users to upload files to the server. An uploaded file could be a text file or binary or image file or any document.

Creating a File Upload Form:

The following HTM code below creates an uploader form. Following are the important points to be noted down:

The form method attribute should be set to POST method and GET method can not be used.
The form enctype attribute should be set to multipart/form-data.
The form action attribute should be set to a JSP file which would handle file uploading at backend server. Following example is using uploadFile.jsp program file to upload file.
To upload a single file you should use a single <input .../> tag with attribute type="file". To allow multiple files uploading, include more than one input tags with different values for the name attribute. The browser associates a Browse button with each of them.

<html>
<head>
<title>File Uploading Form</title>
</head>
<body>
<h3>File Upload:</h3>
Select a file to upload: <br />
<form action="UploadServlet" method="post"
enctype="multipart/form-data">
<input type="file" name="file" size="50" />
<br />
<input type="submit" value="Upload File" />
</form>
</body>
</html>

This will display following result which would allow to select a file from local PC and when user would click at "Upload File", form would be submitted along with the selected file:

File Upload:
Select a file to upload:

NOTE: Above form is just dummy form and would not work, you should try above code at your machine to make it work.

Writing Backend JSP Script:

First let us define a location where uploaded files would be stored. You can hard code this in your program or this directory name could also be added using an external configuration such as a context-param element in web.xml as follows:

<web-app>
....
<context-param>
<description>Location to store uploaded file</description>
<param-name>file-upload</param-name>
<param-value>
c:\apache-tomcat-5.5.29\webapps\data\
</param-value>
</context-param>
....
</web-app>

Following is the source code for UploadFile.jsp which can handle multiple file uploading at a time. Before proceeding you have make sure the followings:

Following example depends on FileUpload, so make sure you have the latest version ofcommons-fileupload.x.x.jar file in your classpath. You can download it fromhttp://commons.apache.org/fileupload/.
FileUpload depends on Commons IO, so make sure you have the latest version of commons-io-x.x.jar file in your classpath. You can download it from http://commons.apache.org/io/.
While testing following example, you should upload a file which has less size than maxFileSizeotherwise file would not be uploaded.
Make sure you have created directories c:\temp and c:\apache-tomcat-5.5.29\webapps\data well in advance.

<%@ page import="java.io.*,java.util.*, javax.servlet.*" %>
<%@ page import="javax.servlet.http.*" %>
<%@ page import="org.apache.commons.fileupload.*" %>
<%@ page import="org.apache.commons.fileupload.disk.*" %>
<%@ page import="org.apache.commons.fileupload.servlet.*" %>
<%@ page import="org.apache.commons.io.output.*" %>
<%
File file ;
int maxFileSize = 5000 * 1024;
int maxMemSize = 5000 * 1024;
ServletContext context = pageContext.getServletContext();
String filePath = context.getInitParameter("file-upload");
// Verify the content type
String contentType = request.getContentType();
if ((contentType.indexOf("multipart/form-data") >= 0)) {

DiskFileItemFactory factory = new DiskFileItemFactory();
// maximum size that will be stored in memory
factory.setSizeThreshold(maxMemSize);
// Location to save data that is larger than maxMemSize.
factory.setRepository(new File("c:\\temp"));

// Create a new file upload handler
ServletFileUpload upload = new ServletFileUpload(factory);
// maximum file size to be uploaded.
upload.setSizeMax( maxFileSize );
try{
// Parse the request to get file items.
List fileItems = upload.parseRequest(request);

// Process the uploaded file items
Iterator i = fileItems.iterator();
out.println("<html>");
out.println("<head>");
out.println("<title>JSP File upload</title>");
out.println("</head>");
out.println("<body>");
while ( i.hasNext () )
{
FileItem fi = (FileItem)i.next();
if ( !fi.isFormField () )
{
// Get the uploaded file parameters
String fieldName = fi.getFieldName();
String fileName = fi.getName();
boolean isInMemory = fi.isInMemory();
long sizeInBytes = fi.getSize();
// Write the file
if( fileName.lastIndexOf("\\") >= 0 ){
file = new File( filePath +
fileName.substring( fileName.lastIndexOf("\\"))) ;
}else{
file = new File( filePath +
fileName.substring(fileName.lastIndexOf("\\")+1)) ;
}
fi.write( file ) ;
out.println("Uploaded Filename: " + filePath +
fileName + "<br>");
}
}
out.println("</body>");
out.println("</html>");
}catch(Exception ex) {
System.out.println(ex);
}
}else{ o
ut.println("<html>");
out.println("<head>");
out.println("<title>Servlet upload</title>");
out.println("</head>");
out.println("<body>");
out.println("<p>No file uploaded</p>");
out.println("</body>");
out.println("</html>");
}
%>

Now try to upload files using the HTML form which you created above. When you would try http://localhost:8080/UploadFile.htm, it would display following result which would help you uploading any file from your local machine.

File Upload:
Select a file to upload: < >

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JSP - File Uploading