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How can you upload a file using JSP?
A JSP can be used with an HTML form tag to allow users to upload files to the server. An uploaded file can be a text file or a binary or an image file or just any document.
Creating a File Upload Form
Let us now understand how to create a file upload form. The following HTML code creates an uploader form. Following are the important points to be noted down −
The form method attribute should be set to the POST method and the GET method cannot 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 tag with different values for the name attribute. The browser associates a Browse button with each of them.
Example
<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 the following result. You can now select a file from the local PC and when the user clicks "Upload File", the form gets submitted along with the selected file −
Output
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
Let us now define a location where the uploaded files will be stored. You can hard code this in your program or this directory name can 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. This can handle the uploading of multiple files at a time. Let us now consider the following before proceeding with the uploading of files.
The following example depends on FileUpload; make sure you have the latest version of the commons-fileupload.x.x.jar file in your classpath. You can download it from https://commons.apache.org/fileupload/.
FileUpload depends on Commons IO; make sure you have the latest version of commons-io-x.x.jar file in your classpath. You can download it from https://commons.apache.org/io/.
While testing the following example, you should upload a file which is of less size than maxFileSize otherwise the file will not be uploaded.
Make sure you have created directories c:\temp and c:\apache-tomcat5.5.29\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 {
out.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 try http://localhost:8080/UploadFile.htm, it will display the following result. This will help you upload any file from your local machine.
File Upload Select a file to upload
If your JSP script works fine, your file should be uploaded in c:\apache-tomcat5.5.29\webapps\data\ directory.
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