How can you upload a file using JSP?

JSPJava 8Object Oriented ProgrammingProgramming

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

 Live Demo

<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.

raja
Published on 22-Mar-2019 10:27:25
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