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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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