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 of commons-fileupload.x.x.jar file in your classpath. You can download it from http://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 maxFileSize otherwise 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{ 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 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:
If your JSP script works fine, your file should be uploaded in c:\apache-tomcat-5.5.29\webapps\data\ directory.
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