Spring MVC failed to convert property value in file upload form
Problem
In Spring MVC application, while clicking on the file upload button, it hits the following property type conversion error?
Failed to convert property value of type [org.springframework.web.multipart.commons.CommonsMultipartFile] to required type [byte[]] for property file; nested exception is java.lang.IllegalArgumentException: Cannot convert value of type [org.springframework.web.multipart.commons.CommonsMultipartFile] to required type [byte] for property file[0]: PropertyEditor [org.springframework.beans.propertyeditors.CustomNumberEditor] returned inappropriate value
Here’s the SimpleFormController …
public class FileUploadController extends SimpleFormController{
public FileUploadController(){
setCommandClass(FileUpload.class);
setCommandName("fileUploadForm");
}
//...
public class FileUpload{
byte[] file;
//...
}
Solution
This is a common issue in handling the uploaded file in Spring MVC, which is unable to convert the uploaded file into byte arrays automatically. To make it work, you have to register a custom editor (ByteArrayMultipartFileEditor) in the SimpleFormController’s initBinder() method to guide Spring to convert the uploaded file into byte array.
public class FileUploadController extends SimpleFormController{
public FileUploadController(){
setCommandClass(FileUpload.class);
setCommandName("fileUploadForm");
}
@Override
protected void initBinder(HttpServletRequest request, ServletRequestDataBinder binder)
throws ServletException {
// Convert multipart object to byte[]
binder.registerCustomEditor(byte[].class, new ByteArrayMultipartFileEditor());
}
//...
About Author
thank you so much sooooo simple yet so helpful i was literally struggling!
How to handle this situation in @Annotated Controllers..?
define a method annotated with @InitBinder,like this:
@InitBinder protected void initBinder(HttpServletRequest request, ServletRequestDataBinder binder) throws ServletException { binder.registerCustomEditor(byte[].class, new ByteArrayMultipartFileEditor()); }As this method is called automatically after that where the controller will be forwarded.