Excel File Upload using GWT - gwt

Question

I am not able to upload excel file and parse using GWT 2.7.0. Referred many links Link1 Link2
using above technique and RequestBuilder I couldn't send parsed excel data back to client. Finally implemented GWT RPC technique but having problem load Excel file as GWT cannot implement File.io api on client(Javascript or browser cannot read)
Code:
Client side FileUploading
public class MyFileUpload extends Composite implements Constants{
private ExcelClientServiceImpl excelServiceClient;
private VerticalPanel vPanel;
public MyFileUpload(ExcelClientServiceImpl excelServiceClient){
this.excelServiceClient = excelServiceClient;
this.vPanel = new VerticalPanel();
initWidget(this.vPanel);
}
public void initiateUpload() {
// Create a FormPanel and point it at a service.
final FormPanel form = new FormPanel();
form.setAction("/excelParser");
// Because we're going to add a FileUpload widget, we'll need to set the
// form to use the POST method, and multipart MIME encoding.
form.setEncoding(FormPanel.ENCODING_MULTIPART);
form.setMethod(FormPanel.METHOD_POST);
// Create a panel to hold all of the form widgets.
vPanel = new VerticalPanel();
form.setWidget(vPanel);
// Create a FileUpload widget.
final FileUpload upload = new FileUpload();
//upload.setName("uploadFormElement");
vPanel.add(upload);
System.out.println("File name is : "+upload.getFilename());
// Add a 'submit' button.
vPanel.add(new Button("Submit", new ClickHandler() {
public void onClick(ClickEvent event) {
Window.alert("In Button >>>>>> "+event);
form.submit();
}
}));
// Add an event handler to the form.
form.addSubmitHandler(new FormPanel.SubmitHandler() {
public void onSubmit(SubmitEvent event) {
Window.alert("In Handler >>>>>> "+event);
}
});
form.addSubmitCompleteHandler(new FormPanel.SubmitCompleteHandler() {
public void onSubmitComplete(SubmitCompleteEvent event) {
// When the form submission is successfully completed, this event is
// fired. Assuming the service returned a response of type text/html,
// we can get the result text here (see the FormPanel documentation for
// further explanation).
Window.alert("In complete >>>>>> "+event.getResults());
}
});
RootPanel.get().add(form);
}
}
Client Interface
public interface ExcelClientServiceInt {
void parse(String fileName, String[] lines, StringBuilder integerNumber, StringBuilder floatNumber,
String separator);
void readingExcel();
}
Client Implementation
public class ExcelClientServiceImpl implements ExcelClientServiceInt{
private ExcelServiceIntAsync service;
private MyFileUpload excelUpload;
public ExcelClientServiceImpl(String url){
this.service = GWT.create(ExcelParserService.class);
ServiceDefTarget endpoint = (ServiceDefTarget) this.service;
endpoint.setServiceEntryPoint(url);
this.excelUpload = new MyFileUpload(this);
}
#Override
public void parse(String fileName, String[] lines, StringBuilder integerNumber, StringBuilder floatNumber,
String separator) {
this.service.parse(fileName, lines, integerNumber, floatNumber, separator, new DefaultCallback());
}
#Override
public void readingExcel() {
this.service.readingExcel(null, new DefaultCallback());
}
private class DefaultCallback implements AsyncCallback{
#Override
public void onFailure(Throwable caught) {
System.out.println("Output failed");
}
#Override
public void onSuccess(Object result) {
System.out.println("Output reieved successfully "+result);
}
}
}
Service Interface
#RemoteServiceRelativePath("excelParser")
public interface ExcelServiceInt extends RemoteService{
void parse(String fileName, String[] lines, StringBuilder integerNumber, StringBuilder floatNumber, String separator);
public List readingExcel(String fileName);
}
Async Call Back
public interface ExcelServiceIntAsync{
void parse(String fileName, String[] lines, StringBuilder integerNumber, StringBuilder floatNumber,
String separator, AsyncCallback<Void> callBack);
void readingExcel(String fileName, AsyncCallback<List<String>> callBack);
}
Server side Service
public class ExcelParserService extends RemoteServiceServlet implements ExcelServiceInt{
public void parse(String fileName, String[] lines, StringBuilder integerNumber, StringBuilder floatNumber,
String separator) {
ExcelParser.parse(fileName, lines, integerNumber, floatNumber, separator);
}
public List<String> readingExcel(String fileName) {
return ExcelParser.readingExcel(fileName);
}
}