Hi Nilesh,
You can use the getDataObject method of the Adobe document object. Below is a sample script that you can attach to the click event of a button to see how it works. For more information on importDataObject and getDataObject go to
http://partners.adobe.com/public/developer/en/acrobat/sdk/pdf/javascript/AcroJS.pdfSAMPLE
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//Get a handle to the Adobe document object
var doc = event.target;
//Display a file dialog box and assign the name Attachment to the
//DataObject that contains the selected file.
doc.importDataObject("Attachment");
//Get the DataObject and store it in MyData
var MyData = doc.getDataObject("Attachment");
//Clear and display the console window
console.show();
console.clear();
//Output the properties of the DataObject
for (var i in MyData) console.println("MyData." + i + "=" + MyData[i]);
Trevor