More helpful error messages when you try to give POIFS an OOXML file

git-svn-id: https://svn.apache.org/repos/asf/poi/branches/ooxml@681365 13f79535-47bb-0310-9956-ffa450edef68

src/java/org/apache/poi/poifs/storage/HeaderBlockReader.java

@@ -105,7 +105,7 @@ public class HeaderBlockReader
 					_data[1] == OOXML_FILE_HEADER[1] && 
 					_data[2] == OOXML_FILE_HEADER[2] &&
 					_data[3] == OOXML_FILE_HEADER[3]) {
-				throw new OfficeXmlFileException("The supplied data appears to be in the Office 2007+ XML. POI only supports OLE2 Office documents");
+				throw new OfficeXmlFileException("The supplied data appears to be in the Office 2007+ XML. You are calling the part of POI that deals with OLE2 Office Documents. You need to call a different part of POI to process this data (eg XSSF instead of HSSF)");
 			}
 
 			// Give a generic error

src/testcases/org/apache/poi/poifs/filesystem/TestOffice2007XMLException.java

@@ -41,7 +41,8 @@ public class TestOffice2007XMLException extends TestCase {
 			fail("expected exception was not thrown");
 		} catch(OfficeXmlFileException e) {
 			// expected during successful test
-			assertTrue(e.getMessage().indexOf("POI only supports OLE2 Office documents") > 0);
+			assertTrue(e.getMessage().indexOf("The supplied data appears to be in the Office 2007+ XML") > -1);
+			assertTrue(e.getMessage().indexOf("You are calling the part of POI that deals with OLE2 Office Documents") > -1);
 		}
 	}