remove warnings and one useless comment

src/org/vaadin/haijian/CSVExporter.java

@@ -7,7 +7,9 @@
 import com.vaadin.ui.Table;
 
 public class CSVExporter extends Exporter {
-    public CSVExporter() {
+	private static final long serialVersionUID = 1L;
+
+	public CSVExporter() {
         super();
     }
 
@@ -25,7 +27,6 @@ public CSVExporter(Container container) {
 
     @Override
     protected FileBuilder createFileBuilder(Container container) {
-        // TODO Auto-generated method stub
         return new CSVFileBuilder(container);
     }
 

src/org/vaadin/haijian/ExcelExporter.java

@@ -7,7 +7,9 @@
 import com.vaadin.ui.Table;
 
 public class ExcelExporter extends Exporter {
-    public ExcelExporter() {
+	private static final long serialVersionUID = 1L;
+
+	public ExcelExporter() {
         super();
     }
 

src/org/vaadin/haijian/Exporter.java

@@ -8,15 +8,16 @@
 import org.vaadin.haijian.filegenerator.FileBuilder;
 
 import com.vaadin.data.Container;
-import com.vaadin.data.util.IndexedContainer;
 import com.vaadin.server.FileDownloader;
 import com.vaadin.server.StreamResource;
 import com.vaadin.server.StreamResource.StreamSource;
 import com.vaadin.ui.Button;
 import com.vaadin.ui.Table;
 
 public abstract class Exporter extends Button implements StreamSource {
-    protected FileBuilder fileBuilder;
+	private static final long serialVersionUID = 1L;
+
+	protected FileBuilder fileBuilder;
     private FileDownloader fileDownloader;
     private Locale locale;
     private String dateFormatString;

src/org/vaadin/haijian/ExporterUI.java

@@ -3,7 +3,6 @@
 import java.text.ParseException;
 import java.text.SimpleDateFormat;
 import java.util.Date;
-import java.util.Locale;
 
 import com.vaadin.server.VaadinRequest;
 import com.vaadin.ui.Table;

src/org/vaadin/haijian/PdfExporter.java

@@ -7,7 +7,9 @@
 import com.vaadin.ui.Table;
 
 public class PdfExporter extends Exporter {
-    public PdfExporter() {
+	private static final long serialVersionUID = 1L;
+
+	public PdfExporter() {
         super();
     }
 

src/org/vaadin/haijian/filegenerator/CSVFileBuilder.java

@@ -5,13 +5,12 @@
 import java.util.Calendar;
 import java.util.Date;
 
-import com.itextpdf.text.Phrase;
-import com.itextpdf.text.Rectangle;
-import com.itextpdf.text.pdf.PdfPCell;
 import com.vaadin.data.Container;
 
 public class CSVFileBuilder extends FileBuilder {
-    private FileWriter writer;
+	private static final long serialVersionUID = 1L;
+
+	private FileWriter writer;
     private int rowNr;
     private int colNr;
 

src/org/vaadin/haijian/filegenerator/ExcelFileBuilder.java

@@ -19,7 +19,8 @@
 import com.vaadin.data.Container;
 
 public class ExcelFileBuilder extends FileBuilder {
-    private static final String DATE_CELL_STYLE = "m/d/yy h:mm";
+	private static final long serialVersionUID = 1L;
+
     private Workbook workbook;
     private Sheet sheet;
     private int rowNr;

src/org/vaadin/haijian/filegenerator/FileBuilder.java

@@ -3,7 +3,6 @@
 import java.io.File;
 import java.io.IOException;
 import java.io.Serializable;
-import java.text.DateFormat;
 import java.text.SimpleDateFormat;
 import java.util.Date;
 import java.util.HashMap;
@@ -14,7 +13,9 @@
 import com.vaadin.data.Property;
 
 public abstract class FileBuilder implements Serializable {
-    protected File file;
+	private static final long serialVersionUID = 1L;
+
+	protected File file;
     public Container container;
     private Object[] visibleColumns;
     private Map<Object, String> columnHeaderMap;

src/org/vaadin/haijian/filegenerator/PdfFileBuilder.java

@@ -18,7 +18,9 @@
 import com.vaadin.data.Container;
 
 public class PdfFileBuilder extends FileBuilder {
-    private Document document;
+	private static final long serialVersionUID = 1L;
+
+	private Document document;
     private PdfPTable table;
     private static Font catFont = new Font(Font.FontFamily.TIMES_ROMAN, 18,
             Font.BOLD);