reformat file

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1913066 13f79535-47bb-0310-9956-ffa450edef68

1 files changed, 502 insertions, 496 deletions

diff --git a/poi-ooxml/src/main/java/org/apache/poi/xssf/eventusermodel/XSSFSheetXMLHandler.java b/poi-ooxml/src/main/java/org/apache/poi/xssf/eventusermodel/XSSFSheetXMLHandler.java
index 14b5046593..42dca23e30 100644
--- a/poi-ooxml/src/main/java/org/apache/poi/xssf/eventusermodel/XSSFSheetXMLHandler.java
+++ b/poi-ooxml/src/main/java/org/apache/poi/xssf/eventusermodel/XSSFSheetXMLHandler.java
@@ -38,12 +38,12 @@ import org.xml.sax.helpers.DefaultHandler;
 
 /**
  * This class handles the streaming processing of a sheet#.xml
- *  sheet part of a XSSF .xlsx file, and generates
- *  row and cell events for it.
- *
+ * sheet part of a XSSF .xlsx file, and generates
+ * row and cell events for it.
+ * <p>
  * This allows to build functionality which reads huge files
  * without needing large amounts of main memory.
- *
+ * <p>
  * See {@link SheetContentsHandler} for the interface that
  * you need to implement for reading information from a file.
  */
@@ -51,499 +51,505 @@ public class XSSFSheetXMLHandler extends DefaultHandler {
     private static final Logger LOG = LogManager.getLogger(XSSFSheetXMLHandler.class);
 
     /**
-    * These are the different kinds of cells we support.
-    * We keep track of the current one between
-    *  the start and end.
-    */
-   enum xssfDataType {
-       BOOLEAN,
-       ERROR,
-       FORMULA,
-       INLINE_STRING,
-       SST_STRING,
-       NUMBER,
-   }
-
-   /**
-    * Table with the styles used for formatting
-    */
-   private final Styles stylesTable;
-
-   /**
-    * Table with cell comments
-    */
-   private final Comments comments;
-
-   /**
-    * Read only access to the shared strings table, for looking
-    *  up (most) string cell's contents
-    */
-   private final SharedStrings sharedStringsTable;
-
-   /**
-    * Where our text is going
-    */
-   private final SheetContentsHandler output;
-
-   // Set when V start element is seen
-   private boolean vIsOpen;
-   // Set when F start element is seen
-   private boolean fIsOpen;
-   // Set when an Inline String "is" is seen
-   private boolean isIsOpen;
-   // Set when a header/footer element is seen
-   private boolean hfIsOpen;
-
-   // Set when cell start element is seen;
-   // used when cell close element is seen.
-   private xssfDataType nextDataType;
-
-   // Used to format numeric cell values.
-   private short formatIndex;
-   private String formatString;
-   private final DataFormatter formatter;
-   private int rowNum;
-   private int nextRowNum;      // some sheets do not have rowNums, Excel can read them so we should try to handle them correctly as well
-   private String cellRef;
-   private final boolean formulasNotResults;
-
-   // Gathers characters as they are seen.
-   private final StringBuilder value = new StringBuilder(64);
-   private final StringBuilder formula = new StringBuilder(64);
-   private final StringBuilder headerFooter = new StringBuilder(64);
-
-   private Queue<CellAddress> commentCellRefs;
-
-   /**
-    * Accepts objects needed while parsing.
-    *
-    * @param styles  Table of styles
-    * @param strings Table of shared strings
-    */
-   public XSSFSheetXMLHandler(
-           Styles styles,
-           Comments comments,
-           SharedStrings strings,
-           SheetContentsHandler sheetContentsHandler,
-           DataFormatter dataFormatter,
-           boolean formulasNotResults) {
-       this.stylesTable = styles;
-       this.comments = comments;
-       this.sharedStringsTable = strings;
-       this.output = sheetContentsHandler;
-       this.formulasNotResults = formulasNotResults;
-       this.nextDataType = xssfDataType.NUMBER;
-       this.formatter = dataFormatter;
-       init(comments);
-   }
-
-   /**
-    * Accepts objects needed while parsing.
-    *
-    * @param styles  Table of styles
-    * @param strings Table of shared strings
-    */
-   public XSSFSheetXMLHandler(
-           Styles styles,
-           SharedStrings strings,
-           SheetContentsHandler sheetContentsHandler,
-           DataFormatter dataFormatter,
-           boolean formulasNotResults) {
-       this(styles, null, strings, sheetContentsHandler, dataFormatter, formulasNotResults);
-   }
-
-   /**
-    * Accepts objects needed while parsing.
-    *
-    * @param styles  Table of styles
-    * @param strings Table of shared strings
-    */
-   public XSSFSheetXMLHandler(
-           Styles styles,
-           SharedStrings strings,
-           SheetContentsHandler sheetContentsHandler,
-           boolean formulasNotResults) {
-       this(styles, strings, sheetContentsHandler, new DataFormatter(), formulasNotResults);
-   }
-
-   private void init(Comments commentsTable) {
-       if (commentsTable != null) {
-           commentCellRefs = new LinkedList<>();
-           for (Iterator<CellAddress> iter = commentsTable.getCellAddresses(); iter.hasNext(); ) {
-               commentCellRefs.add(iter.next());
-           }
-       }
-   }
-
-   private boolean isTextTag(String name) {
-      if("v".equals(name)) {
-         // Easy, normal v text tag
-         return true;
-      }
-      if("inlineStr".equals(name)) {
-         // Easy inline string
-         return true;
-      }
-      if("t".equals(name) && isIsOpen) {
-         // Inline string <is><t>...</t></is> pair
-         return true;
-      }
-      // It isn't a text tag
-      return false;
-   }
-
-   @Override
-   @SuppressWarnings("unused")
-   public void startElement(String uri, String localName, String qName,
-                            Attributes attributes) throws SAXException {
-
-       if (uri != null && ! uri.equals(NS_SPREADSHEETML)) {
-           return;
-       }
-
-       if (isTextTag(localName)) {
-           vIsOpen = true;
-           // Clear contents cache
-           if (!isIsOpen) {
-               value.setLength(0);
-           }
-       } else if ("is".equals(localName)) {
-          // Inline string outer tag
-          isIsOpen = true;
-       } else if ("f".equals(localName)) {
-          // Clear contents cache
-          formula.setLength(0);
-
-          // Mark us as being a formula if not already
-          nextDataType = xssfDataType.FORMULA;
-
-          // Decide where to get the formula string from
-          String type = attributes.getValue("t");
-          if(type != null && type.equals("shared")) {
-             // Is it the one that defines the shared, or uses it?
-             String ref = attributes.getValue("ref");
-             String si = attributes.getValue("si");
-
-             if(ref != null) {
-                // This one defines it
-                // TODO Save it somewhere
-                fIsOpen = true;
-             } else {
-                // This one uses a shared formula
-                // TODO Retrieve the shared formula and tweak it to
-                //  match the current cell
-                if(formulasNotResults) {
-                    LOG.atWarn().log("shared formulas not yet supported!");
-                } /*else {
+     * These are the different kinds of cells we support.
+     * We keep track of the current one between
+     * the start and end.
+     */
+    enum xssfDataType {
+        BOOLEAN,
+        ERROR,
+        FORMULA,
+        INLINE_STRING,
+        SST_STRING,
+        NUMBER,
+    }
+
+    /**
+     * Table with the styles used for formatting
+     */
+    private final Styles stylesTable;
+
+    /**
+     * Table with cell comments
+     */
+    private final Comments comments;
+
+    /**
+     * Read only access to the shared strings table, for looking
+     * up (most) string cell's contents
+     */
+    private final SharedStrings sharedStringsTable;
+
+    /**
+     * Where our text is going
+     */
+    private final SheetContentsHandler output;
+
+    // Set when V start element is seen
+    private boolean vIsOpen;
+    // Set when F start element is seen
+    private boolean fIsOpen;
+    // Set when an Inline String "is" is seen
+    private boolean isIsOpen;
+    // Set when a header/footer element is seen
+    private boolean hfIsOpen;
+
+    // Set when cell start element is seen;
+    // used when cell close element is seen.
+    private xssfDataType nextDataType;
+
+    // Used to format numeric cell values.
+    private short formatIndex;
+    private String formatString;
+    private final DataFormatter formatter;
+    private int rowNum;
+    private int nextRowNum;      // some sheets do not have rowNums, Excel can read them so we should try to handle them correctly as well
+    private String cellRef;
+    private final boolean formulasNotResults;
+
+    // Gathers characters as they are seen.
+    private final StringBuilder value = new StringBuilder(64);
+    private final StringBuilder formula = new StringBuilder(64);
+    private final StringBuilder headerFooter = new StringBuilder(64);
+
+    private Queue<CellAddress> commentCellRefs;
+
+    /**
+     * Accepts objects needed while parsing.
+     *
+     * @param styles  Table of styles
+     * @param strings Table of shared strings
+     */
+    public XSSFSheetXMLHandler(
+            Styles styles,
+            Comments comments,
+            SharedStrings strings,
+            SheetContentsHandler sheetContentsHandler,
+            DataFormatter dataFormatter,
+            boolean formulasNotResults) {
+        this.stylesTable = styles;
+        this.comments = comments;
+        this.sharedStringsTable = strings;
+        this.output = sheetContentsHandler;
+        this.formulasNotResults = formulasNotResults;
+        this.nextDataType = xssfDataType.NUMBER;
+        this.formatter = dataFormatter;
+        init(comments);
+    }
+
+    /**
+     * Accepts objects needed while parsing.
+     *
+     * @param styles  Table of styles
+     * @param strings Table of shared strings
+     */
+    public XSSFSheetXMLHandler(
+            Styles styles,
+            SharedStrings strings,
+            SheetContentsHandler sheetContentsHandler,
+            DataFormatter dataFormatter,
+            boolean formulasNotResults) {
+        this(styles, null, strings, sheetContentsHandler, dataFormatter, formulasNotResults);
+    }
+
+    /**
+     * Accepts objects needed while parsing.
+     *
+     * @param styles  Table of styles
+     * @param strings Table of shared strings
+     */
+    public XSSFSheetXMLHandler(
+            Styles styles,
+            SharedStrings strings,
+            SheetContentsHandler sheetContentsHandler,
+            boolean formulasNotResults) {
+        this(styles, strings, sheetContentsHandler, new DataFormatter(), formulasNotResults);
+    }
+
+    private void init(Comments commentsTable) {
+        if (commentsTable != null) {
+            commentCellRefs = new LinkedList<>();
+            for (Iterator<CellAddress> iter = commentsTable.getCellAddresses(); iter.hasNext(); ) {
+                commentCellRefs.add(iter.next());
+            }
+        }
+    }
+
+    private boolean isTextTag(String name) {
+        if ("v".equals(name)) {
+            // Easy, normal v text tag
+            return true;
+        }
+        if ("inlineStr".equals(name)) {
+            // Easy inline string
+            return true;
+        }
+        if ("t".equals(name) && isIsOpen) {
+            // Inline string <is><t>...</t></is> pair
+            return true;
+        }
+        // It isn't a text tag
+        return false;
+    }
+
+    @Override
+    @SuppressWarnings("unused")
+    public void startElement(String uri, String localName, String qName,
+                             Attributes attributes) throws SAXException {
+
+        if (uri != null && !uri.equals(NS_SPREADSHEETML)) {
+            return;
+        }
+
+        if (isTextTag(localName)) {
+            vIsOpen = true;
+            // Clear contents cache
+            if (!isIsOpen) {
+                value.setLength(0);
+            }
+        } else if ("is".equals(localName)) {
+            // Inline string outer tag
+            isIsOpen = true;
+        } else if ("f".equals(localName)) {
+            // Clear contents cache
+            formula.setLength(0);
+
+            // Mark us as being a formula if not already
+            nextDataType = xssfDataType.FORMULA;
+
+            // Decide where to get the formula string from
+            String type = attributes.getValue("t");
+            if (type != null && type.equals("shared")) {
+                // Is it the one that defines the shared, or uses it?
+                String ref = attributes.getValue("ref");
+                String si = attributes.getValue("si");
+
+                if (ref != null) {
+                    // This one defines it
+                    // TODO Save it somewhere
+                    fIsOpen = true;
+                } else {
+                    // This one uses a shared formula
+                    // TODO Retrieve the shared formula and tweak it to
+                    //  match the current cell
+                    if (formulasNotResults) {
+                        LOG.atWarn().log("shared formulas not yet supported!");
+                    } /*else {
                    // It's a shared formula, so we can't get at the formula string yet
                    // However, they don't care about the formula string, so that's ok!
                 }*/
-             }
-          } else {
-             fIsOpen = true;
-          }
-       }
-       else if("oddHeader".equals(localName) || "evenHeader".equals(localName) ||
-             "firstHeader".equals(localName) || "firstFooter".equals(localName) ||
-             "oddFooter".equals(localName) || "evenFooter".equals(localName)) {
-          hfIsOpen = true;
-          // Clear contents cache
-          headerFooter.setLength(0);
-       }
-       else if("row".equals(localName)) {
-           String rowNumStr = attributes.getValue("r");
-           if(rowNumStr != null) {
-               rowNum = Integer.parseInt(rowNumStr) - 1;
-           } else {
-               rowNum = nextRowNum;
-           }
-           output.startRow(rowNum);
-       }
-       // c => cell
-       else if ("c".equals(localName)) {
-           // Set up defaults.
-           this.nextDataType = xssfDataType.NUMBER;
-           this.formatIndex = -1;
-           this.formatString = null;
-           cellRef = attributes.getValue("r");
-           String cellType = attributes.getValue("t");
-           String cellStyleStr = attributes.getValue("s");
-           if ("b".equals(cellType))
-               nextDataType = xssfDataType.BOOLEAN;
-           else if ("e".equals(cellType))
-               nextDataType = xssfDataType.ERROR;
-           else if ("inlineStr".equals(cellType))
-               nextDataType = xssfDataType.INLINE_STRING;
-           else if ("s".equals(cellType))
-               nextDataType = xssfDataType.SST_STRING;
-           else if ("str".equals(cellType))
-               nextDataType = xssfDataType.FORMULA;
-           else {
-               // Number, but almost certainly with a special style or format
-               XSSFCellStyle style = null;
-               if (stylesTable != null) {
-                   if (cellStyleStr != null) {
-                       int styleIndex = Integer.parseInt(cellStyleStr);
-                       style = stylesTable.getStyleAt(styleIndex);
-                   } else if (stylesTable.getNumCellStyles() > 0) {
-                       style = stylesTable.getStyleAt(0);
-                   }
-               }
-               if (style != null) {
-                   this.formatIndex = style.getDataFormat();
-                   this.formatString = style.getDataFormatString();
-                   if (this.formatString == null)
-                       this.formatString = BuiltinFormats.getBuiltinFormat(this.formatIndex);
-               }
-           }
-       }
-   }
-
-   @Override
-   public void endElement(String uri, String localName, String qName)
-           throws SAXException {
-
-       if (uri != null && ! uri.equals(NS_SPREADSHEETML)) {
-           return;
-       }
-
-       // v => contents of a cell
-       if (isTextTag(localName)) {
-           vIsOpen = false;
-
-           if (!isIsOpen) {
-               outputCell();
-               value.setLength(0);
-           }
-       } else if ("f".equals(localName)) {
-          fIsOpen = false;
-       } else if ("is".equals(localName)) {
-          isIsOpen = false;
-           outputCell();
-           value.setLength(0);
-       } else if ("row".equals(localName)) {
-          // Handle any "missing" cells which had comments attached
-          checkForEmptyCellComments(EmptyCellCommentsCheckType.END_OF_ROW);
-
-          // Finish up the row
-          output.endRow(rowNum);
-
-          // some sheets do not have rowNum set in the XML, Excel can read them so we should try to read them as well
-          nextRowNum = rowNum + 1;
-       } else if ("sheetData".equals(localName)) {
-           // Handle any "missing" cells which had comments attached
-           checkForEmptyCellComments(EmptyCellCommentsCheckType.END_OF_SHEET_DATA);
-
-           // indicate that this sheet is now done
-           output.endSheet();
-       }
-       else if("oddHeader".equals(localName) || "evenHeader".equals(localName) ||
-             "firstHeader".equals(localName)) {
-          hfIsOpen = false;
-          output.headerFooter(headerFooter.toString(), true, localName);
-       }
-       else if("oddFooter".equals(localName) || "evenFooter".equals(localName) ||
-             "firstFooter".equals(localName)) {
-          hfIsOpen = false;
-          output.headerFooter(headerFooter.toString(), false, localName);
-       }
-   }
-
-   /**
-    * Captures characters only if a suitable element is open.
-    * Originally was just "v"; extended for inlineStr also.
-    */
-   @Override
-   public void characters(char[] ch, int start, int length)
-           throws SAXException {
-       if (vIsOpen) {
-           value.append(ch, start, length);
-       }
-       if (fIsOpen) {
-          formula.append(ch, start, length);
-       }
-       if (hfIsOpen) {
-          headerFooter.append(ch, start, length);
-       }
-   }
-
-   private void outputCell() {
-       String thisStr = null;
-
-       // Process the value contents as required, now we have it all
-       switch (nextDataType) {
-           case BOOLEAN:
-               char first = value.charAt(0);
-               thisStr = first == '0' ? "FALSE" : "TRUE";
-               break;
-
-           case ERROR:
-               thisStr = "ERROR:" + value;
-               break;
-
-           case FORMULA:
-               if(formulasNotResults) {
-                   thisStr = formula.toString();
-               } else {
-                   String fv = value.toString();
-
-                   if (this.formatString != null) {
-                       try {
-                           // Try to use the value as a formattable number
-                           double d = Double.parseDouble(fv);
-                           thisStr = formatter.formatRawCellContents(d, this.formatIndex, this.formatString);
-                       } catch(NumberFormatException e) {
-                           // Formula is a String result not a Numeric one
-                           thisStr = fv;
-                       }
-                   } else {
-                       // No formatting applied, just do raw value in all cases
-                       thisStr = fv;
-                   }
-               }
-               break;
-
-           case INLINE_STRING:
-               // TODO: Can these ever have formatting on them?
-               XSSFRichTextString rtsi = new XSSFRichTextString(value.toString());
-               thisStr = rtsi.toString();
-               break;
-
-           case SST_STRING:
-               String sstIndex = value.toString();
-               if (sstIndex.length() > 0) {
-                   try {
-                       int idx = Integer.parseInt(sstIndex);
-                       RichTextString rtss = sharedStringsTable.getItemAt(idx);
-                       thisStr = rtss.toString();
-                   } catch (NumberFormatException ex) {
-                       LOG.atError().withThrowable(ex).log("Failed to parse SST index '{}'", sstIndex);
-                   }
-               }
-               break;
-
-           case NUMBER:
-               String n = value.toString();
-               if (this.formatString != null && n.length() > 0)
-                   thisStr = formatter.formatRawCellContents(Double.parseDouble(n), this.formatIndex, this.formatString);
-               else
-                   thisStr = n;
-               break;
-
-           default:
-               thisStr = "(TODO: Unexpected type: " + nextDataType + ")";
-               break;
-       }
-
-       // Do we have a comment for this cell?
-       checkForEmptyCellComments(EmptyCellCommentsCheckType.CELL);
-       XSSFComment comment = comments != null ? comments.findCellComment(new CellAddress(cellRef)) : null;
-
-       // Output
-       output.cell(cellRef, thisStr, comment);
-   }
-
-   /**
-    * Do a check for, and output, comments in otherwise empty cells.
-    */
-   private void checkForEmptyCellComments(EmptyCellCommentsCheckType type) {
-       if (commentCellRefs != null && !commentCellRefs.isEmpty()) {
-           // If we've reached the end of the sheet data, output any
-           //  comments we haven't yet already handled
-           if (type == EmptyCellCommentsCheckType.END_OF_SHEET_DATA) {
-               while (!commentCellRefs.isEmpty()) {
-                   outputEmptyCellComment(commentCellRefs.remove());
-               }
-               return;
-           }
-
-           // At the end of a row, handle any comments for "missing" rows before us
-           if (this.cellRef == null) {
-               if (type == EmptyCellCommentsCheckType.END_OF_ROW) {
-                   while (!commentCellRefs.isEmpty()) {
-                       if (commentCellRefs.peek().getRow() == rowNum) {
-                           outputEmptyCellComment(commentCellRefs.remove());
-                       } else {
-                           return;
-                       }
-                   }
-                   return;
-               } else {
-                   throw new IllegalStateException("Cell ref should be null only if there are only empty cells in the row; rowNum: " + rowNum);
-               }
-           }
-
-           CellAddress nextCommentCellRef;
-           do {
-               CellAddress cellRef = new CellAddress(this.cellRef);
-               CellAddress peekCellRef = commentCellRefs.peek();
-               if (type == EmptyCellCommentsCheckType.CELL && cellRef.equals(peekCellRef)) {
-                   // remove the comment cell ref from the list if we're about to handle it alongside the cell content
-                   commentCellRefs.remove();
-                   return;
-               } else {
-                   // fill in any gaps if there are empty cells with comment mixed in with non-empty cells
-                   int comparison = peekCellRef.compareTo(cellRef);
-                   if (comparison > 0 && type == EmptyCellCommentsCheckType.END_OF_ROW && peekCellRef.getRow() <= rowNum) {
-                       nextCommentCellRef = commentCellRefs.remove();
-                       outputEmptyCellComment(nextCommentCellRef);
-                   } else if (comparison < 0 && type == EmptyCellCommentsCheckType.CELL && peekCellRef.getRow() <= rowNum) {
-                       nextCommentCellRef = commentCellRefs.remove();
-                       outputEmptyCellComment(nextCommentCellRef);
-                   } else {
-                       nextCommentCellRef = null;
-                   }
-               }
-           } while (nextCommentCellRef != null && !commentCellRefs.isEmpty());
-       }
-   }
-
-
-   /**
-    * Output an empty-cell comment.
-    */
-   private void outputEmptyCellComment(CellAddress cellRef) {
-       XSSFComment comment = comments.findCellComment(cellRef);
-       output.cell(cellRef.formatAsString(), null, comment);
-   }
-
-   private enum EmptyCellCommentsCheckType {
-       CELL,
-       END_OF_ROW,
-       END_OF_SHEET_DATA
-   }
-
-   /**
-    * This interface allows to provide callbacks when reading
-    * a sheet in streaming mode.
-    *
-    * The XSLX file is usually read via {@link XSSFReader}.
-    *
-    * By implementing the methods, you can process arbitrarily
-    * large files without exhausting main memory.
-    */
-   public interface SheetContentsHandler {
-      /** A row with the (zero based) row number has started */
-      void startRow(int rowNum);
-
-      /** A row with the (zero based) row number has ended */
-      void endRow(int rowNum);
-
-      /**
-       * A cell, with the given formatted value (may be null),
-       * and possibly a comment (may be null), was encountered.
-       *
-       * Sheets that have missing or empty cells may result in
-       * sparse calls to <code>cell</code>. See the code in
-       * <code>poi-examples/src/main/java/org/apache/poi/xssf/eventusermodel/XLSX2CSV.java</code>
-       * for an example of how to handle this scenario.
-       */
-      void cell(String cellReference, String formattedValue, XSSFComment comment);
-
-      /** A header or footer has been encountered */
-      default void headerFooter(String text, boolean isHeader, String tagName) {}
-
-      /** Signal that the end of a sheet was been reached */
-      default void endSheet() {}
-   }
+                }
+            } else {
+                fIsOpen = true;
+            }
+        } else if ("oddHeader".equals(localName) || "evenHeader".equals(localName) ||
+                "firstHeader".equals(localName) || "firstFooter".equals(localName) ||
+                "oddFooter".equals(localName) || "evenFooter".equals(localName)) {
+            hfIsOpen = true;
+            // Clear contents cache
+            headerFooter.setLength(0);
+        } else if ("row".equals(localName)) {
+            String rowNumStr = attributes.getValue("r");
+            if (rowNumStr != null) {
+                rowNum = Integer.parseInt(rowNumStr) - 1;
+            } else {
+                rowNum = nextRowNum;
+            }
+            output.startRow(rowNum);
+        }
+        // c => cell
+        else if ("c".equals(localName)) {
+            // Set up defaults.
+            this.nextDataType = xssfDataType.NUMBER;
+            this.formatIndex = -1;
+            this.formatString = null;
+            cellRef = attributes.getValue("r");
+            String cellType = attributes.getValue("t");
+            String cellStyleStr = attributes.getValue("s");
+            if ("b".equals(cellType))
+                nextDataType = xssfDataType.BOOLEAN;
+            else if ("e".equals(cellType))
+                nextDataType = xssfDataType.ERROR;
+            else if ("inlineStr".equals(cellType))
+                nextDataType = xssfDataType.INLINE_STRING;
+            else if ("s".equals(cellType))
+                nextDataType = xssfDataType.SST_STRING;
+            else if ("str".equals(cellType))
+                nextDataType = xssfDataType.FORMULA;
+            else {
+                // Number, but almost certainly with a special style or format
+                XSSFCellStyle style = null;
+                if (stylesTable != null) {
+                    if (cellStyleStr != null) {
+                        int styleIndex = Integer.parseInt(cellStyleStr);
+                        style = stylesTable.getStyleAt(styleIndex);
+                    } else if (stylesTable.getNumCellStyles() > 0) {
+                        style = stylesTable.getStyleAt(0);
+                    }
+                }
+                if (style != null) {
+                    this.formatIndex = style.getDataFormat();
+                    this.formatString = style.getDataFormatString();
+                    if (this.formatString == null)
+                        this.formatString = BuiltinFormats.getBuiltinFormat(this.formatIndex);
+                }
+            }
+        }
+    }
+
+    @Override
+    public void endElement(String uri, String localName, String qName)
+            throws SAXException {
+
+        if (uri != null && !uri.equals(NS_SPREADSHEETML)) {
+            return;
+        }
+
+        // v => contents of a cell
+        if (isTextTag(localName)) {
+            vIsOpen = false;
+
+            if (!isIsOpen) {
+                outputCell();
+                value.setLength(0);
+            }
+        } else if ("f".equals(localName)) {
+            fIsOpen = false;
+        } else if ("is".equals(localName)) {
+            isIsOpen = false;
+            outputCell();
+            value.setLength(0);
+        } else if ("row".equals(localName)) {
+            // Handle any "missing" cells which had comments attached
+            checkForEmptyCellComments(EmptyCellCommentsCheckType.END_OF_ROW);
+
+            // Finish up the row
+            output.endRow(rowNum);
+
+            // some sheets do not have rowNum set in the XML, Excel can read them so we should try to read them as well
+            nextRowNum = rowNum + 1;
+        } else if ("sheetData".equals(localName)) {
+            // Handle any "missing" cells which had comments attached
+            checkForEmptyCellComments(EmptyCellCommentsCheckType.END_OF_SHEET_DATA);
+
+            // indicate that this sheet is now done
+            output.endSheet();
+        } else if ("oddHeader".equals(localName) || "evenHeader".equals(localName) ||
+                "firstHeader".equals(localName)) {
+            hfIsOpen = false;
+            output.headerFooter(headerFooter.toString(), true, localName);
+        } else if ("oddFooter".equals(localName) || "evenFooter".equals(localName) ||
+                "firstFooter".equals(localName)) {
+            hfIsOpen = false;
+            output.headerFooter(headerFooter.toString(), false, localName);
+        }
+    }
+
+    /**
+     * Captures characters only if a suitable element is open.
+     * Originally was just "v"; extended for inlineStr also.
+     */
+    @Override
+    public void characters(char[] ch, int start, int length)
+            throws SAXException {
+        if (vIsOpen) {
+            value.append(ch, start, length);
+        }
+        if (fIsOpen) {
+            formula.append(ch, start, length);
+        }
+        if (hfIsOpen) {
+            headerFooter.append(ch, start, length);
+        }
+    }
+
+    private void outputCell() {
+        String thisStr = null;
+
+        // Process the value contents as required, now we have it all
+        switch (nextDataType) {
+            case BOOLEAN:
+                char first = value.charAt(0);
+                thisStr = first == '0' ? "FALSE" : "TRUE";
+                break;
+
+            case ERROR:
+                thisStr = "ERROR:" + value;
+                break;
+
+            case FORMULA:
+                if (formulasNotResults) {
+                    thisStr = formula.toString();
+                } else {
+                    String fv = value.toString();
+
+                    if (this.formatString != null) {
+                        try {
+                            // Try to use the value as a formattable number
+                            double d = Double.parseDouble(fv);
+                            thisStr = formatter.formatRawCellContents(d, this.formatIndex, this.formatString);
+                        } catch (NumberFormatException e) {
+                            // Formula is a String result not a Numeric one
+                            thisStr = fv;
+                        }
+                    } else {
+                        // No formatting applied, just do raw value in all cases
+                        thisStr = fv;
+                    }
+                }
+                break;
+
+            case INLINE_STRING:
+                // TODO: Can these ever have formatting on them?
+                XSSFRichTextString rtsi = new XSSFRichTextString(value.toString());
+                thisStr = rtsi.toString();
+                break;
+
+            case SST_STRING:
+                String sstIndex = value.toString();
+                if (sstIndex.length() > 0) {
+                    try {
+                        int idx = Integer.parseInt(sstIndex);
+                        RichTextString rtss = sharedStringsTable.getItemAt(idx);
+                        thisStr = rtss.toString();
+                    } catch (NumberFormatException ex) {
+                        LOG.atError().withThrowable(ex).log("Failed to parse SST index '{}'", sstIndex);
+                    }
+                }
+                break;
+
+            case NUMBER:
+                String n = value.toString();
+                if (this.formatString != null && n.length() > 0)
+                    thisStr = formatter.formatRawCellContents(Double.parseDouble(n), this.formatIndex, this.formatString);
+                else
+                    thisStr = n;
+                break;
+
+            default:
+                thisStr = "(TODO: Unexpected type: " + nextDataType + ")";
+                break;
+        }
+
+        // Do we have a comment for this cell?
+        checkForEmptyCellComments(EmptyCellCommentsCheckType.CELL);
+        XSSFComment comment = comments != null ? comments.findCellComment(new CellAddress(cellRef)) : null;
+
+        // Output
+        output.cell(cellRef, thisStr, comment);
+    }
+
+    /**
+     * Do a check for, and output, comments in otherwise empty cells.
+     */
+    private void checkForEmptyCellComments(EmptyCellCommentsCheckType type) {
+        if (commentCellRefs != null && !commentCellRefs.isEmpty()) {
+            // If we've reached the end of the sheet data, output any
+            //  comments we haven't yet already handled
+            if (type == EmptyCellCommentsCheckType.END_OF_SHEET_DATA) {
+                while (!commentCellRefs.isEmpty()) {
+                    outputEmptyCellComment(commentCellRefs.remove());
+                }
+                return;
+            }
+
+            // At the end of a row, handle any comments for "missing" rows before us
+            if (this.cellRef == null) {
+                if (type == EmptyCellCommentsCheckType.END_OF_ROW) {
+                    while (!commentCellRefs.isEmpty()) {
+                        if (commentCellRefs.peek().getRow() == rowNum) {
+                            outputEmptyCellComment(commentCellRefs.remove());
+                        } else {
+                            return;
+                        }
+                    }
+                    return;
+                } else {
+                    throw new IllegalStateException("Cell ref should be null only if there are only empty cells in the row; rowNum: " + rowNum);
+                }
+            }
+
+            CellAddress nextCommentCellRef;
+            do {
+                CellAddress cellRef = new CellAddress(this.cellRef);
+                CellAddress peekCellRef = commentCellRefs.peek();
+                if (type == EmptyCellCommentsCheckType.CELL && cellRef.equals(peekCellRef)) {
+                    // remove the comment cell ref from the list if we're about to handle it alongside the cell content
+                    commentCellRefs.remove();
+                    return;
+                } else {
+                    // fill in any gaps if there are empty cells with comment mixed in with non-empty cells
+                    int comparison = peekCellRef.compareTo(cellRef);
+                    if (comparison > 0 && type == EmptyCellCommentsCheckType.END_OF_ROW && peekCellRef.getRow() <= rowNum) {
+                        nextCommentCellRef = commentCellRefs.remove();
+                        outputEmptyCellComment(nextCommentCellRef);
+                    } else if (comparison < 0 && type == EmptyCellCommentsCheckType.CELL && peekCellRef.getRow() <= rowNum) {
+                        nextCommentCellRef = commentCellRefs.remove();
+                        outputEmptyCellComment(nextCommentCellRef);
+                    } else {
+                        nextCommentCellRef = null;
+                    }
+                }
+            } while (nextCommentCellRef != null && !commentCellRefs.isEmpty());
+        }
+    }
+
+
+    /**
+     * Output an empty-cell comment.
+     */
+    private void outputEmptyCellComment(CellAddress cellRef) {
+        XSSFComment comment = comments.findCellComment(cellRef);
+        output.cell(cellRef.formatAsString(), null, comment);
+    }
+
+    private enum EmptyCellCommentsCheckType {
+        CELL,
+        END_OF_ROW,
+        END_OF_SHEET_DATA
+    }
+
+    /**
+     * This interface allows to provide callbacks when reading
+     * a sheet in streaming mode.
+     * <p>
+     * The XSLX file is usually read via {@link XSSFReader}.
+     * <p>
+     * By implementing the methods, you can process arbitrarily
+     * large files without exhausting main memory.
+     */
+    public interface SheetContentsHandler {
+        /**
+         * A row with the (zero based) row number has started
+         */
+        void startRow(int rowNum);
+
+        /**
+         * A row with the (zero based) row number has ended
+         */
+        void endRow(int rowNum);
+
+        /**
+         * A cell, with the given formatted value (may be null),
+         * and possibly a comment (may be null), was encountered.
+         * <p>
+         * Sheets that have missing or empty cells may result in
+         * sparse calls to <code>cell</code>. See the code in
+         * <code>poi-examples/src/main/java/org/apache/poi/xssf/eventusermodel/XLSX2CSV.java</code>
+         * for an example of how to handle this scenario.
+         */
+        void cell(String cellReference, String formattedValue, XSSFComment comment);
+
+        /**
+         * A header or footer has been encountered
+         */
+        default void headerFooter(String text, boolean isHeader, String tagName) {
+        }
+
+        /**
+         * Signal that the end of a sheet was been reached
+         */
+        default void endSheet() {
+        }
+    }
 }