XLSXCovertCSVReader tool class (XML)

import cn.com.amway.msgcenter.console.util.StringUtil;
import org.apache.poi.hssf.usermodel.HSSFDateUtil;
import org.apache.poi.openxml4j.exceptions.OpenXML4JException;
import org.apache.poi.openxml4j.opc.OPCPackage;
import org.apache.poi.openxml4j.opc.PackageAccess;
import org.apache.poi.ss.usermodel.BuiltinFormats;
import org.apache.poi.ss.usermodel.DataFormatter;
import org.apache.poi.xssf.eventusermodel.ReadOnlySharedStringsTable;
import org.apache.poi.xssf.eventusermodel.XSSFReader;
import org.apache.poi.xssf.model.StylesTable;
import org.apache.poi.xssf.usermodel.XSSFCellStyle;
import org.apache.poi.xssf.usermodel.XSSFRichTextString;
import org.xml.sax.Attributes;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.XMLReader;
import org.xml.sax.helpers.DefaultHandler;

import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintStream;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;

/**

Using CVS mode to solve XLSX files can effectively solve the problem of user mode memory overflow. This mode is officially recommended by POI to read big data. In user mode, the amount of data is large, the sheet is large, or there are many useless Blank line
, Easy to appear memory overflow, the typical code for reading Excel in user mode is as follows: FileInputStream file=new FileInputStream("c:\test.xlsx"); Workbook
wb=new XSSFWorkbook(file);
@author 山人
*/
public class XLSXCovertCSVReader {

/**
- The type of the data value is indicated by an attribute on the cell. The value is usually in
- a "v" element within the cell.
  */
  enum xssfDataType {
  BOOL, ERROR, FORMULA, INLINESTR, SSTINDEX, NUMBER,
  }
/**
- Use xssf_sax_API to process Excel, please refer to: http://poi.apache.org/spreadsheet/how-to.html#xssf_sax_api
- <p/>
- Also see Standard ECMA-376, 1st edition, part 4, pages 1928ff, at
- http://www.ecma-international.org/publications/standards/Ecma-376.htm
- <p/>
- A web-friendly version is http://openiso.org/Ecma/376/Part4
  */
  class MyXSSFSheetHandler extends DefaultHandler {
  
  /**
  - Table with styles
    */
    private StylesTable stylesTable;
  /**
  - Table with unique strings
    */
    private ReadOnlySharedStringsTable sharedStringsTable;
  /**
  - Destination for data
    */
    private final PrintStream output;
  /**
  - Number of columns to read starting with leftmost
    */
    private final int minColumnCount;
  // Set when V start element is seen
  private boolean vIsOpen;
  
  // 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 thisColumn = -1;
  // The last column printed to the output stream
  private int lastColumnNumber = -1;
  
  // Gathers characters as they are seen.
  private StringBuffer value;
  private String[] record;
  private List<String[]> rows = new ArrayList<String[]>();
  private boolean isCellNull = false;
  
  /**
  - Accepts objects needed while parsing.
  - @param styles Table of styles
  - @param strings Table of shared strings
  - @param cols Minimum number of columns to show
  - @param target Sink for output
    */
    public MyXSSFSheetHandler(StylesTable styles, ReadOnlySharedStringsTable strings, int cols, PrintStream target) {
    this.stylesTable = styles;
    this.sharedStringsTable = strings;
    this.minColumnCount = cols;
    this.output = target;
    this.value = new StringBuffer();
    this.nextDataType = xssfDataType.NUMBER;
    this.formatter = new DataFormatter();
    record = new String[this.minColumnCount];
    rows.clear();// 每次读取都清空行集合
    }
  /*
  - (non-Javadoc)
  - @see org.xml.sax.helpers.DefaultHandler#startElement(java.lang.String, java.lang.String,
  - java.lang.String, org.xml.sax.Attributes)
    */
    public void startElement(String uri, String localName, String name, Attributes attributes) throws SAXException {
    
    if ("inlineStr".equals(name) || "v".equals(name)) {
    vIsOpen = true;
    // Clear contents cache
    value.setLength(0);
    }
    // c => cell
    else if ("c".equals(name)) {
    // Get the cell reference
    String r = attributes.getValue("r");
    int firstDigit = -1;
    for (int c = 0; c < r.length(); ++c) {
    if (Character.isDigit(r.charAt(c))) {
    firstDigit = c;
    break;
    }
    }
    thisColumn = nameToColumn(r.substring(0, firstDigit));
```
// Set up defaults.
this.nextDataType = xssfDataType.NUMBER;
this.formatIndex = -1;
this.formatString = null;
String cellType = attributes.getValue("t");
String cellStyleStr = attributes.getValue("s");
if ("b".equals(cellType))
    nextDataType = xssfDataType.BOOL;
else if ("e".equals(cellType))
    nextDataType = xssfDataType.ERROR;
else if ("inlineStr".equals(cellType))
    nextDataType = xssfDataType.INLINESTR;
else if ("s".equals(cellType))
    nextDataType = xssfDataType.SSTINDEX;
else if ("str".equals(cellType))
    nextDataType = xssfDataType.FORMULA;
else if (cellStyleStr != null) {
    // It's a number, but almost certainly one
    // with a special style or format
    int styleIndex = Integer.parseInt(cellStyleStr);
    XSSFCellStyle style = stylesTable.getStyleAt(styleIndex);
    this.formatIndex = style.getDataFormat();
    this.formatString = style.getDataFormatString();
    if (this.formatString == null)
        this.formatString = BuiltinFormats.getBuiltinFormat(this.formatIndex);
}
```
    }
  }
  
  /*
  - (non-Javadoc)
  - @see org.xml.sax.helpers.DefaultHandler#endElement(java.lang.String, java.lang.String,
  - java.lang.String)
    */
    public void endElement(String uri, String localName, String name) throws SAXException {
    
    String thisStr = null;
    
    // v => contents of a cell
    if ("v".equals(name)) {
    // Process the value contents as required.
    // Do now, as characters() may be called more than once
    switch (nextDataType) {
```
    case BOOL:
        char first = value.charAt(0);
        thisStr = first == '0' ? "FALSE" : "TRUE";
        break;

    case ERROR:
        thisStr = "\"ERROR:" + value.toString() + '"';
        break;

    case FORMULA:
        // A formula could result in a string value,
        // so always add double-quote characters.
        thisStr = value.toString();
        break;

    case INLINESTR:
        // TODO: have seen an example of this, so it's untested.
        XSSFRichTextString rtsi = new XSSFRichTextString(value.toString());
        thisStr = rtsi.toString();
        break;

    case SSTINDEX:
        String sstIndex = value.toString();
        try {
            int idx = Integer.parseInt(sstIndex);
            XSSFRichTextString rtss = new XSSFRichTextString(sharedStringsTable.getEntryAt(idx));
            thisStr = rtss.toString();
        } catch (NumberFormatException ex) {
            output.println("Failed to parse SST index '" + sstIndex + "': " + ex.toString());
        }
        break;

    case NUMBER:
        String n = value.toString();
        // 判断是否是日期格式
        if (HSSFDateUtil.isADateFormat(this.formatIndex, n)) {
            Double d = Double.parseDouble(n);
            Date date = HSSFDateUtil.getJavaDate(d);
            thisStr = formateDateToString(date);
        } else if (this.formatString != null)
            thisStr =
                    formatter.formatRawCellContents(Double.parseDouble(n), this.formatIndex,
                            this.formatString);
        else
            thisStr = n;
        break;

    default:
        thisStr = "(TODO: Unexpected type: " + nextDataType + ")";
        break;
}

// Output after we've seen the string contents
// Emit commas for any fields that were missing on this row
if (lastColumnNumber == -1) {
    lastColumnNumber = 0;
}
// 判断单元格的值是否为空
if (thisStr == null || "".equals(isCellNull)) {
    isCellNull = true;// 设置单元格是否为空值
}
record[thisColumn] = thisStr;
// Update column
if (thisColumn > -1) lastColumnNumber = thisColumn;
```
    } else if ("row".equals(name)) {
```
// Print out any missing commas if needed
if (minColumns > 0) {
    // Columns are 0 based
    if (lastColumnNumber == -1) {
        lastColumnNumber = 0;
    }
    if (isCellNull == false)// 判断是否空行
    {
        rows.add(record.clone());
        isCellNull = false;
        for (int i = 0; i < record.length; i++) {
            record[i] = null;
        }
    }
}
lastColumnNumber = -1;
```
    }
  }
  
  public List<String[]> getRows() {
  return rows;
  }
  
  public void setRows(List<String[]> rows) {
  this.rows = rows;
  }
  
  /**
  - Captures characters only if a suitable element is open. Originally was just "v"; extended
  - for inlineStr also.
    */
    public void characters(char[] ch, int start, int length) throws SAXException {
    if (vIsOpen) value.append(ch, start, length);
    }
  /**
  - Converts an Excel column name like "C" to a zero-based index.
  - @param name
  - @return Index corresponding to the specified name
    /
    private int nameToColumn(String name) {
    int column = -1;
    for (int i = 0; i < name.length(); ++i) {
    int c = name.charAt(i);
    column = (column + 1) 26 + c - 'A';
    }
    return column;
    }
  private String formateDateToString(Date date) {
  SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");// 格式化日期
  return sdf.format(date);
  
  }
}

// /////////////////////////////////////

private OPCPackage xlsxPackage;
private int minColumns;
private PrintStream output;

/**
- Creates a new XLSX -> CSV converter
- @param pkg The XLSX package to process
- @param output The PrintStream to output the CSV to
- @param minColumns The minimum number of columns to output, or -1 for no minimum
  */
  public XLSXCovertCSVReader(OPCPackage pkg, PrintStream output, int minColumns) {
  this.xlsxPackage = pkg;
  this.output = output;
  this.minColumns = minColumns;
  }
/**
- Parses and shows the content of one sheet using the specified styles and shared-strings
- tables.
- @param styles
- @param strings
- @param sheetInputStream
  */
  public List<String[]> processSheet(StylesTable styles, ReadOnlySharedStringsTable strings,
  InputStream sheetInputStream) throws IOException, ParserConfigurationException, SAXException {
  
  InputSource sheetSource = new InputSource(sheetInputStream);
  SAXParserFactory saxFactory = SAXParserFactory.newInstance();
  SAXParser saxParser = saxFactory.newSAXParser();
  XMLReader sheetParser = saxParser.getXMLReader();
  MyXSSFSheetHandler handler = new MyXSSFSheetHandler(styles, strings, this.minColumns, this.output);
  sheetParser.setContentHandler(handler);
  sheetParser.parse(sheetSource);
  return handler.getRows();
  }
/**
- Initializing this handler will
- @throws IOException
- @throws OpenXML4JException
- @throws ParserConfigurationException
- @throws SAXException
  */
  public List<String[]> process() throws IOException, OpenXML4JException, ParserConfigurationException, SAXException {
  
  ReadOnlySharedStringsTable strings = new ReadOnlySharedStringsTable(this.xlsxPackage);
  XSSFReader xssfReader = new XSSFReader(this.xlsxPackage);
  List<String[]> list = null;
  StylesTable styles = xssfReader.getStylesTable();
  XSSFReader.SheetIterator iter = (XSSFReader.SheetIterator) xssfReader.getSheetsData();
  while (iter.hasNext()) {
  InputStream stream = iter.next();
  list = processSheet(styles, strings, stream);
  stream.close();
  break;
  }
  return list;
  }
/**
- Read Excel
- @param path file path
- @param sheetName sheet名称
- @param minColumns Total number of columns
- @return
- @throws SAXException
- @throws ParserConfigurationException
- @throws OpenXML4JException
- @throws IOException
  */
  public static List<String[]> readerExcel(String path, int minColumns) throws IOException, OpenXML4JException,
  ParserConfigurationException, SAXException {
  OPCPackage p = OPCPackage.open(path, PackageAccess.READ);
  XLSXCovertCSVReader xlsx2csv = new XLSXCovertCSVReader(p, System.out, minColumns);
  List<String[]> list = xlsx2csv.process();
  p.close();
  return list;
  }
/**
- @param file
- @param minColumns
- @return
- @throws IOException
- @throws OpenXML4JException
- @throws ParserConfigurationException
- @throws SAXException
  */
  public static List<String[]> readerExcel(File file, int minColumns) throws IOException, OpenXML4JException,
  ParserConfigurationException, SAXException {
  OPCPackage p = OPCPackage.open(file, PackageAccess.READ);
  XLSXCovertCSVReader xlsx2csv = new XLSXCovertCSVReader(p, System.out, minColumns);
  List<String[]> list = xlsx2csv.process();
  p.close();
  return list;
  }
/**
- Read Excel
- @param path file path
- @param sheetName sheet名称
- @param minColumns Total number of columns
- @return
- @throws SAXException
- @throws ParserConfigurationException
- @throws OpenXML4JException
- @throws IOException
  */
  public static List<String[]> readerExcel(InputStream in, int minColumns) throws IOException, OpenXML4JException,
  ParserConfigurationException, SAXException {
  
  OPCPackage p = OPCPackage.open(in);
  XLSXCovertCSVReader xlsx2csv = new XLSXCovertCSVReader(p, System.out, minColumns);
  List<String[]> list = xlsx2csv.process();
  List<String[]> newlist=new ArrayList< >();
  p.close();
  for(String [] str:list){
  //Determine whether there is an exception caused by All elements are null in the excle collection
  if(!StringUtil.isEmpty(str[0])){
  newlist .add(str);
  }
  }
  return newlist;
  }

}

XLSXCovertCSVReader tool class (XML)

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