java poi sax方式处理大数据量excel文件

系统需要用到一个导入excel文件的功能，使用poi组件常规方式读取excel时，内存耗尽，OutOfMemoryError,或者读取非常慢
所以写了一个工具类，使用poi sax方式读取excel，速度快很多，内存消耗可以接受。

测试结果如下：
.xlsx文件，35M大小，总4个sheel，
只读取第一个，37434行，54列

总行数：37434
读取耗时：39秒
打印耗时：17秒

主要代码如下：

ExcelUtils.class 主入口

package com.xxx.bi.utils.excel;

import java.util.List;
import java.util.Objects;

import org.apache.commons.lang3.StringUtils;

import com.google.common.collect.Lists;

public class ExcelUtils {
  /** logger日志. */
  // public static final Logger LOGGER = Logger.getLogger(ExcelUtils.class);

  public ExcelUtils() {
  }

  /**
   * 获取excel的表头
   *
   * @param filePath
   *      文件路径
   * @param headerNum
   *      表头所在行数
   * @return
   */
  public static List<String> getHeader(String filePath,int headerNum) {
    if (StringUtils.isBlank(filePath)) {
      throw new IllegalArgumentException("传入文件路径不能为空");
    }
    if (Objects.isNull(headerNum) || headerNum < 1) {
      headerNum = 1;
    }
    try {
      return LargeExcelFileReadUtil.getRowFromSheetOne(filePath,headerNum);
    } catch (Exception e) {
      // LOGGER.info("获取excel[" + filePath + "]表头失败，原因:",e);
      e.printStackTrace();
    }
    return Lists.newArrayList();
  }

  /**
   * 获取excel的所有数据<br/>
   * 所有数据类型都是String<br/>
   * 会以第一行数据的列数为总列数，所以第一行的数据必须都不为空，否则可能出java.lang.IndexOutOfBoundsException
   *
   * @param filePath
   *      文件路径
   * @param headerNum
   *      表头所在行数
   * @return
   */
  public static List<List<String>> getAllData(String filePath) {
    if (StringUtils.isBlank(filePath)) {
      throw new IllegalArgumentException("传入文件路径不能为空");
    }
    try {
      return LargeExcelFileReadUtil.getRowsFromSheetOne(filePath);
    } catch (Exception e) {
      // LOGGER.info("获取excel[" + filePath + "]表头失败，原因:",e);
      e.printStackTrace();
    }
    return Lists.newArrayList();
  }

  public static void main(String[] args) {
    long start = System.currentTimeMillis();
    String filepath = "C:/Users/Administrator/Desktop/05-作业调配表 -快递.xlsx";
    // List<String> result = ExcelUtils.getHeader(filepath,1);
    // for (String col : result) {
    // System.out.println(col);
    // }

    List<List<String>> result = ExcelUtils.getAllData(filepath);
    long end = System.currentTimeMillis();
    for (List<String> list : result) {
      System.out.println(list.toString());
    }
    long end1 = System.currentTimeMillis();
    try {
      Thread.sleep(1000l);
    } catch (InterruptedException e) {
      e.printStackTrace();
    }
    System.err.println("总行数：" + result.size());
    System.err.println(("读取耗时：" + (end - start) / 1000) + "秒");
    System.err.println(("打印耗时：" + (end1 - end) / 1000) + "秒");
  }
}

LargeExcelFileReadUtil.class 真正的工具类

package com.xxx.bi.utils.excel;

import java.io.InputStream;
import java.util.List;
import java.util.Objects;

import org.apache.log4j.Logger;
import org.apache.poi.openxml4j.opc.OPCPackage;
import org.apache.poi.xssf.eventusermodel.XSSFReader;
import org.apache.poi.xssf.model.SharedStringsTable;
import org.xml.sax.InputSource;
import org.xml.sax.XMLReader;
import org.xml.sax.helpers.XMLReaderFactory;

public class LargeExcelFileReadUtil {
  /** logger日志. */
  public static final Logger LOGGER = Logger.getLogger(LargeExcelFileReadUtil.class);

  // 处理一个sheet
  public static List<String> getRowFromSheetOne(String filename,Integer rowNum) throws Exception {
    InputStream inputStream = null;
    OPCPackage pkg = null;
    SingleRowHandler singleRowHandler = null;
    try {
      pkg = OPCPackage.open(filename);
      XSSFReader r = new XSSFReader(pkg);
      SharedStringsTable sst = r.getSharedStringsTable();
      singleRowHandler = new SingleRowHandler(sst,rowNum);
      XMLReader parser = XMLReaderFactory.createXMLReader("com.sun.org.apache.xerces.internal.parsers.SAXParser");
      parser.setContentHandler(singleRowHandler);
      inputStream = r.getSheet("rId1");
      InputSource sheetSource = new InputSource(inputStream);
      parser.parse(sheetSource);
      return singleRowHandler.getRow();
    } catch (Exception e) {
      String message = e.getMessage();
      if (Objects.nonNull(rowNum) && Objects.nonNull(singleRowHandler)
          && SingleRowHandler.FINISH_ROW_MESSAGE.equalsIgnoreCase(message)) {
        // 获取某一行数据完成 ，暂时不知道怎么能终止excel解析，直接抛出了异常，实际是成功的
        return singleRowHandler.getRow();
      }
      throw e;
    } finally {
      if (Objects.nonNull(pkg)) {
        pkg.close();
      }
      if (Objects.nonNull(inputStream)) {
        inputStream.close();
      }
    }
  }

  // 处理一个sheet
  public static List<List<String>> getRowsFromSheetOne(String filename) throws Exception {
    InputStream inputStream = null;
    OPCPackage pkg = null;
    MultiRowHandler multiRowHandler = null;
    try {
      pkg = OPCPackage.open(filename);
      XSSFReader r = new XSSFReader(pkg);
      SharedStringsTable sst = r.getSharedStringsTable();
      multiRowHandler = new MultiRowHandler(sst);
      XMLReader parser = XMLReaderFactory.createXMLReader("com.sun.org.apache.xerces.internal.parsers.SAXParser");
      parser.setContentHandler(multiRowHandler);
      inputStream = r.getSheet("rId1");
      InputSource sheetSource = new InputSource(inputStream);
      parser.parse(sheetSource);
      return multiRowHandler.getRows();
    } catch (Exception e) {
      throw e;
    } finally {
      if (Objects.nonNull(pkg)) {
        pkg.close();
      }
      if (Objects.nonNull(inputStream)) {
        inputStream.close();
      }
    }
  }
}

SingleRowHandler.class 当行处理类，可以只获取表头或表格中的某一行数据

package com.xxx.bi.utils.excel;

import java.util.ArrayList;
import java.util.List;
import java.util.Objects;
import java.util.regex.Pattern;

import org.apache.poi.xssf.model.SharedStringsTable;
import org.apache.poi.xssf.usermodel.XSSFRichTextString;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;

public class SingleRowHandler extends DefaultHandler {
  public final static String FINISH_ROW_MESSAGE = "row data process finish";

  private Integer rowNum = null;// rowNum不为空时则标示只需要获取这一行的数据
  private int curRowNum = 1;
  private String cellType = "";
  private SharedStringsTable sst;
  private String lastContents;
  private boolean nextIsString;
  private String cellPosition;
  private List<String> row = new ArrayList<>();

  public List<String> getRow() {
    return row;
  }

  public SingleRowHandler(SharedStringsTable sst,Integer rowNum) {
    this.sst = sst;
    this.rowNum = rowNum;
  }

  public void startElement(String uri,String localName,String name,Attributes attributes) throws SAXException {
    if (name.equals("c")) {
      cellPosition = attributes.getValue("r");
      // 这是一个新行
      if (Pattern.compile("^A[0-9]+$").matcher(cellPosition).find()) {
        curRowNum = Integer.valueOf(cellPosition.substring(1));
      }
      cellType = "";
      cellType = attributes.getValue("t");
      if ("s".equals(cellType)) {
        nextIsString = true;
      } else {
        nextIsString = false;
      }
    }
    // 清楚缓存内容
    lastContents = "";
    if (Objects.nonNull(rowNum) && curRowNum > rowNum) {
      // 获取某一行数据完成 ，暂时不知道怎么能终止excel解析，直接抛出了异常，实际是成功的
      throw new SAXException(FINISH_ROW_MESSAGE);
    }
  }

  public void endElement(String uri,String name) throws SAXException {
    if (nextIsString) {
      int idx = Integer.parseInt(lastContents);
      lastContents = new XSSFRichTextString(sst.getEntryAt(idx)).toString();
      nextIsString = false;
    }

    if (name.equals("v")) {
      if (Objects.isNull(rowNum) || rowNum == curRowNum) {
        row.add(lastContents);
      }
    }
  }

  public void characters(char[] ch,int start,int length) throws SAXException {
    lastContents += new String(ch,start,length);
  }
}

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