業務描述：
字尾為.xlsx的Excel檔案，只有一個sheet頁，且該sheet頁對應資料庫中的1張表，從A1開始有資料，第1行的資料對應表的各個欄位，從第2行開始是要匯入的資料，將該Excel匯入到資料庫中
解決方案：
因為Excel包含大量資料，如果採用POI的使用者模式，會消耗大量內容，容易造成記憶體溢位

java.lang.OutOfMemoryError

所以這裡採用SAX模式（事件模式）讀取，需要注意的是SAX模式讀取，大部分格式的資料都可以讀取成String型別，日期格式不在此列，需要特殊處理，處理方式詳見下方code
code:

import java.io.InputStream;
import
 
 java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.regex.Pattern;

import org.apache.log4j.Logger;
import org.apache.poi.openxml4j.opc.OPCPackage;
import org.apache.poi.ss.usermodel.DataFormatter;
import org.apache.poi.xssf.eventusermodel.XSSFReader;
import org.apache.poi.xssf.model.SharedStringsTable;
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.ContentHandler;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.XMLReader;
import
 
 org.xml.sax.helpers.DefaultHandler;
import org.xml.sax.helpers.XMLReaderFactory;

/**
 * <p>ClassName: ExampleEventUserModel</p>
 * <p>Description: 事件模式</p>
 * <p>Author: sloth</p>
 * <p>Date: 2018-02-28</p>
 */
public class ExampleEventUserModel {
    /**
     * <p>Field stylesTable: 單元格樣式</p>
     */
    public static StylesTable stylesTable;

    /**
     * <p>Description: 處理單個sheet(本案例呼叫此方法)</p>
     * @param filename 檔名帶路徑
     * @throws Exception 異常
     */
    public void processOneSheet(String filename) throws Exception {
        OPCPackage pkg = OPCPackage.open(filename);
        XSSFReader r = new XSSFReader(pkg);
        SharedStringsTable sst = r.getSharedStringsTable();
        stylesTable = r.getStylesTable();
        XMLReader parser = fetchSheetParser(sst);

        // To look up the Sheet Name / Sheet Order / rID,
        // you need to process the core Workbook stream.
        // Normally it's of the form rId# or rSheet#
        InputStream sheet = r.getSheet("rId1");
        InputSource sheetSource = new InputSource(sheet);
        parser.parse(sheetSource);
        sheet.close();
    }

    /**
     * <p>Description: 處理所有sheet</p>
     * @param filename 檔名帶路徑
     * @throws Exception 異常
     */
    public void processAllSheets(String filename) throws Exception {
        OPCPackage pkg = OPCPackage.open(filename);
        XSSFReader r = new XSSFReader(pkg);
        SharedStringsTable sst = r.getSharedStringsTable();

        XMLReader parser = fetchSheetParser(sst);

        Iterator<InputStream> sheets = r.getSheetsData();
        while (sheets.hasNext()) {
            System.out.println("Processing new sheet:\n");
            InputStream sheet = sheets.next();
            InputSource sheetSource = new InputSource(sheet);
            parser.parse(sheetSource);
            sheet.close();
            System.out.println("");
        }
    }

    /**
     * <p>Description: 獲取XML訪問物件</p>
     * @param sst 共享字串表物件
     * @return XMLReader XML訪問物件
     * @throws SAXException SAX異常
     */
    public XMLReader fetchSheetParser(SharedStringsTable sst) throws SAXException {
        XMLReader parser = XMLReaderFactory.createXMLReader("com.sun.org.apache.xerces.internal.parsers.SAXParser");
        ContentHandler handler = new SheetHandler(sst);
        parser.setContentHandler(handler);
        return parser;
    }

    /**
     * <p>ClassName: SheetHandler</p>
     * <p>Description: sheet處理類</p>
     * <p>Author: sloth</p>
     * <p>Date: 2018-02-26</p>
     */
    private static class SheetHandler extends DefaultHandler {
        /**
         * <p>Field logger: 日誌</p>
         */
        private static Logger logger = Logger.getLogger(SheetHandler.class);
        /**
         * <p>Field sst: 共享字串表物件</p>
         */
        private SharedStringsTable sst;
        /**
         * <p>Field lastContents: 單元格內容</p>
         */
        private String lastContents;
        /**
         * <p>Field nextIsString: 是否是字串</p>
         */
        private boolean nextIsString;
        /**
         * <p>Field nextIsDate: 是否是日期</p>
         */
        private boolean nextIsDate;
        /**
         * <p>Field mapList: 讀取Excel資料集(該變數可去除，因為集合中只有一個map)</p>
         */
        private ArrayList<HashMap<String, String>> mapList;
        /**
         * <p>Field map: 鍵值對{單元格列名,單元格值}</p>
         */
        private HashMap<String, String> map;
        /**
         * <p>Field key: 單元格座標</p>
         */
        private String key;
        /**
         * <p>Field value: 單元格值</p>
         */
        private String value;
        /**
         * <p>Field index: 樣式index</p>
         */
        private int index;

        /**
         * <p>Description: 建構函式初始化</p>
         * @param sst 共享字串表物件
         */
        private SheetHandler(SharedStringsTable sst) {
            this.sst = sst;
            this.mapList = new ArrayList<HashMap<String, String>>();
            this.map = new HashMap<String, String>();
        }

        /**
         * <p>Title: startElement</p>
         * <p>Description: </p>
         * @param uri uri
         * @param localName localName
         * @param name XML標籤名
         * @param attributes XML標籤物件
         * @throws SAXException SAX異常
         * @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 {
            // c => cell
            if ("c".equals(name)) {
                // Print the cell reference
                this.key = attributes.getValue("r");
                this.value = "";
                System.out.print(attributes.getValue("r") + " - ");
                // Figure out if the value is an index in the SST
                String cellType = attributes.getValue("t");
                if (cellType != null && "s".equals(cellType)) {
                    this.nextIsString = true;
                } else {
                    /** 單元格是日期格式時c標籤中s屬性的值是數字 **/
                    cellType = attributes.getValue("s");
                    System.out.println(cellType);
                    this.nextIsString = false;
                }
                /** 判斷是否是日期格式 **/
                if (cellType != null && Pattern.compile("^[-\\+]?[\\d]*$").matcher(cellType).matches()) {
                    this.index = Integer.parseInt(cellType);
                    this.nextIsDate = true;
                } else {
                    this.nextIsDate = false;
                }
            }
            // Clear contents cache
            this.lastContents = "";
        }

        /**
         * <p>Title: endElement</p>
         * <p>Description: </p>
         * @param uri uri
         * @param localName localName
         * @param name XML標籤名
         * @throws SAXException SAX異常
         * @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 {
            // Process the last contents as required.
            // Do now, as characters() may be called more than once
            if (this.nextIsString) {
                int idx = Integer.parseInt(this.lastContents);
                this.lastContents = new XSSFRichTextString(this.sst.getEntryAt(idx)).toString();
                this.nextIsString = false;
            }
            if (this.nextIsDate && !"".equals(this.lastContents)) {
                XSSFCellStyle style = stylesTable.getStyleAt(this.index);
                short formatIndex = style.getDataFormat();
                String formatString = style.getDataFormatString();
                if (formatString.contains("m/d/yy")) {
                    formatString = "yyyy-MM-dd hh:mm:ss";
                }
                DataFormatter formatter = new DataFormatter();
                this.lastContents = formatter.formatRawCellContents(Double.parseDouble(this.lastContents), formatIndex,
                    formatString);
                System.out.println(this.lastContents);
                this.nextIsDate = false;
            }
            // v => contents of a cell
            // Output after we've seen the string contents
            if ("v".equals(name)) {
                System.out.println(this.lastContents);
                this.value = this.lastContents;
            } else if ("c".equals(name)) {
                this.map.put(this.key.replaceAll("\\d+", ""), this.value);
            } else if ("row".equals(name)) {
                String nowRow = this.key.replaceAll(this.key.replaceAll("\\d+", ""), "");
                if (!"1".equals(nowRow)) {
                    this.mapList.add(this.map);
                    logger.info(this.mapList);
                    insert(nowRow);
                }
                /** 清空儲存集 **/
                this.mapList.clear();
                this.map.clear();
            }

        }

        /**
         * <p>Description: 插入資料</p>
         * @param nowRow 插入資料所在行(用於檢查Excel哪一行資料插入報錯)
         */
        private void insert(String nowRow) {
            /** 迭代資料，通過對應列，獲取資料庫欄位和值，拼接SQL **/
            ......
            /** 迭代資料，通過對應列，獲取資料庫欄位和值，拼接SQL **/   
        }

        /**
         * <p>Title: characters</p>
         * <p>Description: </p>
         * @param ch 字元陣列
         * @param start 起始位
         * @param length 長度
         * @throws SAXException SAX異常
         * @see org.xml.sax.helpers.DefaultHandler#characters(char[], int, int)
         */
        public void characters(char[] ch, int start, int length) throws SAXException {
            this.lastContents += new String(ch, start, length);
        }
    }

    public static void main(String[] args) throws Exception {
        ExampleEventUserModel example = new ExampleEventUserModel();
        // System.out.println("11");
        example.processOneSheet("D:/" + "****" + ".xlsx");
        // example.processAllSheets(args[0]);
    }
}