java uses POI to read excel files

Needless to say about the framework, mainly the POIUtil class

The first is the jar package

<!-- https://mvnrepository.com/artifact/org.apache.poi/poi -->  
<dependency>  
    <groupId>org.apache.poi</groupId>  
    <artifactId>poi</artifactId>  
    <version>3.14</version>  
</dependency>  
<!-- https://mvnrepository.com/artifact/org.apache.poi/poi-ooxml -->  
<dependency>  
    <groupId>org.apache.poi</groupId>  
    <artifactId>poi-ooxml</artifactId>  
    <version>3.14</version>  
</dependency>

Then the tool class POIUtil.java

import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.List;
import org.apache.log4j.Logger;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.Workbook;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
import org.springframework.web.multipart.MultipartFile;

/**
 * Excel read and write tools
 *
 * @author sun.kai August 21, 2016
 */
public class POIUtil {
	private static Logger logger = Logger.getLogger(POIUtil.class);
	private final static String xls = "xls";
	private final static String xlsx = "xlsx";

	/**
	 * Read in excel file, parse and return
	 *
	 * @param file
	 * @throws IOException
	 */
	public static List<String[]> readExcel(MultipartFile file) throws IOException {
		// check the file
		checkFile(file);
		// Get the Workbook workbook object
		Workbook workbook = getWorkBook(file);
		// Create the return object, return the values ​​in each row as an array, and return all rows as a collection
		List<String[]> list = new ArrayList<String[]>();
		if (workbook != null) {
			for (int sheetNum = 0; sheetNum < workbook.getNumberOfSheets(); sheetNum++) {
				// Get the current sheet worksheet
				Sheet sheet = workbook.getSheetAt(sheetNum);
				if (sheet == null) {
					continue;
				}
				// Get the start row of the current sheet
				int firstRowNum = sheet.getFirstRowNum();
				// Get the end row of the current sheet
				int lastRowNum = sheet.getLastRowNum();
				// loop through all rows except the first row
				for (int rowNum = firstRowNum; rowNum <= lastRowNum; rowNum++) {
					// get the current row
					Row row = sheet.getRow(rowNum);
					if (row == null) {
						continue;
					}
					// Get the start column of the current row
					int firstCellNum = row.getFirstCellNum();
					// Get the number of columns in the current row
					int lastCellNum = row.getPhysicalNumberOfCells();
					String[] cells = new String[row.getPhysicalNumberOfCells()];
					// loop over the current row
					for (int cellNum = firstCellNum; cellNum < lastCellNum; cellNum++) {
						Cell cell = row.getCell(cellNum);
						cells[cellNum] = getCellValue(cell);
					}
					list.add(cells);
				}
			}
			workbook.close();
		}
		return list;
	}

	public static void checkFile(MultipartFile file) throws IOException {
		// Check if the file exists
		if (null == file) {
			logger.error("File does not exist!");
			throw new FileNotFoundException("File does not exist!");
		}
		// get the filename
		String fileName = file.getOriginalFilename();
		// Determine if the file is an excel file
		if (!fileName.endsWith(xls) && !fileName.endsWith(xlsx)) {
			logger.error(fileName + "not an excel file");
			throw new IOException(fileName + "not an excel file");
		}
	}

	public static Workbook getWorkBook(MultipartFile file) {
		// get the filename
		String fileName = file.getOriginalFilename();
		// Create a Workbook workbook object, representing the entire excel
		Workbook workbook = null;
		try {
			// Get the io stream of the excel file
			InputStream is = file.getInputStream();
			// Obtain different Workbook implementation class objects according to different file suffixes (xls and xlsx)
			if (fileName.endsWith(xls)) {
				// 2003
				workbook = new HSSFWorkbook(is);
			} else if (fileName.endsWith(xlsx)) {
				// 2007
				workbook = new XSSFWorkbook(is);
			}
		} catch (IOException e) {
			logger.info(e.getMessage());
		}
		return workbook;
	}

	public static String getCellValue(Cell cell) {
		String cellValue = "";
		if (cell == null) {
			return cellValue;
		}
		// Read the number as a String to avoid the situation where 1 is read as 1.0
		if (cell.getCellType() == Cell.CELL_TYPE_NUMERIC) {
			cell.setCellType(Cell.CELL_TYPE_STRING);
		}
		// Determine the type of data
		switch (cell.getCellType()) {
		case Cell.CELL_TYPE_NUMERIC: // 数字
			cellValue = String.valueOf(cell.getNumericCellValue());
			break;
		case Cell.CELL_TYPE_STRING: // string
			cellValue = String.valueOf(cell.getStringCellValue());
			break;
		case Cell.CELL_TYPE_BOOLEAN: // Boolean
			cellValue = String.valueOf(cell.getBooleanCellValue());
			break;
		case Cell.CELL_TYPE_FORMULA: // 公式
			cellValue = String.valueOf(cell.getCellFormula());
			break;
		case Cell.CELL_TYPE_BLANK: // 空值
			cellValue = "";
			break;
		case Cell.CELL_TYPE_ERROR: // 故障
			cellValue = "Illegal character";
			break;
		default:
			cellValue = "Unknown type";
			break;
		}
		return cellValue;
	}
}

page:

<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>Import Excel table</title>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
</head>
<body class="dialogBody">
	<div>
		<form id="form2" method="post" action="http://localhost:8080/iot-web-admin/file.do"
			enctype="multipart/form-data" style="align: center">
			<table width="100%" border="0" cellspacing="0" cellpadding="6"
				class="blockTable">
				<tr>
					<td></td>
				</tr>
				<tr>
					<td align="center"><h2>选择Excel表：</h2></td>
					<td align="center">
						<div>
							<input type="file" name="myfile" />
						</div>
					</td>
				</tr>
				<tr>
					<td align="center"><input type="submit" name="submit" value="上传" /></td>
				</tr>
				<tr></tr>
				<tr></tr>
				<tr></tr>
			</table>
		</form>
	</div>
</body>
</html>

Controller

package com.sll.iot.admin.controller.file;

import java.io.IOException;
import java.util.List;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.multipart.MultipartFile;

@Controller
@RequestMapping("/")
public class FileController {
	
	@RequestMapping("file")
	public void file(@RequestParam(value="myfile",required=false)MultipartFile myfile) {
		try {
			List<String[]> lists = POIUtil.readExcel(myfile);
			for (String[] list : lists) {
				for (int i = 0; i < list.length; i++) {
					System.out.println(list[i]);
				}
			}
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace ();
		}
	}
}