What are the basic operating methods of Java WorkBook on Excel?

1. Exception java.lang.NoClassDefFoundError: org/apache/poi/UnsupportedFileFormatException

Solution: The versions of the related jar packages used for poi must be the same! ! ! ! !

2. The jar package used by maven. If maven is not used, use poi-3.9.jar and poi-ooxml-3.9.jar (this is mainly used for Excel2007 and later versions). jar package will do ()

<dependency>
     <groupId>org.apache.poi</groupId>
     <artifactId>poi</artifactId>
     <version>3.9</version>
</dependency>
<dependency>
     <groupId>org.apache.poi</groupId>
     <artifactId>poi-ooxml</artifactId>
     <version>3.9</version>
</dependency>

3. Import Excel from java

Upload Excel first

//上传Excel
@RequestMapping("/uploadExcel")
public boolean uploadExcel(@RequestParam MultipartFile file,HttpServletRequest request) throws IOException {
    if(!file.isEmpty()){
        String filePath = file.getOriginalFilename();
        //windows
        String savePath = request.getSession().getServletContext().getRealPath(filePath);
        //linux
        //String savePath = "/home/odcuser/webapps/file";
        File targetFile = new File(savePath);
        if(!targetFile.exists()){
            targetFile.mkdirs();
        }
 
        file.transferTo(targetFile);
        return true;
    }
    return false;
}

Read the content in Excel

public static void readExcel() throws Exception{
	InputStream is = new FileInputStream(new File(fileName));
	Workbook hssfWorkbook = null;
	if (fileName.endsWith("xlsx")){
		hssfWorkbook = new XSSFWorkbook(is);//Excel 2007
	}else if (fileName.endsWith("xls")){
		hssfWorkbook = new HSSFWorkbook(is);//Excel 2003
	}
	// HSSFWorkbook hssfWorkbook = new HSSFWorkbook(is);
	// XSSFWorkbook hssfWorkbook = new XSSFWorkbook(is);
	User student = null;
	List<User> list = new ArrayList<User>();
	// 循环工作表Sheet
	for (int numSheet = 0; numSheet <hssfWorkbook.getNumberOfSheets(); numSheet++) {
		//HSSFSheet hssfSheet = hssfWorkbook.getSheetAt(numSheet);
		Sheet hssfSheet = hssfWorkbook.getSheetAt(numSheet);
		if (hssfSheet == null) {
			continue;
		}
		// 循环行Row
		for (int rowNum = 1; rowNum <= hssfSheet.getLastRowNum(); rowNum++) {
			//HSSFRow hssfRow = hssfSheet.getRow(rowNum);
			Row hssfRow = hssfSheet.getRow(rowNum);
			if (hssfRow != null) {
				student = new User();
				//HSSFCell name = hssfRow.getCell(0);
				//HSSFCell pwd = hssfRow.getCell(1);
				Cell name = hssfRow.getCell(0);
				Cell pwd = hssfRow.getCell(1);
				//这里是自己的逻辑
				student.setUserName(name.toString());
				student.setPassword(pwd.toString());
				list.add(student);
			}
		}
	}
}

4. Export Excel

//创建Excel
@RequestMapping("/createExcel")
public String createExcel(HttpServletResponse response) throws IOException {
 
	//创建HSSFWorkbook对象(excel的文档对象)
	HSSFWorkbook wb = new HSSFWorkbook();
	//建立新的sheet对象（excel的表单）
	HSSFSheet sheet=wb.createSheet("成绩表");
	//在sheet里创建第一行，参数为行索引(excel的行)，可以是0～65535之间的任何一个
	HSSFRow row1=sheet.createRow(0);
	//创建单元格（excel的单元格，参数为列索引，可以是0～255之间的任何一个
	HSSFCell cell=row1.createCell(0);
	//设置单元格内容
	cell.setCellValue("学员考试成绩一览表");
	//合并单元格CellRangeAddress构造参数依次表示起始行，截至行，起始列， 截至列
	sheet.addMergedRegion(new CellRangeAddress(0,0,0,3));
	//在sheet里创建第二行
	HSSFRow row2=sheet.createRow(1);
	//创建单元格并设置单元格内容
	row2.createCell(0).setCellValue("姓名");
	row2.createCell(1).setCellValue("班级");
	row2.createCell(2).setCellValue("笔试成绩");
	row2.createCell(3).setCellValue("机试成绩");
	//在sheet里创建第三行
	HSSFRow row3=sheet.createRow(2);
	row3.createCell(0).setCellValue("李明");
	row3.createCell(1).setCellValue("As178");
	row3.createCell(2).setCellValue(87);
	row3.createCell(3).setCellValue(78);
	//.....省略部分代码
	//输出Excel文件
	OutputStream output=response.getOutputStream();
	response.reset();
	response.setHeader("Content-disposition", "attachment; filename=details.xls");
	response.setContentType("application/msexcel");
	wb.write(output);
	output.close();
	return null;
}

Supplementary explanation of garbled code problem

1. Garbled file name (I found that as long as the garbled file name is solved, other garbled characters will also be solved) response.setHeader("Content-disposition", "attachment; filename = Chinese. ("Content-disposition", "attachment; filename=" toUtf8String("Chinese.xls"));

When I checked on the Internet, it said

What I want to talk about today is When creating a worksheet, using Chinese as the file name and worksheet name will cause garbled characters. First, let’s use Chinese as the worksheet name. The code for creating a worksheet is generally as follows:

HSSFWorkbook workbook = new HSSFWorkbook() ;//Create EXCEL file

HSSFSheet sheet= workbook.createSheet(sheetName); //Create worksheet

This way, it is okay to use the English name as the worksheet name, but if sheetName If it is Chinese characters, garbled characters will appear. The solution is as follows:

HSSFSheet sheet= workbook.createSheet();

workbook.setSheetName(0, sheetName,(short)1); //Here (short) 1 is the key to solving Chinese garbled characters; and the first parameter is the index number of the worksheet.​​

But I found that there is no such method at all. I only need to change the garbled characters in the file name, and other garbled characters will be solved naturally! ! !

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