如何从.xlsx读取数据并将数据转换成map

Question

我需要从 Excel 表中读取数据，并且需要将数据转换为键值对。

我写了下面的代码。

这是我的代码：

import java.io.File;  
import java.io.FileInputStream;  
import java.util.Iterator;  
import org.apache.poi.ss.usermodel.Cell;  
import org.apache.poi.ss.usermodel.Row;  
import org.apache.poi.xssf.usermodel.XSSFSheet;  
import org.apache.poi.xssf.usermodel.XSSFWorkbook;  

public class XLSXReaderExample  {  
    public static void main(String[] args) {  
       try {  
          File file = new File("C:\\demo\\employee.xlsx");   //creating a new file instance  
          FileInputStream fis = new FileInputStream(file);   //obtaining bytes from the file  
          //creating Workbook instance that refers to .xlsx file  
          XSSFWorkbook wb = new XSSFWorkbook(fis);   
          XSSFSheet sheet = wb.getSheetAt(0);     //creating a Sheet object to retrieve object  
          Iterator<Row> itr = sheet.iterator();    //iterating over excel file  
          while (itr.hasNext()){  
             Row row = itr.next();  
             Iterator<Cell> cellIterator = row.cellIterator();   //iterating over each column  
             while (cellIterator.hasNext()){  
                Cell cell = cellIterator.next();  
                switch (cell.getCellType()){  
                   case Cell.CELL_TYPE_STRING:    //field that represents string cell type  
                      System.out.print(cell.getStringCellValue() + "\t\t\t");  
                      break;  
                   case Cell.CELL_TYPE_NUMERIC:    //field that represents number cell type  
                      System.out.print(cell.getNumericCellValue() + "\t\t\t");  
                      break;  
                   case Cell.CELL_TYPE_Date:    //field that represents Date cell type
                      System.out.print(cell.getDateCellValue() + "\t\t\t");  
                      break; 
                   default:  
                }  
             }  
             System.out.println("");  
          }  
       }catch(Exception e){  
          e.printStackTrace();  
       }  
    }  
 } 

我得到 output 如下：

Employee ID   Employee Name    Salary     Designation          Department   
1223.0         Harsh                      Marketing Manager    Marketing
3213.0         Vivek           15000.0    Financial Advisor    Finance  

但是，我需要 output，因为所有 header 列都应该出现在 map 键中，并且相应的数据应该作为值出现。 还有一件事是我不应该对列名进行硬编码，每次列标题可以不同时，我都需要动态地从 Excel 读取。

我需要将我的数据设置为以下格式，请帮助。 Map<String, List<String>> myMaps = new HashMap<String, List<String>>();

Answer 1

正如评论中所写，由于您无法知道单元格是否包含 header 值或数据值，因此您想要做的事情是不可能的。

乍一看，您有两种方法可以实现您想要的：

• 尝试让文件只有一个表，并且 header 行必须始终位于同一 excel 行（请参见此处） 。
• 为 header 添加自定义标签内容：如<H> </H> ，但当然如果文件在可视化模式下使用，这个解决方案不是最好的

编辑：

您添加了一条注释，确认 header 始终位于第一行，并且文件中只有一个表，因此下一个代码应该可以工作。

public static void main(String[] args) {
    try {
        File file = new File("C:\\demo\\employee.xlsx");   //creating a new file instance
        FileInputStream fis = new FileInputStream(file);   //obtaining bytes from the file
        //creating Workbook instance that refers to .xlsx file
        XSSFWorkbook wb = new XSSFWorkbook(fis);
        XSSFSheet sheet = wb.getSheetAt(0);     //creating a Sheet object to retrieve object
        Iterator<Row> itr = sheet.iterator();    //iterating over excel file

        // CAREFUL HERE! use LinkedHashMap to guarantee the insertion order!
        Map<String, List<String>> myMap = new LinkedHashMap<>();

        // populate map with headers and empty list
        if (itr.hasNext()) {
            Row row = itr.next();
            Iterator<Cell> headerIterator = row.cellIterator();
            while (cellIterator.hasNext()) {
                Cell cell = cellIterator.next();
                myMap.put(getCellValue(cell), new ArrayList<>());
            }
        }

        Iterator<List<String>> columnsIterator;
        // populate lists
        while (itr.hasNext()) {

            // get the list iterator every row to start from first list
            columnsIterator = myMap.values().iterator();
            Row row = itr.next();
            Iterator<Cell> cellIterator = row.cellIterator();   //iterating over each column
            while (cellIterator.hasNext()) {
                Cell cell = cellIterator.next();

                // here don't check hasNext() because if the file not contains problems
                // the # of columns is same as # of headers
                columnsIterator.next().add(getCellValue(cell));
            }
        }

        // here your map should be filled with data as expected

    } catch (Exception e) {
        e.printStackTrace();
    }
}

public static String getCellValue(Cell cell) {
    switch (cell.getCellType()) {
        case Cell.CELL_TYPE_STRING:    //field that represents string cell type
            return cell.getStringCellValue() + "\t\t\t";
        case Cell.CELL_TYPE_NUMERIC:    //field that represents number cell type
            return cell.getNumericCellValue() + "\t\t\t";
        case Cell.CELL_TYPE_Date:    //field that represents Date cell type
            return cell.getDateCellValue() + "\t\t\t";
        default:
            return "";
    }
}