如何從.xlsx讀取數據並將數據轉換成map

Question

我需要從 Excel 表中讀取數據，並且需要將數據轉換為鍵值對。

我寫了下面的代碼。

這是我的代碼：

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，因為所有 header 列都應該出現在 map 鍵中，並且相應的數據應該作為值出現。 還有一件事是我不應該對列名進行硬編碼，每次列標題可以不同時，我都需要動態地從 Excel 讀取。

我需要將我的數據設置為以下格式，請幫助。 Map<String, List<String>> myMaps = new HashMap<String, List<String>>();

Answer 1

正如評論中所寫，由於您無法知道單元格是否包含 header 值或數據值，因此您想要做的事情是不可能的。

乍一看，您有兩種方法可以實現您想要的：

• 嘗試讓文件只有一個表，並且 header 行必須始終位於同一 excel 行（請參見此處） 。
• 為 header 添加自定義標簽內容：如<H> </H> ，但當然如果文件在可視化模式下使用，這個解決方案不是最好的

編輯：

您添加了一條注釋，確認 header 始終位於第一行，並且文件中只有一個表，因此下一個代碼應該可以工作。

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 "";
    }
}