poi 多选

如果您想在Excel或者类似的电子表格软件中进行多选，可以按住 Ctrl 键并单击要选择的单元格或者按住 Shift 键并使用方向键框定区域。如果您在Java中使用Apache POI库来操作Excel文件，可以使用以下代码来进行多选：

CellRangeAddressList cellRangeAddressList = new CellRangeAddressList(0, 0, 0, 1);
DVConstraint dvConstraint = DVConstraint.createExplicitListConstraint(new String[]{"Option1", "Option2", "Option3"});
DataValidation dataValidation = new HSSFDataValidation(cellRangeAddressList, dvConstraint);
sheet.addValidationData(dataValidation);

这段代码会在第一行的第一列和第二列上创建一个下拉列表，其中包含三个选项：“Option1”，“Option2”和“Option3”。您可以根据需要更改这些选项，以及单元格的范围和位置。

相关问题

如何通过java用poi生成多选下拉框的excel

可以通过以下步骤使用Java的POI库生成多选下拉框的Excel：

1. 创建一个工作簿对象，并创建一个工作表对象

Workbook workbook = new XSSFWorkbook();
Sheet sheet = workbook.createSheet("Sheet1");

2. 创建一个下拉列表选项集合，并添加选项

DataValidationHelper dvHelper = new XSSFDataValidationHelper(sheet);
String[] options = {"Option 1", "Option 2", "Option 3", "Option 4", "Option 5"};
List<String> optionList = Arrays.asList(options);
DataValidationConstraint dvConstraint = dvHelper.createExplicitListConstraint(optionList.toArray(new String[0]));

3. 创建一个单元格对象，并设置单元格的下拉列表数据有效性校验

CellRangeAddressList addressList = new CellRangeAddressList(0, 0, 0, 0); // 第一行第一列
DataValidation validation = dvHelper.createValidation(dvConstraint, addressList);
validation.setShowErrorBox(true);
sheet.addValidationData(validation);

4. 将工作簿对象写入到一个文件中

FileOutputStream outputStream = new FileOutputStream("output.xlsx");
workbook.write(outputStream);
outputStream.close();

完整代码示例：

import java.io.FileOutputStream;
import java.util.Arrays;
import java.util.List;

import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.DataValidation;
import org.apache.poi.ss.usermodel.DataValidationConstraint;
import org.apache.poi.ss.usermodel.DataValidationHelper;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.Workbook;
import org.apache.poi.ss.util.CellRangeAddressList;
import org.apache.poi.xssf.usermodel.XSSFDataValidationHelper;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

public class MultipleSelectionDropdown {

    public static void main(String[] args) throws Exception {
        Workbook workbook = new XSSFWorkbook();
        Sheet sheet = workbook.createSheet("Sheet1");

        DataValidationHelper dvHelper = new XSSFDataValidationHelper(sheet);
        String[] options = {"Option 1", "Option 2", "Option 3", "Option 4", "Option 5"};
        List<String> optionList = Arrays.asList(options);
        DataValidationConstraint dvConstraint = dvHelper.createExplicitListConstraint(optionList.toArray(new String[0]));

        CellRangeAddressList addressList = new CellRangeAddressList(0, 0, 0, 0); // 第一行第一列
        DataValidation validation = dvHelper.createValidation(dvConstraint, addressList);
        validation.setShowErrorBox(true);
        sheet.addValidationData(validation);

        FileOutputStream outputStream = new FileOutputStream("output.xlsx");
        workbook.write(outputStream);
        outputStream.close();
    }
}

poi实现下拉多选

Apache POI 本身并不提供下拉多选的功能，但可以通过设置数据验证实现类似的效果。具体步骤如下：

1. 创建下拉列表的选项

DataValidationHelper validationHelper = new XSSFDataValidationHelper(sheet);
XSSFDataValidationConstraint dvConstraint = (XSSFDataValidationConstraint) validationHelper.createExplicitListConstraint(new String[]{"选项1", "选项2", "选项3"});

2. 创建数据验证对象并设置验证范围

CellRangeAddressList addressList = new CellRangeAddressList(0, 0, 0, 0);
XSSFDataValidation validation = (XSSFDataValidation) validationHelper.createValidation(dvConstraint, addressList);

3. 设置多选模式

validation.setValidationType(ValidationType.LIST);
validation.setShowErrorBox(true);
validation.setErrorStyle(DataValidation.ErrorStyle.STOP);
validation.createPromptBox("提示", "请选择多个选项");
validation.setShowPromptBox(true);

4. 将数据验证对象添加到工作表中

sheet.addValidationData(validation);

完整代码示例：

import java.io.FileOutputStream;
import org.apache.poi.ss.usermodel.DataValidation;
import org.apache.poi.ss.usermodel.DataValidationHelper;
import org.apache.poi.ss.usermodel.DataValidationConstraint.ValidationType;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.Workbook;
import org.apache.poi.ss.util.CellRangeAddressList;
import org.apache.poi.xssf.usermodel.XSSFDataValidation;
import org.apache.poi.xssf.usermodel.XSSFDataValidationHelper;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

public class MultiSelectDropDownExample {
    public static void main(String[] args) throws Exception {
        Workbook workbook = new XSSFWorkbook();
        Sheet sheet = workbook.createSheet("Sheet1");

        // create drop down options
        DataValidationHelper validationHelper = new XSSFDataValidationHelper(sheet);
        XSSFDataValidationConstraint dvConstraint = (XSSFDataValidationConstraint) validationHelper.createExplicitListConstraint(new String[]{"Option 1", "Option 2", "Option 3"});

        // create data validation and set range
        CellRangeAddressList addressList = new CellRangeAddressList(0, 0, 0, 0);
        XSSFDataValidation validation = (XSSFDataValidation) validationHelper.createValidation(dvConstraint, addressList);

        // set multi-select mode
        validation.setValidationType(ValidationType.LIST);
        validation.setShowErrorBox(true);
        validation.setErrorStyle(DataValidation.ErrorStyle.STOP);
        validation.createPromptBox("Prompt", "Please select multiple options");
        validation.setShowPromptBox(true);

        // add data validation to sheet
        sheet.addValidationData(validation);

        FileOutputStream fileOut = new FileOutputStream("multi_select_dropdown.xlsx");
        workbook.write(fileOut);
        fileOut.close();

        System.out.println("Excel file created!");
    }
}