您需要:

1. 将您的数据设置为数字(浮点数)，而不是文本.
2. 将单元格格式指定为百分比.

类似于:

cell.setCellValue(0.123); // set value as number
CellStyle style = workbook.createCellStyle();
style.setDataFormat(workbook.createDataFormat().getFormat("0.000%"));
cell.setCellStyle(style);

查看 POI 快速指南的用户定义格式部分更多细节.您可能还想阅读示例，其中展示了如何使用不同的 POI 功能.

Take a look at user defined formats section of POI quick guide for more details. You may also want to go through the examples which show how to use different POI capabilities.