C# 或 .NetCore 如何使用 NPOI 导出图片到 Excel 文件

今天在本文中，我们将尝试使用NPOI库将图像插入到 Excel 文件的特定位置。请将以下逻辑添加到您的写作方法中，在 Excel 文件中添加图像（JPEG、PNG）,我已经有一个示例 jpeg 文件 - Read-write-excel-npoi.jpg ，我们将尝试将其插入索引 (5,5)，即第 5 行和第 5 列。

在第 5 行和第 5 列，将以编程方式插入上述图像，代码如下：

byte[] data = File.ReadAllBytes("Read-write-excel-npoi.jpg");//根据自己路径读取图片

int pictureIndex = workbook.AddPicture(data, PictureType.JPEG);

ICreationHelper helper = workbook.GetCreationHelper();

IDrawing drawing = excelSheet.CreateDrawingPatriarch();

IClientAnchor anchor = helper.CreateClientAnchor();

anchor.Col1 = 5;

anchor.Row1 = 5;

IPicture picture = drawing.CreatePicture(anchor, pictureIndex);

picture.Resize();

用图像写入 EXCEL
下面是一个 POC 完整代码示例，如下所示：

static void WriteExcel()
{
List<UserDetails> persons = new List<UserDetails>()
{

new UserDetails() {ID="1001", Name="ABCD", City ="City1", Country="USA"},

new UserDetails() {ID="1002", Name="PQRS", City ="City2", Country="INDIA"},

new UserDetails() {ID="1003", Name="XYZZ", City ="City3", Country="CHINA"},

new UserDetails() {ID="1004", Name="LMNO", City ="City4", Country="UK"},
};

// Lets converts our object data to Datatable for a simplified logic.
// Datatable is most easy way to deal with complex datatypes for easy reading and formatting.
DataTable table = (DataTable)JsonConvert.DeserializeObject(JsonConvert.SerializeObject(persons), (typeof(DataTable)));

var memoryStream = new MemoryStream();

using (var fs = new FileStream("Result.xlsx", FileMode.OpenOrCreate, FileAccess.Write))
{
IWorkbook workbook = new XSSFWorkbook();
ISheet excelSheet = workbook.CreateSheet("TestSheet1");

List<String> columns = new List<string>();
IRow row = excelSheet.CreateRow(0);
int columnIndex = 0;

foreach (System.Data.DataColumn column in table.Columns)
{
columns.Add(column.ColumnName);
row.CreateCell(columnIndex).SetCellValue(column.ColumnName);
columnIndex++;
}

int rowIndex = 1;
foreach (DataRow dsrow in table.Rows)
{
row = excelSheet.CreateRow(rowIndex);
int cellIndex = 0;
foreach (String col in columns)
{
row.CreateCell(cellIndex).SetCellValue(dsrow[col].ToString());
cellIndex++;
}

rowIndex++;
}

byte[] data = File.ReadAllBytes("Read-write-excel-npoi.jpg");