将数字签名添加到已签名的 Excel 文件

可能的使用场景

Aspose.Cells 提供了Workbook.addDigitalSignature（DigitalSignatureCollection digitalSignatureCollection） 方法，可用于将数字签名添加到已签名的 Excel 文件。

请注意，在为已签名的 Excel 文档添加数字签名时，如果原始文档是 Aspose.Cells 生成的文档，则效果很好。但如果原文档是其他引擎生成的（如Microsoft Excel等），Aspose.Cells加载后重新保存后无法保持原来的文件原样，这样会使原签名失效。

将数字签名添加到已签名的 Excel 文件

下面的示例代码解释了如何使用[Workbook.addDigitalSignature（DigitalSignatureCollection digitalSignatureCollection）](https://reference.aspose.com/cells/java/com.aspose.cells/workbook#addDigitalSignature(com.aspose.cells.DigitalSignatureCollection)方法向已签名的 Excel 文件添加数字签名。请检查示例 Excel 文件在这段代码中使用。此文件已经过数字签名。请检查输出Excel文件由代码生成。我们使用了名为Aspose测试.pfx在这个有密码的代码中提出.截图显示了示例代码在示例Excel文件上执行后的效果。

示例代码

// For complete examples and data files, please go to https://github.com/aspose-cells/Aspose.Cells-for-Java

// Certificate file and its password
String certFileName = "AsposeTest.pfx";
String password = "aspose";
 
// Load the workbook which is already digitally signed to add new digital signature
Workbook workbook = new Workbook(srcDir + "sampleDigitallySignedByCells.xlsx");
 
// Create the digital signature collection
DigitalSignatureCollection dsCollection = new DigitalSignatureCollection();
 
// Create new digital signature and add it in digital signature collection
// ------------------------------------------------------------
// --------------Begin::creating signature---------------------
 
// Load the certificate into an instance of InputStream
InputStream inStream = new FileInputStream(srcDir + certFileName);
 
// Create an instance of KeyStore with PKCS12 cryptography
java.security.KeyStore inputKeyStore = java.security.KeyStore.getInstance("PKCS12");
 
// Use the KeyStore.load method to load the certificate stream and its password
inputKeyStore.load(inStream, password.toCharArray());
 
// Create an instance of DigitalSignature and pass the instance of KeyStore, password, comments and time
DigitalSignature signature = new DigitalSignature(inputKeyStore, password,
		"Aspose.Cells added new digital signature in existing digitally signed workbook.",
		com.aspose.cells.DateTime.getNow());
 
dsCollection.add(signature);
// ------------------------------------------------------------
// --------------End::creating signature-----------------------
 
// Add digital signature collection inside the workbook
workbook.addDigitalSignature(dsCollection);
 
// Save the workbook and dispose it.
workbook.save(outDir + "outputDigitallySignedByCells.xlsx");
workbook.dispose();