1. Excel文件转成base64

public String encryptToBase64(String filePath) {
if (filePath == null) {
return null;
}
try {
byte[] b = Files.readAllBytes(Paths.get(filePath));
return Base64.getEncoder().encodeToString(b);
} catch (IOException e) {
e.printStackTrace();
}
return null;
}

2. base64转为文件

public String decryptByBase64(String base64, String filePath) {
if (base64 == null && filePath == null) {
return "生成文件失败，请给出相应的数据。";
}
try {
Files.write(Paths.get(filePath), Base64.getDecoder().decode(base64),StandardOpenOption.CREATE);
} catch (IOException e) {
e.printStackTrace();
}
return "指定路径下生成文件成功！";
}

3. 导入base64对应的依赖包

<dependency>
            <groupId>commons-codec</groupId>
            <artifactId>commons-codec</artifactId>
        </dependency>