java 如何检查 PDF 是否受密码保护
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How to check if a PDF is Password Protected or not
提问by tusharagrawa
I am trying to use iText's PdfReader to check if a given PDF file is password protected or not, but am getting this exception:
我正在尝试使用 iText 的 PdfReader 检查给定的 PDF 文件是否受密码保护，但出现此异常：
Exception in thread "Main Thread" java.lang.NoClassDefFoundError:org/bouncycastle/asn1/ASN1OctetString
线程“主线程”中的异常 java.lang.NoClassDefFoundError:org/bouncycastle/asn1/ASN1OctetString
But when testing the same code against a non-password protected file it runs fine. Here is the complete code:
但是当针对非密码保护的文件测试相同的代码时，它运行良好。这是完整的代码：
try {
PdfReader pdf = new PdfReader("C:\abc.pdf");
} catch (IOException e) {
e.printStackTrace();
}
采纳答案by Shreyos Adikari
回答by Waleed Madanat
The way I do it is by attempting to read the PDF file using PdfReaderwithout passing a password of course. If the file is password protected, a BadPasswordExceptionwill be thrown. This is using the iText library.
我这样做的方法是尝试在PdfReader不传递密码的情况下尝试读取 PDF 文件。如果文件受密码保护，BadPasswordException则会抛出 a。这是使用 iText 库。
回答by VHS
In the old version of PDFBox
在旧版本的 PDFBox 中
try
{
InputStream fis = new ByteArrayInputStream(pdfBytes);
PDDocument doc = PDDocument.load(fis);
if(doc.isEncrypted())
{
//Then the pdf file is encrypeted.
}
}
In the newer version of PDFBox (e.g. 2.0.4)
在较新版本的 PDFBox（例如 2.0.4）中
InputStream fis = new ByteArrayInputStream(pdfBytes);
boolean encrypted = false;
try {
PDDocument doc = PDDocument.load(fis);
if(doc.isEncrypted())
encrypted=true;
doc.close();
}
catch(InvalidPasswordException e) {
encrypted = true;
}
return encrypted;
回答by Nitin Vavdiya
Try this code:
试试这个代码：
boolean isProtected = true;
PDDocument pdfDocument = null;
try
{
pdfDocument = PDDocument.load(new File("your file path"));
isProtected = false;
}
catch(Exception e){
LOG.error("Error while loading file : ",e);
}
Syste.out.println(isProtected);
If your document is password protected then it can not load document and throw IOException.
Verified above code using pdfbox-2.0.4.jar
如果您的文档受密码保护，则它无法加载文档并抛出 IOException。使用上面的代码验证pdfbox-2.0.4.jar
回答by Shivam
try {
PdfReader pdfReader = new PdfReader(String.valueOf(file));
pdfReader.isEncrypted();
} catch (IOException e) {
e.printStackTrace();
}
Using iText PDF library you can check. If it went to an exception handle it(ask for password)
您可以使用 iText PDF 库进行检查。如果它进入异常处理它（询问密码）
回答by akodiakson
Here's a solution that doesn't require 3rd party libraries, using the PdfRenderer API.
这是一个不需要 3rd 方库的解决方案，使用 PdfRenderer API。
fun checkIfPdfIsPasswordProtected(uri: Uri, contentResolver: ContentResolver): Boolean {
val parcelFileDescriptor = contentResolver.openFileDescriptor(uri, "r")
?: return false
return try {
PdfRenderer(parcelFileDescriptor)
false
} catch (securityException: SecurityException) {
true
}
}
Reference: https://developer.android.com/reference/android/graphics/pdf/PdfRenderer
参考：https: //developer.android.com/reference/android/graphics/pdf/PdfRenderer
