如何保护pdf文件密码？

问题描述

我想要保护pdf文件密码。我只是为了相同而找到一个很好的解决方案。它工作正常但是在使用下面给出的代码保护pdf之后，它消除了我的pdf中已经存在的所有数据。

I want to make pdf file password protected. I just goolge it for the same and find a good solution given below. It's working fine But it wipe out all the data which is already there in my pdf after i secure pdf using below given code.

此代码使用的jar文件是：

Used jar files for this code are:

itextpdf-5.2.1.jar

itextpdf-5.2.1.jar

bcmail-jdk16-1.46.jar

bcmail-jdk16-1.46.jar

bcprov-jdk16-1.46.jar

bcprov-jdk16-1.46.jar

bctsp-jdk16-1.46.jar

bctsp-jdk16-1.46.jar

保护PDF的代码：

import com.itextpdf.text.Document;
import com.itextpdf.text.DocumentException;
import com.itextpdf.text.Paragraph;
import com.itextpdf.text.pdf.PdfWriter;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;

public class Secure_file {
    private static String USER_PASSWORD = "password";
    private static String OWNER_PASSWORD = "secured";
    public static void main(String[] args) throws IOException {
        Document document = new Document();
        try {
            PdfWriter writer = PdfWriter.getInstance(document, new FileOutputStream("E:\\sample.pdf"));
            writer.setEncryption(USER_PASSWORD.getBytes(),OWNER_PASSWORD.getBytes(), PdfWriter.ALLOW_PRINTING,PdfWriter.ENCRYPTION_AES_128);
            document.open();
            document.add(new Paragraph("This is Password Protected PDF document."));
            document.close();
            writer.close();
        } catch (DocumentException e) {
            e.printStackTrace();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
    }
}

我需要做出哪些改变在这个程序中？

what changes i need to made in this program ?

推荐答案

如果你查找你会发现指向示例part3.chapter12。。该示例的方法 createPdf 基本上等同于您的代码，但方法 encryptPdf 是您想要的：

If you look up the iText in Action keywords you'll find encryption pointing to the sample part3.chapter12.EncryptionPdf. That sample's method createPdf essentially is equivalent to your code but the method encryptPdf is what you want:

/** User password. */
public static byte[] USER = "Hello".getBytes();
/** Owner password. */
public static byte[] OWNER = "World".getBytes();

...

public void encryptPdf(String src, String dest) throws IOException, DocumentException {
    PdfReader reader = new PdfReader(src);
    PdfStamper stamper = new PdfStamper(reader, new FileOutputStream(dest));
    stamper.setEncryption(USER, OWNER,
        PdfWriter.ALLOW_PRINTING, PdfWriter.ENCRYPTION_AES_128 | PdfWriter.DO_NOT_ENCRYPT_METADATA);
    stamper.close();
    reader.close();
}

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