需要有关pdf渲染器的帮助 [英] Need help with pdf-renderer

问题描述

我正在使用PDF-Renderer来查看我的Java应用程序中的PDF文件.对于普通的PDF文件，它是完美的工作.

I'm using PDF-Renderer to view PDF files within my java application. It's working perfectly for normal PDF files.

但是，我希望该应用程序能够显示加密的PDF文件.加密后的文件将使用 CipherInputStream 进行解密，但是我不想将解密后的数据保存在磁盘上.我试图找到一种方法，可以将已解密的数据从 CipherInputStream 传递到 PDFFile 构造函数，而不必将已解密的数据写入文件.

However, i want the application to be able to display encrypted PDF files. The ecrypted file will be decrypted with CipherInputStream, but i do not want to save the decrypted data on disk. Am trying to figure a way i can pass the decryted data from CipherInputStream to the PDFFile constructor without having to write the decryted data to file.

如果有人可以帮助您链接到PDF-Renderer教程，我也将不胜感激.

I will also appreciate if someone can help with a link to PDF-Renderer tutorial, so that i can read up more on it.

谢谢.

推荐答案

尝试以下课程:

import com.sun.pdfview.PDFFile;
import java.io.IOException;
import java.io.InputStream;
import java.nio.ByteBuffer;
import java.nio.channels.Channels;
import java.nio.channels.ReadableByteChannel;

public class PDFFileUtility {
private static final int READ_BLOCK = 8192;

public static PDFFile getPDFFile(InputStream in) throws IOException {
   ReadableByteChannel bc = Channels.newChannel(in);
   ByteBuffer bb = ByteBuffer.allocate(READ_BLOCK);
    while (bc.read(bb) != -1) {
        bb = resizeBuffer(bb); //get new buffer for read
    }
   return new PDFFile(bb);

}

 private static ByteBuffer resizeBuffer(ByteBuffer in) {
   ByteBuffer result = in;
   if (in.remaining() < READ_BLOCK) {
    result = ByteBuffer.allocate(in.capacity() * 2);
    in.flip();
    result.put(in);
   }
   return result;
}
}

因此致电:

PDFFileUtility.getPDFFile(myCipherInputStream);

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