如何为Base64转换成PDF？

问题描述

给定一个base64输入，我将如何将其转换为Android中的PDF文件？

  @覆盖
    保护无效的onCreate（捆绑savedInstanceState）{
        super.onCreate（savedInstanceState）;
        上下文=这一点;
        的setContentView（R.layout.activity_main）;
        //获取PDF文件EN code入的Base64
        档案文件=新的文件（到/ mnt / SD卡/下载/ Base64.pdf）;
        尝试{
            //文件是番石榴库
            Files.toByteArray（文件）;
            // EN coded进入的Base64
            字节[]临时= Base64.en code（Files.toByteArray（文件），Base64.DEFAULT）;
            //出于测试目的，写了EN codeD字符串文件
            将writeToFile（Base64.en codeToString（温度，Base64.DEFAULT）的ToString（））;        }赶上（IOException异常五）{
            Log.d（标签，File.toByteArray（）错误）;
            e.printStackTrace（）;
        }
    }
 

我能够使用来测试PDF文件被正确连接codeD。不过，我想能够去code为Base64回PDF自己。我会怎么做呢？

修改1

试过低于code。通过Saneesh CS的建议

  @覆盖
    保护无效的onCreate（捆绑savedInstanceState）{
        super.onCreate（savedInstanceState）;
        上下文=这一点;
        的setContentView（R.layout.activity_main）;
        //获取PDF文件EN code入的Base64
        档案文件=新的文件（到/ mnt / SD卡/下载/ Base64.pdf）;
        尝试{
            //文件是番石榴库
            Files.toByteArray（文件）;
            // EN coded进入的Base64
            字节[]临时= Base64.en code（Files.toByteArray（文件），Base64.DEFAULT）;
            //与下面的线，但同样的结果尝试。
            字节[] =的temp1 Base64.en code（Files.toByteArray（文件），0）;
            //出于测试目的，写了EN codeD字符串文件
//将writeToFile（Base64.en codeToString（温度，Base64.DEFAULT）的ToString（））;
            最终文件dwldsPath =新的文件（Environment.getExternalStorageDirectory（），test7.pdf）;
            字节[] = pdfAsBytes Base64.de code（温度，0）;
            FileOutputStream中的操作系统;
            OS =新的FileOutputStream（dwldsPath，FALSE）;
            os.write（pdfAsBytes）;
            os.flush（）;
            os.close（）;
        }赶上（IOException异常五）{
            Log.d（标签，File.toByteArray（）错误）;
            e.printStackTrace（）;
        }
    }
 

以上code ++工程。

解决方案

 最后文件dwldsPath =新的文件（DOWNLOADS_FOLDER +文件名+.PDF）;
字节[] = pdfAsBytes Base64.de code（TXT，0）;
FileOutputStream中的操作系统;
OS =新的FileOutputStream（dwldsPath，FALSE）;
os.write（pdfAsBytes）;
os.flush（）;
os.close（）;
 

试试这个code。 TXT是的base64 EN codeD字符串。

Given a base64 input, how would I convert it into a PDF file in Android?

@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        context = this;
        setContentView(R.layout.activity_main);
        // Get the PDF file to encode it into Base64
        File file = new File("/mnt/sdcard/download/Base64.pdf");
        try {
            // Files is from Guava library
            Files.toByteArray(file);
            // Encoded into Base64
            byte[] temp = Base64.encode(Files.toByteArray(file), Base64.DEFAULT);
            // For testing purposes, wrote the encoded string to file
            writeToFile(Base64.encodeToString(temp, Base64.DEFAULT).toString());

        } catch (IOException e) {
            Log.d(tag, "File.toByteArray() error");
            e.printStackTrace();
        }
    }

I was able to use http://www.webutils.pl/index.php?idx=base64 to test the PDF file was being encoded properly. But I would like to be able to decode the base64 back to PDF myself. How would I do that?

Edit 1

Tried the below code as suggested by Saneesh CS

@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        context = this;
        setContentView(R.layout.activity_main);
        // Get the PDF file to encode it into Base64
        File file = new File("/mnt/sdcard/download/Base64.pdf");
        try {
            // Files is from Guava library
            Files.toByteArray(file);
            // Encoded into Base64
            byte[] temp = Base64.encode(Files.toByteArray(file), Base64.DEFAULT);
            // Tried with the below line, but same result.
            byte[] temp1 = Base64.encode(Files.toByteArray(file), 0);
            // For testing purposes, wrote the encoded string to file
//          writeToFile(Base64.encodeToString(temp, Base64.DEFAULT).toString());
            final File dwldsPath = new File(Environment.getExternalStorageDirectory(), "test7.pdf");
            byte[] pdfAsBytes = Base64.decode(temp, 0);
            FileOutputStream os;
            os = new FileOutputStream(dwldsPath, false);
            os.write(pdfAsBytes);
            os.flush();
            os.close();
        } catch (IOException e) {
            Log.d(tag, "File.toByteArray() error");
            e.printStackTrace();
        }
    }

Above code works.

解决方案

final File dwldsPath = new File(DOWNLOADS_FOLDER + fileName + ".pdf");
byte[] pdfAsBytes = Base64.decode(txt, 0);
FileOutputStream os;
os = new FileOutputStream(dwldsPath, false);
os.write(pdfAsBytes);
os.flush();
os.close();

Try this code. txt is the base64 encoded string.

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