Java 如何将 Pdf 转换为 base64 和编码/解码

How to Convert Pdf to base64 and Encode / Decode

提问by DKKs

OK, I have some pdf need convert to base64 by base64encoder.

好的，我有一些 pdf 需要通过 base64encoder 转换为 base64。

finally, I use decoder to convert back to pdf format but my content is lost.

最后，我使用解码器转换回 pdf 格式，但我的内容丢失了。

my code :

我的代码：

byte[] input_file = Files.readAllBytes(Paths.get("C:\user\Desktop\dir1\dir2\test3.pdf"));
    byte[] encodedBytes = Base64.getEncoder().encode(input_file);

    String pdfInBase64 = new String(encodedBytes);
    String originalString = new String(Base64.getDecoder().decode(encodedBytes));

    System.out.println("originalString : " + originalString);

    FileOutputStream fos = new FileOutputStream("C:\user\Desktop\dir1\dir2\newtest3.pdf");
    fos.write(originalString.getBytes());
    fos.flush();
    fos.close();

result :

结果 ：

Encode : https://pastebin.com/fnMACZzH

编码：https: //pastebin.com/fnMACZzH

Before base64encode

在 base64encode 之前

After decode

解码后

Thank You

谢谢你

采纳答案by Ajit Soman

You can decode base64 encoded String and pass that byte[]to FileOutputStreamwrite method to fix this issue.

您可以解码 base64 编码的字符串并将其传递byte[]给FileOutputStreamwrite 方法来解决此问题。

        String filePath = "C:\Users\xyz\Desktop\";
        String originalFileName = "96172560100_copy2.pdf";
        String newFileName = "test.pdf";

        byte[] input_file = Files.readAllBytes(Paths.get(filePath+originalFileName));

        byte[] encodedBytes = Base64.getEncoder().encode(input_file);
        String encodedString =  new String(encodedBytes);
        byte[] decodedBytes = Base64.getDecoder().decode(encodedString.getBytes());

        FileOutputStream fos = new FileOutputStream(filePath+newFileName);
        fos.write(decodedBytes);
        fos.flush();
        fos.close();

回答by dev_ramiz_1707

I have used Apache Commons library. The version I used for testing this Utility is commons-code-1.4.jar. There are multiple uses of Base64 Codec. The one I had a need to was during Docusign eSignature webservice call where the files attached were sent in a Base64 encoded format.

我使用过 Apache Commons 库。我用于测试此实用程序的版本是 commons-code-1.4.jar。Base64 编解码器有多种用途。我需要的是在 Docusign eSignature webservice 调用期间，其中附加的文件以 Base64 编码格式发送。

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;

import org.apache.commons.codec.binary.Base64;

public class FileCodecBase64 {

    private static final boolean IS_CHUNKED = true;

    public static void main(String args[]) throws Exception {

        /* Encode a file and write the encoded output to a text file. */
        encode("C:/temp/something.pdf", "c:/temp/something-encoded.txt", IS_CHUNKED);

        /* Decode a file and write the decoded file to file system */
        decode("C:/temp/something-encoded.txt", "c:/temp/something-decoded.pdf");
    }

    /**
     * This method converts the content of a source file into Base64 encoded data and saves that to a target file.
     * If isChunked parameter is set to true, there is a hard wrap of the output  encoded text.
     */
    private static void encode(String sourceFile, String targetFile, boolean isChunked) throws Exception {

        byte[] base64EncodedData = Base64.encodeBase64(loadFileAsBytesArray(sourceFile), isChunked);

        writeByteArraysToFile(targetFile, base64EncodedData);
    }

    public static void decode(String sourceFile, String targetFile) throws Exception {

        byte[] decodedBytes = Base64.decodeBase64(loadFileAsBytesArray(sourceFile));

        writeByteArraysToFile(targetFile, decodedBytes);
    }

    /**
     * This method loads a file from file system and returns the byte array of the content.
     * 
     * @param fileName
     * @return
     * @throws Exception
     */
    public static byte[] loadFileAsBytesArray(String fileName) throws Exception {

        File file = new File(fileName);
        int length = (int) file.length();
        BufferedInputStream reader = new BufferedInputStream(new FileInputStream(file));
        byte[] bytes = new byte[length];
        reader.read(bytes, 0, length);
        reader.close();
        return bytes;

    }

    /**
     * This method writes byte array content into a file.
     * 
     * @param fileName
     * @param content
     * @throws IOException
     */
    public static void writeByteArraysToFile(String fileName, byte[] content) throws IOException {

        File file = new File(fileName);
        BufferedOutputStream writer = new BufferedOutputStream(new FileOutputStream(file));
        writer.write(content);
        writer.flush();
        writer.close();

    }
}

i hope this work

我希望这项工作

回答by Danish Ali

import java.io.File;
import java.io.FileOutputStream;
import java.io.OutputStream;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.Base64;

public class Base64Sample {

public static void main(String... strings) throws Exception {
    String filePath = "/home/user/sample.pdf";
    File pdfFile = new File(filePath);
    byte[] encoded = Files.readAllBytes(Paths.get(pdfFile.getAbsolutePath()));
    Base64.Encoder enc = Base64.getEncoder();
    byte[] strenc = enc.encode(encoded);
    String encode = new String(strenc, "UTF-8");
    Base64.Decoder dec = Base64.getDecoder();
    byte[] strdec = dec.decode(encode);
    OutputStream out = new FileOutputStream("/home/user/out.pdf");
    out.write(strdec);
    out.close();
}
  }