Question

private static String encodeFileToBase64Binary(String fileName)
        throws IOException {

    File file = new File(fileName);
    byte[] bytes = loadFile(file);
    byte[] encoded = Base64.encodeBase64(bytes);
    String encodedString = new String(encoded,StandardCharsets.US_ASCII);

    return encodedString;
}
private static byte[] loadFile(File file) throws IOException {
    InputStream is = new FileInputStream(file);

    long length = file.length();
    if (length > Integer.MAX_VALUE) {
        // File is too large
    }
    byte[] bytes = new byte[(int)length];

    int offset = 0;
    int numRead = 0;
    while (offset < bytes.length
           && (numRead=is.read(bytes, offset, bytes.length-offset)) >= 0) {
        offset += numRead;
    }

    if (offset < bytes.length) {
        throw new IOException("Could not completely read file "+file.getName());
    }

    is.close();
    return bytes;
}

//获取编码字符串

String encoded=encodeFileToBase64Binary("file.fmr");

//编码的字符串是：

Rk1SACAyMAAAAAFiAAABQAHgAMUAxQEAAABGNkDZADP/SEC8AD6CSECqAEcGSED+AFJtO0CgAGCKZEC6AGuFZEDgAHz1ZECzAI6HZEENAJluNEBWAJ4ZZEB1AKkTZEECALbuZEA/ALqfSECCALySSECxAMP/ZECIAMURVUAXAN2jGkCnAOD8ZEAoAOWlZEBnAOyhLkCyAP/tZECHAQMSGkD8AQTdZECfASKFGkCHASUaGkA1ASy6ZEDAAS3JZEDPAS7NZEAnATG4ZEDxATzOZEBOAUPLZEBzAVbuGkCAAWF8NEDTAWsxLkDnAXa0LkC/AX2nLkC0AYojIEBMAYvkSEDJAa0fT0CsAbwVIIDqANTsZIDIAPfnZICbAQKHO4D5AR/XZIBlASS7IIEoASbYO4CsAUetLoDvAVXSZIDaAVvDO4EHAWrLZICsAX2fNIDnAYEwNIDQAZKnT4BfAZxtZAAA

//使用其他来源从文件编码的字符串。

Rk1SACAyMAAAAAFiAAABQAHgAMUAxQEAAABGNkCLACELSEDAADYDZEEYAGFxO0DGAGJ9SEC1AGkCSEA6AHWYVUDJAHp5ZEBEAHwVZECVAJgIZEEaALHrZEB4ALuOZEELAMFqZEEzAM/sNEDRANvwZEBkAN0VZECcAOIAZEEwAOjnLkEvAPXlO0CnAP71ZEB7AQYRNEBdAQ0eZED8ARDhZEDXASXcZECZAS3uGkBoAT4eO0AUAUMxSEA7AUYqZEDxAUnSZECmAVNDO0EIAXDHSEDYAXW7ZEEUAXXKSEEGAYY8IEEhAYrDNEDfAZ81ZEDQAcGqLoEBAC/7O4EGAE7zVYB+AP2QSICEARuLZIBnATUfO4D/ATXaZIDEATjSZIDRATrVZICnATvSNIBTATwnZIARAV1LGoB1AV2oO4CrAV68SIDnAWHGZIB+AWauNICVAX0ySICNAYytO4CJAZorSAAA

当我试图匹配编码的字符串时，我得到了一个错配。请建议编码文件到base64的方法，以匹配从其他来源找到的编码字符串。我尝试过使用StandardCharsets.UTF_8和StandardCharsets.US_ASCII。

Answer 1

您已经使用了apache commons-codec，所以我建议添加commons-io来读取文件。这样你可以删除你的loadFile（）方法，只需：

date_default_timezone_set('Asia/Bangkok');
$objPHPExcel->getActiveSheet()->SetCellValue('S1', 'Show DateTime');
$dateValue = PHPExcel_Shared_Date::PHPToExcel( strtotime('23-Apr-1989 17:05:50') );
$objPHPExcel->getActiveSheet()
    ->setCellValue('S2', $dateValue);
$objPHPExcel->getActiveSheet()
    ->getStyle('S2')
    ->getNumberFormat()
    ->setFormatCode(PHPExcel_Style_NumberFormat::FORMAT_DATE_YYYYMMDDSLASH);

Answer 2

从Java 8开始，您可以使用类java.util.Base64和相应的内部类：

java.util.Base64.Encoder
java.util.Base64.Decoder

请参阅JavaDoc：Base64-Doc

以及使用示例：Example from Oracle

Answer 3

此示例对我来说非常有用：https://grokonez.com/java/java-advanced/java-8-encode-decode-an-image-base64

public static String encoder(String filePath) {
        String base64File = "";
        File file = new File(filePath);
        try (FileInputStream imageInFile = new FileInputStream(file)) {
            // Reading a file from file system
            byte fileData[] = new byte[(int) file.length()];
            imageInFile.read(fileData);
            base64File = Base64.getEncoder().encodeToString(fileData);
        } catch (FileNotFoundException e) {
            System.out.println("File not found" + e);
        } catch (IOException ioe) {
            System.out.println("Exception while reading the file " + ioe);
        }
        return base64File;
    }

Answer 4

这是一个不需要任何依赖项（ Apacha等人）的解决方案，只需要JDK 8 +：

import java.util.Base64;
import java.nio.file.Files;

private static String encodeFileToBase64(File file) {
    try {
        byte[] fileContent = Files.readAllBytes(file.toPath());
        return Base64.getEncoder().encodeToString(fileContent);
    } catch (IOException e) {
        throw new IllegalStateException("could not read file " + file, e);
    }
}

Java将文件编码为Base64字符串以与其他编码字符串匹配

4 个答案: