Java Encode file to Base64 string 以匹配其他编码的字符串

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");

// 编码后的字符串是：

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

//使用其他来源从文件中编码的字符串。

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

当我尝试匹配两个编码字符串时，我遇到了不匹配。请建议将文件编码为 base64 的方法，以匹配从其他来源找到的编码字符串。我试过 StandardCharsets.UTF_8 和 StandardCharsets.US_ASCII 。

原文由 Sanket Sawant 发布，翻译遵循 CC BY-SA 4.0 许可协议

Answer 1

您已经在使用 apache commons-codec，所以我建议添加 commons-io 来读取文件。这样你就可以删除你的 loadFile() 方法并且只需要：

 private static String encodeFileToBase64Binary(String fileName) throws IOException {
    File file = new File(fileName);
    byte[] encoded = Base64.encodeBase64(FileUtils.readFileToByteArray(file));
    return new String(encoded, StandardCharsets.US_ASCII);
}

原文由 gfelisberto 发布，翻译遵循 CC BY-SA 3.0 许可协议