Java Encode file to Base64 string To match with other encoded string(Java 将文件编码为 Base64 字符串以与其他编码字符串匹配)

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问题描述

私有静态字符串 encodeFileToBase64Binary(String fileName)抛出 IOException {文件文件 = 新文件(文件名)；字节 [] 字节 = 加载文件(文件)；byte[] 编码 = Base64.encodeBase64(bytes);String encodedString = new String(encoded,StandardCharsets.US_ASCII);返回编码字符串；}私有静态字节 [] 加载文件(文件文件)抛出 IOException {InputStream is = new FileInputStream(file);长长度 = file.length();如果(长度>整数.MAX_VALUE){//文件太大}字节[]字节=新字节[(int)长度]；整数偏移 = 0；int numRead = 0;而(偏移量<字节.长度&&(numRead=is.read(bytes, offset, bytes.length-offset)) >= 0) {偏移量 += 读数；}if (offset < bytes.length) {throw new IOException("无法完全读取文件 "+file.getName());}is.close();返回字节；}//获取编码字符串字符串编码=encodeFileToBase64Binary("file.fmr");//编码后的字符串是:<预> <代码> Rk1SACAyMAAAAAFiAAABQAHgAMUAxQEAAABGNkDZADP/SEC8AD6CSECqAEcGSED + AFJtO0CgAGCKZEC6AGuFZEDgAHz1ZECzAI6HZEENAJluNEBWAJ4ZZEB1AKkTZEECALbuZEA/ALqfSECCALySSECxAMP/ZECIAMURVUAXAN2jGkCnAOD8ZEAoAOWlZEBnAOyhLkCyAP/tZECHAQMSGkD8AQTdZECfASKFGkCHASUaGkA1ASy6ZEDAAS3JZEDPAS7NZEAnATG4ZEDxATzOZEBOAUPLZEBzAVbuGkCAAWF8NEDTAWsxLkDnAXa0LkC/AX2nLkC0AYojIEBMAYvkSEDJAa0fT0CsAbwVIIDqANTsZIDIAPfnZICbAQKHO4D5AR/XZIBlASS7IIEoASbYO4CsAUetLoDvAVXSZIDaAVvDO4EHAWrLZICsAX2fNIDnAYEwNIDQAZKnT4BfAZxtZAAA//使用其他来源的文件中的编码字符串.<预> <代码> Rk1SACAyMAAAAAFiAAABQAHgAMUAxQEAAABGNkCLACELSEDAADYDZEEYAGFxO0DGAGJ9SEC1AGkCSEA6AHWYVUDJAHp5ZEBEAHwVZECVAJgIZEEaALHrZEB4ALuOZEELAMFqZEEzAM/sNEDRANvwZEBkAN0VZECcAOIAZEEwAOjnLkEvAPXlO0CnAP71ZEB7AQYRNEBdAQ0eZED8ARDhZEDXASXcZECZAS3uGkBoAT4eO0AUAUMxSEA7AUYqZEDxAUnSZECmAVNDO0EIAXDHSEDYAXW7ZEEUAXXKSEEGAYY8IEEhAYrDNEDfAZ81ZEDQAcGqLoEBAC/7O4EGAE7zVYB + AP2QSICEARuLZIBnATUfO4D/ATXaZIDEATjSZIDRATrVZICnATvSNIBTATwnZIARAV1LGoB1AV2oO4CrAV68SIDnAWHGZIB + AWauNICVAX0ySICNAYytO4CJAZorSAAA

当我试图匹配两个编码字符串时，我得到一个不匹配的结果.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.我尝试过使用 StandardCharsets.UTF_8 和 StandardCharsets.US_ASCII.

解决方案

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，只需要:

private static String encodeFileToBase64Binary(String fileName) throws IOException {文件文件 = 新文件(文件名)；byte[] 编码 = Base64.encodeBase64(FileUtils.readFileToByteArray(file));返回新字符串(编码，StandardCharsets.US_ASCII)；}

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;
}

// to get encode string

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

// encoded string is :

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

//encoded string from file using some other source. 

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

When i am trying to match both the encoded string , i am getting a missmatch. please suggest method for encode file to base64 to match encoded string found from other source. i have tried with StandardCharsets.UTF_8 and StandardCharsets.US_ASCII.

解决方案

You already using apache commons-codec so I recommend adding commons-io for reading the file. That way you can remove your loadFile() method and just have:

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);
}

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