二进制文件与base64编码文本文件转换

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一下是参考链接地址：

http://ghostfromheaven.iteye.com/blog/1611551

https://www.cnblogs.com/lukyw/archive/2012/09/12/2682102.html

static final byte[] BASE64_TABLE = { 'A', 'B', 'C', 'D', 'E', 'F',
            'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S',
            'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
            'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's',
            't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5',
            '6', '7', '8', '9', '+', '/' };

private static final byte BASE64_PAD = '=';

    public static String encodeBase64ToUTF8(byte[] bytes) {
        StringBuilder sb = new StringBuilder();

        int idx = 0;
        final int end = bytes.length;
        for (; idx < end - 2; idx += 3) {
            int data = (bytes[idx] & 0xff) << 16 | (bytes[idx + 1] & 0xff) << 8
                    | bytes[idx + 2] & 0xff;
            sb.append((char) BASE64_TABLE[data >> 18 & 0x3f]);
            sb.append((char) BASE64_TABLE[data >> 12 & 0x3f]);
            sb.append((char) BASE64_TABLE[data >> 6 & 0x3f]);
            sb.append((char) BASE64_TABLE[data & 0x3f]);
        }

        if (idx == end - 2) {
            int data = (bytes[idx] & 0xff) << 16 | (bytes[idx + 1] & 0xff) << 8;
            sb.append((char) BASE64_TABLE[data >> 18 & 0x3f]);
            sb.append((char) BASE64_TABLE[data >> 12 & 0x3f]);
            sb.append((char) BASE64_TABLE[data >> 6 & 0x3f]);
            sb.append((char) BASE64_PAD);

        } else if (idx == end - 1) {
            int data = (bytes[idx] & 0xff) << 16;
            sb.append((char) BASE64_TABLE[data >> 18 & 0x3f]);
            sb.append((char) BASE64_TABLE[data >> 12 & 0x3f]);
            sb.append((char) BASE64_PAD);
            sb.append((char) BASE64_PAD);
        }

        return sb.toString();
    }

    private static String encodeString(String value){
       String newValue = "";
       if(value == null) return null;

       try{
           byte[] bytes = value.getBytes("UTF-8");
           newValue = encodeB(bytes);
           newValue = "=?utf-8?B?"+newValue+"?=";
       }catch(java.io.UnsupportedEncodingException e){
           newValue = value;
           e.printStackTrace();
       }
       return newValue;
    }

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