Java Base64 Encode base64EncodeGeneric(String digits, byte[] data)

Description

base Encode Generic

License

Open Source License

Declaration

public static String base64EncodeGeneric(String digits, byte[] data) 

Method Source Code

//package com.java2s;
//License from project: Open Source License 

public class Main {
    private static final char[] HexDigits = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd',
            'e', 'f', };

    public static String base64EncodeGeneric(String digits, byte[] data) {
        if (data == null)
            throw new IllegalArgumentException("'data' can't be null");
        if (digits == null)
            throw new IllegalArgumentException("'digits' can't be null");
        if (digits.length() != 64)
            throw new IllegalArgumentException("'digits' must be 64 characters long: " + jq(digits));

        int numGroupsOfThreeInputBytes = (data.length + 2) / 3;
        int numOutputChars = numGroupsOfThreeInputBytes * 4;
        StringBuilder buf = new StringBuilder(numOutputChars);

        // Do chunks of three bytes at a time.
        int i = 0;
        while ((i + 3) <= data.length) {
            int b1 = ((int) data[i++]) & 0xff;
            int b2 = ((int) data[i++]) & 0xff;
            int b3 = ((int) data[i++]) & 0xff;

            int d1 = b1 >>> 2;
            int d2 = ((b1 & 0x3) << 4) | (b2 >>> 4);
            int d3 = ((b2 & 0xf) << 2) | (b3 >>> 6);
            int d4 = b3 & 0x3f;

            buf.append(digits.charAt(d1));
            buf.append(digits.charAt(d2));
            buf.append(digits.charAt(d3));
            buf.append(digits.charAt(d4));
        }// w ww .jav  a 2  s .  c om

        // Do the leftover bytes (either 1 or 2)
        int remaining = data.length - i;
        if (remaining == 0) {
            // All done.
        } else if (remaining == 1) {
            int b1 = ((int) data[i++]) & 0xff;

            int d1 = b1 >>> 2;
            int d2 = (b1 & 0x3) << 4;

            buf.append(digits.charAt(d1));
            buf.append(digits.charAt(d2));
            buf.append("==");
        } else if (remaining == 2) {
            int b1 = ((int) data[i++]) & 0xff;
            int b2 = ((int) data[i++]) & 0xff;

            int d1 = b1 >>> 2;
            int d2 = ((b1 & 0x3) << 4) | (b2 >>> 4);
            int d3 = ((b2 & 0xf) << 2);

            buf.append(digits.charAt(d1));
            buf.append(digits.charAt(d2));
            buf.append(digits.charAt(d3));
            buf.append('=');
        } else {
            throw new AssertionError("data.length: " + data.length + ", i: " + i);
        }

        return buf.toString();
    }

    /** Shorthand for {@link #javaQuotedLiteral}. */
    public static String jq(String value) {
        return javaQuotedLiteral(value);
    }

    /**
     * Given a string, returns the representation of that string
     * as a Java string literal.
     */
    public static String javaQuotedLiteral(String value) {
        StringBuilder b = new StringBuilder(value.length() * 2);
        b.append('"');
        for (int i = 0; i < value.length(); i++) {
            char c = value.charAt(i);
            switch (c) {
            case '"':
                b.append("\\\"");
                break;
            case '\\':
                b.append("\\\\");
                break;
            case '\n':
                b.append("\\n");
                break;
            case '\r':
                b.append("\\t");
                break;
            case '\t':
                b.append("\\r");
                break;
            case '\0':
                b.append("\\000");
                break; // Inserting '\0' isn't safe if there's a digit after
            default:
                if (c >= 0x20 && c <= 0x7e) {
                    b.append(c);
                } else {
                    int h1 = (c >> 12) & 0xf;
                    int h2 = (c >> 8) & 0xf;
                    int h3 = (c >> 4) & 0xf;
                    int h4 = c & 0xf;
                    b.append("\\u");
                    b.append(hexDigit(h1));
                    b.append(hexDigit(h2));
                    b.append(hexDigit(h3));
                    b.append(hexDigit(h4));
                }
                break;
            }
        }
        b.append('"');
        return b.toString();
    }

    public static char hexDigit(int i) {
        return HexDigits[i];
    }
}

Related

1. base64Encode(String s)
2. base64encode(String str)
3. base64Encode(String string)
4. base64Encode(String string)
5. base64encode(String text)
6. base64Encoder(byte[] src, int start, int wrapAt)
7. base64Encoder(String str)
8. base64encoding(byte[] bytes)
9. base64UrlDecode(final String encodedString)