Base64编辑解码的使用

来源：互联网发布：vb msdn中文版下载编辑：程序博客网时间：2024/06/14 13:02

public class Base64Codec
{
    protected final byte[] encodingTable =
        {
            (byte)'A', (byte)'B', (byte)'C', (byte)'D', (byte)'E', (byte)'F', (byte)'G',
            (byte)'H', (byte)'I', (byte)'J', (byte)'K', (byte)'L', (byte)'M', (byte)'N',
            (byte)'O', (byte)'P', (byte)'Q', (byte)'R', (byte)'S', (byte)'T', (byte)'U',
            (byte)'V', (byte)'W', (byte)'X', (byte)'Y', (byte)'Z',
            (byte)'a', (byte)'b', (byte)'c', (byte)'d', (byte)'e', (byte)'f', (byte)'g',
            (byte)'h', (byte)'i', (byte)'j', (byte)'k', (byte)'l', (byte)'m', (byte)'n',
            (byte)'o', (byte)'p', (byte)'q', (byte)'r', (byte)'s', (byte)'t', (byte)'u',
            (byte)'v',
            (byte)'w', (byte)'x', (byte)'y', (byte)'z',
            (byte)'0', (byte)'1', (byte)'2', (byte)'3', (byte)'4', (byte)'5', (byte)'6',
            (byte)'7', (byte)'8', (byte)'9',
            (byte)'+', (byte)'/'
        };
    protected byte    padding = (byte)'=';

    /*
     * set up the decoding table.
     */
    protected final byte[] decodingTable = new byte[128];
    protected void initialiseDecodingTable()
    {
        for (int i = 0; i < encodingTable.length; i++)
        {
            decodingTable[encodingTable[i]] = (byte)i;
        }
    }

    public Base64Codec()
    {
        initialiseDecodingTable();
    }

    /**
     * encode the input data producing a base 64 output stream.
     *
     * @return the number of bytes produced.
     */
    public int encode(
        byte[]                data,
        int                    off,
        int                    length,
        OutputStream    out)
        throws IOException
    {
        int modulus = length % 3;
        int dataLength = (length - modulus);
        int a1, a2, a3;

        for (int i = off; i < off + dataLength; i += 3)
        {
            a1 = data[i] & 0xff;
            a2 = data[i + 1] & 0xff;
            a3 = data[i + 2] & 0xff;
            out.write(encodingTable[(a1 >>> 2) & 0x3f]);
            out.write(encodingTable[((a1 << 4) | (a2 >>> 4)) & 0x3f]);
            out.write(encodingTable[((a2 << 2) | (a3 >>> 6)) & 0x3f]);
            out.write(encodingTable[a3 & 0x3f]);
        }
        /*
         * process the tail end.
         */
        int    b1, b2, b3;
        int    d1, d2;
        switch (modulus)
        {
        case 0:        /* nothing left to do */
            break;
        case 1:
            d1 = data[off + dataLength] & 0xff;
            b1 = (d1 >>> 2) & 0x3f;
            b2 = (d1 << 4) & 0x3f;
            out.write(encodingTable[b1]);
            out.write(encodingTable[b2]);
            out.write(padding);
            out.write(padding);
            break;
        case 2:
            d1 = data[off + dataLength] & 0xff;
            d2 = data[off + dataLength + 1] & 0xff;
            b1 = (d1 >>> 2) & 0x3f;
            b2 = ((d1 << 4) | (d2 >>> 4)) & 0x3f;
            b3 = (d2 << 2) & 0x3f;
            out.write(encodingTable[b1]);
            out.write(encodingTable[b2]);
            out.write(encodingTable[b3]);
            out.write(padding);
            break;
        }
        return (dataLength / 3) * 4 + ((modulus == 0) ? 0 : 4);
    }
    private boolean ignore(
        char    c)
    {
        return (c == '\n' || c =='\r' || c == '\t' || c == ' ');
    }

    /**
     * decode the base 64 encoded byte data writing it to the given output stream,
     * whitespace characters will be ignored.
     *
     * @return the number of bytes produced.
     */
    public int decode(
        byte[]          data,
        int             off,
        int             length,
        OutputStream    out)
        throws IOException
    {
        byte    b1, b2, b3, b4;
        int     outLen = 0;

        int     end = off + length;

        while (end > off)
        {
            if (!ignore((char)data[end - 1]))
            {
                break;
            }

            end--;
        }

        int i = off;
        int finish = end - 4;

        i = nextI(data, i, finish);
        while (i < finish)
        {
            b1 = decodingTable[data[i++]];

            i = nextI(data, i, finish);

            b2 = decodingTable[data[i++]];

            i = nextI(data, i, finish);

            b3 = decodingTable[data[i++]];

            i = nextI(data, i, finish);

            b4 = decodingTable[data[i++]];
            out.write((b1 << 2) | (b2 >> 4));
            out.write((b2 << 4) | (b3 >> 2));
            out.write((b3 << 6) | b4);

            outLen += 3;

            i = nextI(data, i, finish);
        }
        outLen += decodeLastBlock(out, (char)data[end - 4], (char)data[end - 3], (char)data[end - 2], (char)data[end - 1]);

        return outLen;
    }
    private int nextI(byte[] data, int i, int finish)
    {
        while ((i < finish) && ignore((char)data[i]))
        {
            i++;
        }
        return i;
    }

    /**
     * decode the base 64 encoded String data writing it to the given output stream,
     * whitespace characters will be ignored.
     *
     * @return the number of bytes produced.
     */
    public int decode(
        String          data,
        OutputStream    out)
        throws IOException
    {
        byte    b1, b2, b3, b4;
        int     length = 0;

        int     end = data.length();

        while (end > 0)
        {
            if (!ignore(data.charAt(end - 1)))
            {
                break;
            }

            end--;
        }

        int i = 0;
        int finish = end - 4;

        i = nextI(data, i, finish);

        while (i < finish)
        {
            b1 = decodingTable[data.charAt(i++)];

            i = nextI(data, i, finish);

            b2 = decodingTable[data.charAt(i++)];

            i = nextI(data, i, finish);

            b3 = decodingTable[data.charAt(i++)];

            i = nextI(data, i, finish);

            b4 = decodingTable[data.charAt(i++)];
            out.write((b1 << 2) | (b2 >> 4));
            out.write((b2 << 4) | (b3 >> 2));
            out.write((b3 << 6) | b4);

            length += 3;

            i = nextI(data, i, finish);
        }
        length += decodeLastBlock(out, data.charAt(end - 4), data.charAt(end - 3), data.charAt(end - 2), data.charAt(end - 1));
        return length;
    }
    private int decodeLastBlock(OutputStream out, char c1, char c2, char c3, char c4)
        throws IOException
    {
        byte    b1, b2, b3, b4;

        if (c3 == padding)
        {
            b1 = decodingTable[c1];
            b2 = decodingTable[c2];
            out.write((b1 << 2) | (b2 >> 4));

            return 1;
        }
        else if (c4 == padding)
        {
            b1 = decodingTable[c1];
            b2 = decodingTable[c2];
            b3 = decodingTable[c3];
            out.write((b1 << 2) | (b2 >> 4));
            out.write((b2 << 4) | (b3 >> 2));

            return 2;
        }
        else
        {
            b1 = decodingTable[c1];
            b2 = decodingTable[c2];
            b3 = decodingTable[c3];
            b4 = decodingTable[c4];
            out.write((b1 << 2) | (b2 >> 4));
            out.write((b2 << 4) | (b3 >> 2));
            out.write((b3 << 6) | b4);

            return 3;
        }
    }
    private int nextI(String data, int i, int finish)
    {
        while ((i < finish) && ignore(data.charAt(i)))
        {
            i++;
        }
        return i;
    }
}
------------------------------------------------------------------------------------------------
public class Base64
{
    private static final Base64Codec encoder = new Base64Codec();
    /**
     * encode the input data producing a base 64 encoded byte array.
     *
     * @return a byte array containing the base 64 encoded data.
     */
    public static byte[] encode(byte[] data)
    {
        int len = (data.length + 2) / 3 * 4;
        ByteArrayOutputStream bOut = new ByteArrayOutputStream(len);
        try
        {
            encoder.encode(data, 0, data.length, bOut);
        }
        catch (IOException e)
        {
            throw new RuntimeException("exception encoding base64 string: " + e);
        }
        return bOut.toByteArray();
    }

    public static String encode(String data)
    {
    if(IsStringNullOrEmpty(data))
      return "";

        byte[] byte_encoded = encode(data.getBytes());

        return new String(byte_encoded);
    }
    public static Boolean IsStringNullOrEmpty(String str) {
  return str == null || str.length() <= 0;
}
    /**
     * Encode the byte data to base 64 writing it to the given output stream.
     *
     * @return the number of bytes produced.
     */
    public static int encode(byte[] data, OutputStream out) throws IOException
    {
        return encoder.encode(data, 0, data.length, out);
    }
    /**
     * Encode the byte data to base 64 writing it to the given output stream.
     *
     * @return the number of bytes produced.
     */
    public static int encode(byte[] data, int off, int length, OutputStream out)
            throws IOException
    {
        return encoder.encode(data, off, length, out);
    }
    /**
     * decode the base 64 encoded input data. It is assumed the input data is
     * valid.
     *
     * @return a byte array representing the decoded data.
     */
    public static byte[] decode(byte[] data)
    {
        int len = data.length / 4 * 3;
        ByteArrayOutputStream bOut = new ByteArrayOutputStream(len);
        try
        {
            encoder.decode(data, 0, data.length, bOut);
        }
        catch (IOException e)
        {
            throw new RuntimeException("exception decoding base64 string: " + e);
        }
        return bOut.toByteArray();
    }
    /**
     * decode the base 64 encoded String data - whitespace will be ignored.
     *
     * @return a byte array representing the decoded data.
     */
    public static byte[] decodeToByteArray(String data)
    {
    if(IsStringNullOrEmpty(data))
      return null;

        int len = data.length() / 4 * 3;
        ByteArrayOutputStream bOut = new ByteArrayOutputStream(len);
        try
        {
            encoder.decode(data, bOut);
        }
        catch (IOException e)
        {
            throw new RuntimeException("exception decoding base64 string: " + e);
        }
        return bOut.toByteArray();
    }
    /**
     * decode the base 64 encoded String data writing it to the given output
     * stream, whitespace characters will be ignored.
     *
     * @return the number of bytes produced.
     */
    public static int decode(String data, OutputStream out) throws IOException
    {
    if(IsStringNullOrEmpty(data))
      return 0;

        return encoder.decode(data, out);
    }


    public static String decode(String data)
    {
    if(IsStringNullOrEmpty(data))
      return "";

        return decode(data, "utf-8");
    }

    public static String decode(String data, String codec)
    {
        byte[] bytes_out = decodeToByteArray(data);
        try {
   return new String(bytes_out, codec);
//        return new String(bytes_out);
  } catch (UnsupportedEncodingException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }
        return "";
    }
}
使用的时候可以直接调用Base64.encode（string s）进行加密，直接调用Base64.decode(s)进行解密

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