base64.java

这个是我们做土地局的一个项目。感觉不错。欢迎下载

package Base64;

import java.io.PrintStream;

public class Base64
{

    public Base64()
    {
    }

    public static String encode(String s)
    {
        return getString(encode(getBinaryBytes(s)));
    }

    public static byte[] encode(byte abyte0[])
    {
        int l = abyte0.length;
        StringBuffer stringbuffer = new StringBuffer((l / 3 + 1) * 4);
        for(int i1 = 0; i1 < l; i1++)
        {
            int i = abyte0[i1] >> 2 & 0x3f;
            stringbuffer.append("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".charAt(i));
            i = abyte0[i1] << 4 & 0x3f;
            if(++i1 < l)
                i |= abyte0[i1] >> 4 & 0xf;
            stringbuffer.append("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".charAt(i));
            if(i1 < l)
            {
                int j = abyte0[i1] << 2 & 0x3f;
                if(++i1 < l)
                    j |= abyte0[i1] >> 6 & 3;
                stringbuffer.append("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".charAt(j));
            } else
            {
                i1++;
                stringbuffer.append('=');
            }
            if(i1 < l)
            {
                int k = abyte0[i1] & 0x3f;
                stringbuffer.append("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".charAt(k));
            } else
            {
                stringbuffer.append('=');
            }
        }

        return getBinaryBytes(stringbuffer.toString());
    }

    public static String decode(String s)
    {
        return getString(decode(getBinaryBytes(s)));
    }

    public static byte[] decode(byte abyte0[])
    {
        int k = abyte0.length;
        StringBuffer stringbuffer = new StringBuffer((k * 3) / 4);
        for(int l = 0; l < k; l++)
        {
            int i = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".indexOf(abyte0[l]);
            l++;
            int j = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".indexOf(abyte0[l]);
            i = i << 2 | j >> 4 & 3;
            stringbuffer.append((char)i);
            if(++l < k)
            {
                i = abyte0[l];
                if(61 == i)
                    break;
                i = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".indexOf((char)i);
                j = j << 4 & 0xf0 | i >> 2 & 0xf;
                stringbuffer.append((char)j);
            }
            if(++l >= k)
                continue;
            j = abyte0[l];
            if(61 == j)
                break;
            j = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".indexOf((char)j);
            i = i << 6 & 0xc0 | j;
            stringbuffer.append((char)i);
        }

        return getBinaryBytes(stringbuffer.toString());
    }

    private static String getString(byte abyte0[])
    {
        StringBuffer stringbuffer = new StringBuffer();
        for(int i = 0; i < abyte0.length; i++)
            stringbuffer.append((char)abyte0[i]);

        return stringbuffer.toString();
    }

    private static byte[] getBinaryBytes(String s)
    {
        byte abyte0[] = new byte[s.length()];
        for(int i = 0; i < abyte0.length; i++)
            abyte0[i] = (byte)s.charAt(i);

        return abyte0;
    }

    public static void main(String args[])
    {
        String s;
        if(args.length > 0)
            s = args[0];
        else
            s = "101";
        System.out.println("Encoding string [" + s + "]");
        s = encode(s);
        System.out.println("Encoded string  [" + s + "]");
        s = decode(s);
        System.out.println("Decoded string  [" + s + "]");
        System.out.println();
        byte abyte0[] = getBinaryBytes(s);
        System.out.println("Encoding bytes  [" + getString(abyte0) + "]");
        abyte0 = encode(abyte0);
        System.out.println("Encoded bytes   [" + getString(abyte0) + "]");
        abyte0 = decode(abyte0);
        System.out.println("Decoded bytes   [" + getString(abyte0) + "]");
    }

    private static final int fillchar = 61;
    private static final String cvt = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
}