java base64 工具类

import java.io.UnsupportedEncodingException;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import java.util.SortedMap;

public class Base64Util {

    private static final char[] legalChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".toCharArray();
    public  String getBase64Str(SortedMap<Object, Object> parameters) throws UnsupportedEncodingException {


        StringBuffer sb = new StringBuffer();
        Set es = parameters.entrySet();
        Iterator it = es.iterator();
        while (it.hasNext())
        {
            Map.Entry entry = (Map.Entry) it.next();
            String k = (String) entry.getKey();
            Object v = entry.getValue();
            if (null != v && !"".equals(v))
            {
                sb.append(k + "=" + v + "&");
            }
        }
        sb.deleteCharAt(sb.lastIndexOf("&"));
        return encode(sb.toString().getBytes("UTF-8")).replaceAll(" ", "");
    }


    public static String encode(byte[] data)
    {

        int start = 0;
        int len = data.length;
        StringBuffer buf = new StringBuffer(data.length * 3 / 2);

        int end = len - 3;
        int i = start;
        int n = 0;

        while (i <= end)
        {
            int d = ((((int) data[i]) & 0x0ff) << 16) | ((((int) data[i + 1]) & 0x0ff) << 8) | (((int) data[i + 2]) & 0x0ff);

            buf.append(legalChars[(d >> 18) & 63]);
            buf.append(legalChars[(d >> 12) & 63]);
            buf.append(legalChars[(d >> 6) & 63]);
            buf.append(legalChars[d & 63]);

            i += 3;

            if (n++ >= 14)
            {
                n = 0;
                buf.append(" ");
            }
        }

        if (i == start + len - 2)
        {
            int d = ((((int) data[i]) & 0x0ff) << 16) | ((((int) data[i + 1]) & 255) << 8);

            buf.append(legalChars[(d >> 18) & 63]);
            buf.append(legalChars[(d >> 12) & 63]);
            buf.append(legalChars[(d >> 6) & 63]);
            buf.append("=");
        }
        else if (i == start + len - 1)
        {
            int d = (((int) data[i]) & 0x0ff) << 16;

            buf.append(legalChars[(d >> 18) & 63]);
            buf.append(legalChars[(d >> 12) & 63]);
            buf.append("==");
        }

        return buf.toString();
    }
}