BASE64Encoder

从其它博客转过来的一个处理base64的代码，忘记出处了，使用原因为jdk自带的base64在encode时，会多一个换行，与php的base64交换时，会出错。

public class BASE64Encoder { 

    private static char[] codec_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', '+', '/' }; 

    public BASE64Encoder() {     } 

    public static String encode(byte[] a) { 
        int totalBits = a.length * 8; 
        int nn = totalBits % 6; 
        int curPos = 0;// process bits 
        StringBuffer toReturn = new StringBuffer(); 
        while (curPos < totalBits) { 
            int bytePos = curPos / 8; 
            switch (curPos%8) { 
            case 0: 
                toReturn.append(codec_table[(a[bytePos]&0xfc)>>2]); 
                break; 
            case 2: 
                toReturn.append(codec_table[(a[bytePos]&0x3f)]); 
                break; 
            case 4: 
                if (bytePos == a.length - 1) { 
                    toReturn.append(codec_table[((a[bytePos]&0x0f)<< 2)&0x3f]); 
                } else { 
                    int pos = (((a[bytePos] & 0x0f) << 2) | ((a[bytePos + 1] & 0xc0) >> 6)) & 0x3f; 
                    toReturn.append(codec_table[pos]); 
                } 
                break; 
            case 6: 
                if (bytePos == a.length - 1) { 
                    toReturn.append(codec_table[((a[bytePos] & 0x03) << 4) & 0x3f]); 
                } else { 
                    int pos = (((a[bytePos] & 0x03) << 4) | ((a[bytePos + 1] & 0xf0) >> 4))&0x3f;toReturn.append(codec_table[pos]); 
                } 
                break; 
            default: 
                //never hanppen 
                break; 
            } 
            curPos+=6; 
        } 
        if(nn==2) { 
            toReturn.append("=="); 
        } 
        else if(nn==4){ 
            toReturn.append("="); 
        } 
        return toReturn.toString(); 
    } 
}