BASE64Encoder.java

package com.github.javautils.encrypt;

import java.io.IOException;
import java.io.OutputStream;

/**
 * <p>
 * Description:base64编码类
 * </p>
 */
public class BASE64Encoder extends CharacterEncoder {

    public BASE64Encoder() {
    }

    protected int bytesPerAtom() {
        return 3;
    }

    protected int bytesPerLine() {
        return 57;
    }

    protected void encodeAtom(OutputStream outputstream, byte abyte0[], int i, int j) throws IOException {
        if (j == 1) {
            byte byte0 = abyte0[i];
            int k = 0;
            outputstream.write(pem_array[byte0 >>> 2 & 0x3f]);
            outputstream.write(pem_array[(byte0 << 4 & 0x30) + (k >>> 4 & 0xf)]);
            outputstream.write(61);
            outputstream.write(61);
        } else if (j == 2) {
            byte byte1 = abyte0[i];
            byte byte3 = abyte0[i + 1];
            int l = 0;
            outputstream.write(pem_array[byte1 >>> 2 & 0x3f]);
            outputstream.write(pem_array[(byte1 << 4 & 0x30) + (byte3 >>> 4 & 0xf)]);
            outputstream.write(pem_array[(byte3 << 2 & 0x3c) + (l >>> 6 & 3)]);
            outputstream.write(61);
        } else {
            byte byte2 = abyte0[i];
            byte byte4 = abyte0[i + 1];
            byte byte5 = abyte0[i + 2];
            outputstream.write(pem_array[byte2 >>> 2 & 0x3f]);
            outputstream.write(pem_array[(byte2 << 4 & 0x30) + (byte4 >>> 4 & 0xf)]);
            outputstream.write(pem_array[(byte4 << 2 & 0x3c) + (byte5 >>> 6 & 3)]);
            outputstream.write(pem_array[byte5 & 0x3f]);
        }
    }

    private static final char pem_array[] = {'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', '+', '/'};

}