base64encoder.java

来自「用纯java语言实现的数字证书制作工具。」· Java 代码 · 共 69 行

package data;
import java.io.IOException;
import java.io.OutputStream;



public class BASE64Encoder extends CharacterEncoder
{

    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', '+', '/'
    };

    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;
            boolean flag = false;
            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]);
        }
    }

}