base64.java

进行与数字证书相关开发必须的java源码

// Decompiled by Jad v1.5.7g. Copyright 2000 Pavel Kouznetsov.
// Jad home page: http://www.geocities.com/SiliconValley/Bridge/8617/jad.html
// Decompiler options: packimports(3) fieldsfirst ansi 
// Source File Name:   Base64.java

package jit.util.encoders;


public class Base64
{

    private static final byte encodingTable[] = {
        65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 
        75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 
        85, 86, 87, 88, 89, 90, 97, 98, 99, 100, 
        101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 
        111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 
        121, 122, 48, 49, 50, 51, 52, 53, 54, 55, 
        56, 57, 43, 47
    };
    private static final byte decodingTable[];

    public Base64()
    {
    }

    public static byte[] encode(byte data[])
    {
        int modulus = data.length % 3;
        byte bytes[];
        if(modulus == 0)
            bytes = new byte[(4 * data.length) / 3];
        else
            bytes = new byte[4 * (data.length / 3 + 1)];
        int dataLength = data.length - modulus;
        int i = 0;
        for(int j = 0; i < dataLength; j += 4)
        {
            int a1 = data[i] & 0xff;
            int a2 = data[i + 1] & 0xff;
            int a3 = data[i + 2] & 0xff;
            bytes[j] = encodingTable[a1 >>> 2 & 0x3f];
            bytes[j + 1] = encodingTable[(a1 << 4 | a2 >>> 4) & 0x3f];
            bytes[j + 2] = encodingTable[(a2 << 2 | a3 >>> 6) & 0x3f];
            bytes[j + 3] = encodingTable[a3 & 0x3f];
            i += 3;
        }

        switch(modulus)
        {
        case 1: // '\001'
            int d1 = data[data.length - 1] & 0xff;
            int b1 = d1 >>> 2 & 0x3f;
            int b2 = d1 << 4 & 0x3f;
            bytes[bytes.length - 4] = encodingTable[b1];
            bytes[bytes.length - 3] = encodingTable[b2];
            bytes[bytes.length - 2] = 61;
            bytes[bytes.length - 1] = 61;
            break;

        case 2: // '\002'
            int d1 = data[data.length - 2] & 0xff;
            int d2 = data[data.length - 1] & 0xff;
            int b1 = d1 >>> 2 & 0x3f;
            int b2 = (d1 << 4 | d2 >>> 4) & 0x3f;
            int b3 = d2 << 2 & 0x3f;
            bytes[bytes.length - 4] = encodingTable[b1];
            bytes[bytes.length - 3] = encodingTable[b2];
            bytes[bytes.length - 2] = encodingTable[b3];
            bytes[bytes.length - 1] = 61;
            break;
        }
        return bytes;
    }

    public static byte[] decode(byte data[])
    {
        byte bytes[];
        if(data[data.length - 2] == 61)
            bytes = new byte[(data.length / 4 - 1) * 3 + 1];
        else
        if(data[data.length - 1] == 61)
            bytes = new byte[(data.length / 4 - 1) * 3 + 2];
        else
            bytes = new byte[(data.length / 4) * 3];
        int i = 0;
        for(int j = 0; i < data.length - 4; j += 3)
        {
            byte b1 = decodingTable[data[i]];
            byte b2 = decodingTable[data[i + 1]];
            byte b3 = decodingTable[data[i + 2]];
            byte b4 = decodingTable[data[i + 3]];
            bytes[j] = (byte)(b1 << 2 | b2 >> 4);
            bytes[j + 1] = (byte)(b2 << 4 | b3 >> 2);
            bytes[j + 2] = (byte)(b3 << 6 | b4);
            i += 4;
        }

        if(data[data.length - 2] == 61)
        {
            byte b1 = decodingTable[data[data.length - 4]];
            byte b2 = decodingTable[data[data.length - 3]];
            bytes[bytes.length - 1] = (byte)(b1 << 2 | b2 >> 4);
        } else
        if(data[data.length - 1] == 61)
        {
            byte b1 = decodingTable[data[data.length - 4]];
            byte b2 = decodingTable[data[data.length - 3]];
            byte b3 = decodingTable[data[data.length - 2]];
            bytes[bytes.length - 2] = (byte)(b1 << 2 | b2 >> 4);
            bytes[bytes.length - 1] = (byte)(b2 << 4 | b3 >> 2);
        } else
        {
            byte b1 = decodingTable[data[data.length - 4]];
            byte b2 = decodingTable[data[data.length - 3]];
            byte b3 = decodingTable[data[data.length - 2]];
            byte b4 = decodingTable[data[data.length - 1]];
            bytes[bytes.length - 3] = (byte)(b1 << 2 | b2 >> 4);
            bytes[bytes.length - 2] = (byte)(b2 << 4 | b3 >> 2);
            bytes[bytes.length - 1] = (byte)(b3 << 6 | b4);
        }
        return bytes;
    }

    public static byte[] decode(String data)
    {
        byte bytes[];
        if(data.charAt(data.length() - 2) == '=')
            bytes = new byte[(data.length() / 4 - 1) * 3 + 1];
        else
        if(data.charAt(data.length() - 1) == '=')
            bytes = new byte[(data.length() / 4 - 1) * 3 + 2];
        else
            bytes = new byte[(data.length() / 4) * 3];
        int i = 0;
        for(int j = 0; i < data.length() - 4; j += 3)
        {
            byte b1 = decodingTable[data.charAt(i)];
            byte b2 = decodingTable[data.charAt(i + 1)];
            byte b3 = decodingTable[data.charAt(i + 2)];
            byte b4 = decodingTable[data.charAt(i + 3)];
            bytes[j] = (byte)(b1 << 2 | b2 >> 4);
            bytes[j + 1] = (byte)(b2 << 4 | b3 >> 2);
            bytes[j + 2] = (byte)(b3 << 6 | b4);
            i += 4;
        }

        if(data.charAt(data.length() - 2) == '=')
        {
            byte b1 = decodingTable[data.charAt(data.length() - 4)];
            byte b2 = decodingTable[data.charAt(data.length() - 3)];
            bytes[bytes.length - 1] = (byte)(b1 << 2 | b2 >> 4);
        } else
        if(data.charAt(data.length() - 1) == '=')
        {
            byte b1 = decodingTable[data.charAt(data.length() - 4)];
            byte b2 = decodingTable[data.charAt(data.length() - 3)];
            byte b3 = decodingTable[data.charAt(data.length() - 2)];
            bytes[bytes.length - 2] = (byte)(b1 << 2 | b2 >> 4);
            bytes[bytes.length - 1] = (byte)(b2 << 4 | b3 >> 2);
        } else
        {
            byte b1 = decodingTable[data.charAt(data.length() - 4)];
            byte b2 = decodingTable[data.charAt(data.length() - 3)];
            byte b3 = decodingTable[data.charAt(data.length() - 2)];
            byte b4 = decodingTable[data.charAt(data.length() - 1)];
            bytes[bytes.length - 3] = (byte)(b1 << 2 | b2 >> 4);
            bytes[bytes.length - 2] = (byte)(b2 << 4 | b3 >> 2);
            bytes[bytes.length - 1] = (byte)(b3 << 6 | b4);
        }
        return bytes;
    }

    static 
    {
        decodingTable = new byte[128];
        for(int i = 65; i <= 90; i++)
            decodingTable[i] = (byte)(i - 65);

        for(int i = 97; i <= 122; i++)
            decodingTable[i] = (byte)((i - 97) + 26);

        for(int i = 48; i <= 57; i++)
            decodingTable[i] = (byte)((i - 48) + 52);

        decodingTable[43] = 62;
        decodingTable[47] = 63;
    }
}