sun base64解码实现

java 代码

// Decompiled by DJ v3.7.7.81 Copyright 2004 Atanas Neshkov  Date: 2007-6-11 11:45:48
// Home Page : http://members.fortunecity.com/neshkov/dj.html  - Check often for new version!
// Decompiler options: packimports(3)
// Source File Name:   CharacterDecoder.java

package sun.misc;

import java.io.*;
import java.nio.ByteBuffer;

// Referenced classes of package sun.misc:
//            CEStreamExhausted

public abstract class CharacterDecoder
{

    public CharacterDecoder()
    {
    }

    protected abstract int bytesPerAtom();

    protected abstract int bytesPerLine();

    protected void decodeBufferPrefix(PushbackInputStream pushbackinputstream, OutputStream outputstream)
        throws IOException
    {
    }

    protected void decodeBufferSuffix(PushbackInputStream pushbackinputstream, OutputStream outputstream)
        throws IOException
    {
    }

    protected int decodeLinePrefix(PushbackInputStream pushbackinputstream, OutputStream outputstream)
        throws IOException
    {
        return bytesPerLine();
    }

    protected void decodeLineSuffix(PushbackInputStream pushbackinputstream, OutputStream outputstream)
        throws IOException
    {
    }

    protected void decodeAtom(PushbackInputStream pushbackinputstream, OutputStream outputstream, int i)
        throws IOException
    {
        throw new CEStreamExhausted();
    }

    protected int readFully(InputStream inputstream, byte abyte0[], int i, int j)
        throws IOException
    {
        for(int k = 0; k < j; k++)
        {
            int l = inputstream.read();
            if(l == -1)
                return k != 0 ? k : -1;
            abyte0[k + i] = (byte)l;
        }

        return j;
    }

    public void decodeBuffer(InputStream inputstream, OutputStream outputstream)
        throws IOException
    {
        int j = 0;
        PushbackInputStream pushbackinputstream = new PushbackInputStream(inputstream);
        decodeBufferPrefix(pushbackinputstream, outputstream);
        try
        {
            do
            {
                int k = decodeLinePrefix(pushbackinputstream, outputstream);
                int i;
                for(i = 0; i + bytesPerAtom() < k; i += bytesPerAtom())
                {
                    decodeAtom(pushbackinputstream, outputstream, bytesPerAtom());
                    j += bytesPerAtom();
                }

                if(i + bytesPerAtom() == k)
                {
                    decodeAtom(pushbackinputstream, outputstream, bytesPerAtom());
                    j += bytesPerAtom();
                } else
                {
                    decodeAtom(pushbackinputstream, outputstream, k - i);
                    j += k - i;
                }
                decodeLineSuffix(pushbackinputstream, outputstream);
            } while(true);
        }
        catch(CEStreamExhausted cestreamexhausted)
        {
            decodeBufferSuffix(pushbackinputstream, outputstream);
        }
    }

    public byte[] decodeBuffer(String s)
        throws IOException
    {
        byte abyte0[] = new byte[s.length()];
        s.getBytes(0, s.length(), abyte0, 0);
        ByteArrayInputStream bytearrayinputstream = new ByteArrayInputStream(abyte0);
        ByteArrayOutputStream bytearrayoutputstream = new ByteArrayOutputStream();
        decodeBuffer(((InputStream) (bytearrayinputstream)), ((OutputStream) (bytearrayoutputstream)));
        return bytearrayoutputstream.toByteArray();
    }

    public byte[] decodeBuffer(InputStream inputstream)
        throws IOException
    {
        ByteArrayOutputStream bytearrayoutputstream = new ByteArrayOutputStream();
        decodeBuffer(inputstream, ((OutputStream) (bytearrayoutputstream)));
        return bytearrayoutputstream.toByteArray();
    }

    public ByteBuffer decodeBufferToByteBuffer(String s)
        throws IOException
    {
        return ByteBuffer.wrap(decodeBuffer(s));
    }

    public ByteBuffer decodeBufferToByteBuffer(InputStream inputstream)
        throws IOException
    {
        return ByteBuffer.wrap(decodeBuffer(inputstream));
    }
}


// Decompiled by DJ v3.7.7.81 Copyright 2004 Atanas Neshkov  Date: 2007-6-11 11:45:29
// Home Page : http://members.fortunecity.com/neshkov/dj.html  - Check often for new version!
// Decompiler options: packimports(3)
// Source File Name:   BASE64Decoder.java

package sun.misc;

import java.io.*;

// Referenced classes of package sun.misc:
//            CharacterDecoder, CEFormatException, CEStreamExhausted

public class BASE64Decoder extends CharacterDecoder
{

    public BASE64Decoder()
    {
        decode_buffer = new byte[4];
    }

    protected int bytesPerAtom()
    {
        return 4;
    }

    protected int bytesPerLine()
    {
        return 72;
    }

    protected void decodeAtom(PushbackInputStream pushbackinputstream, OutputStream outputstream, int i)
        throws IOException
    {
        byte byte0 = -1;
        byte byte1 = -1;
        byte byte2 = -1;
        byte byte3 = -1;
        if(i < 2)
            throw new CEFormatException("BASE64Decoder: Not enough bytes for an atom.");
        int j;
        do
        {
            j = pushbackinputstream.read();
            if(j == -1)
                throw new CEStreamExhausted();
        } while(j == 10 || j == 13);
        decode_buffer[0] = (byte)j;
        j = readFully(pushbackinputstream, decode_buffer, 1, i - 1);
        if(j == -1)
            throw new CEStreamExhausted();
        if(i > 3 && decode_buffer[3] == 61)
            i = 3;
        if(i > 2 && decode_buffer[2] == 61)
            i = 2;
        switch(i)
        {
        case 4: // '\004'
            byte3 = pem_convert_array[decode_buffer[3] & 0xff];
            // fall through

        case 3: // '\003'
            byte2 = pem_convert_array[decode_buffer[2] & 0xff];
            // fall through

        case 2: // '\002'
            byte1 = pem_convert_array[decode_buffer[1] & 0xff];
            byte0 = pem_convert_array[decode_buffer[0] & 0xff];
            // fall through

        default:
            switch(i)
            {
            case 2: // '\002'
                outputstream.write((byte)(byte0 << 2 & 0xfc | byte1 >>> 4 & 3));
                break;

            case 3: // '\003'
                outputstream.write((byte)(byte0 << 2 & 0xfc | byte1 >>> 4 & 3));
                outputstream.write((byte)(byte1 << 4 & 0xf0 | byte2 >>> 2 & 0xf));
                break;

            case 4: // '\004'
                outputstream.write((byte)(byte0 << 2 & 0xfc | byte1 >>> 4 & 3));
                outputstream.write((byte)(byte1 << 4 & 0xf0 | byte2 >>> 2 & 0xf));
                outputstream.write((byte)(byte2 << 6 & 0xc0 | byte3 & 0x3f));
                break;
            }
            break;
        }
    }

    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', '+', '/'
    };
    private static final byte pem_convert_array[];
    byte decode_buffer[];

    static
    {
        pem_convert_array = new byte[256];
        for(int i = 0; i < 255; i++)
            pem_convert_array[i] = -1;

        for(int j = 0; j < pem_array.length; j++)
            pem_convert_array[pem_array[j]] = (byte)j;

    }
}

 

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