Android Base64 Decode decode(String data, OutputStream out)

Description

Decode base64 encoded data.

Declaration

public static void decode(String data, OutputStream out)
        throws IOException 

Method Source Code

//package com.java2s;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;

import java.io.Reader;

public class Main {
    /**//w  w  w  .j  a  va2s. c o m
     * Charset used for base64 encoded data (7-bit ASCII).
     */
    private final static String CHARSET = "US-ASCII";
    /**
     * Decoding table.
     */
    private final static byte[] DECODETABLE = new byte[128];
    /**
     * pad character.
     */
    private static final char BASE64PAD = '=';

    /**
     * Decode base64 encoded data.
     */
    public static void decode(Reader reader, OutputStream out)
            throws IOException {
        char[] chunk = new char[8192];
        int read;
        while ((read = reader.read(chunk)) > -1) {
            decode(chunk, 0, read, out);
        }
    }

    /**
     * Decode base64 encoded data. The data read from the inputstream is assumed to be of charset "US-ASCII".
     */
    public static void decode(InputStream in, OutputStream out)
            throws IOException {
        decode(new InputStreamReader(in, CHARSET), out);
    }

    /**
     * Decode base64 encoded data.
     */
    public static void decode(String data, OutputStream out)
            throws IOException {
        char[] chars = data.toCharArray();
        decode(chars, 0, chars.length, out);
    }

    public static byte[] decode(String data) {
        ByteArrayOutputStream baos = new ByteArrayOutputStream(
                data.length());
        try {
            decode(data, baos);
        } catch (IOException ioe) {
            throw new IllegalStateException(ioe);
        }
        return baos.toByteArray();
    }

    /**
     * Decode base64 encoded data.
     */
    public static void decode(char[] chars, OutputStream out)
            throws IOException {
        decode(chars, 0, chars.length, out);
    }

    /**
     * Decode base64 encoded data.
     */
    public static void decode(char[] chars, int off, int len,
            OutputStream out) throws IOException {
        if (len == 0) {
            return;
        }
        if (len < 0 || off >= chars.length || len + off > chars.length) {
            throw new IllegalArgumentException();
        }
        char[] chunk = new char[4];
        byte[] dec = new byte[3];
        int posChunk = 0;
        // decode in chunks of 4 characters
        for (int i = off; i < (off + len); i++) {
            char c = chars[i];
            if (c < DECODETABLE.length && DECODETABLE[c] != 0x7f
                    || c == BASE64PAD) {
                chunk[posChunk++] = c;
                if (posChunk == chunk.length) {
                    int b0 = DECODETABLE[chunk[0]];
                    int b1 = DECODETABLE[chunk[1]];
                    int b2 = DECODETABLE[chunk[2]];
                    int b3 = DECODETABLE[chunk[3]];
                    if (chunk[3] == BASE64PAD && chunk[2] == BASE64PAD) {
                        dec[0] = (byte) (b0 << 2 & 0xfc | b1 >> 4 & 0x3);
                        out.write(dec, 0, 1);
                    } else if (chunk[3] == BASE64PAD) {
                        dec[0] = (byte) (b0 << 2 & 0xfc | b1 >> 4 & 0x3);
                        dec[1] = (byte) (b1 << 4 & 0xf0 | b2 >> 2 & 0xf);
                        out.write(dec, 0, 2);
                    } else {
                        dec[0] = (byte) (b0 << 2 & 0xfc | b1 >> 4 & 0x3);
                        dec[1] = (byte) (b1 << 4 & 0xf0 | b2 >> 2 & 0xf);
                        dec[2] = (byte) (b2 << 6 & 0xc0 | b3 & 0x3f);
                        out.write(dec, 0, 3);
                    }
                    posChunk = 0;
                }
            } else {
                throw new IllegalArgumentException(
                        "specified data is not base64 encoded");
            }
        }
    }
}

Related

1. decode(String str)
2. fromBase64(String data)
3. decodes(String base64)
4. decodeBase64(String encodedString)
5. decoderBase64File(String base64Code, String type)
6. decode(Reader reader, OutputStream out)
7. decode(char c)
8. decode(String s, OutputStream os)
9. decode(char[] arr)