Java Byte Array Decode decode(byte[] bytes)

Description

Decodes the specified bytes.

License

Apache License

Parameter

Parameter	Description
bytes	string to decode

Return

byte[]

Declaration

public static byte[] decode(byte[] bytes) throws IOException 

Method Source Code

//package com.java2s;
//License from project: Apache License 

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

public class Main {
    private static final int BUFFER_SIZE = 1024;
    public static final String ENCODING = "UTF-8";
    private static byte[] B64LOOKUP = new byte[256];

    /**/*from  w w w .j  a  va 2  s  . c  o m*/
     * Decodes the specified string.
     *
     * @param value   string to decode
     * @return byte[]
     */
    public static byte[] decode(String value) throws IOException {
        ByteArrayInputStream in = new ByteArrayInputStream(value.getBytes(ENCODING));
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        decode(in, out);
        return out.toByteArray();
    }

    /**
     * Decodes the specified bytes.
     *
     * @param bytes   string to decode
     * @return byte[]
     */
    public static byte[] decode(byte[] bytes) throws IOException {
        ByteArrayInputStream in = new ByteArrayInputStream(bytes);
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        decode(in, out);
        return out.toByteArray();
    }

    /**
     * Create a decoder to decode a String to the specified output stream
     *
     * @param value   string to be decoded.
     */
    public static void decode(String value, OutputStream out) throws IOException {
        decode(new ByteArrayInputStream(value.getBytes(ENCODING)), out);
    }

    /**
     * Create a decoder to decode a stream.
     *
     * @param in  The input stream (to be decoded).
     * @param out The output stream, to write decoded data to.
     */
    public static void decode(InputStream in, OutputStream out) throws IOException {
        byte buffer[] = new byte[BUFFER_SIZE];

        int shift = 0; // # of excess bits stored in accum
        int accum = 0; // excess bits
        int index = 0;

        int c = -1;

        // read through the input stream
        while ((c = in.read(buffer)) > 0) {

            for (int i = 0; i < c; i++) {
                int value = B64LOOKUP[buffer[i] & 0xFF]; // ignore high byte of char

                // skip over non-code
                if (value >= 0) {
                    accum <<= 6; // bits shift up by 6 each time thru
                    shift += 6; // loop, with new bits being put in
                    accum |= value; // at the bottom.

                    // whenever there are 8 or more shifted in,
                    if (shift >= 8) {
                        shift -= 8;

                        // write them out from the top, leaving any excess at the bottom for next iteration.
                        out.write((byte) ((accum >> shift) & 0xff));
                    }
                }
            }
        }
    }
}

Related

1. decode(byte[] b)
2. decode(byte[] bytes)
3. decode(byte[] bytes)
4. decode(byte[] msgToDecode)
5. decode(byte[] source)
6. decode(byte[] source, int off, int len)
7. decode(byte[] src, String charset)