Main.java Source code

Introduction

Here is the source code for Main.java

Source

//package com.java2s;
/*
 * Copyright 2004-2014 the Seasar Foundation and the Others.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
 * either express or implied. See the License for the specific language
 * governing permissions and limitations under the License.
 */

public class Main {
    private static final char PAD = '=';
    private static final byte[] DECODE_TABLE = new byte[128];

    public static byte[] decodeAsBase64(final String inData) {
        int num = (inData.length() / 4) - 1;
        int lastBytes = getLastBytes(inData);
        byte[] outData = new byte[num * 3 + lastBytes];
        for (int i = 0; i < num; i++) {
            decode(inData, i * 4, outData, i * 3);
        }
        switch (lastBytes) {
        case 1:
            decode1byte(inData, num * 4, outData, num * 3);
            break;
        case 2:
            decode2byte(inData, num * 4, outData, num * 3);
            break;
        default:
            decode(inData, num * 4, outData, num * 3);
        }
        return outData;
    }

    private static int getLastBytes(final String inData) {
        int len = inData.length();
        if (inData.charAt(len - 2) == PAD) {
            return 1;
        } else if (inData.charAt(len - 1) == PAD) {
            return 2;
        } else {
            return 3;
        }
    }

    private static void decode(final String inData, final int inIndex, final byte[] outData, final int outIndex) {
        byte b0 = DECODE_TABLE[inData.charAt(inIndex)];
        byte b1 = DECODE_TABLE[inData.charAt(inIndex + 1)];
        byte b2 = DECODE_TABLE[inData.charAt(inIndex + 2)];
        byte b3 = DECODE_TABLE[inData.charAt(inIndex + 3)];
        outData[outIndex] = (byte) (b0 << 2 & 0xfc | b1 >> 4 & 0x3);
        outData[outIndex + 1] = (byte) (b1 << 4 & 0xf0 | b2 >> 2 & 0xf);
        outData[outIndex + 2] = (byte) (b2 << 6 & 0xc0 | b3 & 0x3f);
    }

    private static void decode1byte(final String inData, final int inIndex, final byte[] outData,
            final int outIndex) {
        byte b0 = DECODE_TABLE[inData.charAt(inIndex)];
        byte b1 = DECODE_TABLE[inData.charAt(inIndex + 1)];
        outData[outIndex] = (byte) (b0 << 2 & 0xfc | b1 >> 4 & 0x3);
    }

    private static void decode2byte(final String inData, final int inIndex, final byte[] outData,
            final int outIndex) {
        byte b0 = DECODE_TABLE[inData.charAt(inIndex)];
        byte b1 = DECODE_TABLE[inData.charAt(inIndex + 1)];
        byte b2 = DECODE_TABLE[inData.charAt(inIndex + 2)];
        outData[outIndex] = (byte) (b0 << 2 & 0xfc | b1 >> 4 & 0x3);
        outData[outIndex + 1] = (byte) (b1 << 4 & 0xf0 | b2 >> 2 & 0xf);
    }
}