com.hecloud.runtime.common.encryptor.Base64Coder Maven / Gradle / Ivy

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package com.hecloud.runtime.common.encryptor;

/**
 * @author LoveInBj
 */
public class Base64Coder {
    static private char[] alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=".toCharArray();
    static private byte[] codes = new byte[256];
    static char A = 'A';
    static char a = 'a';
    static char Z = 'Z';
    static char z = 'z';
    static char ZERO = '0';
    static char NINE = '9';

    static {
        for (int i = 0; i < 256; i++) {
            codes[i] = -1;
        }
        for (int i = A; i <= Z; i++) {
            codes[i] = (byte) (i - A);
        }
        for (int i = a; i <= z; i++) {
            codes[i] = (byte) (26 + i - a);
        }
        for (int i = ZERO; i <= NINE; i++) {
            codes[i] = (byte) (52 + i - ZERO);
        }
        codes['+'] = 62;
        codes['/'] = 63;
    }

    /**
     * 将原始数据编码为base64编码
     *
     * @param data 数据
     * @return 编码后字符串
     * @throws Exception 运行异常 异常
     */
    static public String encode(byte[] data) throws Exception {
        char[] out = new char[((data.length + 2) / 3) * 4];
        for (int i = 0, index = 0; i < data.length; i += 3, index += 4) {
            boolean quad = false;
            boolean trip = false;
            int val = (0xFF & (int) data[i]);
            val <<= 8;
            if ((i + 1) < data.length) {
                val |= (0xFF & (int) data[i + 1]);
                trip = true;
            }
            val <<= 8;
            if ((i + 2) < data.length) {
                val |= (0xFF & (int) data[i + 2]);
                quad = true;
            }
            out[index + 3] = alphabet[(quad ? (val & 0x3F) : 64)];
            val >>= 6;
            out[index + 2] = alphabet[(trip ? (val & 0x3F) : 64)];
            val >>= 6;
            out[index + 1] = alphabet[val & 0x3F];
            val >>= 6;
            out[index + 0] = alphabet[val & 0x3F];
        }

        return new String(out);
    }

    /**
     * 将base64编码的数据解码成原始数据
     *
     * @param data 编码数据
     * @return 原始数据
     * @throws Exception 运行异常 运行异常
     */
    static public byte[] decode(char[] data) throws Exception {
        int len = ((data.length + 3) / 4) * 3;
        if (data.length > 0 && data[data.length - 1] == '=') {
            --len;
        }
        if (data.length > 1 && data[data.length - 2] == '=') {
            --len;
        }
        byte[] out = new byte[len];
        int shift = 0;
        int accum = 0;
        int index = 0;
        for (int ix = 0; ix < data.length; ix++) {
            int value = codes[data[ix] & 0xFF];
            if (value >= 0) {
                accum <<= 6;
                shift += 6;
                accum |= value;
                if (shift >= 8) {
                    shift -= 8;
                    out[index++] = (byte) ((accum >> shift) & 0xff);
                }
            }
        }
        if (index != out.length) {
            throw new Exception("数据长度计算错误!");
        }
        return out;
    }
}