java base64utils_【Java-API工具类】Base64Util类

Base64Util：https://ai.baidu.com/file/658A35ABAB2D404FBF903F64D47C1F72

Base64Util工具类

package com.baidu.ai.aip.utils;

/**

* Base64 工具类

*/

public class Base64Util {

private static final char last2byte = (char) Integer.parseInt("00000011", 2);

private static final char last4byte = (char) Integer.parseInt("00001111", 2);

private static final char last6byte = (char) Integer.parseInt("00111111", 2);

private static final char lead6byte = (char) Integer.parseInt("11111100", 2);

private static final char lead4byte = (char) Integer.parseInt("11110000", 2);

private static final char lead2byte = (char) Integer.parseInt("11000000", 2);

private static final char[] encodeTable = new char[]{'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', '+', '/'};

public Base64Util() {

}

public static String encode(byte[] from) {

StringBuilder to = new StringBuilder((int) ((double) from.length * 1.34D) + 3);

int num = 0;

char currentByte = 0;

int i;

for (i = 0; i < from.length; ++i) {

for (num %= 8; num < 8; num += 6) {

switch (num) {

case 0:

currentByte = (char) (from[i] & lead6byte);

currentByte = (char) (currentByte >>> 2);

case 1:

case 3:

case 5:

default:

break;

case 2:

currentByte = (char) (from[i] & last6byte);

break;

case 4:

currentByte = (char) (from[i] & last4byte);

currentByte = (char) (currentByte << 2);

if (i + 1 < from.length) {

currentByte = (char) (currentByte | (from[i + 1] & lead2byte) >>> 6);

}

break;

case 6:

currentByte = (char) (from[i] & last2byte);

currentByte = (char) (currentByte << 4);

if (i + 1 < from.length) {

currentByte = (char) (currentByte | (from[i + 1] & lead4byte) >>> 4);

}

}

to.append(encodeTable[currentByte]);

}

}

if (to.length() % 4 != 0) {

for (i = 4 - to.length() % 4; i > 0; --i) {

to.append("=");

}

}

return to.toString();

}

}