一个比较快的Base64 编码/解码 算法

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转自: 中国开源社区  最快的 Base64 编码/解码 算法

 

需要的jar包  commons-lang-2.5.jar

 

import java.util.Arrays;

import java.io.UnsupportedEncodingException;

import org.apache.commons.lang.time.StopWatch;

public class Base64 {
	private static final char[] CHARS = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
			.toCharArray();

	private static final int[] INV = new int[256];

	static {

		Arrays.fill(INV, -1);

		for (int i = 0, iS = CHARS.length; i < iS; i++) {

			INV[CHARS[i]] = i;

		}

		INV['='] = 0;

	}

	/**
	 * 
	 * Returns Base64 characters, a clone of used array.
	 */

	public static char[] getAlphabet() {

		return CHARS.clone();

	}

	// ---------------------------------------------------------------- char[]

	public static char[] encodeToChar(String s) {

		try {

			return encodeToChar(s.getBytes("UTF-8"), false);

		} catch (UnsupportedEncodingException ignore) {

			return null;

		}

	}

	public static char[] encodeToChar(byte[] arr) {

		return encodeToChar(arr, false);

	}

	/**
	 * 
	 * Encodes a raw byte array into a BASE64 char[].
	 */

	public static char[] encodeToChar(byte[] arr, boolean lineSeparator) {

		int len = arr != null ? arr.length : 0;

		if (len == 0) {

			return new char[0];

		}

		int evenlen = (len / 3) * 3;

		int cnt = ((len - 1) / 3 + 1) << 2;

		int destLen = cnt + (lineSeparator ? (cnt - 1) / 76 << 1 : 0);

		char[] dest = new char[destLen];

		for (int s = 0, d = 0, cc = 0; s < evenlen;) {

			int i = (arr[s++] & 0xff) << 16 | (arr[s++] & 0xff) << 8

			| (arr[s++] & 0xff);

			dest[d++] = CHARS[(i >>> 18) & 0x3f];

			dest[d++] = CHARS[(i >>> 12) & 0x3f];

			dest[d++] = CHARS[(i >>> 6) & 0x3f];

			dest[d++] = CHARS[i & 0x3f];

			if (lineSeparator && (++cc == 19) && (d < (destLen - 2))) {

				dest[d++] = '\r';

				dest[d++] = '\n';

				cc = 0;

			}

		}

		int left = len - evenlen; // 0 - 2.

		if (left > 0) {

			int i = ((arr[evenlen] & 0xff) << 10)

			| (left == 2 ? ((arr[len - 1] & 0xff) << 2) : 0);

			dest[destLen - 4] = CHARS[i >> 12];

			dest[destLen - 3] = CHARS[(i >>> 6) & 0x3f];

			dest[destLen - 2] = left == 2 ? CHARS[i & 0x3f] : '=';

			dest[destLen - 1] = '=';

		}

		return dest;

	}

	/**
	 * 
	 * Decodes a BASE64 encoded char array.
	 */

	public byte[] decode(char[] arr) {

		int length = arr.length;

		if (length == 0) {

			return new byte[0];

		}

		int sndx = 0, endx = length - 1;

		int pad = arr[endx] == '=' ? (arr[endx - 1] == '=' ? 2 : 1) : 0;

		int cnt = endx - sndx + 1;

		int sepCnt = length > 76 ? (arr[76] == '\r' ? cnt / 78 : 0) << 1 : 0;

		int len = ((cnt - sepCnt) * 6 >> 3) - pad;

		byte[] dest = new byte[len];

		int d = 0;

		for (int cc = 0, eLen = (len / 3) * 3; d < eLen;) {

			int i = INV[arr[sndx++]] << 18 | INV[arr[sndx++]] << 12

			| INV[arr[sndx++]] << 6 | INV[arr[sndx++]];

			dest[d++] = (byte) (i >> 16);

			dest[d++] = (byte) (i >> 8);

			dest[d++] = (byte) i;

			if (sepCnt > 0 && ++cc == 19) {

				sndx += 2;

				cc = 0;

			}

		}

		if (d < len) {

			int i = 0;

			for (int j = 0; sndx <= endx - pad; j++) {

				i |= INV[arr[sndx++]] << (18 - j * 6);

			}

			for (int r = 16; d < len; r -= 8) {

				dest[d++] = (byte) (i >> r);

			}

		}

		return dest;

	}

	// ---------------------------------------------------------------- byte

	public static byte[] encodeToByte(String s) {

		try {

			return encodeToByte(s.getBytes("UTF-8"), false);

		} catch (UnsupportedEncodingException ignore) {

			return null;

		}

	}

	public static byte[] encodeToByte(byte[] arr) {

		return encodeToByte(arr, false);

	}

	/**
	 * 
	 * Encodes a raw byte array into a BASE64 byte[].
	 */

	public static byte[] encodeToByte(byte[] arr, boolean lineSep) {

		int len = arr != null ? arr.length : 0;

		if (len == 0) {

			return new byte[0];

		}

		int evenlen = (len / 3) * 3;

		int cnt = ((len - 1) / 3 + 1) << 2;

		int destlen = cnt + (lineSep ? (cnt - 1) / 76 << 1 : 0);

		byte[] dest = new byte[destlen];

		for (int s = 0, d = 0, cc = 0; s < evenlen;) {

			int i = (arr[s++] & 0xff) << 16 | (arr[s++] & 0xff) << 8

			| (arr[s++] & 0xff);

			dest[d++] = (byte) CHARS[(i >>> 18) & 0x3f];

			dest[d++] = (byte) CHARS[(i >>> 12) & 0x3f];

			dest[d++] = (byte) CHARS[(i >>> 6) & 0x3f];

			dest[d++] = (byte) CHARS[i & 0x3f];

			if (lineSep && ++cc == 19 && d < destlen - 2) {

				dest[d++] = '\r';

				dest[d++] = '\n';

				cc = 0;

			}

		}

		int left = len - evenlen;

		if (left > 0) {

			int i = ((arr[evenlen] & 0xff) << 10)

			| (left == 2 ? ((arr[len - 1] & 0xff) << 2) : 0);

			dest[destlen - 4] = (byte) CHARS[i >> 12];

			dest[destlen - 3] = (byte) CHARS[(i >>> 6) & 0x3f];

			dest[destlen - 2] = left == 2 ? (byte) CHARS[i & 0x3f] : (byte) '=';

			dest[destlen - 1] = '=';

		}

		return dest;

	}

	/**
	 * 
	 * Decodes a BASE64 encoded byte array.
	 */

	public static byte[] decode(byte[] arr) {

		int length = arr.length;

		if (length == 0) {

			return new byte[0];

		}

		int sndx = 0, endx = length - 1;

		int pad = arr[endx] == '=' ? (arr[endx - 1] == '=' ? 2 : 1) : 0;

		int cnt = endx - sndx + 1;

		int sepCnt = length > 76 ? (arr[76] == '\r' ? cnt / 78 : 0) << 1 : 0;

		int len = ((cnt - sepCnt) * 6 >> 3) - pad;

		byte[] dest = new byte[len];

		int d = 0;

		for (int cc = 0, eLen = (len / 3) * 3; d < eLen;) {

			int i = INV[arr[sndx++]] << 18 | INV[arr[sndx++]] << 12

			| INV[arr[sndx++]] << 6 | INV[arr[sndx++]];

			dest[d++] = (byte) (i >> 16);

			dest[d++] = (byte) (i >> 8);

			dest[d++] = (byte) i;

			if (sepCnt > 0 && ++cc == 19) {

				sndx += 2;

				cc = 0;

			}

		}

		if (d < len) {

			int i = 0;

			for (int j = 0; sndx <= endx - pad; j++) {

				i |= INV[arr[sndx++]] << (18 - j * 6);

			}

			for (int r = 16; d < len; r -= 8) {

				dest[d++] = (byte) (i >> r);

			}

		}

		return dest;

	}

	// ---------------------------------------------------------------- string

	public static String encodeToString(String s) {

		try {

			return new String(encodeToChar(s.getBytes("UTF-8"), false));

		} catch (UnsupportedEncodingException ignore) {

			return null;

		}

	}

	public static String decodeToString(String s) {

		try {

			return new String(decode(s), "UTF-8");

		} catch (UnsupportedEncodingException ignore) {

			return null;

		}

	}

	public static String encodeToString(byte[] arr) {

		return new String(encodeToChar(arr, false));

	}

	/**
	 * 
	 * Encodes a raw byte array into a BASE64 String.
	 */

	public static String encodeToString(byte[] arr, boolean lineSep) {

		return new String(encodeToChar(arr, lineSep));

	}

	/**
	 * 
	 * Decodes a BASE64 encoded string.
	 */

	public static byte[] decode(String s) {

		int length = s.length();

		if (length == 0) {

			return new byte[0];

		}

		int sndx = 0, endx = length - 1;

		int pad = s.charAt(endx) == '=' ? (s.charAt(endx - 1) == '=' ? 2 : 1)

		: 0;

		int cnt = endx - sndx + 1;

		int sepCnt = length > 76 ? (s.charAt(76) == '\r' ? cnt / 78 : 0) << 1

		: 0;

		int len = ((cnt - sepCnt) * 6 >> 3) - pad;

		byte[] dest = new byte[len];

		int d = 0;

		for (int cc = 0, eLen = (len / 3) * 3; d < eLen;) {

			int i = INV[s.charAt(sndx++)] << 18 | INV[s.charAt(sndx++)] << 12

			| INV[s.charAt(sndx++)] << 6 | INV[s.charAt(sndx++)];

			dest[d++] = (byte) (i >> 16);

			dest[d++] = (byte) (i >> 8);

			dest[d++] = (byte) i;

			if (sepCnt > 0 && ++cc == 19) {

				sndx += 2;

				cc = 0;

			}

		}

		if (d < len) {

			int i = 0;

			for (int j = 0; sndx <= endx - pad; j++) {

				i |= INV[s.charAt(sndx++)] << (18 - j * 6);

			}

			for (int r = 16; d < len; r -= 8) {

				dest[d++] = (byte) (i >> r);

			}

		}

		return dest;

	}

	public static void main(String[] args) {

		StopWatch sw = new StopWatch();
		sw.start();

		String str = "!@#¥%……&*()——+brown fox jumps 你好,我是谁,Hello,我dogThe quick brown fox jumps over the lazy dog";

		for (int i = 0; i < 100000; i++) {
			//Base64.encodeToByte(str);
			Base64.encodeToString(str);
		}

		//System.out.println(Base64.encodeToString(str));

		sw.stop();

		System.out.println(sw.getTime() + "毫秒");

	}

}

 

 

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