去掉"/"后的base64加解密，js和java版

开发了一个 百度网盘热门资源站，因为用了spring mvc的resturl和有静态化需要，即把url生成对应的物理文件。所以想到用base64对用户的搜索关键词进行转码。但是因为原base64中，有字符“/”影响resturl的解析，所以对base64进行了稍加改造，去掉了“/”,改为“!”

js端转码代码：

function searchJump(key){
	key = base64encode(utf16to8(key));
	window.location.href = "/search/" + key+".html";
}

var base64EncodeChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+!";
function base64encode(str) {
	var out, i, len;
	var c1, c2, c3;
	len = str.length;
	i = 0;
	out = "";
	while (i < len) {
		c1 = str.charCodeAt(i++) & 0xff;
		if (i == len) {
			out += base64EncodeChars.charAt(c1 >> 2);
			out += base64EncodeChars.charAt((c1 & 0x3) << 4);
			out += "==";
			break;
		}
		c2 = str.charCodeAt(i++);
		if (i == len) {
			out += base64EncodeChars.charAt(c1 >> 2);
			out += base64EncodeChars.charAt(((c1 & 0x3) << 4)
					| ((c2 & 0xF0) >> 4));
			out += base64EncodeChars.charAt((c2 & 0xF) << 2);
			out += "=";
			break;
		}
		c3 = str.charCodeAt(i++);
		out += base64EncodeChars.charAt(c1 >> 2);
		out += base64EncodeChars.charAt(((c1 & 0x3) << 4) | ((c2 & 0xF0) >> 4));
		out += base64EncodeChars.charAt(((c2 & 0xF) << 2) | ((c3 & 0xC0) >> 6));
		out += base64EncodeChars.charAt(c3 & 0x3F);
	}
	return out;
}

function utf16to8(str) {
	var out, i, len, c;
	out = "";
	len = str.length;
	for (i = 0; i < len; i++) {
		c = str.charCodeAt(i);
		if ((c >= 0x0001) && (c <= 0x007F)) {
			out += str.charAt(i);
		} else if (c > 0x07FF) {
			out += String.fromCharCode(0xE0 | ((c >> 12) & 0x0F));
			out += String.fromCharCode(0x80 | ((c >> 6) & 0x3F));
			out += String.fromCharCode(0x80 | ((c >> 0) & 0x3F));
		} else {
			out += String.fromCharCode(0xC0 | ((c >> 6) & 0x1F));
			out += String.fromCharCode(0x80 | ((c >> 0) & 0x3F));
		}
	}
	return out;
}

java的转码代码：

package com.savetao.util;

public class Base64 {
    private static final char[] S_BASE64CHAR = {
        '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','+','!'
    };
    private static final char S_BASE64PAD = '=';
    private static final byte[] S_DECODETABLE = new byte[128];
    static {
        for (int i = 0;   i < S_DECODETABLE.length;   i ++)
            S_DECODETABLE[i] = Byte.MAX_VALUE;  // 127
        for (int i = 0;   i < S_BASE64CHAR.length;   i ++) // 0 to 63
            S_DECODETABLE[S_BASE64CHAR[i]] = (byte)i;
    }
    
    private static int decode0(char[] ibuf, byte[] obuf, int wp) {
        int outlen = 3;
        if (ibuf[3] == S_BASE64PAD)   outlen = 2;
        if (ibuf[2] == S_BASE64PAD)   outlen = 1;
        int b0 = S_DECODETABLE[ibuf[0]];
        int b1 = S_DECODETABLE[ibuf[1]];
        int b2 = S_DECODETABLE[ibuf[2]];
        int b3 = S_DECODETABLE[ibuf[3]];
        switch (outlen) {
        case 1:
            obuf[wp] = (byte)(b0 << 2 & 0xfc | b1 >> 4 & 0x3);
            return 1;
        case 2:
            obuf[wp++] = (byte)(b0 << 2 & 0xfc | b1 >> 4 & 0x3);
            obuf[wp] = (byte)(b1 << 4 & 0xf0 | b2 >> 2 & 0xf);
            return 2;
        case 3:
            obuf[wp++] = (byte)(b0 << 2 & 0xfc | b1 >> 4 & 0x3);
            obuf[wp++] = (byte)(b1 << 4 & 0xf0 | b2 >> 2 & 0xf);
            obuf[wp] = (byte)(b2 << 6 & 0xc0 | b3 & 0x3f);
            return 3;
        default:
            throw new RuntimeException("Couldn't decode.");
        }
    }


    public static byte[] decode(String data) {
        char[] ibuf = new char[4];
        int ibufcount = 0;
        byte[] obuf = new byte[data.length()/4*3+3];
        int obufcount = 0;
        for (int i = 0;   i < data.length();   i ++) {
            char ch = data.charAt(i);
            if (ch == S_BASE64PAD
                || ch < S_DECODETABLE.length && S_DECODETABLE[ch] != Byte.MAX_VALUE) {
                ibuf[ibufcount++] = ch;
                if (ibufcount == ibuf.length) {
                    ibufcount = 0;
                    obufcount += decode0(ibuf, obuf, obufcount);
                }
            }
        }
        if (obufcount == obuf.length)
            return obuf;
        byte[] ret = new byte[obufcount];
        System.arraycopy(obuf, 0, ret, 0, obufcount);
        return ret;
    }
    public static String encode(byte[] data) {
        return encode(data, 0, data.length);
    }
    
    public static String encode(byte[] data, int off, int len) {
        if (len <= 0)   return "";
        char[] out = new char[len/3*4+4];
        int rindex = off;
        int windex = 0;
        int rest = len-off;
        while (rest >= 3) {
            int i = ((data[rindex]&0xff)<<16)
                    +((data[rindex+1]&0xff)<<8)
                    +(data[rindex+2]&0xff);
            out[windex++] = S_BASE64CHAR[i>>18];
            out[windex++] = S_BASE64CHAR[(i>>12)&0x3f];
            out[windex++] = S_BASE64CHAR[(i>>6)&0x3f];
            out[windex++] = S_BASE64CHAR[i&0x3f];
            rindex += 3;
            rest -= 3;
        }
        if (rest == 1) {
            int i = data[rindex]&0xff;
            out[windex++] = S_BASE64CHAR[i>>2];
            out[windex++] = S_BASE64CHAR[(i<<4)&0x3f];
            out[windex++] = S_BASE64PAD;
            out[windex++] = S_BASE64PAD;
        } else if (rest == 2) {
            int i = ((data[rindex]&0xff)<<8)+(data[rindex+1]&0xff);
            out[windex++] = S_BASE64CHAR[i>>10];
            out[windex++] = S_BASE64CHAR[(i>>4)&0x3f];
            out[windex++] = S_BASE64CHAR[(i<<2)&0x3f];
            out[windex++] = S_BASE64PAD;
        }
        return new String(out, 0, windex);
    }    
    public static void main(String []args){
    	String s="美国队长";
    	System.out.println(Base64.encode(s.getBytes()));
    	System.out.println(new String(Base64.decode("576O5Zu96Zif6ZW!")));
    }    
}