// JavaScript代码：
StringUtil = {
Base64Chars:
"ABCDEFGHIJKLMNOP" +
"QRSTUVWXYZabcdef" +
"ghijklmnopqrstuv" +
"wxyz0123456789@*" +
"-",
/**
* Encode a string to a Base64 string follow Bse64 regular.
* @param s, a normal string
* @return a Base64 string
*/
base64Encode: function(s){
if(!s || s.length == 0) return s;
var d = "";
var b = this.ucs2_utf8(s);
var b0, b1, b2, b3;
var len = b.length;
var i = 0;
while(i < len){
var tmp = b[i++];
b0 = (tmp & 0xfc) >> 2;
b1 = (tmp & 0x03) << 4;
if(i < len){
tmp = b[i++];
b1 |= (tmp & 0xf0) >> 4;
b2 = (tmp & 0x0f) << 2;
if(i< len){
tmp = b[i++];
b2 |= (tmp & 0xc0) >> 6;
b3 = tmp & 0x3f;
}else{
b3 = 64; // 1 byte "-" is supplement
}
}else{
b2 = b3 = 64; // 2 bytes "-" are supplement
}
d+=this.Base64Chars.charAt(b0);
d+=this.Base64Chars.charAt(b1);
d+=this.Base64Chars.charAt(b2);
d+=this.Base64Chars.charAt(b3);
}
return d;
},
/**
* Decode a Base64 string to a string follow Base64 regular.
* @param s, a Base64 string
* @return a normal string
*/
base64Decode: function(s){
if(!s) return null;
var len = s.length;
if(len%4 != 0){
throw s+" is not a valid Base64 string.";
}
var b = new Array();
var i=0, j=0, e=0, c, tmp;
while(i < len){
c = this.Base64Chars.indexOf(s.charAt(i++));
tmp = c << 18;
c = this.Base64Chars.indexOf(s.charAt(i++));
tmp |= c << 12;
c = this.Base64Chars.indexOf(s.charAt(i++));
if(c < 64){
tmp |= c << 6;
c = this.Base64Chars.indexOf(s.charAt(i++));
if(c < 64){
tmp |= c;
}else{
e = 1;
}
}else{
e = 2;
i++;
}
b[j+2] = tmp & 0xff;
tmp >>= 8;
b[j+1] = tmp & 0xff;
tmp >>= 8;
b[j+0] = tmp & 0xff;
j += 3;
}
b.splice(b.length-e, e);
return this.utf8_ucs2(b);
},
/**
* Encodes a ucs2 string to a utf8 integer array.
* @param s, a string
* @return an integer array
*/
ucs2_utf8: function(s){
if (!s) return null;
var d = new Array();
if (s == "") return d;
var c = 0, i = 0, j = 0;
var len = s.length;
while(i < len){
c = s.charCodeAt(i++);
if(c <= 0x7f){
// 1 byte
d[j++] = c;
}else
if((c >= 0x80) && (c <= 0x7ff)){
// 2 bytes
d[j++] = ((c >> 6) & 0x1f) | 0xc0;
d[j++] = (c & 0x3f) | 0x80;
}else{
// 3 bytes
d[j++] = (c >> 12) | 0xe0;
d[j++] = ((c >> 6) & 0x3f) | 0x80;
d[j++] = (c & 0x3f) | 0x80;
}
}
return d;
},
/**
* Encodes a utf8 integer array to a ucs2 string.
* @param s, an integer array
* @return a string
*/
utf8_ucs2: function(s){
if(!s) return null;
var len = s.length;
if(len == 0) return "";
var d = "";
var c = 0, i = 0, tmp = 0;
while(i < len){
c = s[i++];
if((c & 0xe0) == 0xe0){
// 3 bytes
tmp = (c & 0x0f) << 12;
c = s[i++];
tmp |= ((c & 0x3f) << 6);
c = s[i++];
tmp |= (c & 0x3f);
}else
if((c & 0xc0) == 0xc0){
// 2 bytes
tmp = (c & 0x1f) << 6;
c = s[i++];
tmp |= (c & 0x3f);
}else{
// 1 byte
tmp = c;
}
d += String.fromCharCode(tmp);
}
return d;
},
}
//以下是相应的Java代码：
public final class StringUtil {
public static final String Base64Chars =
"ABCDEFGHIJKLMNOP" +
"QRSTUVWXYZabcdef" +
"ghijklmnopqrstuv" +
"wxyz0123456789@*" +
"-"; // supplement
/**
* Encoding a string to a string follow the Base64 regular
*
* @param s
* @return
*/
public static String base64Encode(final String s){
if(s == null || s.length()==0) return s;
byte[] b = null;
try {
b = s.getBytes("UTF-8");
} catch (java.io.UnsupportedEncodingException e) {
e.printStackTrace();
return s;
}
return base64EncodeFoArray(b);
}
/**
* Encoding a byte array to a string follow the Base64 regular.
*
* @param s byte array
* @return
*/
public static String base64EncodeFoArray(final byte[] s){
if(s == null) return null;
if(s.length == 0) return "";
StringBuffer buf = new StringBuffer();
int b0, b1, b2, b3;
int len = s.length;
int i=0;
while(i < len){
byte tmp = s[i++];
b0 = (tmp & 0xfc) >> 2;
b1 = (tmp & 0x03) << 4;
if(i < len){
tmp = s[i++];
b1 |=(tmp & 0xf0) >> 4;
b2 = (tmp & 0x0f) << 2;
if(i < len){
tmp = s[i++];
b2 |= (tmp & 0xc0) >> 6;
b3 = tmp & 0x3f;
}else{
b3 = 64; // 1 byte "-" is supplement
}
}else{
b2 = b3 = 64;// 2 bytes "-" are supplement
}
buf.append(Base64Chars.charAt(b0));
buf.append(Base64Chars.charAt(b1));
buf.append(Base64Chars.charAt(b2));
buf.append(Base64Chars.charAt(b3));
}
return buf.toString();
}
/**
* Decoding a string to a string follow the Base64 regular.
*
* @param s
* @return
*/
public static String base64Decode(final String s){
byte[] b = base64DecodeToArray(s);
if(b == null) return null;
if(b.length == 0) return "";
try {
return new String(b, "UTF-8");
} catch (java.io.UnsupportedEncodingException e) {
e.printStackTrace();
return null;
}
}
/**
* Decoding a string to a byte array follow the Base64 regular
*
* @param s
* @return
*/
public static byte[] base64DecodeToArray(final String s){
if(s == null) return null;
int len = s.length();
if(len == 0) return new byte[0];
if(len%4 != 0){
throw new java.lang.IllegalArgumentException(s);
}
byte[] b = new byte[(len/4)*3];
int i = 0, j=0, e = 0, c, tmp;
while(i<len){
c = Base64Chars.indexOf((int)s.charAt(i++));
tmp = c << 18;
c = Base64Chars.indexOf((int)s.charAt(i++));
tmp |= c<< 12;
c = Base64Chars.indexOf((int)s.charAt(i++));
if(c < 64) {
tmp |= c << 6;
c = Base64Chars.indexOf((int)s.charAt(i++));
if(c < 64){
tmp |= c;
}else{
e = 1;
}
}else{
e = 2;
i++;
}
b[j+2] = (byte)(tmp & 0xff);
tmp >>= 8;
b[j+1] = (byte)(tmp & 0xff);
tmp >>= 8;
b[j+0] = (byte)(tmp & 0xff);
j += 3;
}
if(e != 0){
len = b.length - e;
byte[] copy = new byte[len];
System.arraycopy(b, 0, copy, 0, len);
return copy;
}
return b;
}
/**
* @param args
*/
public static void main(String[] args) {
String s0 = "AB枫知`~!@#$%^&*()-_=+[{]}\\|;:'\",<.>/?";
String s1 = base64Encode(s0);
System.err.println(s0+" --> "+ s1);
String s2 = base64Decode(s1);
System.err.println(s1+" --> "+s2);
}
}
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