<html>
<head>
<title>JavaScript字符串之压缩与还原</title>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<script type="text/javascript">
<!--
/**
* 压缩
*/
function Compress(strNormalString) {
alert("压缩前长度：" + strNormalString.length);
var strCompressedString = "";
var ht = new Array();
for(i = 0; i < 128; i++) {
ht[i] = i;
}
var used = 128;
var intLeftOver = 0;
var intOutputCode = 0;
var pcode = 0;
var ccode = 0;
var k = 0;
for(var i=0; i<strNormalString.length; i++) {
ccode = strNormalString.charCodeAt(i);
k = (pcode << 8) | ccode;
if(ht[k] != null) {
pcode = ht[k];
} else {
intLeftOver += 12;
intOutputCode <<= 12;
intOutputCode |= pcode;
pcode = ccode;
if(intLeftOver >= 16) {
strCompressedString += String.fromCharCode( intOutputCode >> ( intLeftOver - 16 ) );
intOutputCode &= (Math.pow(2, (intLeftOver - 16)) - 1);
intLeftOver -= 16;
}
if(used < 4096) {
used ++;
ht[k] = used - 1;
}
}
}
if(pcode != 0) {
intLeftOver += 12;
intOutputCode <<= 12;
intOutputCode |= pcode;
}
if(intLeftOver >= 16) {
strCompressedString += String.fromCharCode( intOutputCode >> ( intLeftOver - 16 ) );
intOutputCode &= (Math.pow(2,(intLeftOver - 16)) - 1);
intLeftOver -= 16;
}
if( intLeftOver > 0) {
intOutputCode <<= (16 - intLeftOver);
strCompressedString += String.fromCharCode( intOutputCode );
}
alert("压缩后长度：" + strCompressedString.length);
return strCompressedString;
}
/**
* 解压缩
*/
function Decompress(strCompressedString) {
var strNormalString = "";
var ht = new Array();
for(i = 0; i < 128; i++) {
ht[i] = String.fromCharCode(i);
}
var used = 128;
var intLeftOver = 0;
var intOutputCode = 0;
var ccode = 0;
var pcode = 0;
var key = 0;
for(var i=0; i<strCompressedString.length; i++) {
intLeftOver += 16;
intOutputCode <<= 16;
intOutputCode |= strCompressedString.charCodeAt(i);
while(1) {
if(intLeftOver >= 12) {
ccode = intOutputCode >> (intLeftOver - 12);
if( typeof( key = ht[ccode] ) != "undefined" ) {
strNormalString += key;
if(used > 128) {
ht[ht.length] = ht[pcode] + key.substr(0, 1);
}
pcode = ccode;
} else {
key = ht[pcode] + ht[pcode].substr(0, 1);
strNormalString += key;
ht[ht.length] = ht[pcode] + key.substr(0, 1);
pcode = ht.length - 1;
}
used ++;
intLeftOver -= 12;
intOutputCode &= (Math.pow(2,intLeftOver) - 1);
} else {
break;
}
}
}
return strNormalString;
}
//-->
</script>
</head>
<body>
压缩前：
<input type="text" id="txtNormal" value="" />
<input type="button" value="↓压缩" onclick="document.getElementById('txtCompressed').value=Compress(document.getElementById('txtNormal').value);" />
<input type="button" value="清除" onclick="document.getElementById('txtNormal').value='';" />
压缩后：<br>
<input type="text" id="txtCompressed" value="" />
<input type="button" value="↑解压" onclick="document.getElementById('txtNormal').value=Decompress(document.getElementById('txtCompressed').value);" />
<input type="button" value="清除" onclick="document.getElementById('txtCompressed').value='';" />
</body>
</html>
<head>
<title>JavaScript字符串之压缩与还原</title>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<script type="text/javascript">
<!--
/**
* 压缩
*/
function Compress(strNormalString) {
alert("压缩前长度：" + strNormalString.length);
var strCompressedString = "";
var ht = new Array();
for(i = 0; i < 128; i++) {
ht[i] = i;
}
var used = 128;
var intLeftOver = 0;
var intOutputCode = 0;
var pcode = 0;
var ccode = 0;
var k = 0;
for(var i=0; i<strNormalString.length; i++) {
ccode = strNormalString.charCodeAt(i);
k = (pcode << 8) | ccode;
if(ht[k] != null) {
pcode = ht[k];
} else {
intLeftOver += 12;
intOutputCode <<= 12;
intOutputCode |= pcode;
pcode = ccode;
if(intLeftOver >= 16) {
strCompressedString += String.fromCharCode( intOutputCode >> ( intLeftOver - 16 ) );
intOutputCode &= (Math.pow(2, (intLeftOver - 16)) - 1);
intLeftOver -= 16;
}
if(used < 4096) {
used ++;
ht[k] = used - 1;
}
}
}
if(pcode != 0) {
intLeftOver += 12;
intOutputCode <<= 12;
intOutputCode |= pcode;
}
if(intLeftOver >= 16) {
strCompressedString += String.fromCharCode( intOutputCode >> ( intLeftOver - 16 ) );
intOutputCode &= (Math.pow(2,(intLeftOver - 16)) - 1);
intLeftOver -= 16;
}
if( intLeftOver > 0) {
intOutputCode <<= (16 - intLeftOver);
strCompressedString += String.fromCharCode( intOutputCode );
}
alert("压缩后长度：" + strCompressedString.length);
return strCompressedString;
}
/**
* 解压缩
*/
function Decompress(strCompressedString) {
var strNormalString = "";
var ht = new Array();
for(i = 0; i < 128; i++) {
ht[i] = String.fromCharCode(i);
}
var used = 128;
var intLeftOver = 0;
var intOutputCode = 0;
var ccode = 0;
var pcode = 0;
var key = 0;
for(var i=0; i<strCompressedString.length; i++) {
intLeftOver += 16;
intOutputCode <<= 16;
intOutputCode |= strCompressedString.charCodeAt(i);
while(1) {
if(intLeftOver >= 12) {
ccode = intOutputCode >> (intLeftOver - 12);
if( typeof( key = ht[ccode] ) != "undefined" ) {
strNormalString += key;
if(used > 128) {
ht[ht.length] = ht[pcode] + key.substr(0, 1);
}
pcode = ccode;
} else {
key = ht[pcode] + ht[pcode].substr(0, 1);
strNormalString += key;
ht[ht.length] = ht[pcode] + key.substr(0, 1);
pcode = ht.length - 1;
}
used ++;
intLeftOver -= 12;
intOutputCode &= (Math.pow(2,intLeftOver) - 1);
} else {
break;
}
}
}
return strNormalString;
}
//-->
</script>
</head>
<body>
压缩前：
<input type="text" id="txtNormal" value="" />
<input type="button" value="↓压缩" onclick="document.getElementById('txtCompressed').value=Compress(document.getElementById('txtNormal').value);" />
<input type="button" value="清除" onclick="document.getElementById('txtNormal').value='';" />
压缩后：<br>
<input type="text" id="txtCompressed" value="" />
<input type="button" value="↑解压" onclick="document.getElementById('txtNormal').value=Decompress(document.getElementById('txtCompressed').value);" />
<input type="button" value="清除" onclick="document.getElementById('txtCompressed').value='';" />
</body>
</html>
及Viterbi算法)
