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Web高性能开发之疯狂的HTML压缩

作者: BearRui(AK-47)  来源: 博客园  发布时间: 2011-05-01 17:55  阅读: 2026 次  推荐: 0   原文链接   [收藏]  
摘要:在“JS、CSS的合并、压缩、缓存管理”一文中说到自己写过的1个自动合并、压缩JS,CSS,并添加版本号的组件。这次把压缩html的功能也加入到该组件中,流程很简单,就是在程序启动(contextInitialized or Application_Start)的时候扫描所有html,jsp(aspx)进行压缩。

  前言:

  上一篇随笔中网友skyaspnet问我如何压缩HTML,当时回答是推荐他使用gzip,后来想想,要是能把所有的html,jsp(aspx)在运行前都压缩成1行未免不是一件好事啊。一般我们启动gzip都比较少对html启动gzip,因为现在的html都是动态的,不会使用浏览器缓存,而启用gzip的话每次请求都需要压缩,会比较消耗服务器资源,对js,css启动gzip比较好是因为js,css都会使用缓存。我个人觉得的压缩html的最大好处就是一本万利,只要写好了一次,以后所有程序都可以使用,不会增加任何额外的开发工作。

  在JS、CSS的合并、压缩、缓存管理一文中说到自己写过的1个自动合并、压缩JS,CSS,并添加版本号的组件。这次把压缩html的功能也加入到该组件中,流程很简单,就是在程序启动(contextInitialized or Application_Start)的时候扫描所有html,jsp(aspx)进行压缩。

  压缩的注意事项:

  实现的方式主要是用正则表达式去查找,替换。在html压缩的时候,主要要注意下面几点:

  1. pre,textarea标签里面的内容格式需要保留,不能压缩。

  2. 去掉html注释的时候,有些注释是不能去掉的,比如:!--[if IE 6] ..... ![endif]--

  3. 压缩嵌入式js中的注释要注意,因为可能注释符号会出现在字符串中,比如: var url = "http://www.cnblogs.com"; // 前面的//不是注释

  去掉JS换行符的时候,不能直接跟一下行动内容,需要有空格,考虑下面的代码:

else
return;

  如果不带空格,则变成elsereturn。

  4. jsp(aspx) 中很有可能会使用% %嵌入一些服务器代码,这个时候也需要单独处理,里面注释的处理方法跟js的一样。

  源代码:

  下面是java实现的源代码,也可以 猛击此处 下载该代码,相信大家都看的懂,也很容易改成net代码:

import java.io.StringReader;
import java.io.StringWriter;
import java.util.
*;
import java.util.regex.
*;

/*******************************************
* 压缩jsp,html中的代码,去掉所有空白符、换行符
* @author bearrui(ak-47)
* @version 0.1
* @date 2010-5-13
******************************************
*/
public class HtmlCompressor {
private static String tempPreBlock = "%%%HTMLCOMPRESS~PRE&&&";
private static String tempTextAreaBlock = "%%%HTMLCOMPRESS~TEXTAREA&&&";
private static String tempScriptBlock = "%%%HTMLCOMPRESS~SCRIPT&&&";
private static String tempStyleBlock = "%%%HTMLCOMPRESS~STYLE&&&";
private static String tempJspBlock = "%%%HTMLCOMPRESS~JSP&&&";

private static Pattern commentPattern = Pattern.compile("!--\\s*[^\\[].*?--", Pattern.DOTALL | Pattern.CASE_INSENSITIVE | Pattern.MULTILINE);
private static Pattern itsPattern = Pattern.compile("\\s+?", Pattern.DOTALL | Pattern.CASE_INSENSITIVE | Pattern.MULTILINE);
private static Pattern prePattern = Pattern.compile("pre[^]*?.*?/pre", Pattern.DOTALL | Pattern.CASE_INSENSITIVE | Pattern.MULTILINE);
private static Pattern taPattern = Pattern.compile("textarea[^]*?.*?/textarea", Pattern.DOTALL | Pattern.CASE_INSENSITIVE | Pattern.MULTILINE);
private static Pattern jspPattern = Pattern.compile("%([^-@][\\w\\W]*?)%", Pattern.DOTALL | Pattern.CASE_INSENSITIVE | Pattern.MULTILINE);
// script/script
private static Pattern scriptPattern = Pattern.compile("(?:script\\s*|script type=['\"]text/javascript['\"]\\s*)(.*?)/script", Pattern.DOTALL | Pattern.CASE_INSENSITIVE | Pattern.MULTILINE);
private static Pattern stylePattern = Pattern.compile("style[^()]*?(.+)/style", Pattern.DOTALL | Pattern.CASE_INSENSITIVE | Pattern.MULTILINE);

// 单行注释,
private static Pattern signleCommentPattern = Pattern.compile("//.*");
// 字符串匹配
private static Pattern stringPattern = Pattern.compile("(\"[^\"\\n]*?\"|'[^'\\n]*?')");
// trim去空格和换行符
private static Pattern trimPattern = Pattern.compile("\\n\\s*",Pattern.MULTILINE);
private static Pattern trimPattern2 = Pattern.compile("\\s*\\r",Pattern.MULTILINE);
// 多行注释
private static Pattern multiCommentPattern = Pattern.compile("/\\*.*?\\*/", Pattern.DOTALL | Pattern.CASE_INSENSITIVE | Pattern.MULTILINE);

private static String tempSingleCommentBlock = "%%%HTMLCOMPRESS~SINGLECOMMENT&&&"; // //占位符
private static String tempMulitCommentBlock1 = "%%%HTMLCOMPRESS~MULITCOMMENT1&&&"; // /*占位符
private static String tempMulitCommentBlock2 = "%%%HTMLCOMPRESS~MULITCOMMENT2&&&"; // */占位符


public static String compress(String html) throws Exception {
if(html == null || html.length() == 0) {
return html;
}

List
 String  preBlocks = new ArrayListString();
List
String taBlocks = new ArrayListString();
List
String scriptBlocks = new ArrayListString();
List
String styleBlocks = new ArrayListString();
List
String jspBlocks = new ArrayListString();

String result
= html;

//preserve inline java code
Matcher jspMatcher = jspPattern.matcher(result);
while(jspMatcher.find()) {
jspBlocks.add(jspMatcher.group(
0));
}
result
= jspMatcher.replaceAll(tempJspBlock);

//preserve PRE tags
Matcher preMatcher = prePattern.matcher(result);
while(preMatcher.find()) {
preBlocks.add(preMatcher.group(
0));
}
result
= preMatcher.replaceAll(tempPreBlock);

//preserve TEXTAREA tags
Matcher taMatcher = taPattern.matcher(result);
while(taMatcher.find()) {
taBlocks.add(taMatcher.group(
0));
}
result
= taMatcher.replaceAll(tempTextAreaBlock);

//preserve SCRIPT tags
Matcher scriptMatcher = scriptPattern.matcher(result);
while(scriptMatcher.find()) {
scriptBlocks.add(scriptMatcher.group(
0));
}
result
= scriptMatcher.replaceAll(tempScriptBlock);

// don't process inline css
Matcher styleMatcher = stylePattern.matcher(result);
while(styleMatcher.find()) {
styleBlocks.add(styleMatcher.group(
0));
}
result
= styleMatcher.replaceAll(tempStyleBlock);

//process pure html
result = processHtml(result);

//process preserved blocks
result = processPreBlocks(result, preBlocks);
result
= processTextareaBlocks(result, taBlocks);
result
= processScriptBlocks(result, scriptBlocks);
result
= processStyleBlocks(result, styleBlocks);
result
= processJspBlocks(result, jspBlocks);

preBlocks
= taBlocks = scriptBlocks = styleBlocks = jspBlocks = null;

return result.trim();
}

private static String processHtml(String html) {
String result
= html;

//remove comments
// if(removeComments) {
result = commentPattern.matcher(result).replaceAll("");
// }

//remove inter-tag spaces
// if(removeIntertagSpaces) {
result = itsPattern.matcher(result).replaceAll("");
// }

//remove multi whitespace characters
// if(removeMultiSpaces) {
result = result.replaceAll("\\s{2,}"," ");
// }

return result;
}

private static String processJspBlocks(String html, ListString blocks){
String result
= html;
for(int i = 0; i blocks.size(); i++) {
blocks.
set(i, compressJsp(blocks.get(i)));
}
//put preserved blocks back
while(result.contains(tempJspBlock)) {
result
= result.replaceFirst(tempJspBlock, Matcher.quoteReplacement(blocks.remove(0)));
}

return result;
}
private static String processPreBlocks(String html, ListString blocks) throws Exception {
String result
= html;

//put preserved blocks back
while(result.contains(tempPreBlock)) {
result
= result.replaceFirst(tempPreBlock, Matcher.quoteReplacement(blocks.remove(0)));
}

return result;
}

private static String processTextareaBlocks(String html, ListString blocks) throws Exception {
String result
= html;

//put preserved blocks back
while(result.contains(tempTextAreaBlock)) {
result
= result.replaceFirst(tempTextAreaBlock, Matcher.quoteReplacement(blocks.remove(0)));
}

return result;
}

private static String processScriptBlocks(String html, ListString blocks) throws Exception {
String result
= html;

// if(compressJavaScript) {
for(int i = 0; i blocks.size(); i++) {
blocks.
set(i, compressJavaScript(blocks.get(i)));
}
// }

//put preserved blocks back
while(result.contains(tempScriptBlock)) {
result
= result.replaceFirst(tempScriptBlock, Matcher.quoteReplacement(blocks.remove(0)));
}

return result;
}

private static String processStyleBlocks(String html, ListString blocks) throws Exception {
String result
= html;

// if(compressCss) {
for(int i = 0; i blocks.size(); i++) {
blocks.
set(i, compressCssStyles(blocks.get(i)));
}
// }

//put preserved blocks back
while(result.contains(tempStyleBlock)) {
result
= result.replaceFirst(tempStyleBlock, Matcher.quoteReplacement(blocks.remove(0)));
}

return result;
}

private static String compressJsp(String source) {
//check if block is not empty
Matcher jspMatcher = jspPattern.matcher(source);
if(jspMatcher.find()) {
String result
= compressJspJs(jspMatcher.group(1));
return (new StringBuilder(source.substring(0, jspMatcher.start(1))).append(result).append(source.substring(jspMatcher.end(1)))).toString();
}
else {
return source;
}
}
private static String compressJavaScript(String source) {
//check if block is not empty
Matcher scriptMatcher = scriptPattern.matcher(source);
if(scriptMatcher.find()) {
String result
= compressJspJs(scriptMatcher.group(1));
return (new StringBuilder(source.substring(0, scriptMatcher.start(1))).append(result).append(source.substring(scriptMatcher.end(1)))).toString();
}
else {
return source;
}
}

private static String compressCssStyles(String source) {
//check if block is not empty
Matcher styleMatcher = stylePattern.matcher(source);
if(styleMatcher.find()) {
// 去掉注释,换行
String result= multiCommentPattern.matcher(styleMatcher.group(1)).replaceAll("");
result
= trimPattern.matcher(result).replaceAll("");
result
= trimPattern2.matcher(result).replaceAll("");
return (new StringBuilder(source.substring(0, styleMatcher.start(1))).append(result).append(source.substring(styleMatcher.end(1)))).toString();
}
else {
return source;
}
}

private static String compressJspJs(String source){
String result
= source;
// 因注释符合有可能出现在字符串中,所以要先把字符串中的特殊符好去掉
Matcher stringMatcher = stringPattern.matcher(result);
while(stringMatcher.find()){
String tmpStr
= stringMatcher.group(0);

if(tmpStr.indexOf("//") != -1 || tmpStr.indexOf("/*") != -1 || tmpStr.indexOf("*/") != -1){
String blockStr
= tmpStr.replaceAll("//", tempSingleCommentBlock).replaceAll("/\\*", tempMulitCommentBlock1)
.replaceAll(
"\\*/", tempMulitCommentBlock2);
result
= result.replace(tmpStr, blockStr);
}
}
// 去掉注释
result = signleCommentPattern.matcher(result).replaceAll("");
result
= multiCommentPattern.matcher(result).replaceAll("");
result
= trimPattern2.matcher(result).replaceAll("");
result
= trimPattern.matcher(result).replaceAll(" ");
// 恢复替换掉的字符串
result = result.replaceAll(tempSingleCommentBlock, "//").replaceAll(tempMulitCommentBlock1, "/*")
.replaceAll(tempMulitCommentBlock2,
"*/");

return result;
}
}

  使用注意事项

  使用了上面方法后,再运行程序,是不是发现每个页面查看源代码的时候都变成1行啦,还不错吧,但是在使用的时候还是要注意一些问题:

  1. 嵌入js本来想调用yuicompressor来压缩,yuicompressor压缩JS前,会先编译js是否合法,因我们嵌入的js中可能很多会用到一些服务器端代码,比如 var now = %=DateTime.now % ,这样的代码会编译不通过,所以无法使用yuicompressor。

  最后只能自己写压缩JS代码,自己写的比较粗燥,所以有个问题还解决,就是如果开发人员在一句js代码后面没有加分号的话,压缩成1行就很有可能出问题。所以使用这个需要保证每条语句结束后都必须带分号。

  2. 因为是在程序启动的时候压缩所有jsp(aspx),所以如果是用户请求的时候动态产生的html就无法压缩。

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