WEB 高性能开发(10) - 疯狂的HTML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 ArrayList<String>();
		List<String> taBlocks = new ArrayList<String>();
		List<String> scriptBlocks = new ArrayList<String>();
		List<String> styleBlocks = new ArrayList<String>();
		List<String> jspBlocks = new ArrayList<String>();
		
		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, List<String> 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, List<String> 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, List<String> 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, List<String> 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, List<String> 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。