WEB高性能开发(10) – 疯狂的HTML压缩

作者: nick 分类: css, java, js, web, 学习 发布时间: 2010-05-17 11:26 ė 6没有评论

随笔中有网友 skyaspnet 问到如何压缩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:

 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("", 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("]*?>.*?

“, Pattern.DOTALL | Pattern.CASE_INSENSITIVE | Pattern.MULTILINE);
private static Pattern taPattern = Pattern.compile(“]*?>.*?“, Pattern.DOTALL | Pattern.CASE_INSENSITIVE | Pattern.MULTILINE);
private static Pattern jspPattern = Pattern.compile(“<%([^-@][\\w\\W]*?)%>“, Pattern.DOTALL | Pattern.CASE_INSENSITIVE | Pattern.MULTILINE);
//
private static Pattern scriptPattern = Pattern.compile(“(?:|“, Pattern.DOTALL | Pattern.CASE_INSENSITIVE | Pattern.MULTILINE);
private static Pattern stylePattern = Pattern.compile(“()]*?>(.+)

“, 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 trimPattern= 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 preBlocks = new ArrayList();
List taBlocks = new ArrayList();
List scriptBlocks = new ArrayList();
List styleBlocks = new ArrayList();
List jspBlocks = new ArrayList();

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 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 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 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 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 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; } } 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:

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。

有需要请查看:高性能WEB开发系列

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