360SDN.COM

WEB高性能开发(10) - java压缩HTML页面

来源:  2018-08-21 14:26:44    评论:0点击:

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。


    有需要请查看:高性能WEB开发系列

[作者]:BearRui(AK-47)
[博客]: http://www.cnblogs.com/BearsTaR/
为您推荐

友情链接 |九搜汽车网 |手机ok生活信息网|ok生活信息网|ok微生活
 Powered by www.360SDN.COM   京ICP备11022651号-4 © 2012-2016 版权