WEB高性能开发 - 疯狂的HTML压缩
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);
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;
}
47
48 List<String> preBlocks = new ArrayList<String>();
49 List<String> taBlocks = new ArrayList<String>();
50 List<String> scriptBlocks = new ArrayList<String>();
51 List<String> styleBlocks = new ArrayList<String>();
52 List<String> jspBlocks = new ArrayList<String>();
53
54 String result = html;
55
56 //preserve inline java code
57 Matcher jspMatcher = jspPattern.matcher(result);
58 while(jspMatcher.find()) {
59 jspBlocks.add(jspMatcher.group(0));
60 }
61 result = jspMatcher.replaceAll(tempJspBlock);
62
63 //preserve PRE tags
64 Matcher preMatcher = prePattern.matcher(result);
65 while(preMatcher.find()) {
66 preBlocks.add(preMatcher.group(0));
67 }
68 result = preMatcher.replaceAll(tempPreBlock);
69
70 //preserve TEXTAREA tags
71 Matcher taMatcher = taPattern.matcher(result);
72 while(taMatcher.find()) {
73 taBlocks.add(taMatcher.group(0));
74 }
75 result = taMatcher.replaceAll(tempTextAreaBlock);
76
77 //preserve SCRIPT tags
78 Matcher scriptMatcher = scriptPattern.matcher(result);
79 while(scriptMatcher.find()) {
80 scriptBlocks.add(scriptMatcher.group(0));
81 }
82 result = scriptMatcher.replaceAll(tempScriptBlock);
83
84 // don't process inline css
85 Matcher styleMatcher = stylePattern.matcher(result);
86 while(styleMatcher.find()) {
87 styleBlocks.add(styleMatcher.group(0));
88 }
89 result = styleMatcher.replaceAll(tempStyleBlock);
90
91 //process pure html
92 result = processHtml(result);
93
94 //process preserved blocks
95 result = processPreBlocks(result, preBlocks);
96 result = processTextareaBlocks(result, taBlocks);
97 result = processScriptBlocks(result, scriptBlocks);
98 result = processStyleBlocks(result, styleBlocks);
99 result = processJspBlocks(result, jspBlocks);
100
101 preBlocks = taBlocks = scriptBlocks = styleBlocks = jspBlocks = null;
102
103 return result.trim();
104 }
105
106 private static String processHtml(String html) {
107 String result = html;
108
109 //remove comments
110 // if(removeComments) {
111 result = commentPattern.matcher(result).replaceAll("");
112 // }
113
114 //remove inter-tag spaces
115 // if(removeIntertagSpaces) {
116 result = itsPattern.matcher(result).replaceAll("><");
117 // }
118
119 //remove multi whitespace characters
120 // if(removeMultiSpaces) {
121 result = result.replaceAll("\\s{2,}"," ");
122 // }
123
124 return result;
125 }
126
127 private static String processJspBlocks(String html, List<String> blocks){
128 String result = html;
129 for(int i = 0; i < blocks.size(); i++) {
130 blocks.set(i, compressJsp(blocks.get(i)));
131 }
132 //put preserved blocks back
133 while(result.contains(tempJspBlock)) {
134 result = result.replaceFirst(tempJspBlock, Matcher.quoteReplacement(blocks.remove(0)));
135 }
136
137 return result;
138 }
139 private static String processPreBlocks(String html, List<String> blocks) throws Exception {
140 String result = html;
141
142 //put preserved blocks back
143 while(result.contains(tempPreBlock)) {
144 result = result.replaceFirst(tempPreBlock, Matcher.quoteReplacement(blocks.remove(0)));
145 }
146
147 return result;
148 }
149
150 private static String processTextareaBlocks(String html, List<String> blocks) throws Exception {
151 String result = html;
152
153 //put preserved blocks back
154 while(result.contains(tempTextAreaBlock)) {
155 result = result.replaceFirst(tempTextAreaBlock, Matcher.quoteReplacement(blocks.remove(0)));
156 }
157
158 return result;
159 }
160
161 private static String processScriptBlocks(String html, List<String> blocks) throws Exception {
162 String result = html;
163
164 // if(compressJavaScript) {
165 for(int i = 0; i < blocks.size(); i++) {
166 blocks.set(i, compressJavaScript(blocks.get(i)));
167 }
168 // }
169
170 //put preserved blocks back
171 while(result.contains(tempScriptBlock)) {
172 result = result.replaceFirst(tempScriptBlock, Matcher.quoteReplacement(blocks.remove(0)));
173 }
174
175 return result;
176 }
177
178 private static String processStyleBlocks(String html, List<String> blocks) throws Exception {
179 String result = html;
180
181 // if(compressCss) {
182 for(int i = 0; i < blocks.size(); i++) {
183 blocks.set(i, compressCssStyles(blocks.get(i)));
184 }
185 // }
186
187 //put preserved blocks back
188 while(result.contains(tempStyleBlock)) {
189 result = result.replaceFirst(tempStyleBlock, Matcher.quoteReplacement(blocks.remove(0)));
190 }
191
192 return result;
193 }
194
195 private static String compressJsp(String source) {
196 //check if block is not empty
197 Matcher jspMatcher = jspPattern.matcher(source);
198 if(jspMatcher.find()) {
199 String result = compressJspJs(jspMatcher.group(1));
200 return (new StringBuilder(source.substring(0, jspMatcher.start(1))).append(result).append(source.substring(jspMatcher.end(1)))).toString();
201 } else {
202 return source;
203 }
204 }
205 private static String compressJavaScript(String source) {
206 //check if block is not empty
207 Matcher scriptMatcher = scriptPattern.matcher(source);
208 if(scriptMatcher.find()) {
209 String result = compressJspJs(scriptMatcher.group(1));
210 return (new StringBuilder(source.substring(0, scriptMatcher.start(1))).append(result).append(source.substring(scriptMatcher.end(1)))).toString();
211 } else {
212 return source;
213 }
214 }
215
216 private static String compressCssStyles(String source) {
217 //check if block is not empty
218 Matcher styleMatcher = stylePattern.matcher(source);
219 if(styleMatcher.find()) {
220 // 去掉注释，换行
221 String result= multiCommentPattern.matcher(styleMatcher.group(1)).replaceAll("");
222 result = trimPattern.matcher(result).replaceAll("");
223 result = trimPattern2.matcher(result).replaceAll("");
224 return (new StringBuilder(source.substring(0, styleMatcher.start(1))).append(result).append(source.substring(styleMatcher.end(1)))).toString();
225 } else {
226 return source;
227 }
228 }
229
230 private static String compressJspJs(String source){
231 String result = source;
232 // 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
233 Matcher stringMatcher = stringPattern.matcher(result);
234 while(stringMatcher.find()){
235 String tmpStr = stringMatcher.group(0);
236
237 if(tmpStr.indexOf("//") != -1 || tmpStr.indexOf("/*") != -1 || tmpStr.indexOf("*/") != -1){
238 String blockStr = tmpStr.replaceAll("//", tempSingleCommentBlock).replaceAll("/\\*", tempMulitCommentBlock1)
239 .replaceAll("\\*/", tempMulitCommentBlock2);
240 result = result.replace(tmpStr, blockStr);
241 }
242 }
243 // 去掉注释
244 result = signleCommentPattern.matcher(result).replaceAll("");
245 result = multiCommentPattern.matcher(result).replaceAll("");
246 result = trimPattern2.matcher(result).replaceAll("");
247 result = trimPattern.matcher(result).replaceAll(" ");
248 // 恢复替换掉的字符串
249 result = result.replaceAll(tempSingleCommentBlock, "//").replaceAll(tempMulitCommentBlock1, "/*")
250 .replaceAll(tempMulitCommentBlock2, "*/");
251
252 return result;
253 }
254 }
255
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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