在web开发者,宽带资源是很珍贵的,所以尽量把不要的字符去掉,我们就可以把换行符和空格去掉,那怎么做呢,我们利用拦截器实现
<!--压缩html页面-->
<filter>
<filter-name>HtmlFilter</filter-name>
<filter-class>com.zhizhuo.web.intercepter.HtmlFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>HtmlFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
首先这是我的web中xml配置
那么代码如下:
package com.zhizhuo.web.intercepter;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpServletResponseWrapper;
/**
*
*/
public class HtmlFilter implements Filter {
public static final String codePatternStr = "(<|<)p-re[\\w\\W]*?[\\w\\W]*?/p-re[\\w\\W]*?(>|>)";
public static final Pattern codePattern = Pattern.compile(codePatternStr,
Pattern.CASE_INSENSITIVE);
private FilterConfig filterConfig = null;
class CodeFragment {
private String left;
private String fragment;
private String right;
public CodeFragment(String left, String fragment, String right) {
this.left = left;
this.fragment = fragment;
this.right = right;
}
public String getLeft() {
return left;
}
public void setLeft(String left) {
this.left = left;
}
public String getFragment() {
return fragment;
}
public void setFragment(String fragment) {
this.fragment = fragment;
}
public String getRight() {
return right;
}
public void setRight(String right) {
this.right = right;
}
}
private static class ByteArrayServletStream extends ServletOutputStream {
ByteArrayOutputStream baos;
ByteArrayServletStream(ByteArrayOutputStream baos) {
this.baos = baos;
}
public void write(int param) throws IOException {
baos.write(param);
}
}
private static class ByteArrayPrintWriter {
private ByteArrayOutputStream baos = new ByteArrayOutputStream();
private PrintWriter pw = new PrintWriter(baos);
private ServletOutputStream sos = new ByteArrayServletStream(baos);
public PrintWriter getWriter() {
return pw;
}
public ServletOutputStream getStream() {
return sos;
}
byte[] toByteArray() {
return baos.toByteArray();
}
}
public class CharResponseWrapper extends HttpServletResponseWrapper {
private ByteArrayPrintWriter output;
private boolean usingWriter;
public CharResponseWrapper(HttpServletResponse response) {
super(response);
usingWriter = false;
output = new ByteArrayPrintWriter();
}
public byte[] getByteArray() {
return output.toByteArray();
}
@Override
public ServletOutputStream getOutputStream() throws IOException {
// will error out, if in use
if (usingWriter) {
super.getOutputStream();
}
usingWriter = true;
return output.getStream();
}
@Override
public PrintWriter getWriter() throws IOException {
// will error out, if in use
if (usingWriter) {
super.getWriter();
}
usingWriter = true;
return output.getWriter();
}
public String toString() {
return output.toString();
}
}
public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException {
HttpServletRequest _request = (HttpServletRequest) request;
if (_request.getRequestURI().indexOf("update") != -1
|| _request.getRequestURI().indexOf("create") != -1) {
chain.doFilter(request, response);
return;
}
CharResponseWrapper wrappedResponse = new CharResponseWrapper(
(HttpServletResponse) response);
chain.doFilter(request, wrappedResponse);
byte[] bytes = wrappedResponse.getByteArray();
String contentType = wrappedResponse.getContentType();
if (contentType != null && contentType.matches(".*?(html|json).*?")) {
String out = new String(bytes);
Matcher matcher = codePattern.matcher(out);
List<CodeFragment> codeFragments = new ArrayList<CodeFragment>();
while (matcher.find()) {
String fragment = matcher.group(0);
String left = matcher.group(1);
String right = matcher.group(2);
CodeFragment codeFragment = new CodeFragment(left, fragment,
right);
codeFragments.add(codeFragment);
// 占位符<pr-e>idx</pr-e>
out = out.replace(fragment, left + "p-re" + right
+ codeFragments.size() + left + "/p-re" + right);
}
out = out.replaceAll("[\r\n]", "").replaceAll("[\n]", "").replaceAll(">\\s*?<", "><")
.trim();
while (out.contains(" ")){
out=out.replaceAll(" "," " );
}
// 还原占位符
for (int i = 0; i < codeFragments.size(); i++) {
CodeFragment codeFragment = codeFragments.get(i);
String fragment = codeFragment.getFragment();
String left = codeFragment.getLeft();
String right = codeFragment.getRight();
out = out.replace(left + "p-re" + right + (i + 1) + left
+ "/p-re" + right, fragment);
}
response.getWriter().write(new String(out.getBytes()));
} else {
response.getOutputStream().write(bytes);
}
}
@Override
public void init(FilterConfig filterConfig) throws ServletException {
this.filterConfig = filterConfig;
}
@Override
public void destroy() {
filterConfig = null;
}
}
这样我们就获取了压缩后的页面
其实还是挺有用的,我的jsp页面用了大量的el’和jstl表达式使得页面多余字符太多
其实我们jsp有支持,但是我感觉不是兼容,而且达不到最简的目的
<%@ page trimDirectiveWhitespaces="true"%>
但是我感觉这样不好,所以就写了上面的方法