前段时间做自己社区的论坛,在jive的基础上做一个页面显示所有论坛的帖子,可以称之为总版,模仿Forum类的接口做个SuperForum并且实现Cachable,不过因为这个页面刷新量比较大,虽然被Cache了,我还是想办法进行页面的缓存,感觉用jsp产生的html静态内容当缓存,页面访问速度应该有所提高。
首先想到的一种办法,是采用java.net的URLConnection把服务器上的jsp抓过来做缓存,不过我觉得这样做太见外了,自己服务器上的东西,为何要用HTTP去访问.于是想另外一个办法,把jsp的out对象的输出控制到自己希望的地方.比如输出到静态文件,又或者保存成全局的字符串变量.这样的话,浏览就不需要执行jsp,只是浏览该html了.仅仅在数据有更新的时候进行一次update操作,把jsp重新输出为html.
我觉得,浏览事件比数据插入或更新发生的次数多的时候.不妨试试这个办法来提高页面访问速度.
整件事情有点像把jsp当作模板,生成静态的html页面.
将如下代码写入web-xml
<filter> <filter-name>FileCaptureFilter</filter-name> <filter-class>com.junjing.filter.FileCaptureFilter</filter-class> </filter>
<filter-mapping> <filter-name>FileCaptureFilter</filter-name> <url-pattern>/latest.jsp</url-pattern> </filter-mapping>
latest.jsp是我要cache的页面
java源码代码如下
/** * START File FileCaptureFilter.java */
package
com.junjing.filter; import javax.servlet.*; import
javax.servlet.http.*; import java.io.*; public class
FileCaptureFilter implements Filter { private String
protDirPath; public void init(FilterConfig filterConfig)
throws ServletException { protDirPath =
filterConfig.getServletContext().getRealPath("/"); } public void
doFilter(ServletRequest request,ServletResponse response,FilterChain
chain) throws IOException, ServletException { String
fileName = protDirPath + "forum/lastest.html"; PrintWriter out =
response.getWriter(); FileCaptureResponseWrapper responseWrapper =
new
FileCaptureResponseWrapper((HttpServletResponse)response); chain.doFilter(request,
responseWrapper); // fill responseWrapper up String html =
responseWrapper.toString(); //得到的html页面结果字符串 //
responseWrapper.writeFile(fileName); // dump the contents
写成html文件,也可以保存在内存 //responseWrapper.writeResponse( out ); //
back to browser
//responseWrapper.sendRedirect("lastestThread.jsp"); }
public
void destroy() {} }
/** * END File FileCaptureFilter.java
*/ /** * START File FileCaptureResponseWrapper.java */
package
com.junjing.filter; import javax.servlet.*; import
javax.servlet.http.*; import java.io.*;
public class
FileCaptureResponseWrapper extends
HttpServletResponseWrapper { private CharArrayWriter
output; public String toString() { return
output.toString(); } public
FileCaptureResponseWrapper(HttpServletResponse
response) { super(response); output = new
CharArrayWriter(); }
public PrintWriter
getWriter() { return new PrintWriter(output);
}
public void writeFile(String fileName) throws
IOException { FileWriter fw = new
FileWriter(fileName); fw.write( output.toCharArray()
); fw.close(); }
public void
writeResponse(PrintWriter out) { out.print(
output.toCharArray() ); } } /** * END File
FileCaptureResponseWrapper.java */
15a
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