Go语言视频零基础入门到精通

javalearner

用过滤器为JSP文件生成静态页面，这只是一个简单的实例，客户端浏览器第一次请求JSP页面时，服务器将生成对应的HTML文件，以后访问同一JSP文件，将转为访问生成的HTML文件。
一、过滤器

1. package com.kenfor.lyb.toHtmlfilter;
   
2. import java.io.*;
   
3. import java.io.IOException;
   
4. import java.text.SimpleDateFormat;
   
5. import java.util.Date;
   
6. import javax.servlet.Filter;
   
7. import javax.servlet.FilterChain;
   
8. import javax.servlet.FilterConfig;
   
9. import javax.servlet.RequestDispatcher;
   
10. import javax.servlet.ServletException;
    
11. import javax.servlet.ServletRequest;
    
12. import javax.servlet.ServletResponse;
    
13. import javax.servlet.http.HttpServletRequest;
    
14. import javax.servlet.http.HttpServletResponse;
    
15. import org.apache.log4j.*;
    
16. public class JspFilter implements Filter {
    
17. 
    
18. Logger logger = Logger.getLogger(this.getClass());
    
19. 
    
20.     protected FilterConfig config;
    
21.     public void init(FilterConfig config)
    
22.         throws ServletException
    
23.     {
    
24.         // Save the config object
    
25.         this.config = config;
    
26.     }
    
27. public void destroy() {
    
28. }
    
29. public void doFilter(ServletRequest request, ServletResponse response,
    
30.    FilterChain chain) throws IOException, ServletException {
    
31.   HttpServletRequest hreq = (HttpServletRequest) request;
    
32.   HttpServletResponse hresp = (HttpServletResponse) response;
    
33.   String name = hreq.getRequestURL().substring(hreq.getRequestURL().lastIndexOf("/") + 1,
    
34.     hreq.getRequestURL().lastIndexOf("."));
    
35.    //logger.info("fileName="+name);
    
36.   String str_uri = hreq.getRequestURI();
    
37.    //logger.info("str_uri="+str_uri);
    
38.    String htmpath=hreq.getSession().getServletContext().getRealPath(
    
39.     "/")
    
40.     + "HTML"
    
41.     + str_uri.substring(0, str_uri.lastIndexOf("/"))
    
42.     //+"/"+time
    
43.     + "/" + name + ".html";
    
44.     File file = new File(htmpath);
    
45.     //logger.info("file="+file);
    
46.    String to=hreq.getContextPath() + "/HTML"
    
47.      + str_uri.substring(0, str_uri.lastIndexOf("/"))
    
48.      +"/"+ name + ".html";
    
49.      //logger.info(to);
    
50.   
    
51.       
    
52.   if (!file.exists()&&hreq.getRequestURL().indexOf(".jsp")> 0) {
    
53.        ServletResponse newResponse =new CharResponseWrapper(hresp);   
    
54.         chain.doFilter(request, newResponse);
    
55.         String text = newResponse.toString();
    
56.             if (text != null)
    
57.             {
    
58.                    PrintWriter pw=new PrintWriter(htmpath);
    
59.                    pw.println(text);
    
60.                    pw.close();
    
61.                    hresp.sendRedirect(to);
    
62.             }
    
63.     } else {
    
64.      
    
65.    hresp.sendRedirect(to);
    
66.   }
    
67. 
    
68. }
    
69. 
    
70. }

复制代码

二、响应包装器

1. package com.kenfor.lyb.toHtmlfilter;
   
2. import javax.servlet.*;
   
3. import javax.servlet.http.*;
   
4. import java.io.*;
   
5. /**
   
6. * Simple response wrapper that utilizes a local CharArrayWriter
   
7. * for output
   
8. */
   
9. public class CharResponseWrapper
   
10.         extends HttpServletResponseWrapper
    
11. {
    
12.     protected CharArrayWriter charWriter;
    
13.     protected PrintWriter writer;
    
14.     protected boolean getOutputStreamCalled;
    
15.     protected boolean getWriterCalled;
    
16.     public CharResponseWrapper(HttpServletResponse response)
    
17.     {
    
18.         super(response);
    
19.         // Create the writer
    
20.         charWriter = new CharArrayWriter();
    
21.     }
    
22.     public ServletOutputStream getOutputStream()
    
23.         throws IOException
    
24.     {
    
25.         // Can"t call getOutputStream if getWriter
    
26.         // has already been called
    
27.         if (getWriterCalled)
    
28.         {
    
29.             throw new IllegalStateException(
    
30.                     "getWriter already called");
    
31.         }
    
32.         getOutputStreamCalled = true;
    
33.         return super.getOutputStream();
    
34.     }
    
35.     public PrintWriter getWriter()
    
36.         throws IOException
    
37.     {
    
38.         if (writer != null)
    
39.         {
    
40.             return writer;
    
41.         }
    
42.         // Can"t call getWriter if getOutputStream
    
43.         // has already been called
    
44.         if (getOutputStreamCalled)
    
45.         {
    
46.             throw new IllegalStateException(
    
47.                     "getOutputStream already called");
    
48.         }
    
49.         getWriterCalled = true;
    
50.         writer = new PrintWriter(charWriter);
    
51.         return writer;
    
52.     }
    
53.     public String toString()
    
54.     {
    
55.         String s = null;
    
56.         // Only return a String if the writer was
    
57.         // used.
    
58.         if (writer != null)
    
59.         {
    
60.             s = charWriter.toString();
    
61.         }
    
62.         return s;
    
63.     }
    
64.    public char[] toCharArray(){//将响应数据以字符数组返回
    
65.          return(charWriter.toCharArray());
    
66.    }
    
67.   
    
68. }
    

复制代码

三、web.xml文件
<?xml version="1.0" encoding="ISO-8859-1"?> <web-app xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd" version="2.4">  <display-name>Welcome to Tomcat</display-name>
<description>
Welcome to Tomcat
</description> <filter>
   <filter-name>jspfilter</filter-name>
   <filter-class>com.kenfor.lyb.toHtmlfilter.JspFilter</filter-class>
</filter>  <filter-mapping>
   <filter-name>jspfilter</filter-name>
   <url-pattern>*.jsp</url-pattern>
</filter-mapping>  <Servlet>
   <servlet-name>log4j-init</servlet-name>
   <servlet-class>example.Log4jInit</servlet-class>
   <init-param>
    <param-name>log4j</param-name>
    <param-value>WEB-INF/log4j.properties</param-value>
   </init-param>
  <load-on-startup>1</load-on-startup>
</servlet>
</web-app>

测试文件：tohtml.jsp <%@ page contentType="text/html; charset=gb2312" %>
<%
String name = request.getRequestURL().substring(request.getRequestURL().lastIndexOf("/") + 1,
request.getRequestURL().lastIndexOf("."));
String cox=request.getContextPath();  String str_uri = request.getRequestURI();
out.println(request.getRequestURL()+"<br>");
out.println(name+"<br>");
out.println(str_uri+"<br>");
out.println(cox+"<br>");
out.println(request.getParameter("type"));
%>
第二次请求tohtml.jsp时，运行图：   

  
  
   
   

     
   

     
   
  

复制代码

源码下载：http://file.javaxxz.com/2014/10/2/034014188.zip