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Java生成静态HTML页面

2015-01-12 13:58 375 查看
生成静态页面技术解决方案之一 

转载者前言:这是一个全面的jsp动态页面静态化方案,本站的帖子静态化方案将借鉴这篇帖子中方法。向http://www.agilejava.org的single的共享精神致敬。 

转帖正文: 

       相信很多人都希望自己的页面越快越好,最好是能静态的,提高客户访问速度。也便于搜索引擎搜索。所以,就希望我们的动态读取数据库的页面,尽可能的生成静态页面。一下系列文章,介绍一下个人的解决方案。 

      本系列将介绍个人的一种方法,在不改变原来jsp文件的基础上,只需要加入少量的代码,就让你的新闻发布系统,很容易就完全变成静态的页面。 

            本文假设你是用java开发的web动态页面。 

           第一步,加入servlet.代码如下。 

      public class ToHtml extends HttpServlet { 

       public void service(HttpServletRequest request, HttpServletResponse response) 
         throws ServletException, IOException { 
        String url = ""; 
        String name = ""; 

        ServletContext sc = getServletContext(); 

        String file_name = request.getParameter("file_name");// 你要访问的jsp文件名,如index,不包括扩展名 

        // 则你访问这个servlet时加参数.如http://localhost/test/toHtml?file_name=index 

        url = "/" + file_name + ".jsf";// 你要生成的页面的文件名。我的扩展名为jsf . 

        name = ConfConstants.CONTEXT_PATH+"\\"+ file_name + ".htm";// 这是生成的html文件名,如index.htm.文件名字与源文件名相同。扩展名为htm 

      //ConfConstants.CONTEXT_PATH为你的应用的上下文路径。 

        RequestDispatcher rd = sc.getRequestDispatcher(url); 

        final ByteArrayOutputStream ōs = new ByteArrayOutputStream(); 

        final ServletOutputStream stream = new ServletOutputStream() { 
         public void write(byte[] data, int offset, int length) { 
          os.write(data, offset, length); 
         } 

         public void write(int b) throws IOException { 
          os.write(b); 
         } 
        }; 

        final PrintWriter pw = new PrintWriter(new OutputStreamWriter(os)); 

        HttpServletResponse rep = new HttpServletResponseWrapper(response) { 
         public ServletOutputStream getOutputStream() { 
          return stream; 
         } 

         public PrintWriter getWriter() { 
          return pw; 
         } 
        }; 
        rd.include(request, rep); 
        pw.flush(); 
        FileOutputStream fos = new FileOutputStream(name); // 把jsp输出的内容写到xxx.htm 
        os.writeTo(fos); 
        fos.close(); 
        PrintWriter ōut = response.getWriter(); 
        out 
          .print("<p align=center><font size=3 color=red>页面已经成功生成!single<br>http://www.agilejava.org/space/? 233</font></p>"); 
       } 
      } 

      第二步、配置你的web.xml 

       <servlet> 
        <servlet-name>toHtml</servlet-name> 
        <servlet-class>mj.util.html.ToHtml</servlet-class>//你的servlet的类。 
       </servlet> 
       <servlet-mapping> 
        <servlet-name>toHtml</servlet-name> 
        <url-pattern>/toHtml</url-pattern> 
       </servlet-mapping> 

      第三步、运行servlet。如:http://localhost:8080/test/toHtml?file_name=index 

       

      OK,这就在你的test项目的根目录下,生成了一个index.htm的静态文件。  

       

      局限性:本文只能生成一个文件!访问一次,生成一个文件。并且生成的文件名也与原来的文件名相同。 

      比较适合主页生成静态页面。 

       

      本系列的后续文章将解决更多的问题。使之在新闻发布系统中,很容易就集成应用。 

---------------------------------------------------------------------------------------------------- 

生成静态页面技术解决方案之二 

            注意:转贴本文,请加上本文链接http://www.agilejava.org/space/?233/action_viewspace_itemid_21.html  

           在上一篇文章中,生成静态页面,是有一定的局限性的。生成主页是很方便,但要生成二级页面,就不方便了。 

             本文假设一个新闻发布系统。希望后台发布的,前台显示的是静态的文档。这就涉及,主页要是静态的,同时二级列表也是静态的,新闻内容也是静态的。也就是说, 在发布一篇新闻的时候,可能涉及到三个地方生成静态文档。并且,要生成一个网页,必须访问一个servlet。在大量生成静态网页的时候, 

            以下方法,可以解决这些问题。 

          一、加入一下servelet 

          /** 
           * @file_name 文件名及文件之后的参数.最好为a.jsf?fileId=aaaa 
           * @path 文件所在的路径.相对于根目录而言的. 
           * @realName文件要保存的名字 
           * @realPath文件要保存的真实路径。默认与文件所在的目录相同。 
           */ 
          public class ToHtmlPath extends HttpServlet { 

           public void service(HttpServletRequest request, HttpServletResponse response) 
             throws ServletException, IOException { 
            String url = ""; 
            String name = ""; 

            ServletContext sc = getServletContext(); 

            String file_name = request.getParameter("file_name");// 你要访问的jsp文件,如news.jsf。 
            // file_name如:fileDetail.jsf?fileId=56.要是有参数, 只有一个参数。并且以参数名作为文件名。 
            String realName = request.getParameter("realName");// 要保存的文件名。如aaa;注意可以没有这个参数。 

            String path = request.getParameter("path");// 你要访问的jsp文件路径。如news。注意可以没有这个参数。 

            String realPath = request.getParameter("realPath");// 你要保存的文件路径,如htmlNews.注意可以没有这个参数。 
            // 下面确定要保存的文件名字。 
            if (realName == null || realName == "") { 
             int a = 0; 
             a = file_name.indexOf("=") + 1; 
             realName = file_name.substring(a); 
             if (realName.indexOf(".")>0) { 
              realName = file_name.substring(0, file_name.indexOf(".")); 
             } 
            } 
            // 下面构造要访问的页面。 
            if (path == null || path == "") { 
             url = "/" + file_name;// 这是你要生成HTML的jsp文件,如 
            } else { 
             url = "/" + path + "/" + file_name;// 这是你要生成HTML的jsp文件,如 
            } 
            // 下面构造要保存的文件名,及路径。 
            // 1、如果有realPath,则保存在realPath下。 
            // 2、如果有path则保存在path下。 
            // 3、否则,保存在根目录下。 
            if (realPath == null || realPath == "") { 
             if (path == null || path == "") { 
              name = ConfConstants.CONTEXT_PATH + "\\" + realName + ".htm";// 这是生成的html文件名,如index.htm.说明: ConfConstants.CONTEXT_PATH为你的上下文路径。 
             } else { 
              name = ConfConstants.CONTEXT_PATH + "\\" + path + "\\" 
                + realName + ".htm";// 这是生成的html文件名,如index.htm. 
             } 
            } else { 
             name = ConfConstants.CONTEXT_PATH + "\\" + realPath + "\\" 
               + realName + ".htm";// 这是生成的html文件名,如index.htm. 
            } 

            // 访问请求的页面,并生成指定的文件。 
            RequestDispatcher rd = sc.getRequestDispatcher(url); 

            final ByteArrayOutputStream ōs = new ByteArrayOutputStream(); 

            final ServletOutputStream stream = new ServletOutputStream() { 
             public void write(byte[] data, int offset, int length) { 
              os.write(data, offset, length); 
             } 

             public void write(int b) throws IOException { 
              os.write(b); 
             } 
            }; 

            final PrintWriter pw = new PrintWriter(new OutputStreamWriter(os)); 

            HttpServletResponse rep = new HttpServletResponseWrapper(response) { 
             public ServletOutputStream getOutputStream() { 
              return stream; 
             } 

             public PrintWriter getWriter() { 
              return pw; 
             } 
            }; 
            rd.include(request, rep); 
            pw.flush(); 
            FileOutputStream fos = new FileOutputStream(name); // 把jsp输出的内容写到xxx.htm 
            os.writeTo(fos); 
            fos.close(); 
            PrintWriter ōut = response.getWriter(); 
            out.print("<p align=center><font size=3 color=red>success!</font></p>"); 
           } 
          } 

           

          二、在web.xml里面配置你的servlet 

           <servlet> 
            <servlet-name>toHtmlPath</servlet-name> 
            <servlet-class>mj.util.html.ToHtmlPath</servlet-class> 
           </servlet> 
           <servlet-mapping> 
            <servlet-name>toHtmlPath</servlet-name> 
            <url-pattern>/toHtmlPath</url-pattern> 
           </servlet-mapping> 

          三、写一个通用的方法, 供调用。 

          public class CallHtml { 

           public static void callOnePage(String fileName, String path, 
             String realName, String realPath) { 
            try { 
             String str = "http://localhost:8080/test/toHtmlPath?file_name=" 
               + fileName + "&&path=" + path + "&&realName=" + realName 
               + "&&realPath=" + realPath; 
             int httpResult; 
             URL url = new URL(str); 
             URLConnection connection = url.openConnection(); 
             connection.connect(); 
             HttpURLConnection httpURLConnection = (HttpURLConnection) connection; 
             httpResult = httpURLConnection.getResponseCode(); 
             if (httpResult != HttpURLConnection.HTTP_OK) { 
              System.out.println("没有连接成功"); 
             } else { 
              System.out.println("连接成功了 "); 
             } 
            } catch (Exception e) { 
             // TODO: handle exception 
            } 
           } 

          //这个方法适当重载,就可以省去一些参数传递。 

          } 

          四、在你的新闻发布save时,调用方法。 

          1、CallHtml.callOnePage("info.jsf?file_id=aaa",news,"", "");//将在news目录下生成一个aaa.htm的静态文件 

          2、CallHtml.callOnePage("newsList.jsf",news,"", "");//将在news目录下生成一个newsList.htm的静态文件,显示最新的新闻。 

          3、CallHtml.callOnePage("index.jsf","","", "");//生成主页。 

          好了,这就保持了,主页、列表、新闻内容都是最新的静态页面了。 

---------------------------------------------------------------------------------------------------- 

一个实现将动态页面转为静态的方案 

1.前言 
为了能深入浅出的理解这个框架的由来,我们首先来了解一下JSP解析器将我们写的JSP代码转换成的JAVA文件的内容。 
下面是一个JSP文件test.jsp 
经过TOMCAT转换出的JAVA文件test$jsp.java内容如下: 
package org.apache.jsp; 
import javax.servlet.*; 
import javax.servlet.http.*; 
import javax.servlet.jsp.*; 
import org.apache.jasper.runtime.*; 

public class test$jsp extends HttpJspBase { 

    static { 
    } 
    public testOutRedir$jsp( ) { 
    } 

    private static boolean _jspx_inited = false; 

    public final void _jspx_init() throws org.apache.jasper.runtime.JspException { 
    } 

    public void _jspService(HttpServletRequest request, HttpServletResponse  response) 
        throws java.io.IOException, ServletException { 

        JspFactory _jspxFactory = null; 
        PageContext pageContext = null; 
        HttpSession session = null; 
        ServletContext application = null; 
        ServletConfig config = null; 
        JspWriter out = null; 
        Object page = this; 
        String  _value = null; 
        try { 

            if (_jspx_inited == false) { 
                synchronized (this) { 
                    if (_jspx_inited == false) { 
                        _jspx_init(); 
                        _jspx_inited = true; 
                    } 
                } 
            } 
            _jspxFactory = JspFactory.getDefaultFactory(); 
            response.setContentType(text/html;charset=GB2312); 
            pageContext = _jspxFactory.getPageContext(this, request, response, 
                            , true, 8192, true); 

            application = pageContext.getServletContext(); 
            config = pageContext.getServletConfig(); 
            session = pageContext.getSession(); 
            out = pageContext.getOut(); 
                //为了节省篇幅,我删除了解释器添加的注释 
                out.write(\r\n); 
//上一句是由于后面的换行产生的 
                out.write(); 
                out.write(\r\n\r\n\r\n\r\n); 
                out.print( 输出 ); 
                out.write(\r\n\r\n\r\n\r\n); 
        } catch (Throwable t) { 
            if (out != null && out.getBufferSize() != 0) 
                out.clearBuffer(); 
            if (pageContext != null) pageContext.handlePageException(t); 
        } finally { 
            if (_jspxFactory != null) _jspxFactory.releasePageContext(pageContext); 
        } 
    } 

从上面的代码中可以清晰的看到JSP内建的几个对象(out、request、response、session、pageContext、application、config、page)是怎么产生的,懂servlet的朋友一看就能明白。 
下面重点理解一下out对象,它被声明为JspWriter类型,JspWriter是一个抽象类,在包javax.servlet.jsp中可以找到它的定义。 
abstract public class javax.servlet.jsp.JspWriter extends java.io.Writer{ 
       final public static int NO_BUFFER = 0; 
       final public static int DEFAULT_BUFFER = -1; 
       final public static int UNBOUNDED_BUFFER = -2; 
       protected int bufferSize; 
       protected Boolean autoFlush; 
       protected javax.servlet.jsp.JspWriter(int arg1, boolean arg2); 
       
    abstract public void newLine() throws IOException ; 
    abstract public void print(boolean arg0) throws IOException ; 
    abstract public void print(char arg0) throws IOException ; 
    abstract public void print(int arg0) throws IOException ; 
    abstract public void print(long arg0) throws IOException ; 
    abstract public void print(float arg0) throws IOException ; 
    abstract public void print(double arg0) throws IOException ; 
    abstract public void print(char[] arg0) throws IOException ; 
    abstract public void print(String arg0) throws IOException ; 
    abstract public void print(Object arg0) throws IOException ; 
    abstract public void println() throws IOException ; 
    abstract public void println(boolean arg0) throws IOException ; 
    abstract public void println(char arg0) throws IOException ; 
    abstract public void println(int arg0) throws IOException ; 
    abstract public void println(long arg0) throws IOException ; 
    abstract public void println(float arg0) throws IOException ; 
    abstract public void println(double arg0) throws IOException ; 
    abstract public void println(char[] arg0) throws IOException ; 
    abstract public void println(String arg0) throws IOException ; 
    abtract public void println(Object arg0) throws IOException ; 
    abstract public void clear() throws IOException ; 
    abstract public void clearBuffer() throws IOException ; 
    abstract public void flush() throws IOException ; 
    abstract public void close() throws IOException ; 
    public int getBufferSize() ; 
    abstract public int getRemaining() ; 
    public boolean isAutoFlush() ; 

我相信当我写到这里你可能已经知道我想怎么做了。是的,来个偷天换日,继承JspWriter类,然后实现其定义的虚函数,然后把out变量替换成你自己实现的类的实例就ok了。 
2.实现替换 
假设 
3.更新问题 
下面就讨论一下如何更新生成静态文件,其实从上面实现中你可以看到,很简单的就是将生成的静态文件删除即可,至于什么时候删除,要看你的需求了。我能想到的几种情况如下 
当用来生成页面的数据更新时 
如果不需要很提供时时的数据可以定时更新 
永远不更新 
---------------------------------------------------------------------------------------------------- 

JSP生成静态HTML页面范例 

先建立一个模本页面:template.htm 

<Html> 
<head> 
<title>###title###</title> 
<meta http-equiv="Content-Type" content="text/html; charset=gb2312"> 
<LINK href="../Css.css" rel=stylesheet type=text/css> 
</head> 
<body> 
<table width="500" border="0" align="center" cellpadding="0" cellspacing="2"> 
<tr> 
<td align="center">###title###</td> 
</tr> 
<tr> 
<td align="center">作者:###author###  </td> 
</tr> 
<tr> 
<td>###content### 
</td> 
</tr> 
</table> 
</body> 
</html> 

========================================= 
再写一个jsp页面: buildhtml.jsp 

<%@ page contentType="text/html; charset=gb2312" import="Java.util.*,java.io.*"%> 
<% 
try{ 
String title="jsp生成静态html文件"; 
String content="小样,还搞不定你?"; 
String editer="webjxcom"; 
String filePath = ""; 
filePath = request.getRealPath("/")+"template.htm"; 
out.print(filePath); 
String templateContent=""; 
FileInputStream fileinputstream = new FileInputStream(filePath);//读取模块文件 
int lenght = fileinputstream.available(); 
byte bytes[] = new byte[lenght]; 
fileinputstream.read(bytes); 
fileinputstream.close(); 
templateContent = new String(bytes); 
out.print(templateContent); 
templateContent=templateContent.replaceAll("###title###",title); 
templateContent=templateContent.replaceAll("###content###",content); 
templateContent=templateContent.replaceAll("###author###",editer);//替换掉模块中相应的地方 
out.print(templateContent); 
// 根据时间得文件名 
Calendar calendar = Calendar.getInstance(); 
String fileame = String.valueOf(calendar.getTimeInMillis()) +".html"; 
fileame = request.getRealPath("/")+fileame;//生成的html文件保存路径 
FileOutputStream fileoutputstream = new FileOutputStream(fileame);//建立文件输出流 
out.print("文件输出路径:<br>"); 
out.print(fileame); 
byte tag_bytes[] = templateContent.getBytes(); 
fileoutputstream.write(tag_bytes); 
fileoutputstream.close(); 

catch(Exception e){ 
out.print(e.toString()); 

%> 

------------------------------------------- 
mport java.io.*; 

import java.net.*; 

public class Tools { 

    final static Object lock = new Object(); 

    public static void makeHtml(String page, String filePath)...{ 

        makeHtml(page,filePath,"UTF-8"); 

    } 

    public static void makeHtml(String page, String filePath,String chartset) { 

        synchronized (lock) { 

            HttpURLConnection huc = null; 

            BufferedReader br = null; 

            BufferedWriter bw = null; 

            try { 

                huc = (HttpURLConnection)new URL(page).openConnection(); 

                System.setProperty("sun.net.client.defaultConnectTimeout", "30000"); 

                System.setProperty("sun.net.client.defaultReadTimeout", "30000"); 

                huc.connect(); 

                InputStream stream = huc.getInputStream(); 

                bw = new BufferedWriter(new OutputStreamWriter (new FileOutputStream(filePath),chartset)); 

                br = new BufferedReader(new InputStreamReader(stream, chartset)); 

                String line; 

                while((line = br.readLine())!= null){ 

                   if(line.trim().length() > 0){ 

                        bw.write(line); 

                        bw.newLine(); 

                   } 

                } 

            }catch (Exception e) { 

                e.printStackTrace(); 

            }finally { 

                try { 

                    br.close(); 

                    bw.close(); 

                    huc.disconnect(); 

                }catch (Exception e) { 

                    e.printStackTrace(); 

                } 

            } 

        } 

}
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