本文是介紹了jsp技術(shù)實(shí)現(xiàn)動(dòng)態(tài)頁(yè)面到靜態(tài)頁(yè)面的方法，分享給大家，具體如下：
對(duì)于JSP技術(shù)實(shí)現(xiàn)動(dòng)態(tài)頁(yè)面到靜態(tài)頁(yè)面的方案，我們從三個(gè)步驟來說明：
JSP技術(shù)實(shí)現(xiàn)動(dòng)態(tài)頁(yè)面到靜態(tài)頁(yè)面的方案第一：
為了能深入淺出的理解這個(gè)框架的由來，我們首先來了解一下JSP解析器將我們寫的JSP代碼轉(zhuǎn)換成的JAVA文件的內(nèi)容。
下面是一個(gè)JSP文件test.jsp
﹤%@ page language=java contentType=text/html;charset=GB2312 %﹥
﹤%
out.write(﹤!--文件開始--﹥);
%﹥
﹤html﹥
﹤head﹥
﹤body﹥
﹤%=輸出%﹥
﹤/body﹥
﹤/head﹥
﹤/html﹥
經(jīng)過Tomcat轉(zhuǎn)換出的Java文件test$jsp.java內(nèi)容如下：
package org.apache.jsp;
import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.jsp.*;
import org.apache.jasper.runtime.*;
public class test$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();
//為了節(jié)省篇幅，我刪除了解釋器添加的注釋
out.write(\r\n);
//上一句是由于
﹤%@ page language=java contentType=text/html;charset=GB2312 %﹥后面的換行產(chǎn)生的
out.write(﹤!--文件開始--﹥);
out.write(\r\n﹤html﹥\r\n﹤head﹥\r\n﹤body﹥\r\n);
out.print(輸出);
out.write(\r\n﹤/body﹥\r\n﹤/head﹥\r\n﹤/html﹥\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);
}
}
}
從上面的代碼中可以清晰的看到JSP內(nèi)建的幾個(gè)對(duì)象（out、request、response、session、pageContext、application、config、page）是怎么產(chǎn)生的，懂servlet的朋友一看就能明白。
下面重點(diǎn)理解一下out對(duì)象，它被聲明為JspWriter類型，JspWriter是一個(gè)抽象類，在包javax.servlet.jsp中可以找到它的定義。
abstractpublicclassjavax.servlet.jsp.JspWriterextends java.io.Writer{
final public static intNO_BUFFER = 0;
final public static intDEFAULT_BUFFER = -1;
final public static intUNBOUNDED_BUFFER = -2;
protected intbufferSize;
protected BooleanautoFlush;
protectedjavax.servlet.jsp.JspWriter(intarg1,booleanarg2);
abstractpublicvoidnewLine()throwsIOException;
abstractpublicvoidprint(booleanarg0)throwsIOException;
abstractpublicvoidprint(chararg0)throwsIOException;
abstractpublicvoidprint(intarg0)throwsIOException;
abstractpublicvoidprint(longarg0)throwsIOException;
abstractpublicvoidprint(floatarg0)throwsIOException;
abstractpublicvoidprint(doublearg0)throwsIOException;
abstractpublicvoidprint(char[]arg0)throwsIOException;
abstractpublicvoidprint(Stringarg0)throwsIOException;
abstractpublicvoidprint(Objectarg0)throwsIOException;
abstractpublicvoidprintln()throwsIOException;
abstractpublicvoidprintln(booleanarg0)throwsIOException;
abstractpublicvoidprintln(chararg0)throwsIOException;
abstractpublicvoidprintln(intarg0)throwsIOException;
abstractpublicvoidprintln(longarg0)throwsIOException;
abstractpublicvoidprintln(floatarg0)throwsIOException;
abstractpublicvoidprintln(doublearg0)throwsIOException;
abstractpublicvoidprintln(char[]arg0)throwsIOException;
abstractpublicvoidprintln(Stringarg0)throwsIOException;
abtractpublicvoidprintln(Objectarg0)throwsIOException;
abstractpublicvoidclear()throwsIOException;
abstractpublicvoidclearBuffer()throwsIOException;
abstractpublicvoidflush()throwsIOException;
abstractpublicvoidclose()throwsIOException;
publicintgetBufferSize() ;
abstractpublicintgetRemaining();
publicbooleanisAutoFlush();
}
相信到這里你可能已經(jīng)知道怎么做了。是的，來個(gè)偷天換日，繼承JspWriter類，然后實(shí)現(xiàn)其定義的虛函數(shù)，然后把out變量替換成你自己實(shí)現(xiàn)的類的實(shí)例就ok了。
JSP技術(shù)實(shí)現(xiàn)動(dòng)態(tài)頁(yè)面到靜態(tài)頁(yè)面的方案第二：
實(shí)現(xiàn)替換
假設(shè)
﹤%@ page language=java contentType=text/html;charset=GB2312 import=jwb.util.HtmlIntoFile,jwb.util.TempSinglet,java.io.File%﹥
﹤%
JspWriter outout_bak =out;String arg1=argument1;String filePath = /cache/根據(jù)參數(shù)生成文件名_ + arg1 + .html;
//首先判斷文件是否已經(jīng)存在，如果不存在則執(zhí)行本頁(yè)面，否則跳轉(zhuǎn)到靜態(tài)頁(yè)面就OK了File f = new File(pageContext.getServletContext().getRealPath(filePath));
if(f.exists()){ out_bak.clear(); pageContext.forward(filePath); System.out.println(直接轉(zhuǎn)到靜態(tài)頁(yè)面);
return;}out= new HtmlIntoFile(pageContext.getServletContext().getRealPath(filePath));out.write(﹤!--文件開始--﹥);
%﹥
﹤html﹥
﹤head﹥
﹤body﹥
﹤%= 看吧，這就是輸出被重定向到文件的實(shí)現(xiàn)，很簡(jiǎn)單吧^_^%﹥
﹤/body﹥
﹤/head﹥
﹤/html﹥
﹤%
out.close();
//關(guān)閉生成的靜態(tài)文件out_bak.clear();pageContext.forward(filePath);
System.out.println(執(zhí)行本頁(yè)面后再轉(zhuǎn)到靜態(tài)頁(yè)面);return;
%﹥
JSP技術(shù)實(shí)現(xiàn)動(dòng)態(tài)頁(yè)面到靜態(tài)頁(yè)面的方案第三：
更新問題
下面就討論一下如何更新生成靜態(tài)文件，其實(shí)從上面實(shí)現(xiàn)中你可以看到，很簡(jiǎn)單的就是將生成的靜態(tài)文件刪除即可，至于什么時(shí)候刪除，要看你的需求了。我能想到的幾種情況如下：
◆當(dāng)用來生成頁(yè)面的數(shù)據(jù)更新時(shí)
◆如果不需要很提供時(shí)時(shí)的數(shù)據(jù)可以定時(shí)更新
◆永遠(yuǎn)不更新
那么通過這個(gè)JSP技術(shù)實(shí)現(xiàn)動(dòng)態(tài)頁(yè)面到靜態(tài)頁(yè)面的方案，從動(dòng)態(tài)頁(yè)面到靜態(tài)的轉(zhuǎn)變就已經(jīng)告一段落，你是否有點(diǎn)啟發(fā)呢？感謝閱讀，希望能幫助到大家，謝謝大家對(duì)本站的支持！
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