public ? class ?ValidatorPlugIn
???? implements ?PlugIn
{
.

???? public ?String?getPathnames()
???? {
???????? return ?pathnames;
????}

???? public ? void ?setPathnames(String?pathnames)
???? {
???????? this .pathnames? = ?pathnames;
????}


???? public ? void ?init(ActionServlet?servlet,?ModuleConfig?config)
???????? throws ?ServletException
???? {
???????? this .config? = ?config;
???????? this .servlet? = ?servlet;
???????? try
???????? {
????????????initResources();
???????? catch (Exception?e)
???????? {
????????????log.error(e.getMessage(),?e);
???????????? throw ? new ?UnavailableException( " Cannot?load?a?validator?resource?from?' " ? + ?pathnames? + ? " ' " );
????????}
????}

???? protected ? void ?initResources()
???????? throws ?IOException,?ServletException
???? {
???????? if (pathnames? == ? null ? || ?pathnames.length()? <= ? 0 )
???????????? return ;
????????StringTokenizer?st? = ? new ?StringTokenizer(pathnames,? " , " );
????????List?streamList? = ? new ?ArrayList();
???????? try
???????? {
???????????? while (st.hasMoreTokens())?
???????????? {
????????????????String?validatorRules? = ?st.nextToken().trim();
???????????????? if (log.isInfoEnabled())

.

}

學(xué)習(xí)Java Web 技術(shù)，首先必須先把Servlet搞明白。沒(méi)有Servlet基礎(chǔ)，別的都是扯淡！

主要就是掌握Servlet的生命周期，所關(guān)聯(lián)到的類，以及他們的方法。

我簡(jiǎn)要回顧一下

打開(kāi)Servlet-API

Servlet接口，三個(gè)關(guān)乎生命周期的重要方法簽名

??????????????????ServletConfig，是一個(gè)較重要的對(duì)象。

??????????????????????????????????????????功能:1，獲得初始化參數(shù)
???????????????????????????????????????????????????2，獲得Servlet上下文對(duì)象。public ServletContextgetServletContext()

GeneralServlet抽象類，等待你去重寫(xiě)service方法。

??????????????????功能主要就是，為程序員編寫(xiě)Servlet提供一些方便
??????????????????????????????????????????方便:1，直接覆蓋public void init() throws ServletException?
???????????????????????????????????????????????????2，直接調(diào)用getInitParameter(java.lang.String?name)?
?????????????????????????????????????????????????????????直接調(diào)用public ServletContextgetServletContext()
?????????????????????????????????????????????????????????直接調(diào)用public void log(java.lang.String?msg)

?????????????????????????????????????????????????????????因?yàn)镚eneralServlet是個(gè)懶家伙，都委托給相應(yīng)ServletConfig/ServletContext完成功能


HttpServlet沒(méi)什么，自己看API吧

ServletRequest能做什么，幾件事

?????????????????????????????????????????????事情1: public java.lang.Object getAttribute(java.lang.String?name)/////還有set
?????????????????????????????????????????????事情2: public java.lang.String getParameter(java.lang.String?name)
????????????????????????????????????????????????????????????????????????????????????????兩方面參數(shù),
??????????????????????????????????????????????????????????????????????????????????????????????????????方面1:html表單中，有name屬性的值.
??????????????????????????????????????????????????????????????????????????????????????????????????????????????????eg. <input type="text" name="userid" size="20" maxlength="20" />
?????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????request.getParameter("userid");
??????????????????????????????????????????????????????????????????????????????????????????????????????方面2:地址欄參數(shù)，eg. http://www.infogo.com.cn/action.do?name=admin
??????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????request.getParameter("name");
???????????????????????????????????????????????????????????
??????????????????????????????????????????????????????????由于參數(shù)的值有時(shí)會(huì)是一組，那么就要用public java.lang.String[] getParameterValues(java.lang.String?name)
?eg.
???====================================================
?? <c:forEach items="${cart.cartItem}" var="item">
? <TR align=middle>
??? <TD height=30><INPUT type=checkbox value="${item.value.product.id}" name=item></TD>
??? <TD height=30>${item.value.product.name}&nbsp;</TD>
??? <TD height=30>${item.value.product.price}&nbsp;</TD>
??? <TD height=30><INPUT maxLength=10 size=10 value="${item.value.number}" name=itemnum></TD>
??? <TD height=30>${item.value.cost}&nbsp;</TD>
? </TR>
? </c:forEach>
????====================================================

//獲得頁(yè)面,checkbox組的信息,可以知道用戶選擇的商品
??String[] itemkeystr = request.getParameterValues("item");
??System.out.println(itemkeystr);
??????????????? Integer[] itemkeyigr = new Integer[itemkeystr.length];
??????????????? for(int i = 0; i < itemkeystr.length; i++)
??????????????? {
??????????????????????? itemkeyigr[i] = Integer.valueOf(itemkeystr[i]);
??????????????? }
================================================

??????????????????????????????????????????????????????????????????????????????????事情3:public RequestDispatchergetRequestDispatcher(java.lang.String?path)
????????????????????????????????????????????????????????????????????????????????? 事情4:public void setCharacterEncoding(java.lang.String?env)
????????????????????????? throws java.io.UnsupportedEncodingException
eg.主要防止用戶在表單中輸入了中文。

過(guò)濾器實(shí)例:

public ? final ? class ?CharacterEncodingFilter? implements ?Filter
{
???? private ?String??encoding? = ? " gb2312 " ;

???? private ? boolean ?ignore??? = ? false ;

???? public ? void ?init(FilterConfig?config)
???? {
???????? if ?(config.getInitParameter( " encoding " )? != ? null )
???????? {
????????????encoding? = ?config.getInitParameter( " encoding " );
????????}

???????? if ?(config.getInitParameter( " ignore " )? != ? null )
???????? {
????????????ignore? = ? new ?Boolean(config.getInitParameter( " ignore " )).booleanValue();
????????}

????}

???? public ? void ?doFilter(ServletRequest?request,?ServletResponse?response,?FilterChain?chain)? throws ?IOException,
????????????ServletException
???? {
????????HttpServletRequest?req? = ?(HttpServletRequest)?request;
????????HttpServletResponse?res? = ?(HttpServletResponse)?response;

???????? if ?( ! ignore)
???????? {
????????????req.setCharacterEncoding(encoding);
????????????res.setCharacterEncoding(encoding);
????????}

????????chain.doFilter(request,?response);
????}

???? public ? void ?destroy()
???? {

????}
}

ServletResponse，就是負(fù)責(zé)輸出唄。

??????????????????????????????????????????????????????????????????????????????負(fù)責(zé)1:??public void setContentType(java.lang.String?type)?
????????????????????????????????????????????????????????????????????????????????????????????eg.?response.setContentType(text/html;charse=gbk)
??????????????????????????????????????????????????????????????????????????????負(fù)責(zé)2:? public java.io.PrintWriter getWriter() throws java.io.IOException
??????????????????????????????????????????????????????????????????????????????這里注意：
????????????????????????????????????????????????????????????????????????????1必須先設(shè)置setContextType或者setCharacterEncoding，再獲得輸出。否則設(shè)置編碼無(wú)效！
????????????????????????????????????????????????????????????????????????????2不得在ResquestDispatcher.forward()調(diào)用前，進(jìn)行向客戶端的輸出。有風(fēng)險(xiǎn)。
??????????????????????????????????????????????????????????????????????????????


ServletContext整個(gè)應(yīng)用只有一個(gè)實(shí)例，可以為應(yīng)用放置一些只讀的共享數(shù)據(jù)。

責(zé)任1:public java.lang.String getInitParameter(java.lang.String?name)
責(zé)任2:public RequestDispatchergetRequestDispatcher(java.lang.String?path)絕對(duì)路徑
責(zé)任3:public void log(java.lang.String?msg)


Filter接口，實(shí)現(xiàn)對(duì)于某一個(gè)url匹配的過(guò)濾。是一個(gè)責(zé)任鏈模式的應(yīng)用

package ?ljl.shop.common;

import ?java.io.IOException;
???????????????????????????????????????????????????????????????????????????????????????????????????????????????
import ?javax.servlet.Filter;
import ?javax.servlet.FilterChain;
import ?javax.servlet.FilterConfig;
import ?javax.servlet.ServletException;
import ?javax.servlet.ServletRequest;
import ?javax.servlet.ServletResponse;
import ?javax.servlet.http.HttpServletRequest;
import ?javax.servlet.http.HttpServletResponse;


/**?*/ /**
?*?權(quán)限過(guò)濾器?通過(guò)配置web.xml中的filter初始化參數(shù)，實(shí)現(xiàn)動(dòng)態(tài)判別
?*?
?*??<filter-mapping>
?*???????<filter-name>CharacterEncodingFilter</filter-name>
?*???????<url-pattern>/*</url-pattern>
?*???</filter-mapping>????????????????????????????????????????????????????????????????????????????
?*
?*???<filter>
?*???????<filter-name>PermissionFilter</filter-name>
?*???????<filter-class>ljl.shop.common.PermissionFilter</filter-class>
?*???????<init-param>
?*???????????????<param-name>checkpage</param-name>
?*???????????????<param-value>checkout.jsp#order_created.jsp#postLogin.jsp</param-value>
?*???????</init-param>
?*???</filter>
?*?
?*? @author ?lujl
? */
public ? class ?PermissionFilter? implements ?Filter
{
???? private ?String?checkpage? = ? null ;

???? private ?FilterConfig?config? = ? null ;

???? public ? void ?init(FilterConfig?config)
???? {
????????System.out.println(config.getInitParameter( " checkpage " ));
???????? if (config.getInitParameter( " checkpage " )? != ? null )
???????? {
????????????System.out.println(config.getInitParameter( " checkpage " ));
???????????? // vip.jsp#checkout.jsp#
????????????checkpage? = ?config.getInitParameter( " checkpage " );????????????
????????}
???????? this .config? = ?config;
????}

???? public ? void ?doFilter(ServletRequest?request,?ServletResponse?response,?FilterChain?chain)? throws ?IOException,ServletException
???? {
????????HttpServletRequest?hrequest? = ?(HttpServletRequest)request;
????????String?path? = ?hrequest.getServletPath();
????????String[]?pages? = ?checkpage.split( " # " );
????????System.out.println(pages.length);
???????? for ( int ?i? = ? 0 ;?i? < ?pages.length;?i ++ )
???????? {
???????????? if (path.indexOf(pages[i])? != ? - 1 ) // 解析的path包含這些頁(yè)面,那么就檢查是否登錄
???????????? {
???????????????? if (hrequest.getSession().getAttribute( " user " )? != ? null )
???????????????? {
????????????????????chain.doFilter(request,?response);
???????????????????? return ;
????????????????}
???????????????? else
???????????????? {
???????????????????? this .config.getServletContext().getRequestDispatcher( " /login.jsp " ).forward(request,response);
???????????????????? return ;
????????????????}
????????????}
????????????
????????}
????????chain.doFilter(request,response);????
????}

???? public ? void ?destroy()
???????? {
???????????????????????????????????????????????????????????????????????????????????????????????????????????????
????????}
}

===========================================================================?????

HttpServletRequest

還有一些Http協(xié)議的特征方法

public Cookie[] getCookies()

public java.lang.String getPathInfo()???????????????? http://www.infogo.com.cn/webapp/servlet/aaa
?????????????????????????????????????????????????????????????????????????????????如果url-pattern是/servlet/*???????? 那么request.getPathInfo() 返回 /aaa

public java.lang.String getContextPath()?????????
?????????????????????????????????????????????????????????????????????????????????/webapp
???????????????????????????????????????????????????????????????????????????????? jsp el??也可以取到此值??? ${pageContext.request.contextPath}
?????????????????????????????????????????????????????????????????????????????????也就是<%=request.getContextPath()%>
public java.lang.String getQueryString()
???????????????????????????????????????????????????????????????????????????????? 只拿到地址欄參數(shù)字符串，自己解析吧:)

public java.lang.String getServletPath()
?????????????????????????????????????????????????????????????????????????????????/servlet

public HttpSessiongetSession(boolean?create)

?????????????????????????????????????????????????????????????????????????????????傳入true，如果有，直接返回，沒(méi)有創(chuàng)建??????? 等同于getSession()無(wú)參
?????????????????????????????????????????????????????????????????????????????????傳入false，沒(méi)有則返回null
request.getRequestURI()???????????????????? /WebTest/servlet/MethodServlet
request.getRequestURL()??????????????????? http://localhost:8080/WebTest/servlet/MethodServlet?

URI是一個(gè)相對(duì)的位置，或者說(shuō)就是一個(gè)標(biāo)識(shí)，URL是資源定位，所以很精確。

HttpServletResponse

public void addCookie(Cookie?cookie)

public java.lang.String encodeURL(java.lang.String?url)???????? URL回寫(xiě)機(jī)制，說(shuō)白了就是把jsessionid放在連接里，下回請(qǐng)求時(shí)就能穿回來(lái)了，不在需要Cookie了。注意，如果瀏覽器支持Cookie，無(wú)效果！！！

public java.lang.String encodeRedirectURL(java.lang.String?url)????? 用于response.sendRedirect()函數(shù)中。


最后一招：
public void sendError(int?sc)? throws java.io.IOException??

把API上面的靜態(tài)常量往里放！

+++++++++++++++++++++++

public boolean isRequestedSessionIdValid()?? 待使用

+++++++++++++++++++++++
--------------------------------------------------------------

HttpSessionListener

public void sessionCreated(HttpSessionEvent?se)

做JSP開(kāi)發(fā)時(shí)，由于Session是在用戶訪問(wèn)jsp時(shí)，自動(dòng)創(chuàng)建的。如果能在用戶一訪問(wèn)就往Session中放入一個(gè)容器對(duì)象呢，而不是在用戶發(fā)出某一個(gè)特定Action請(qǐng)求時(shí)，再判斷，再setAttribute();

那么就用Listener吧，這時(shí)使用是一個(gè)完全充分的理由。[還有ServletContextListener]

public void sessionDestroyed(HttpSessionEvent?se)???基本可以統(tǒng)計(jì)用戶在線時(shí)間。

或者做考試系統(tǒng)時(shí)，會(huì)使用到。

====================================

HttpSessionAttributeListener監(jiān)聽(tīng)Session

HttpSessionBindingListener監(jiān)聽(tīng)被session的setAttribute方法加入的對(duì)象。

實(shí)現(xiàn)接口的類型不同！！注意區(qū)分。

====================================

HttpServletResponseWrapper

是個(gè)適配器。

在制作一個(gè)filter的時(shí)候，如果想在原有的輸出，某部分，添加一部分內(nèi)容，必須對(duì)HttpServletResponse進(jìn)行適配。

MyResponse myRes = new?MyResponse(response);
chain.doFilter(request,myRes);
String contents = myRes.toString();
//解析字符串，比如尋找</body>

myRes.getResponse().getWriter();//取回原來(lái)的response????????? ServletResponseWrapper有個(gè)有參的構(gòu)造方法。
//真正輸出


public class MyResponse extends HttpServletResponseWrapper
{
??????
??????MyResponse(ServletResponse res)
??????{
????????????super(res);
??????}

??????public PrintWriter getWriter()
??????{
????????????return new PrintWriter(caw);
??????}
??????
??????private CharArrayWriter caw = new CharArrayWriter();//IO 我就不廢話了，也就是一個(gè)內(nèi)存中的字符輸出流。

??????public String toString()
??????{
????????????return caw.toString();
??????}
}


================================================================================

?HttpSession接口

public void setMaxInactiveInterval(int?interval)

<session-config>
<session-timeout>30</session-timeout>
</session-config>

public void invalidate()

public boolean isNew(),就是創(chuàng)建后，還沒(méi)讓客戶端知道呢！


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


JSP

就是一個(gè)Servlet

<%
??????!
%>??

定義那個(gè)Servlet的成員

?<%!class ABC{}%>定一個(gè)類都沒(méi)有問(wèn)題！

表達(dá)式

<%=request.getParameter("user")%>?????????????????????

代碼段

<%

%>

指令

<% @page errorPage="relativeURL"%>
<% @page isErrorPage="true"%>
<% @page contextType="text/html;charset=gb2312" %>
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>

動(dòng)作

http://java.sun.com/products/jsp/syntax/2.0/syntaxref20.html

<jsp:include page="scripts/login.jsp">
???<jsp:param name="username" value="jsmith" />
</jsp:include>


<jsp:forward page="/servlet/login">
???<jsp:param name="username" value="jsmith" />
</jsp:forward>

================

<tt:screen id="/bookcatalog">
???<tt:parameter name="title" direct="true">
??????<jsp:attribute name="value" >
?????????<fmt:message key="TitleBookCatalog"/>
??????</jsp:attribute>
???</tt:parameter>
...
</tt:screen>

注意，也就是<tt:parameter這個(gè)標(biāo)簽，還有一個(gè)屬性就是value，那么它的值是通過(guò)變化取得。

jsp先回把html，翻譯成為xml的標(biāo)準(zhǔn)試圖，再使用一個(gè)引擎翻譯成為java代碼。

<jsp:element name="h1">
???<jsp:attribute name="align">
??????center
???</jsp:attribute>
???<jsp:body>
??????This is the header!
???</jsp:body>
</jsp:element>

您把這段代碼放入jsp，可以通過(guò)的。

<h1 align="center">
?????? This is the header!
</h1>????????????????????






<%
Person p = null;
synchronized(application){
???p = (Person)application.getAttribute("person");
???if(p==null)
???{
?????????p = new Person();
?????????application.setAttribute("person",p);???
???}
}
%>

通用一些

Class.forName("com.infogo.bean.Person").newInstance();

<jsp:useBean id="p" class="com.infogo.bean.Person" scope="application" />? scope默認(rèn)為page

這就是useBean指令做的事情。



<jsp:useBean id="persons" type="java.util.Collection" scope="request" />

注意type就是只說(shuō)明它是什么類型的，不做實(shí)例化的步驟

MVC中的視圖，就是使用集合bean的。如果不存在，會(huì)拋異常。bean persons not found within scope


<jsp:getProperty name="p" property="name" />


Stores all of the values of request parameters in bean properties. The names of the bean properties must match the names of the request parameters. A bean property is usually defined by a variable declaration with matching getter and setter methods (for more information, see http://java.sun.com/products/javabeans/docs/).

<jsp:setProperty name="mybean" property="*" />	
<jsp:setProperty name="mybean" property="username" />	
<jsp:setProperty name="mybean" property="username" value="Steve" />

====================================

先來(lái)說(shuō)說(shuō)，JSTL和EL的東西

Sun專門定制了一組標(biāo)簽庫(kù)來(lái)完成頁(yè)面的程序流程控制，避免了代碼片斷的出現(xiàn)。而EL則避免了頁(yè)面出現(xiàn)表達(dá)式，而且對(duì)于attribute中的數(shù)據(jù)的非空驗(yàn)證是自動(dòng)完成。如果為空，只會(huì)出現(xiàn)沒(méi)有輸出內(nèi)容。

EL還是比較簡(jiǎn)單的。

http://java.sun.com/products/jsp/syntax/2.0/syntaxref207.html#1010522

上面是sun的教程。

=====================================

在說(shuō)標(biāo)簽和EL原理之前，必須把JSP的原理搞清楚。

客戶端請(qǐng)求jsp，由一個(gè)翻譯引擎對(duì)jsp進(jìn)行java代碼的翻譯，然后由容器進(jìn)行編譯，加載到容器，invoke Servlet。

一個(gè)jsp

<% @?page?language = " java " ?import = " java.util.* " ?pageEncoding = " UTF-8 " %>
<% @?page?info = " view?jsp?translate " %>
<! DOCTYPE?HTML?PUBLIC?"-//W3C//DTD?HTML?4.01?Transitional//EN" >
< html >
?? < head >
????
???? < title > View?Jsp?Translation </ title >
????
???? < meta? http-equiv ="pragma" ?content ="no-cache" >
???? < meta? http-equiv ="cache-control" ?content ="no-cache" >
???? < meta? http-equiv ="expires" ?content ="0" >
???? < meta? http-equiv ="keywords" ?content ="keyword1,keyword2,keyword3" >
???? < meta? http-equiv ="description" ?content ="This?is?my?page" >
????
?? </ head >
??
?? < body >
????This?is?my?JSP?page.? < br >
?? </ body >
</ html >

package?org.apache.jsp;

import?javax.servlet.*;
import?javax.servlet.http.*;
import?javax.servlet.jsp.*;
import?java.util.*;

public?final?class?ViewJspTranslate_jsp?extends?org.apache.jasper.runtime.HttpJspBase
????implements?org.apache.jasper.runtime.JspSourceDependent?{

//這就是page指令生成的
??public?String?getServletInfo()?{
????return?"view?jsp?translate";
??}

??private?static?java.util.Vector?_jspx_dependants;

??public?java.util.List?getDependants()?{
????return?_jspx_dependants;
??}

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

//內(nèi)置對(duì)象
????JspFactory?_jspxFactory?=?null;
????PageContext?pageContext?=?null;
//使用page 指令中 Session=false，就不會(huì)出現(xiàn)session變量了，提高一些效率，注意只是不出現(xiàn)該引用。一訪問(wèn)jsp/Session就創(chuàng)建了。只能通過(guò)SessionListener進(jìn)行創(chuàng)建時(shí)的截獲，放置一些初始對(duì)象。
????HttpSession?session?=?null;
????ServletContext?application?=?null;
????ServletConfig?config?=?null;
????JspWriter?out?=?null;
????Object?page?=?this;
????JspWriter?_jspx_out?=?null;

//關(guān)鍵的JSP上下文對(duì)象
????PageContext?_jspx_page_context?=?null;


????try?{
??????_jspxFactory?=?JspFactory.getDefaultFactory();
??????response.setContentType("text/html;charset=UTF-8");
??????pageContext?=?_jspxFactory.getPageContext(this,?request,?response,
??????????????????null,?true,?8192,?true);
??????_jspx_page_context?=?pageContext;
??????application?=?pageContext.getServletContext();
??????config?=?pageContext.getServletConfig();
??????session?=?pageContext.getSession();
??????out?=?pageContext.getOut();
??????_jspx_out?=?out;

??????out.write("\r\n");
??????out.write("\r\n");
??????out.write("<!DOCTYPE?HTML?PUBLIC?\"-//W3C//DTD?HTML?4.01?Transitional//EN\">\r\n");
??????out.write("<html>\r\n");
??????out.write("??<head>\r\n");
??????out.write("????\r\n");
??????out.write("????<title>View?Jsp?Translation</title>\r\n");
??????out.write("????\r\n");
??????out.write("????<meta?http-equiv=\"pragma\"?content=\"no-cache\">\r\n");
??????out.write("????<meta?http-equiv=\"cache-control\"?content=\"no-cache\">\r\n");
??????out.write("????<meta?http-equiv=\"expires\"?content=\"0\">\r\n");
??????out.write("????<meta?http-equiv=\"keywords\"?content=\"keyword1,keyword2,keyword3\">\r\n");
??????out.write("????<meta?http-equiv=\"description\"?content=\"This?is?my?page\">\r\n");
??????out.write("????\r\n");
??????out.write("??</head>\r\n");
??????out.write("??\r\n");
??????out.write("??<body>\r\n");
??????out.write("????This?is?my?JSP?page.?<br>\r\n");
??????out.write("??</body>\r\n");
??????out.write("</html>\r\n");
????}?catch?(Throwable?t)?{
??????if?(!(t?instanceof?SkipPageException)){
????????out?=?_jspx_out;
????????if?(out?!=?null?&&?out.getBufferSize()?!=?0)
??????????out.clearBuffer();
????????if?(_jspx_page_context?!=?null)?_jspx_page_context.handlePageException(t);
??????}
????}?finally?{
??????if?(_jspxFactory?!=?null)?_jspxFactory.releasePageContext(_jspx_page_context);
????}
??}
}

所以如果發(fā)生編譯不過(guò)，就到tomcat的work目錄里看看java代碼，比較容易看到錯(cuò)誤。jsp的提示對(duì)于嚴(yán)重的語(yǔ)法錯(cuò)誤是不太友好的。


對(duì)于隱含對(duì)象，就可以直接使用了。
<%=request.getContextPath()%>

<%=request.getInitParameter("user")%>

對(duì)于JSP也可以配置初始化參數(shù)。

web.xml對(duì)于JSP進(jìn)行部署
<servlet>
???<servlet-name>some name</servlet-name>
???<jsp-file>/internal/config.jsp</jsp-file>
</servlet>

<servlet-mapping>
???<servlet-name>some name</servlet-name>
???<url-pattern>/internal/config.jsp</url-pattern>
</servlet-mapping>

url-pattern如果配置與jsp路徑不一樣，那么只有從這個(gè)pattern訪問(wèn)的jsp才能獲得初始化參數(shù)。直接訪問(wèn)jsp的沒(méi)有。
=========================


繼續(xù)使用PageContext，可以得到很多信息。

<%@?page?language="java"?pageEncoding="UTF-8"%>
<%@?page?info="view?jsp?translate"%>
<jsp:useBean?id="client"?class="com.bean.SthBizBean"?scope="page">
????<jsp:setProperty?name="client"?property="currentPage"?value="<%=pageContext%>"/>
</jsp:useBean>
<!DOCTYPE?HTML?PUBLIC?"-//W3C//DTD?HTML?4.01?Transitional//EN">
<html>
??<head>
????
????<title>View?Jsp?Translation</title>
????
????<meta?http-equiv="pragma"?content="no-cache">
????<meta?http-equiv="cache-control"?content="no-cache">
????<meta?http-equiv="expires"?content="0">
????<meta?http-equiv="keywords"?content="keyword1,keyword2,keyword3">
????<meta?http-equiv="description"?content="This?is?my?page">
????
??</head>
??
??<body>
????Client?Info:<jsp:getProperty?name="client"?property="clientInfo"?/>
??</body>
</html>

?

package?com.bean;

import?javax.servlet.ServletRequest;
import?javax.servlet.jsp.PageContext;

public?class?SthBizBean?{

????PageContext?pctx?=?null;

????public?void?setCurrentPage(PageContext?pctx)?{
????????this.pctx?=?pctx;
????}

????public?String?getClientInfo()?{
????????StringBuffer?buf?=?new?StringBuffer();
????????ServletRequest?request?=?pctx.getRequest();
????????buf.append("<br>協(xié)議:"?+?request.getProtocol()?+?"<br>").append(
????????????????"地址:"?+?request.getRemoteAddr()?+?"<br>").append(
????????????????"端口:"?+?request.getRemotePort());
????????return?buf.toString();
????}

}

==========================

java.lang.Object
? javax.servlet.jsp.JspContext
????? javax.servlet.jsp.PageContext

去查看一下PageContext這個(gè)父類型。

public abstract java.lang.Object findAttribute(java.lang.String?name)

Searches for the named attribute in page, request, session (if valid), and application scope(s) in order and returns the value associated or null.

看好這個(gè)方法是試圖從四個(gè)范圍內(nèi)取值，如果都取不到，就會(huì)返回null。

public abstract void removeAttribute(java.lang.String?name)

去除所有的屬性值。

可以單獨(dú)設(shè)置，作用范圍

public abstract void removeAttribute(java.lang.String?name,
???????????????????????????????????? int?scope)

就是用子類PageContext設(shè)置的常量。

============================================================

可以自己寫(xiě)自定義標(biāo)簽完成復(fù)雜的頁(yè)面表現(xiàn)功能。

直接使用JSTL就行了。

=======================

JSTL配置EL，就可以使得JSP開(kāi)發(fā)人員與JavaBean業(yè)務(wù)實(shí)現(xiàn)人員完全獨(dú)立工作。測(cè)試也可以獨(dú)立進(jìn)行。

因?yàn)槭褂肊L語(yǔ)言，不再需要<jsp:useBean>指令來(lái)設(shè)置一個(gè)JavaBean的對(duì)象到某一個(gè)范圍內(nèi)，并設(shè)置一個(gè)變量。

使用EL，直接可以使用Attribute了。

${user.name}

等價(jià)于

判斷是否為空
<%=user.getName()%>

而且不需要判斷user是否為空。

---------

EL有很多內(nèi)嵌對(duì)象，當(dāng)然只限制于在EL表達(dá)式中使用。

${pageContext.request.contextPath}

看到按照J(rèn)AVABEAN命名的好處了吧，都可以按照標(biāo)準(zhǔn)命名去取值的。多方便。

參數(shù)

<c:if test=""${!empty param.username}">
??????do sth
</c:if>

訪問(wèn)javabean

${bean1.a.c}

相當(dāng)于

<%=bean1.getA().getC()%>

注意getA()方法本身就是返回一個(gè)javabean對(duì)象，所以可以繼續(xù)javabean訪問(wèn)。



對(duì)于集合對(duì)象,Map對(duì)象。

訪問(wèn)可以通過(guò)另外的方式訪問(wèn)。

<%@?page?language="java"?import="java.util.*"?pageEncoding="UTF-8"%>
<%@?page?import="com.bean.UserBean"%>
<%
String?path?=?request.getContextPath();
String?basePath?=?request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";

Map?userMap?=?new?HashMap();
UserBean?user_a?=?new?UserBean();
user_a.setName("ljl");
user_a.setAddress("bj");
UserBean?user_b?=?new?UserBean();
user_b.setName("superman");
user_b.setAddress("Mars");

userMap.put("ua",user_a);
userMap.put("ub",user_b);

request.setAttribute("userMap",userMap);

%>

<!DOCTYPE?HTML?PUBLIC?"-//W3C//DTD?HTML?4.01?Transitional//EN">
<html>
??<head>
????<base?href="<%=basePath%>">
????
????<title>My?JSP?'ViewEL.jsp'?starting?page</title>
????
????<meta?http-equiv="pragma"?content="no-cache">
????<meta?http-equiv="cache-control"?content="no-cache">
????<meta?http-equiv="expires"?content="0">
????<meta?http-equiv="keywords"?content="keyword1,keyword2,keyword3">
????<meta?http-equiv="description"?content="This?is?my?page">
????
????<!--
????<link?rel="stylesheet"?type="text/css"?href="styles.css">
????-->
??</head>
??
??<body>
????This?is?my?JSP?page.?<br>
????
????${"${userMap.ua}"}:?${userMap.ua}
????<br>
????${'${userMap["ua"]}'}:?${userMap["ua"]}
??</body>
</html>

結(jié)果:

This is my JSP page.
${userMap.ua}: com.bean.UserBean@21af3d5
${userMap["ua"]}: com.bean.UserBean@21af3d5

-----------

????????
??? ${userMap["ub"].name}?
??? ${userMap["ub"].address}

直接訪問(wèn)屬性

這只是一種簡(jiǎn)單的情況，有時(shí)做應(yīng)用并不是這樣。

====================

?代碼示例:

? <c:forEach items="${cart.cartItem}" var="item">
? <TR align=middle>
??? <TD height=30><INPUT type=checkbox value="${item.value.product.id}" name=item></TD>
??? <TD height=30>${item.value.product.name}&nbsp;</TD>
??? <TD height=30>${item.value.product.price}&nbsp;</TD>
??? <TD height=30><INPUT maxLength=10 size=10 value="${item.value.number}" name=itemnum></TD>
??? <TD height=30>${item.value.cost}&nbsp;</TD>
? </TR>
? </c:forEach>

以上為一個(gè)購(gòu)物籃的頁(yè)面的部分代碼:

這設(shè)計(jì)時(shí)。Cart類 有一個(gè)HashMap集合保存著選購(gòu)的Item。key為產(chǎn)品Id，而value是頁(yè)面需要展示的東西。

是一個(gè)個(gè)Item對(duì)象。

對(duì)于key為Id，或者頁(yè)面不關(guān)心，甚至根本不知道是什么的HashMap如何遍歷呢？

EL，和JavaBean的完美組合再次讓我理解JavaBean的封裝性的好處。

java.util
Interface Map.Entry<K,V>

A map entry (key-value pair). The Map.entrySet method returns a collection-view of the map, whose elements are of this class.

也就是說(shuō)Map里每一個(gè)元素是一個(gè)一個(gè)的Entry。

再看看Entry方法。

??<c:forEach?items="${cart.cartItem}"?var="item"?varStatus="i">
??<TR?align=middle>
????<TD?height=30>${i.count}&nbsp;</TD><%--?${i.index}??--%>
????<TD?height=30>${item.value.product.name}&nbsp;</TD>
????<TD?height=30>${item.value.product.price}&nbsp;</TD>
????<TD?height=30>${item.value.number}&nbsp;</TD>
????<TD?height=30>${item.value.cost}&nbsp;</TD>
??</TR>
??</c:forEach>

????public?ActionErrors?validate(ActionMapping?actionMapping,?HttpServletRequest?httpServletRequest)?
????{
????????ActionErrors?errors?=?new?ActionErrors();
????????
????????if(name?==?null?||?name.trim().length()?==?0)
????????{
????????????ActionError?error?=?new?ActionError("errors.name.required");
????????????errors.add("name",?error);
????????}
????????
????????if(password?==?null?||?password.trim().length()?==?0)
????????{
????????????ActionError?error?=?new?ActionError("errors.password.required");
????????????errors.add("password",?error);
????????}
????????
????????return?errors;
????}

<action?attribute="addcourseForm"?name="addcourseForm"?parameter="addcourse"?path="/addcourse"?scope="request"?type="exam.java.advanced.action.ExamIssueMappingActionAction">
????????????<exception?key="operate.addcourse"?path="/error.jsp"?type="exam.java.advanced.BusinessException"?/>
????????????<forward?name="success"?path="/success.jsp"?redirect="true"?/>
????????</action>

public?class?ExamIssueMappingActionAction?extends?MappingDispatchAction?{

????public?ActionForward?addcourse(ActionMapping?mapping,?ActionForm?arg1,
????????????HttpServletRequest?request,?HttpServletResponse?arg3)
????????????throws?Exception?{
????????EnrollmentBiz?biz?=?new?EnrollmentBiz();
????????try?{
????????????Course?crs?=?new?Course();
????????????DynaActionForm?f?=?(DynaActionForm)?arg1;
????????????crs.setId((String)?f.get("courseid"));
????????????crs.setName((String)?f.get("name"));
????????????crs.setDescription((String)?f.get("description"));

????????????biz.saveCourse(crs);
????????????return?mapping.findForward("success");
????????}?catch?(Exception?ex)?{
????????????ex.printStackTrace();
????????????throw?new?BusinessException(ex);
????????}
????}

=============

驗(yàn)證框架

現(xiàn)在struts-config.xml注冊(cè)驗(yàn)證的插件，

<plug-in className="org.apache.struts.validator.ValidatorPlugIn">
??<set-property property="pathnames" value="/WEB-INF/validator-rules.xml,
??????????????????????????? /WEB-INF/validation.xml" />
?</plug-in>

org.apache.struts.action
Interface PlugIn

這個(gè)接口就是插件接口，可以自己實(shí)現(xiàn)這個(gè)接口。

按照人家ValidatorPlugIn的方式寫(xiě)一個(gè)屬性，以便在struts-config.xml中描述插件時(shí)，提供具體值。

pathnames

??? public String getPathnames()
??? {
??????? return pathnames;
??? }

??? public void setPathnames(String pathnames)
??? {
??????? this.pathnames = pathnames;
??? }


StringTokenizer st = new StringTokenizer(pathnames, ",");


-----------

org.apache.struts.config.ModuleConfig

該對(duì)象在init時(shí)傳入，可以利用來(lái)獲得struts-config.xml這個(gè)文件的信息。

=====================

DispatchAction就是對(duì)于不同form表單在同一Action中處理的解決方案，struts-config.xml在Action標(biāo)記中加一個(gè)parameter屬性method，form的action則用function.do?method=add

LookupDispatchAction就是對(duì)于同一個(gè)頁(yè)面不同的按鈕想都在一個(gè)Action中處理。需要重寫(xiě)一個(gè)getMap方法。

MappingDispatchAction就是每個(gè)方法一個(gè)Action標(biāo)記對(duì)應(yīng)。



最后就是使用令牌的方式來(lái)防止重復(fù)提交。

org.apache.struts.action.Action

這個(gè)父類的方法

protected java.lang.String generateToken(javax.servlet.http.HttpServletRequest?request)

protected boolean isTokenValid(javax.servlet.http.HttpServletRequest?request)

protected void resetToken(javax.servlet.http.HttpServletRequest?request)