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放在web應用程序中除了WEB-INF及其子目錄之外的任何目錄下。
每個JSP頁面在第一次被訪問時，JSP引擎將它翻譯成一個Servlet源程序，接著再把這個Servlet源程序編譯成Servlet的class類文件，然后再由WEB容器（Servlet引擎）像調用普通Servlet程序一樣的方式來裝在和解釋執行這個由JSP頁面翻譯成的Servlet程序。
JSP文件翻譯成的Java文件去這個路徑下找
E:\JavaWorkSpace（eclipse工程目錄）\.metadata\.plugins\org.eclipse.wst.server.core\tmp0\work\Catalina\localhost\day_0206\org\apache\jsp\xxx.jsp
例：hello_jsp.java文件如下
/*
* Generated by the Jasper component of Apache Tomcat
* Version: Apache Tomcat/7.0.75
* Generated at: 2017-02-16 02:13:19 UTC
* Note: The last modified time of this file was set to
* the last modified time of the source file after
* generation to assist with modification tracking.
*/
package org.apache.jsp;
import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.jsp.*;
import day_0206.Person;
public final class hello_jsp extends org.apache.jasper.runtime.HttpJspBase
implements org.apache.jasper.runtime.JspSourceDependent {
private static final javax.servlet.jsp.JspFactory _jspxFactory =
javax.servlet.jsp.JspFactory.getDefaultFactory();
private static java.util.Map<java.lang.String,java.lang.Long> _jspx_dependants;
private volatile javax.el.ExpressionFactory _el_expressionfactory;
private volatile org.apache.tomcat.InstanceManager _jsp_instancemanager;
public java.util.Map<java.lang.String,java.lang.Long> getDependants() {
return _jspx_dependants;
}
public javax.el.ExpressionFactory _jsp_getExpressionFactory() {
if (_el_expressionfactory == null) {
synchronized (this) {
if (_el_expressionfactory == null) {
_el_expressionfactory = _jspxFactory.getJspApplicationContext(getServletConfig().getServletContext()).getExpressionFactory();
}
}
}
return _el_expressionfactory;
}
public org.apache.tomcat.InstanceManager _jsp_getInstanceManager() {
if (_jsp_instancemanager == null) {
synchronized (this) {
if (_jsp_instancemanager == null) {
_jsp_instancemanager = org.apache.jasper.runtime.InstanceManagerFactory.getInstanceManager(getServletConfig());
}
}
}
return _jsp_instancemanager;
}
public void _jspInit() {
}
public void _jspDestroy() {
}
public void _jspService(final javax.servlet.http.HttpServletRequest request, final javax.servlet.http.HttpServletResponse response)
throws java.io.IOException, javax.servlet.ServletException {
//隱含對象在這里，還有一個叫exception的隱含對象
final javax.servlet.jsp.PageContext pageContext;
javax.servlet.http.HttpSession session = null;
final javax.servlet.ServletContext application;
final javax.servlet.ServletConfig config;
javax.servlet.jsp.JspWriter out = null;
final java.lang.Object page = this;
javax.servlet.jsp.JspWriter _jspx_out = null;
javax.servlet.jsp.PageContext _jspx_page_context = null;
try {
response.setContentType("text/html; charset=ISO-8859-1");
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\" \"http://www.w3.org/TR/html4/loose.dtd\">\r\n");
out.write("<html>\r\n");
out.write("<head>\r\n");
out.write("<meta http-equiv=\"Content-Type\" content=\"text/html; charset=ISO-8859-1\">\r\n");
out.write("<title>Insert title here</title>\r\n");
out.write("</head>\r\n");
out.write("<body>\r\n");
out.write("\r\n");
//在JSP頁面中使用<% %>編寫的代碼在這個位置
Person person = new Person();
System.out.println(person.getInfo());
out.write("\r\n");
out.write("</body>\r\n");
out.write("</html>");
} catch (java.lang.Throwable t) {
if (!(t instanceof javax.servlet.jsp.SkipPageException)){
out = _jspx_out;
if (out != null && out.getBufferSize() != 0)
try {
if (response.isCommitted()) {
out.flush();
} else {
out.clearBuffer();
}
} catch (java.io.IOException e) {}
if (_jspx_page_context != null) _jspx_page_context.handlePageException(t);
else throw new ServletException(t);
}
} finally {
_jspxFactory.releasePageContext(_jspx_page_context);
}
}
}JSP頁面的隱含變量：沒有聲明就可以使用的對象，有request, response, pageContext, session, application, config,out, page, exception
request：HttpServletRequest的對象
response:HttpServletResponse的一個對象（在JSP頁面中幾乎不會調用response的任何方法）
pageContext：頁面的上下文，是PageContext的一個對象，可以從該對象中獲取到其他8個隱含對象，也可以從中獲取到當前頁面的其他信息
session：代表瀏覽器和服務器的一次會話，是HttpSession的一個對象
application：代表當前web應用，是ServletContext對象
config：當前JSP對應的Servlet的ServletConfig對象。（開發的時候幾乎不用）若需要訪問當前JSP配置的初始化參數，需要通過映射的地址才可以獲取到
<servlet> <servlet-name>hellojsp</servlet-name> <jsp-file>/hello.jsp</jsp-file> <init-param> <param-name>test</param-name> <param-value>testValue</param-value> </init-param> </servlet> <servlet-mapping> <servlet-name>hellojsp</servlet-name> <url-pattern>/hellojsp</url-pattern><!-- 通過這個地址訪問才能獲取到初始化參數--> </servlet-mapping>
7.out：JspWriter對象，調用out.println()可以直接把字符串打印到瀏覽器上
8.page：指向當前JSP對應的Servlet對象的引用，但為Object類型，只能調用Object類的方法（幾乎不使用）
9.exception：聲明了<%@ page isErrorPage = "true" %>的頁面才可以使用
pageContext,request, session, application 作用域的范圍從小到大
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