JSP 初始化参数

时间：2023-08-05 22:18:14

JSP 初始化参数：

tomcat启动的时候就会执行那个函数；

xml：

<?xml version="1.0" encoding="UTF-8"?>

<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee

    http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID"

    version="3.0">

    <display-name>TestBootWeb</display-name>

    <servlet>

        <servlet-name>index007</servlet-name>

        <jsp-file>/index007.jsp</jsp-file>

        <init-param>

            <param-name>email</param-name>

            <param-value>s@s.com</param-value>

        </init-param>

    </servlet>

    <servlet-mapping>

        <servlet-name>index007</servlet-name>

        <url-pattern>/index007.jsp</url-pattern>

        <!-- 写成/index007.jsp的话，竟然index007.jsp和index0071.jsp都可以访问，而且是两个实例，但是获取初始化参数的时候有问题 -->

    </servlet-mapping>

    <jsp-config>

        <jsp-property-group>

            <url-pattern>/index006.jsp</url-pattern>

            <scripting-invalid>true</scripting-invalid>

        </jsp-property-group>

    </jsp-config>

    <welcome-file-list>

        <welcome-file>index.jsp</welcome-file>

    </welcome-file-list>

</web-app>

jsp：

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>

<%

    String path = request.getContextPath();

    String basePath = request.getScheme() + "://" + request.getServerName() + ":" + request.getServerPort() + path + "/";

%>

<!DOCTYPE html>

<html>

<head>

<meta charset="UTF-8">

<title>007index</title>

</head>

<body>

    cnt is :<%=++cnt%>

    <hr>

    <%!int cnt = 0;%>

    <%!

        public void jspInit(){

        ServletConfig config = getServletConfig();

        String s = config.getInitParameter("email");

        System.out.println("s is :"+s);

    }

    %>

</body>

</html>

生成的java：

/*

 * Generated by the Jasper component of Apache Tomcat

 * Version: Apache Tomcat/7.0.35

 * Generated at: 2015-10-20 01:19:21 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 java.util.*;

public final class index007_jsp extends org.apache.jasper.runtime.HttpJspBase

    implements org.apache.jasper.runtime.JspSourceDependent {

int cnt = 0;

        public void jspInit(){

        ServletConfig config = getServletConfig();

        String s = config.getInitParameter("email");

        System.out.println("s is :"+s);

    }

  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 javax.el.ExpressionFactory _el_expressionfactory;

  private org.apache.tomcat.InstanceManager _jsp_instancemanager;

  public java.util.Map<java.lang.String,java.lang.Long> getDependants() {

    return _jspx_dependants;

  }

  public void _jspInit() {

    _el_expressionfactory = _jspxFactory.getJspApplicationContext(getServletConfig().getServletContext()).getExpressionFactory();

    _jsp_instancemanager = org.apache.jasper.runtime.InstanceManagerFactory.getInstanceManager(getServletConfig());

  }

  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 {

    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=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');

      out.write('\n');

    String path = request.getContextPath();

    String basePath = request.getScheme() + "://" + request.getServerName() + ":" + request.getServerPort() + path + "/";

      out.write("\r\n");

      out.write("<!DOCTYPE html>\r\n");

      out.write("<html>\r\n");

      out.write("<head>\r\n");

      out.write("<meta charset=\"UTF-8\">\r\n");

      out.write("<title>007index</title>\r\n");

      out.write("</head>\r\n");

      out.write("<body>\r\n");

      out.write("\tcnt is :");

      out.print(++cnt);

      out.write("\r\n");

      out.write("\t<hr>\r\n");

      out.write("\t");

      out.write('\r');

      out.write('\n');

      out.write('    ');

      out.write("\r\n");

      out.write("</body>\r\n");

      out.write("</html>\r\n");

    } catch (java.lang.Throwable t) {

      if (!(t instanceof javax.servlet.jsp.SkipPageException)){

        out = _jspx_out;

        if (out != null && out.getBufferSize() != 0)

          try { 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);

    }

  }

}

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