JSP userBean setProperty getProperty指令使用

javaBean的属性取决于get/set方法，而不是真实的属性名称。

jsp文件：

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

<%

    String path = request.getContextPath();

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

    pageContext.setAttribute("pca", "pageContextAttribute");

%>

<!DOCTYPE html>

<html>

<head>

<meta charset="UTF-8">

<title>009index</title>

</head>

<body>

    <jsp:useBean id="person" class="com.stono.servlet.bean.Person">

        <jsp:setProperty property="name" name="person" value="stono" />

    </jsp:useBean>

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

</body>

</html>

转换的java文件：

/*

 * Generated by the Jasper component of Apache Tomcat

 * Version: Apache Tomcat/7.0.35

 * Generated at: 2015-10-20 04:32:26 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 index009_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 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 + "/";

    pageContext.setAttribute("pca", "pageContextAttribute");

      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>009index</title>\r\n");

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

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

      out.write("\t");

      com.stono.servlet.bean.Person person = null;

      person = (com.stono.servlet.bean.Person) _jspx_page_context.getAttribute("person", javax.servlet.jsp.PageContext.PAGE_SCOPE);

      if (person == null){

        person = new com.stono.servlet.bean.Person();

        _jspx_page_context.setAttribute("person", person, javax.servlet.jsp.PageContext.PAGE_SCOPE);

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

        out.write("\t\t");

        org.apache.jasper.runtime.JspRuntimeLibrary.introspecthelper(_jspx_page_context.findAttribute("person"), "name", "stono", null, null, false);

        out.write('\r');

        out.write('\n');

        out.write('    ');

      }

      out.write('\r');

      out.write('\n');

      out.write('    ');

      out.write(org.apache.jasper.runtime.JspRuntimeLibrary.toString((((com.stono.servlet.bean.Person)_jspx_page_context.findAttribute("person")).getName())));

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

      out.write("\t\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);

    }

  }

}

JavaBean：

package com.stono.servlet.bean;

public class Person {

    // 对外的属性名称还是name，

    private String name2;

    public String getName() {

        return name2;

    }

    public void setName(String name) {

        this.name2 = name;

    }

}

jsp:userBean的使用：

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

<%

    String path = request.getContextPath();

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

    pageContext.setAttribute("pca", "pageContextAttribute");

%>

<!DOCTYPE html>

<html>

<head>

<meta charset="UTF-8">

<title>009index</title>

</head>

<body>

    <p>

        jsp:useBean id="person" class="com.stono.servlet.bean.Person",如果Person是抽象类，会有异常：

        <pre>

            严重: Servlet.service() for servlet [jsp] in context with path [/TestBootWeb] threw exception [/index013.jsp (line: 14, column: 1) The value for the useBean class attribute com.stono.servlet.bean.Person is invalid.] with root cause

            org.apache.jasper.JasperException: /index013.jsp (line: 14, column: 1) The value for the useBean class attribute com.stono.servlet.bean.Person is invalid.

        </pre>

    </p>

    <p>

        对于抽象类需要使用jsp:useBean id="person" type="com.stono.servlet.bean.Person" class="com.stono.servlet.bean.Employee"进行使用。

    </p>

    <jsp:useBean id="person" type="com.stono.servlet.bean.Person" class="com.stono.servlet.bean.Employee">

        <jsp:setProperty property="name" name="person" value="stono" />

    </jsp:useBean>

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

    <p>

        直接输入jsp:useBean id="person2" type="com.stono.servlet.bean.Person"会报错：

        <pre>

            严重: Servlet.service() for servlet [jsp] in context with path [/TestBootWeb] threw exception [javax.servlet.ServletException: java.lang.InstantiationException: bean person2 not found within scope] with root cause

            java.lang.InstantiationException: bean person2 not found within scope

        </pre>

        输入jsp:useBean id="person" type="com.stono.servlet.bean.Person"也是有问题的：

        <pre>

            严重: Servlet.service() for servlet [jsp] in context with path [/TestBootWeb] threw exception [/index013.jsp (line: 35, column: 1) useBean: Duplicate bean name: {0}] with root cause

            org.apache.jasper.JasperException: /index013.jsp (line: 35, column: 1) useBean: Duplicate bean name: {0}

        </pre>

    </p>

    <p>

        在servlet中进行request.setAttribute("person3",person3),但是在jsp中直接写：jsp:useBean id="person3" type="com.stono.servlet.bean.Person"会报错：

        <pre>

            严重: Servlet.service() for servlet jsp threw exception

            java.lang.InstantiationException: bean person3 not found within scope

        </pre>

        因为默认的scope是page；修改为scope="request"，就可以读取到request传递过来的值；

    </p>

    <p>

        如果希望使用jsp:useBean id="person3" type="com.stono.servlet.bean.Person",还不能在scriplet中使用名称为person3的变量，需要如下定义使用：

        <pre>

            &lt;%@ page import="com.stono.servlet.bean.*" %&gt;

            &lt;%

                Person person33 = new Employee();

                person33.setName("stono3inJsp");

                pageContext.setAttribute("person3", person33);

            %&gt

            &lt;jsp:useBean id="person3" type="com.stono.servlet.bean.Person"&gt&lt;/jsp:useBean&gt

            &lt;jsp:getProperty property="name" name="person3"/&gt

        </pre>

    </p>

</body>

</html>

JSP userBean setProperty getProperty指令使用的更多相关文章

  1. JSP userBean setProperty直接从request中获取参数

    JSP userBean setProperty直接从request中获取参数: form表单Jsp: <%@ page language="java" import=&qu ...

  2. JSP动作元素之useBean、setProperty、getProperty指令

    简介 这三个指令都是与JavaBean相关的指令,其中useBean指令用于在JSP页面中初始化一个Java实例:setProperty指令用于为JavaBean实例的属性设置值:getPropert ...

  3. JSP之使用useBean、setProperty、getProperty指令

    useBean指令用于在JSP页面中初始化一个Java实例,setProperty指令用于为JavaBean实例的属性设置值,getProperty指令用于输出JavaBean实例的属性. 例子: J ...

  4. JavaWeb（三）JSP之3个指令、6个动作、9个内置对象和4大作用域

    前言 前面大概介绍了什么是JSP,今天我给大家介绍一下JSP的三个指令.6个动作以及它的9大内置对象.接下来我们就直接进入正题 一.JSP的3个指令 JSP指令(directive)是为JSP引擎而设 ...

  5. jsp笔记2(编译指令与动作指令)

    一.jsp的编译指令是通知jsp引擎的消息,不会生成输出. jsp的3个编译指令: page:针对当前页面的指令   include:包含另一个页面的指令   taglib:用于定义和访问自定义标签 ...

  6. JAVAWEB开发之Session的追踪创建和销毁、JSP具体解释（指令，标签，内置对象，动作即转发和包括）、JavaBean及内省技术以及EL表达式获取内容的使用

    Session的追踪技术 已知Session是利用cookie机制的server端技术.当client第一次訪问资源时 假设调用request.getSession() 就会在server端创建一个由 ...

  7. JSP基本语法--Page指令 <%@page 属性=”内容“%>

    page指令语法:<%@page 属性=”内容“%> 常用:contentType,import,pageEncoding 例子,设置MIME属性,如果使用一些高版本的tomcat,可能自 ...

  8. JSP中的编译指令和动作指令的区别

    JSP中的编译指令和动作指令的区别 1.编译指令是通知Servlet引擎的处理消息,而动作指令只是运行时的脚本动作 2.编译指令是在将JSP编译成Servlet时起作用,而动作指令可替换成JSP脚本, ...

  9. jsp 基础知识之指令元素

    由于考研和结业的事情,这里荒废了许久,而如今重新捡起来,是因为带到公司的碳素笔没有油了......    jsp的指令元素:通常以<%@开始,以%>结尾. jsp主要包括三种指令元素:pa ...

随机推荐

  1. c# 错误 两个输出文件名解析为同一个输出路径

    检查同项目的其他文件夹下面已有其他同名窗体,影响设计器

  2. smarty的ASSIGN()函数

    http://blog.sina.com.cn/s/blog_6721f25c01011qdj.html 主要是把程序里面的值付给模板,因为使用smarty时,模板里面是没有PHP代码的,无法显示在操 ...

  3. 基于Nginx的Rtmp流媒体服务器环境搭建

    一.编译安装 wget http://nginx.org/download/nginx-1.4.2.tar.gz wget https://github.com/arut/nginx-rtmp-mod ...

  4. 操作IFRAME及元素

    内容里有两个ifame <iframe id="leftiframe"...</iframe> <iframe id="mainiframe..& ...

  5. pandas 基础

    pandas 是基于 Numpy 构建的含有更高级数据结构和工具的数据分析包 类似于 Numpy 的核心是 ndarray,pandas 也是围绕着 Series 和 DataFrame 两个核心数据 ...

  6. HDU 4081 Qin Shi Huang's National Road System 次小生成树变种

    Qin Shi Huang's National Road System Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/3 ...

  7. UWSGITOP-----监控uwsgi 性能

    启动 uwsgi -x etc/bfdds_cookiemapping_conf.xml --stats /tmp/stats.socket 查看 uwsgitop /tmp/stats.socket ...

  8. Oracle使用rowid删除重复记录

    /**如何删除重复记录?*//*1. 先按重复字段分组   2. 在每组里找出最小的rowid   3. 把整个表中与上面查询出来的rowid不相等的记录删除掉*/delete from test_t ...

  9. Linux 软件包安装管理

    转自:http://www.cnblogs.com/Quains/archive/2012/01/03/2311049.html 本文主要是记录下RedHat系列的软件包管理. 内容分为以下三个部分: ...

  10. libconfig第二篇----两个小例子

    本文只看粗体即可,太多catch语句.两个例子均来自libconfig包的example文件夹下面,. 例子一: #include <iostream> #include <ioma ...