JSP userBean setProperty getProperty指令使用
2015-10-20 12:38
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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：
转换的java文件：
JavaBean：
jsp:userBean的使用：
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>
<%@ page import="com.stono.servlet.bean.*" %>
<%
Person person33 = new Employee();
person33.setName("stono3inJsp");
pageContext.setAttribute("person3", person33);
%>
<jsp:useBean id="person3" type="com.stono.servlet.bean.Person"></jsp:useBean>
<jsp:getProperty property="name" name="person3"/>
</pre>
</p>
</body>
</html>
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