JavaBean是一种规范，可以理解。但实在想不出JSP中这样使用JavaBean有啥意义。算了，按照一个小例子做下，当熟悉JSP。
Bean类：
package com.my.beans; import java.lang.*; public class User { private String name; private String password; private int age; public String getName() { return name; } public void setName(String name) { this.name = name; } public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } public User() {} }
JSP:
<%@ page contentType="text/html;charset=utf-8" pageEncoding="utf-8"%> <%@ page import="java.util.*"%> <html> <header> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> </header> <body> <jsp:useBean id="user" class="com.my.beans.User" scope="page" /> <jsp:setProperty name="user" property="name" value="robin" /> <jsp:setProperty name="user" property="password" value="123" /> <jsp:setProperty name="user" property="age" value="18" /> User name:<jsp:getProperty name="user" property="name" /><br/> Passoword:<jsp:getProperty name="user" property="password" /><br/> Age:<jsp:getProperty name="user" property="age" /> </body> </html>
生成的java servlet文件：
/* * Generated by the Jasper component of Apache Tomcat * Version: Apache Tomcat/7.0.52 * Generated at: 2014-03-28 09:16:40 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.pages; import javax.servlet.*; import javax.servlet.http.*; import javax.servlet.jsp.*; import java.util.*; public final class testbean_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(" "); out.write(" "); out.write(" "); out.write("<html> "); out.write(" <header> "); out.write(" <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> "); out.write(" </header> "); out.write(" <body> "); out.write(" "); com.my.beans.User user = null; user = (com.my.beans.User) _jspx_page_context.getAttribute("user", javax.servlet.jsp.PageContext.PAGE_SCOPE); if (user == null){ user = new com.my.beans.User(); _jspx_page_context.setAttribute("user", user, javax.servlet.jsp.PageContext.PAGE_SCOPE); } out.write(" "); out.write(" "); org.apache.jasper.runtime.JspRuntimeLibrary.introspecthelper(_jspx_page_context.findAttribute("user"), "name", "robin", null, null, false); out.write(" "); out.write(" "); org.apache.jasper.runtime.JspRuntimeLibrary.introspecthelper(_jspx_page_context.findAttribute("user"), "password", "123", null, null, false); out.write(" "); out.write(" "); org.apache.jasper.runtime.JspRuntimeLibrary.introspecthelper(_jspx_page_context.findAttribute("user"), "age", "18", null, null, false); out.write(" "); out.write(" "); out.write(" User name:"); out.write(org.apache.jasper.runtime.JspRuntimeLibrary.toString((((com.my.beans.User)_jspx_page_context.findAttribute("user")).getName()))); out.write("<br/> "); out.write(" Passoword:"); out.write(org.apache.jasper.runtime.JspRuntimeLibrary.toString((((com.my.beans.User)_jspx_page_context.findAttribute("user")).getPassword()))); out.write("<br/> "); out.write(" Age:"); out.write(org.apache.jasper.runtime.JspRuntimeLibrary.toString((((com.my.beans.User)_jspx_page_context.findAttribute("user")).getAge()))); out.write(" "); out.write(" </body> "); 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 { 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); } } }
其实就是new一个object，然后调用set and get方法。