JSP获取spring 的容器ApplicationContext 博客分类： Java WebJava spring容器JSP获取beanJSP获取容器WebApplicationContextUtils
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2024-02-24 19:50:46
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Jsp 中如何获取spring的bean呢？
方式一：通过上下文
<?xml version="1.0" encoding="UTF-8" ?>
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@page import="org.springframework.web.context.support.WebApplicationContextUtils"%>
<%@page import="org.springframework.context.ApplicationContext"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<title>Insert title here</title>
</head>
<body>
<%
ServletContext context = request.getSession().getServletContext();
ApplicationContext ctx = WebApplicationContextUtils.getWebApplicationContext(context);
Object supermarketDao= ctx.getBean("supermarketDao");
System.out.println("jsp:"+supermarketDao);
%>
</body>
</html>
问题：JSP页面中获取的bean与spring 容器中的bean是同一个吗？
是的。
方式二：通过类路径加载bean文件,得到bean工厂
<?xml version="1.0" encoding="UTF-8" ?>
<%@page import="org.springframework.beans.factory.BeanFactory"%>
<%@page import="org.springframework.context.support.ClassPathXmlApplicationContext"%>
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@page import="org.springframework.web.context.support.WebApplicationContextUtils"%>
<%@page import="org.springframework.context.ApplicationContext"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<title>Insert title here</title>
</head>
<body>
<%
ClassPathXmlApplicationContext appContext = new ClassPathXmlApplicationContext("beans.xml","user_beans.xml","goods_beans.xml","supermarket_beans.xml","aop.xml","upload_beans.xml");
BeanFactory factory = (BeanFactory) appContext;
Object obj=factory.getBean("supermarketDao");
System.out.println("jsp2:"+obj);
%>
</body>
</html>
问题：JSP页面中获取的bean与spring 容器中的bean是同一个吗？
不是的。
总结：（1）通过WebApplicationContextUtils 获取bean是直接从spring容器中拿的；
（2）通过ClassPathXmlApplicationContext，实际上又解析了一遍xml，即又创建了一个新的spring容器，所有获取的bean与web上下文中是不同的。
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