applicationContext object in JSP_问答_开发者_运维开发者技术经验分享

How to configur开发者_开发问答e in my spring project to retrieve the applicationContext object in jsp using JSTL.

<%@page import="org.springframework.web.context.WebApplicationContext"%>
<%@page import="org.springframework.web.context.support.WebApplicationContextUtils"%>
<%
  WebApplicationContext context = WebApplicationContextUtils
        .getWebApplicationContext(application);
%>

application is the JSP defined ServletContext.

If you want to retrieve a bean and use JSTL, you can then do something like:

<%pageContext.setAttribute("bean", context.getBean("myBean"));%>
<c:out value="${bean.property}"/>

But, just because you can, doesn't mean you should. If you are doing anything more than displaying a bean's property you probably want to put this in a Servlet or some other controller.

Also, you do not want to be using the ApplicationContext as a way to pass beans between your controllers and views.

Spring root web application context is available in servlet context attribute named: org.springframework.web.context.WebApplicationContext.ROOT:

${applicationScope['org.springframework.web.context.WebApplicationContext.ROOT']}

Haven't tried it, but should be accessible via JSTL. But what you want to achieve? Is JSP really a good place to fetch beans manually and perform some business operations? Shouldn't you do all the work in servlet/controller and let JSP do only the view, as it was intended?

EDIT: I was worng, it doesn't work. Anyway, you would be able to access all beans by name, with no need of ApplicationContext, depending on what you need to do.

If you set property exposeContextBeansAsAttributes of InternalResourceViewResolver to true, you would be able to access from JSP using EL: ${applicationContext}. Depending of what you're trying to do, this can be more or less suitable.

EDIT: Your view resolver for JSP must be something similar to:

<bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
    <property name="viewClass" value="org.springframework.web.servlet.view.JstlView" />
    <property name="prefix" value="/WEB-INF/views/" />
    <property name="suffix" value=".jsp" />
    <property name="exposeContextBeansAsAttributes" value="true" />
</bean>

The best thing is that you can get the bean you want by its name. So, probably, you won't need ApplicationContext there.

For Spring 4 it works well:

<%
ApplicationContext context = RequestContextUtils.findWebApplicationContext(request);
%>

Well, with spring-boot 2.1.5.RELEASE I am allowed to do these:

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@ taglib prefix="spring" uri="http://www.springframework.org/tags" %>
thumbs.dir: <spring:eval expression="@environment.getProperty('thumbs.dir')"/><br>
users.file: <spring:eval expression="@environment.getProperty('users.file')"/><br>
jdbc.url: <spring:eval expression="@jdbcProperties.jdbcUrl"/><br>
<spring:eval expression="@jdbcProperties" var="jdbcProperties"/>
<c:if test="${empty jdbcProperties}">jdbcProperties is empty<br></c:if>
<c:if test="${!empty jdbcProperties}">jdbc.username: ${jdbcProperties.username}<br></c:if>

where @jdbcProperties is this spring bean:

@Bean("jdbcProperties")
public Properties stageDsProperties() throws IOException {
    return PropertiesLoaderUtils.loadAllProperties("jdbc-datasource/jdbc-stage.properties");
}

Here's what worked for me, hoping this helps someone else since it took me quite some time to figure out. Building on Pavel Vlasov's answer:

<% ApplicationContext context = RequestContextUtils.findWebApplicationContext(request); %>
<% pageContext.setAttribute("myKey", context.getBean("myObject")); %>

And then further down my JSP page I have

<body>
  <div>
    <% 
       MyObject coolObject = (MyObject)pageContext.getAttribute("myKey");
       coolObject.doSomething();
    %>
  </div>
</body>