java - Spring Web MVC : Simple controller - $-expression doesn't work

Question

我从 Spring Web MVC 开始。我有非常简单的 Controller 和 View ，但是当我打开页面时 http://localhost:8080/springonly/spring/hello我得到:${message}，而不是Hello World

有人知道这是怎么回事吗？为什么$-表达式未被识别？

查看 - hello.jsp:

${message}

Controller - HelloController.java:

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.servlet.ModelAndView;

@Controller
public class HelloController {

    @RequestMapping("/hello")
    public ModelAndView hello(HttpServletRequest request,
            HttpServletResponse response) throws Exception {
        return new ModelAndView("hello", "message", "Hello World");
    }

}

web.xml:

<web-app>
    <display-name>Spring Only WebApp</display-name>

    <servlet>
        <servlet-name>springonly</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>/WEB-INF/config/applicationContext.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>

    <servlet-mapping>
        <servlet-name>springonly</servlet-name>
        <url-pattern>/spring/*</url-pattern>
    </servlet-mapping>

</web-app>

applicationContext.xml:

<!-- scan for Controllers -->
<context:component-scan base-package="net.marioosh.spring.springonly" />

<!-- view resolver -->
<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/pages/" />
    <property name="suffix" value=".jsp" />
</bean>

日志说:

2011-03-15 13:43:12,703 DEBUG [DispatcherServlet:693] : DispatcherServlet with name 'springonly' processing GET request for [/springonly/spring/hello]
2011-03-15 13:43:12,718 DEBUG [DefaultAnnotationHandlerMapping:221] : Mapping [/hello] to HandlerExecutionChain with handler [net.marioosh.spring.springonly.HelloController@120b2da] and 1 interceptor
2011-03-15 13:43:12,718 DEBUG [DispatcherServlet:769] : Last-Modified value for [/springonly/spring/hello] is: -1
2011-03-15 13:43:12,718 DEBUG [HandlerMethodInvoker:173] : Invoking request handler method: public org.springframework.web.servlet.ModelAndView net.marioosh.spring.springonly.HelloController.hello(javax.servlet.http.HttpServletRequest,javax.servlet.http.HttpServletResponse) throws java.lang.Exception
2011-03-15 13:43:12,718 DEBUG [DispatcherServlet:1045] : Rendering view [org.springframework.web.servlet.view.JstlView: name 'hello'; URL [/WEB-INF/pages/hello.jsp]] in DispatcherServlet with name 'springonly'
2011-03-15 13:43:12,718 DEBUG [JstlView:328] : Added model object 'message' of type [java.lang.String] to request in view with name 'hello'
2011-03-15 13:43:12,718 DEBUG [JstlView:236] : Forwarding to resource [/WEB-INF/pages/hello.jsp] in InternalResourceView 'hello'
2011-03-15 13:43:12,718 DEBUG [DispatcherServlet:674] : Successfully completed request

Answer 1

您的web.xml缺少正确的 header ，它应该类似于:

<web-app 
    xmlns="http://java.sun.com/xml/ns/j2ee" 
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd" 
    version="2.4"> 

如果你把它省略掉，而只是一个裸露的 <web-app> ，容器将默认为旧的、前 EL 版本的 JSP。