@ManagedBean注释不起作用，但@Named起作用

问题内容：

我遇到了麻烦。具有@Named作品的类：

@Named
@SessionScoped
public class UserBean {

@Autowired
UserBo userBo;

public void setUserBo(UserBo userBo) {
    this.userBo = userBo;
}

public String printMsgFromSpring() {
    return userBo.getMessage();
}

}

但这不起作用并产生错误：

javax.servlet.ServletException
javax.faces.webapp.FacesServlet.service（FacesServlet.java:606）根本原因java.lang.NullPointerException
com.mkyong.UserBean.printMsgFromSpring（UserBean.java:24）

@ManagedBean
@SessionScoped
public class UserBean {

@Autowired
UserBo userBo;

public void setUserBo(UserBo userBo) {
  this.userBo = userBo;
}

public String printMsgFromSpring() {
  return userBo.getMessage();
}

}

xhtml页面：

  <?xml version="1.0" encoding="UTF-8"?>
  <!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"   
  xmlns:h="http://java.sun.com/jsf/html">

<h:body>

    <h1>JSF 2.0 + Spring Example</h1>

    #{userBean.printMsgFromSpring()}


</h:body>

faces-config.xml：

   <?xml version="1.0" encoding="UTF-8"?>
  <faces-config xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee   http://java.sun.com/xml/ns/javaee/web-facesconfig_2_1.xsd"
version="2.1">

<application>
    <el-resolver>org.springframework.web.jsf.el.SpringBeanFacesELResolver</el-resolver>
</application>

    </faces-config>

服务等级：

@Named
public class UserBoImpl implements UserBo{

  public String getMessage() {
        return "JSF 2 + Spring Integration";

  }

}

web.xml：

 <?xml version="1.0" encoding="UTF-8"?>
 <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
xmlns="http://java.sun.com/xml/ns/javaee" 
xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" 
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" 
id="WebApp_ID" version="2.5">

    <display-name>JavaServerFaces</display-name>

      <!-- Add Support for Spring -->
   <listener>
      <listener-class>
       org.springframework.web.context.ContextLoaderListener
       </listener-class>
   </listener>
   <listener>
      <listener-class>
       org.springframework.web.context.request.RequestContextListener
       </listener-class>
   </listener>

   <welcome-file-list>
        <welcome-file>default.xhtml</welcome-file>
    </welcome-file-list>

  <servlet>
    <servlet-name>facesServlet</servlet-name>
    <servlet-class>javax.faces.webapp.FacesServlet</servlet-class>
    <load-on-startup>1</load-on-startup>
  </servlet>

  <servlet-mapping>
   <servlet-name>facesServlet</servlet-name>
    <url-pattern>*.xhtml</url-pattern>
   </servlet-mapping>

  </web-app>

applicationContext.xml：

     <beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans-3.1.xsd
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context-3.1.xsd">

   <context:component-scan base-package="com.mkyong" />
     </beans>

问题答案：

JSF不会处理@Autowired。@ManagedProperty在下面的示例中，应将其替换为：

    @ManagedProperty(value="#{userBoSpringName}")
    UserBo userBo;

这里userBoSpringName应该与您的spring上下文文件中的bean名称相对应。此选项仅在JSF托管Bean中可用。

从JSF 2.2开始，您还可以@Inject在JSF托管Bean中使用它来执行资源注入

@ManagedBean注释不起作用，但@Named起作用

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