Java EE 6:目标不可达，标识符“helloBean"解析为空 [英] Java EE 6: Target Unreachable, identifier 'helloBean' resolved to null
问题描述
我正在尝试使用一个简单的 JSF 2 教程示例.
I am trying to get a simple JSF 2 tutorial example to work.
我在 Eclipse 中使用动态 Web 项目并发布到 Glassfish 3 服务器(运行 -> 在服务器上运行).第一个 index.xhtml 页面正确加载，但是当我必须访问托管 bean 时，显示以下错误:
I am using the dynamic web project in Eclipse and publishing to a Glassfish 3 server (run -> run on server). The first index.xhtml page loads correctly, but when I have to access a managed bean, the following error displays:
/index.xhtml @14,48 value="#{helloBean.name}": Target Unreachable, identifier 'helloBean' resolved to null
我已经查看了有关此主题的各种其他讨论，但是这些解决方案似乎对我不起作用(例如，添加 beans.xml、为托管 bean 命名等，遵循命名约定).
I've had a look at the various other discussions on this topic, however the solutions never seem to work for me (e.g. adding beans.xml, giving the managed bean a name etc, following naming conventions).
任何帮助将不胜感激.
这是我目前正在使用的代码:
Here is the code I am currently working with:
索引.xhtml
<?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:f="http://java.sun.com/jsf/core"
xmlns:h="http://java.sun.com/jsf/html">
<h:head>
<title>JSF 2.0 Hello World</title>
</h:head>
<h:body>
<h3>JSF 2.0 Hello World Example - hello.xhtml</h3>
<h:form>
<h:inputText value="#{helloBean.name}"></h:inputText>
<h:commandButton value="Welcome Me" action="response"></h:commandButton>
</h:form>
</h:body>
</html>
response.xhtml:
response.xhtml:
<?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:head>
<title>JSF 2.0 Hello World</title>
</h:head>
<h:body bgcolor="white">
<h3>JSF 2.0 Hello World Example - welcome.xhtml</h3>
<h4>Welcome #{helloBean.name}</h4>
</h:body>
</html>
托管 bean:
package java.hello1;
import javax.faces.bean.ManagedBean;
import javax.faces.bean.SessionScoped;
import java.io.Serializable;
@ManagedBean
@SessionScoped
public class HelloBean implements Serializable {
private static final long serialVersionUID = 1L;
private String name = "Ricardo";
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
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>
<!-- Change to "Production" when you are ready to deploy -->
<context-param>
<param-name>javax.faces.PROJECT_STAGE</param-name>
<param-value>Development</param-value>
</context-param>
<!-- Welcome page -->
<welcome-file-list>
<welcome-file>faces/index.xhtml</welcome-file>
</welcome-file-list>
<!-- JSF mapping -->
<servlet>
<servlet-name>Faces Servlet</servlet-name>
<servlet-class>javax.faces.webapp.FacesServlet</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet>
<!-- Map these files with JSF -->
<servlet-mapping>
<servlet-name>Faces Servlet</servlet-name>
<url-pattern>/faces/*</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>Faces Servlet</servlet-name>
<url-pattern>*.jsf</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>Faces Servlet</servlet-name>
<url-pattern>*.faces</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>Faces Servlet</servlet-name>
<url-pattern>*.xhtml</url-pattern>
</servlet-mapping>
</web-app>
推荐答案
您需要有一个符合 JSF 2.0 的 /WEB-INF/faces-config.xml 文件才能让 JSF 进行解释注释.
You need to have a JSF 2.0 compliant /WEB-INF/faces-config.xml file in order to get JSF to interpret the annotations.
<?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_0.xsd"
version="2.0">
<!-- Config here. Can even be kept empty. -->
</faces-config>
如果你已经有一个或者如果这不能解决问题，如果你没有看到任何警告/错误，请注意服务器启动日志.
If you already have one or if that doesn't solve the problem, please pay attention to server startup logs if you don't see any warnings/errors.
顺便说一下，您的 /WEB-INF/web.xml 文件被声明为符合 Servlet 2.5 规范.虽然这不一定有害，但如果您使用的是 Servlet 3.0 兼容容器，则毫无意义.更新根声明如下:
By the way, your /WEB-INF/web.xml file is declared conform Servlet 2.5 specification. While this may not necessarily harm, it makes no sense if you're using a Servlet 3.0 compliant container. Update the root declaration as follows:
<?xml version="1.0" encoding="UTF-8"?>
<web-app
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-app_3_0.xsd"
version="3.0">
<!-- Config here. -->
</web-app>
/WEB-INF/beans.xml 用于 CDI 注释，如 @Named、@Inject 等.只需一个完全空的文件就足以将其打开.它与 @ManagedBean、@ManagedProperty 等 JSF 注释完全没有关系.它也不应该相互混淆/混合.
The /WEB-INF/beans.xml is intented for CDI annotations like @Named, @Inject and so on. Just a completely empty file is sufficient to turn it on. It has totally no relationship to JSF annotations like @ManagedBean, @ManagedProperty and so on. It should also not be confused/mixed with each other.
这篇关于Java EE 6:目标不可达，标识符“helloBean"解析为空的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
