运行简单的JSF应用程序时出错
[英]Getting error while running a simple JSF application
问题描述
I am getting following exception while I am trying to run a basic JSF application . 
我在尝试运行基本的JSF应用程序时遇到异常。 I am using JSF1.1 , JDK 6 and tomcat 6.0.18 for the same. 我使用JSF1.1，JDK 6和tomcat 6.0.18相同。
exception 例外
description The server encountered an internal error () that prevented it from fulfilling this request.
exception
javax.servlet.ServletException: Error testing property 'lastname' in bean of type null
javax.faces.webapp.FacesServlet.service(FacesServlet.java:209)
root cause
javax.faces.el.PropertyNotFoundException: Error testing property 'lastname' in bean of type null
com.sun.faces.el.PropertyResolverImpl.getType(PropertyResolverImpl.java:342)
com.sun.faces.el.impl.ArraySuffix.getType(ArraySuffix.java:240)
com.sun.faces.el.impl.ComplexValue.getType(ComplexValue.java:208)
com.sun.faces.el.ValueBindingImpl.getType(ValueBindingImpl.java:345)
com.sun.faces.renderkit.html_basic.HtmlBasicInputRenderer.getConvertedValue(HtmlBasicInputRenderer.java:111)
javax.faces.component.UIInput.getConvertedValue(UIInput.java:713)
javax.faces.component.UIInput.validate(UIInput.java:638)
javax.faces.component.UIInput.executeValidate(UIInput.java:849)
javax.faces.component.UIInput.processValidators(UIInput.java:412)
javax.faces.component.UIForm.processValidators(UIForm.java:170)
javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:912)
javax.faces.component.UIViewRoot.processValidators(UIViewRoot.java:342)
com.sun.faces.lifecycle.ProcessValidationsPhase.execute(ProcessValidationsPhase.java:78)
com.sun.faces.lifecycle.LifecycleImpl.phase(LifecycleImpl.java:200)
com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:90)
javax.faces.webapp.FacesServlet.service(FacesServlet.java:197)
Following are the files I have created for the same : 以下是我为同一文件创建的文件：
//jsfmbean.jsp //jsfmbean.jsp
<!DOCTYPE HTML PUBLIC
"-//W3C//DTD HTML 4.01 Transitional//EN">
<%@ taglib uri="http://java.sun.com/jsf/html" prefix="h" %>
<%@ taglib uri="http://java.sun.com/jsf/core" prefix="f" %>
<f:view>
<html>
<body bgcolor="cyan">
<h:form id="form1" >
<h:inputText id="text1" value="#{text2}" />
<h:inputText id="text2" value="#{player.lastname}" />
<h:commandButton action="success" value="success" />
<h:commandButton action="#{player.changeName}" value="failure" />
</h:form>
</body>
</html>
</f:view>
//faces-config.xml //faces-config.xml
<?xml version='1.0' encoding='UTF-8'?>
<!DOCTYPE faces-config PUBLIC
"-//Sun Microsystems, Inc.//DTD JavaServer Faces Config 1.1//EN"
"http://java.sun.com/dtd/web-facesconfig_1_1.dtd">
<faces-config>
<application>
<locale-config>
<default-locale>en</default-locale>
</locale-config>
</application>
<navigation-rule>
<from-view-id>
/jsfevent.jsp
</from-view-id>
<navigation-case>
<from-outcome>success</from-outcome>
<to-view-id>/mathew.jsp</to-view-id>
</navigation-case>
<navigation-case>
<from-outcome>failure</from-outcome>
<to-view-id>/amy.jsp</to-view-id>
</navigation-case>
</navigation-rule>
<navigation-rule>
<from-view-id>/jsfmbean.jsp</from-view-id>
<navigation-case>
<from-outcome>success</from-outcome>
<to-view-id>/mathew.jsp</to-view-id>
</navigation-case>
</navigation-rule>
<managed-bean>
<managed-bean-name>player</managed-bean-name>
<managed-bean-class>
ourdemo.player
</managed-bean-class>
<managed-bean-scope>
session
</managed-bean-scope>
<managed-property>
<property-name>firstname</property-name>
<property-type>java.lang.String</property-type>
<value>Mahatma</value>
</managed-property>
<managed-property>
<property-name>lastname</property-name>
<property-type>java.lang.String</property-type>
<value>Gandhiji</value>
</managed-property>
</managed-bean>
</faces-config>
//Player.java //Player.java
package ourdemo;
import javax.faces.context.*;
import javax.faces.component.*;
import javax.faces.validator.*;
public class Player
{
String firstname ;
String lastname ;
public void setFirstname(String a)
{
firstname=a;
}
public String getFirstname()
{
return firstname;
}
//----------
public void setLastname(String b)
{
lastname=b;
}
public String getLastname()
{
return lastname;
}
//-------------------
public void changeName()
{
lastname= firstname+" "+lastname;
}
} }
Please help ... 请帮忙 ...
3 个解决方案
解决方案1
1 已采纳 2011-09-04 13:30:32
#{player}指向的Bean尚未正确初始化，因此#{player.lastname}引发NullPointerException。
解决方案2
1 2011-09-04 15:31:21
Java is case sensitive. Java区分大小写。 You've created a managed bean with full qualified class name of ourdemo.Player , but yet you're declaring the bean in faces-config.xml as ourdemo.player (note the lowercase p instead of the uppercase P ). 您已经创建了具有完全合格的类名ourdemo.Player的托管bean，但是您在faces-config.xml中将bean声明为ourdemo.player （请注意，小写字母p代替大写字母P ）。 This way JSF can't find and create the bean class, which results that #{player} is null which in turn results in this exception. 这样，JSF无法找到并创建bean类，从而导致#{player}为null ，从而导致此异常。
Fix it accordingly: 相应地修复它：
<managed-bean>
<managed-bean-name>player</managed-bean-name>
<managed-bean-class>ourdemo.Player</managed-bean-class>
<managed-bean-scope>session</managed-bean-scope>
</managed-bean>
Unrelated to the concrete problem: I fully agree with Arjan Tijms in the question comment: use JSF 2.0 or newer if ever possible. 与具体问题无关 ：我完全同意Arjan Tijms的问题评论：尽可能使用JSF 2.0或更高版本。 JSF 1.1 is obsolete for over 5 years and has so many disadvantages. JSF 1.1已过时5年，并且有许多缺点。 If you're using JSF 1.1 due to business restrictions, convince your manager. 如果由于业务限制而使用JSF 1.1，请说服您的经理。 Or if you're using JSF 1.1 because you're reading outdated books/tutorials, throw them away and read the proper ones. 或者，如果您正在使用JSF 1.1，因为您正在阅读过时的书籍/教程，则将它们扔掉并阅读正确的书籍/教程。
解决方案3
0 2013-09-15 20:20:50
Your faces-config.xml is wrong. 您的faces-config.xml错误。
class name declaration must be the same as 类名声明必须与
<managed-bean-class>
ourdemo.Player
</managed-bean-class>
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