javax.el.PropertyNotFoundException：/[email protected],55 value =「＃{UserBean.favYear3}」：目標無法訪問，標識符'UserBean'解析爲空

我想在JSF中有一個列表框。我寫了一個簡單的代碼，但它不起作用。在演示頁面中，我看到一個帶有列表和用戶頁面的空框，我有錯誤。javax.el.PropertyNotFoundException：/[email protected],55 value =「＃{UserBean.favYear3}」：目標無法訪問，標識符'UserBean'解析爲空

UserBean.java

@ManagedBean 
@SessionScoped 
public class UserBean implements Serializable{ 
    public String favYear3;//list box 

    public String getFavYear3() { 
     return favYear3; 
    } 

    public void setFavYear3(String favYear3) { 
     this.favYear3 = favYear3; 
    } 
    public static class Year{ 
     public String yearLabel; 
     public String yearValue; 

     public Year(String yearLabel, String yearValue){ 
      this.yearLabel = yearLabel; 
      this.yearValue = yearValue; 
     } 

     public String getYearLabel(){ 
      return yearLabel; 
     } 

     public String getYearValue(){ 
      return yearValue; 
     } 

    } 

    public Year[] year3List; 

    public Year[] getFavYear3Value() { 

     year3List = new Year[3]; 
     year3List[0] = new Year("Year3 - 2000", "2000"); 
     year3List[1] = new Year("Year3 - 2010", "2010"); 
     year3List[2] = new Year("Year3 - 2020", "2020"); 

     return year3List; 
    } 

}

demo.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" 
xmlns:f="http://java.sun.com/jsf/core"> 
<head> 
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> 
    <title>first jsf page</title> 
</head> 
<h:body> 
    <h1>JSF 2 check example</h1> 

    <h:form> 
     <h:selectOneListbox value="#{UserBean.favYear3}"> 
      <f:selectItems value="#{UserBean.favYear3Value}" var="y" 
       itemLabel="#{y.yearLabel}" itemValue="#{y.yearValue}" /> 
     </h:selectOneListbox> 
    </h:form> 

</h:body> 
</html>

user.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"> 
<head> 
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> 
    <title>second jsf page</title> 
</head> 
<h:body> 
    <h:outputText value="#{UserBean.favYear3}"/> 
</h:body> 
</html>

我的問題：在演示頁面我有一個空箱子。在用戶頁面錯誤是：

type Exception report 

message 

description The server encountered an internal error() that prevented it from fulfilling this request. 

exception 

javax.servlet.ServletException: javax.el.PropertyNotFoundException: /demo.xhtml @24,55 value="#{UserBean.favYear3}": Target Unreachable, identifier 'UserBean' resolved to null 
    javax.faces.webapp.FacesServlet.service(FacesServlet.java:321) 


root cause 

javax.faces.component.UpdateModelException: javax.el.PropertyNotFoundException: /demo.xhtml @24,55 value="#{UserBean.favYear3}": Target Unreachable, identifier 'UserBean' resolved to null 
    javax.faces.component.UIInput.updateModel(UIInput.java:848) 
    javax.faces.component.UIInput.processUpdates(UIInput.java:730) 
    javax.faces.component.UIForm.processUpdates(UIForm.java:268) 
    javax.faces.component.UIComponentBase.processUpdates(UIComponentBase.java:1109) 
    javax.faces.component.UIComponentBase.processUpdates(UIComponentBase.java:1109) 
    javax.faces.component.UIViewRoot.processUpdates(UIViewRoot.java:1218) 
    com.sun.faces.lifecycle.UpdateModelValuesPhase.execute(UpdateModelValuesPhase.java:74) 
    com.sun.faces.lifecycle.Phase.doPhase(Phase.java:97) 
    com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:114) 
    javax.faces.webapp.FacesServlet.service(FacesServlet.java:308)

什麼是錯？

來源

2012-06-13 samira

你必須使你的bean可達/管理。對於這一點，您可以

與CDI（@Named）或JSF（@ManagedBean）註釋標註爲：

@Named 
@SessionScoped 
public class UserBean implements Serializable{...}

或描述它在faces-config.xml爲managed-bean這樣的：

<managed-bean> 
    <managed-bean-name>userBean</managed-bean-name> 
    <managed-bean-class>com.example.UserBean</managed-bean-class> 
    <managed-bean-scope>session</managed-bean-scope> 
</managed-bean>

來源

2012-06-13 07:25:13 kostja

，我以前做過，我編輯的職位。 – samira

我將你的代碼添加到我的face-config中。現在我沒有錯誤，但它不起作用。我的列表是空的，我不能選擇 – samira

@Sami：如果答案沒有*不*解決您的具體問題，那麼你不應該立即將其標記接受。這隻會讓其他讀者感到困惑。只有在真正*解決了具體問題時，才接受接受的答案。 – BalusC

在EL你的託管bean的名字是錯的。你已經聲明瞭豆如下：

@ManagedBean 
@SessionScoped 
public class UserBean implements Serializable{

當你不指定@ManagedBean的name屬性，那麼它將符合JavaBeans的命名約定默認與第1個字符的類名小寫像這樣userBean，但但你試圖用精確的類名#{UserBean}引用它們。您需要相應地修復此名稱爲#{userBean}。

faces-config.xml註冊爲對於JSF 2.x不必要的。去掉它。

來源

2012-06-13 10:49:42 BalusC

javax.el.PropertyNotFoundException：/[email protected],55 value =「＃{UserBean.favYear3}」：目標無法訪問，標識符'UserBean'解析爲空

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