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EntityManager空指針異常

2014-06-06 31 views
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另一個'EntityManager爲空'的問題。我搜索了一個答案，但沒有找到一個適合我的。我正在接管一個大型項目，我試圖簡化它以在調試時切出紅鯡魚。我只是簡單的客戶/訂單系統，我只是想部署它並查看客戶列表。基於另一個問題，我問及resulting suggestion我到以下（實際問題和堆棧跟蹤底部）：EntityManager空指針異常

的persistence.xml

<?xml version="1.0" encoding="UTF-8"?> 
<persistence version="2.0" xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd"> 
    <persistence-unit name="my_PU" transaction-type="JTA"> 
     <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider> 
     <jta-data-source>my_datasource</jta-data-source> 
     <class>my.database.model.Customer</class> 
     <class>my.database.model.Order</class> 
     <exclude-unlisted-classes>false</exclude-unlisted-classes> 
    </persistence-unit> 
</persistence>

的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_3_0.xsd" id="WebApp_ID" version="3.0"> 
    <display-name>MyWebApp</display-name> 
    <welcome-file-list> 
    <welcome-file>index.html</welcome-file> 
    <welcome-file>index.htm</welcome-file> 
    <welcome-file>index.jsp</welcome-file> 
    <welcome-file>default.html</welcome-file> 
    <welcome-file>default.htm</welcome-file> 
    <welcome-file>default.jsp</welcome-file> 
    </welcome-file-list> 
    <servlet> 
    <servlet-name>Faces Servlet</servlet-name> 
    <servlet-class>javax.faces.webapp.FacesServlet</servlet-class> 
    <load-on-startup>1</load-on-startup> 
    </servlet> 
    <servlet-mapping> 
    <servlet-name>Faces Servlet</servlet-name> 
    <url-pattern>/faces/*</url-pattern> 
    </servlet-mapping> 
    <context-param> 
    <description>State saving method: 'client' or 'server' (=default). See JSF Specification 2.5.2</description> 
    <param-name>javax.faces.STATE_SAVING_METHOD</param-name> 
    <param-value>client</param-value> 
    </context-param> 
    <context-param> 
    <param-name>javax.servlet.jsp.jstl.fmt.localizationContext</param-name> 
    <param-value>resources.application</param-value> 
    </context-param> 
    <context-param> 
    <param-name>javax.faces.FACELETS_LIBRARIES</param-name> 
    <param-value>/WEB-INF/balusc.taglib.xml</param-value> 
    </context-param> 
    <context-param> 
    <param-name>javax.faces.INTERPRET_EMPTY_STRING_SUBMITTED_VALUES_AS_NULL</param-name> 
    <param-value>true</param-value> 
    </context-param> 
    <filter> 
    <filter-name>PrimeFaces FileUpload Filter</filter-name> 
    <filter-class>org.primefaces.webapp.filter.FileUploadFilter</filter-class> 
    </filter> 
    <filter-mapping> 
    <filter-name>PrimeFaces FileUpload Filter</filter-name> 
    <servlet-name>Faces Servlet</servlet-name> 
    </filter-mapping> 
    <context-param> 
    <param-name>javax.faces.PARTIAL_STATE_SAVING</param-name> 
    <param-value>false</param-value> 
    </context-param> 
    <listener> 
    <listener-class>com.sun.faces.config.ConfigureListener</listener-class> 
    </listener> 
</web-app>

網頁 - menu.xhtml

<html 
xmlns="http://www.w3.org/1999/xhtml" 
    xmlns:ui="http://java.sun.com/jsf/facelets" 
    xmlns:h="http://java.sun.com/jsf/html" 
    xmlns:f="http://java.sun.com/jsf/core"> 
<head> 
<link rel="stylesheet" type="text/css" media="screen,projection" 
    href="../css/menu.css" /></head> 
<ui:component> 
    <div class="menu-container"> 
     <div class="menu-tab"> 
      <ul> 
       <li><a href="index.xhtml"><span>Home</span></a></li> 

       <li><h:outputLink 
         value="#{customerController.getUrl()}"> 
         <span><h:outputText value="Customer" /></span> 
        </h:outputLink></li> 
       <li><a href=""><span>Logout</span></a></li> 
      </ul> 
     </div> 
    </div> 
</ui:component> 
</html>

CustomerController.java

package my.webapp.web.controller; 

import java.util.List; 
import javax.annotation.PostConstruct; 
import javax.enterprise.context.RequestScoped; 
import javax.inject.Named; 
import my.model.Customer; 

@Named(value = "customerController") 
@RequestScoped 
public class CustomerController// extends FormRequestController 
{ 
    private Customer customer; 
    private String id; 
    protected List<?> entityObjectList; 
    protected boolean editMode; 

    @PostConstruct 
    public void init() { 
     System.out.println("CustomerController init"); 
     setEntityObjectList(findAll()); 
    } 

    public List<?> findAll() { 
     List<Customer> dataList = Customer.getAllRecords(); 
     return dataList; 

    } 

    public String getUrl() 
    { 
     System.out.println("CustomerController getUrl"); 
     return "www.google.com"; 
    } 
    //getters and setters ommitted for brevity 
}

Customer.java

package my.model; 

import java.io.Serializable; 
import java.util.HashMap; 
import java.util.List; 
import java.util.Map; 
import java.util.Set; 
import javax.ejb.EJB; 
import javax.persistence.Entity; 
import javax.persistence.GeneratedValue; 
import javax.persistence.GenerationType; 
import javax.persistence.Id; 
import javax.persistence.NamedQueries; 
import javax.persistence.NamedQuery; 
import javax.persistence.OneToMany; 
import javax.persistence.Table; 
import my.database.manager.PersistenceStoreManager; 

@Entity 
@Table(name=Customer.TBL_NAME) 
@NamedQueries({ 
    @NamedQuery(name=Customer.QRY_ALL, query="select object(a) from Customer a") 
}) 
public class Customer implements Serializable { 
    private static final long serialVersionUID = 1L; 

    /** 
    * Manager class to manager DB connections 
    */ 
    @EJB 
    private static PersistenceStoreManager<Customer> psm; 
    // Table constants 
    public static final String TBL_NAME = "Customer"; 
    public static final String QRY_ALL = TBL_NAME + ".all"; 

    private int id; 
    private String name; 
    private Set<Order> orders; 

    public Customer() { 
    } 


    @Id 
    @GeneratedValue(strategy=GenerationType.IDENTITY) 
    public int getId() { 
     return this.id; 
    } 

    //bi-directional many-to-one association to Order 
    @OneToMany(mappedBy="id") 
    public Set<Order> getOrders() { 
     return this.orders; 
    } 

    public void setOrders(Set<Order> orders) { 
     this.orders = orders; 
    } 

    public static List<Customer> getAllRecords(){ 
     Map<String, Object> params = new HashMap<String, Object>(); 
     return psm.getResultSetList(QRY_ALL, params); 
    } 
    //other getters and setters omitted for brevity 
}

PersistenceStoreManager.java

package my.database.manager; 

import java.util.List; 
import java.util.Map; 
import javax.annotation.PostConstruct; 
import javax.ejb.Stateless; 
import javax.persistence.EntityManager; 
import javax.persistence.PersistenceContext; 
import javax.persistence.Query; 

/** 
* This class is responsible for performing CRUD operations using the 
* EntityManager of the PersistenceContext. 
* 
* 
*/ 
@Stateless 
public class PersistenceStoreManager<T> 
{ 
    @PersistenceContext(unitName = "my_PU") 
    private EntityManager em; 


    public PersistenceStoreManager() 
    { 
     System.out.println("PersistenceStoreManager loaded"); 
     System.out.println("em is null: "+(em==null)); 
    } 

    @PostConstruct 
    public void postInject() 
    { 
     System.out.println("postInject"); 
     System.out.println("em is null: "+(em==null)); 
    } 

    /** 
    * @param namedQuery 
    * @param criteria 
    * @return 
    */ 
    public List<T> getResultSetList(String namedQuery, 
      Map<String, Object> criteria) { 

     Query q = em.createNamedQuery(namedQuery); 
     for (Map.Entry<String, Object> entry : criteria.entrySet()) { 
      q.setParameter(entry.getKey(), entry.getValue()); 
     } 
     List<T> resultSetList = q.getResultList(); 
     return resultSetList; 
    } 
}

我的應用程序部署，但我得到了無處不在的NullPointerException試圖查看menu.xhtml頁面時。當部署應用程序將記錄以下：

-warning | org.apache.catalina.connector.Request | _ThreadID = 37; _ThreadName =螺紋-2; | PWC4011：無法請求的字符編碼設定爲UTF -8，因爲請求參數已被讀取，或者ServletRequest.getReader（）已被調用|＃]
-INFO | uploadFileName = MyWebApp-0.0.1-SNAPSHOT.war |＃]
-INFO | javax.enterprise.system.container.ejb.com.sun.ejb.containers | EJB PersistenceStoreManager的可移植JNDI名稱：[java：global/MyWebApp-0.0.1-SNAPSHOT/PersistenceStoreManager，java：global/MyWebApp-0.0.1- SNAPSHOT/PersistenceStoreManager！my.database.manager.PersistenceStoreManager] |＃]
-INFO | javax.enterprise.system.std.com.sun.enterprise.server.logging | PersistenceStoreManager已加載 |＃]
-INFO | javax.enterprise.system.std.com.sun.enterprise.server.logging | em is null：true |＃]
-INFO | javax.enterprise.resource.webcontainer.jsf.config |初始化Mojarra 2.1.6（SNAPSHOT 20111206）上下文'/MyWebApp-0.0.1-SNAPSHOT'|# ]
-INFO | org.primefaces.webapp.PostConstructApplicationEventListener |在PrimeFaces上運行3.4.1 |＃]
-INFO | javax.enterprise.system.container.web.com.sun.enterprise.web | WEB0671：加載應用程序[MyWebApp-0.0.1-SNAPSH 6243 OT] |＃]
-INFO | javax.enterprise.system.tools.admin.org.glassfish.deployment.admin | MyWebApp-0.0.1-SNAPSHOT | 0.0.1-SNAPSHOT已成功部署在1,598毫秒。|＃]

當我導航到MYSERVER：8080/MyWebApp-0.0.1-SNAPSHOT /面/的index.xhtml以下記錄：

[＃| 2014-06-06T16：51：56.988 + 0100 |嚴重| glassfish3.1.2 | javax.enterprise.resource。webcontainer.jsf.application | _ThreadID = 36; _ThreadName = Thread-2; |錯誤呈現視圖[/index.xhtml]
javax.el.E​​LException：/templates/menu.xhtml @ 15,64 value =「＃{customerController .getUrl（）}「：org.jboss.weld.exceptions.WeldException：WELD-000049無法在my.webapp.web.controller上調用[method] @PostConstruct public my.webapp.web.controller.CustomerController.init .CustomerController @ 4085f7ff
在com.sun.faces.facelets.el.TagValueExpression.getValue（TagValueExpression.java:114）
在javax.faces.component.ComponentStateHelper.eval（ComponentStateHelper.java:194）
.. [long stack trace] ...
引起：java.lang.NullPointerException
a噸my.model.Customer.getAllRecords（Customer.java:64）
在my.webapp.web.controller.CustomerController.findAll（CustomerController.java:41）
在my.webapp.web.controller.CustomerController.init （CustomerController.java:37）
在sun.reflect.NativeMethodAccessorImpl.invoke0（本機方法）
在sun.reflect.NativeMethodAccessorImpl.invoke（NativeMethodAccessorImpl.java:39）
... [長堆棧跟蹤] .. 。

無記錄在postInject()方法Customer，CustomerController正在輸出PersistenceStoreManager。由於它們注有@PostConstruct，應在注入後調用，因此我認爲EJB注入沒有發生。

任何人都可以看到爲什麼EJB注入沒有發生？

來源

2014-06-06 user3337410

回答

1

EJB沒有被注入，因爲它們只能被注入到容器管理的類中，實體不是容器管理的類。容器管理類例如在Java EE 6 specification中列出。

來源

2014-06-06 18:45:24

+0

非常感謝，這是一個更基本的問題的結果 - 我試圖讓一個實體做自己的持久性。該任務應該被分配給控制器，然後由控制器進行容器管理。我將'psm'對象和使用它的方法移到了'CustomerController'類中，並將它改爲非靜態的（就像你引用的規範中所指出的那樣）並且它正在工作！ – user3337410

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