原因：JBoss Wildfly和JPA注入中的java.lang.NullPointerException_Java_Hibernate_Jpa_Cdi_Inject

原因：JBoss Wildfly和JPA注入中的java.lang.NullPointerException

java hibernate jpa

原因：JBoss Wildfly和JPA注入中的java.lang.NullPointerException,java,hibernate,jpa,cdi,inject,Java,Hibernate,Jpa,Cdi,Inject,我尝试将entityManager从一个JPAUtil.class简单地注入到我的DAO中。当我创建一个实例时，它可以工作，但是当一个用户尝试创建@Inject时，我会得到一个空指针异常。也许这很容易，但我不明白 Persistence.xml <persistence xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instanc

我尝试将entityManager从一个JPAUtil.class简单地注入到我的DAO中。当我创建一个实例时，它可以工作，但是当一个用户尝试创建@Inject时，我会得到一个空指针异常。也许这很容易，但我不明白

Persistence.xml

<persistence 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"
             version="2.0">
    <persistence-unit name="jpa" transaction-type="JTA">
        <provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
        <class>model.Client</class>
        <properties>
            <property name="hibernate.dialect" value="org.hibernate.dialect.PostgreSQL9Dialect" />
            <property name="hibernate.connection.driver_class" value="org.postgresql.Driver" />
            <property name="hibernate.connection.url" value="jdbc:postgresql://localhost:5432/prueba1" />
            <property name="hibernate.connection.username" value="kevinsantiago" />
            <property name="hibernate.connection.password" value="" />
            <!--<property name="hibernate.show_sql" value="true"/>
            <property name="hibernate.format_sql" value="true"/>
            <property name="hibernate.flushMode" value="FLUSH_AUTO" />
           <property name="hibernate.hbm2ddl.auto" value="update" />-->
        </properties>
    </persistence-unit>
</persistence>

现在a只想复制错误

Context Path:/JSFJPA_HelloWorld_war_exploded
Servlet Path:/index.xhtml
Path Info:null
Query String:null
Stack Trace:
javax.servlet.ServletException
    at javax.faces.api@3.0.0.Final//javax.faces.webapp.FacesServlet.executeLifecyle(FacesServlet.java:725)
    at javax.faces.api@3.0.0.Final//javax.faces.webapp.FacesServlet.service(FacesServlet.java:451)
    at io.undertow.servlet@2.0.27.Final//io.undertow.servlet.handlers.ServletHandler.handleRequest(ServletHandler.java:74)
    at io.undertow.servlet@2.0.27.Final//io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:129)
    at io.opentracing.contrib.opentracing-jaxrs2//io.opentracing.contrib.jaxrs2.server.SpanFinishingFilter.doFilter(SpanFinishingFilter.java:52)
    at io.undertow.servlet@2.0.27.Final//io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:61)
    at io.undertow.servlet@2.0.27.Final//io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:131)
    at io.undertow.servlet@2.0.27.Final//io.undertow.servlet.handlers.FilterHandler.handleRequest(FilterHandler.java:84)
    at io.undertow.servlet@2.0.27.Final//io.undertow.servlet.handlers.security.ServletSecurityRoleHandler.handleRequest(ServletSecurityRoleHandler.java:62)
    at io.undertow.servlet@2.0.27.Final//io.undertow.servlet.handlers.ServletChain$1.handleRequest(ServletChain.java:68)
    at io.undertow.servlet@2.0.27.Final//io.undertow.servlet.handlers.ServletDispatchingHandler.handleRequest(ServletDispatchingHandler.java:36)
    at org.wildfly.extension.undertow@18.0.1.Final//org.wildfly.extension.undertow.security.SecurityContextAssociationHandler.handleRequest(SecurityContextAssociationHandler.java:78)
    at io.undertow.core@2.0.27.Final//io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
    at io.undertow.servlet@2.0.27.Final//io.undertow.servlet.handlers.RedirectDirHandler.handleRequest(RedirectDirHandler.java:68)
    at io.undertow.servlet@2.0.27.Final//io.undertow.servlet.handlers.security.SSLInformationAssociationHandler.handleRequest(SSLInformationAssociationHandler.java:132)
    at io.undertow.servlet@2.0.27.Final//io.undertow.servlet.handlers.security.ServletAuthenticationCallHandler.handleRequest(ServletAuthenticationCallHandler.java:57)
    at io.undertow.core@2.0.27.Final//io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
    at io.undertow.core@2.0.27.Final//io.undertow.security.handlers.AbstractConfidentialityHandler.handleRequest(AbstractConfidentialityHandler.java:46)
    at io.undertow.servlet@2.0.27.Final//io.undertow.servlet.handlers.security.ServletConfidentialityConstraintHandler.handleRequest(ServletConfidentialityConstraintHandler.java:64)
    at io.undertow.core@2.0.27.Final//io.undertow.security.handlers.AuthenticationMechanismsHandler.handleRequest(AuthenticationMechanismsHandler.java:60)
    at io.undertow.servlet@2.0.27.Final//io.undertow.servlet.handlers.security.CachedAuthenticatedSessionHandler.handleRequest(CachedAuthenticatedSessionHandler.java:77)
    at io.undertow.core@2.0.27.Final//io.undertow.security.handlers.NotificationReceiverHandler.handleRequest(NotificationReceiverHandler.java:50)
    at io.undertow.core@2.0.27.Final//io.undertow.security.handlers.AbstractSecurityContextAssociationHandler.handleRequest(AbstractSecurityContextAssociationHandler.java:43)
    at io.undertow.core@2.0.27.Final//io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
    at org.wildfly.extension.undertow@18.0.1.Final//org.wildfly.extension.undertow.security.jacc.JACCContextIdHandler.handleRequest(JACCContextIdHandler.java:61)
    at io.undertow.core@2.0.27.Final//io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
    at org.wildfly.extension.undertow@18.0.1.Final//org.wildfly.extension.undertow.deployment.GlobalRequestControllerHandler.handleRequest(GlobalRequestControllerHandler.java:68)
    at io.undertow.core@2.0.27.Final//io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
    at io.undertow.servlet@2.0.27.Final//io.undertow.servlet.handlers.ServletInitialHandler.handleFirstRequest(ServletInitialHandler.java:269)
    at io.undertow.servlet@2.0.27.Final//io.undertow.servlet.handlers.ServletInitialHandler.access$100(ServletInitialHandler.java:78)
    at io.undertow.servlet@2.0.27.Final//io.undertow.servlet.handlers.ServletInitialHandler$2.call(ServletInitialHandler.java:133)
    at io.undertow.servlet@2.0.27.Final//io.undertow.servlet.handlers.ServletInitialHandler$2.call(ServletInitialHandler.java:130)
    at io.undertow.servlet@2.0.27.Final//io.undertow.servlet.core.ServletRequestContextThreadSetupAction$1.call(ServletRequestContextThreadSetupAction.java:48)
    at io.undertow.servlet@2.0.27.Final//io.undertow.servlet.core.ContextClassLoaderSetupAction$1.call(ContextClassLoaderSetupAction.java:43)
    at org.wildfly.extension.undertow@18.0.1.Final//org.wildfly.extension.undertow.security.SecurityContextThreadSetupAction.lambda$create$0(SecurityContextThreadSetupAction.java:105)
    at org.wildfly.extension.undertow@18.0.1.Final//org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService$UndertowThreadSetupAction.lambda$create$0(UndertowDeploymentInfoService.java:1504)
    at org.wildfly.extension.undertow@18.0.1.Final//org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService$UndertowThreadSetupAction.lambda$create$0(UndertowDeploymentInfoService.java:1504)
    at org.wildfly.extension.undertow@18.0.1.Final//org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService$UndertowThreadSetupAction.lambda$create$0(UndertowDeploymentInfoService.java:1504)
    at org.wildfly.extension.undertow@18.0.1.Final//org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService$UndertowThreadSetupAction.lambda$create$0(UndertowDeploymentInfoService.java:1504)
    at org.wildfly.extension.undertow@18.0.1.Final//org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService$UndertowThreadSetupAction.lambda$create$0(UndertowDeploymentInfoService.java:1504)
    at io.undertow.servlet@2.0.27.Final//io.undertow.servlet.handlers.ServletInitialHandler.dispatchRequest(ServletInitialHandler.java:249)
    at io.undertow.servlet@2.0.27.Final//io.undertow.servlet.handlers.ServletInitialHandler.access$000(ServletInitialHandler.java:78)
    at io.undertow.servlet@2.0.27.Final//io.undertow.servlet.handlers.ServletInitialHandler$1.handleRequest(ServletInitialHandler.java:99)
    at io.undertow.core@2.0.27.Final//io.undertow.server.Connectors.executeRootHandler(Connectors.java:376)
    at io.undertow.core@2.0.27.Final//io.undertow.server.HttpServerExchange$1.run(HttpServerExchange.java:830)
    at org.jboss.threads@2.3.3.Final//org.jboss.threads.ContextClassLoaderSavingRunnable.run(ContextClassLoaderSavingRunnable.java:35)
    at org.jboss.threads@2.3.3.Final//org.jboss.threads.EnhancedQueueExecutor.safeRun(EnhancedQueueExecutor.java:1982)
    at org.jboss.threads@2.3.3.Final//org.jboss.threads.EnhancedQueueExecutor$ThreadBody.doRunTask(EnhancedQueueExecutor.java:1486)
    at org.jboss.threads@2.3.3.Final//org.jboss.threads.EnhancedQueueExecutor$ThreadBody.run(EnhancedQueueExecutor.java:1377)
    at java.base/java.lang.Thread.run(Thread.java:834)
Caused by: java.lang.NullPointerException
    at deployment.JSFJPA_HelloWorld_war_exploded.war//dao.ClientDAO.findall(ClientDAO.java:43)
    at deployment.JSFJPA_HelloWorld_war_exploded.war//controller.ClientBean.AllClients(ClientBean.java:41)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.base/java.lang.reflect.Method.invoke(Method.java:566)
    at javax.el.api@2.0.0.Final//javax.el.ELUtil.invokeMethod(ELUtil.java:245)
    at javax.el.api@2.0.0.Final//javax.el.BeanELResolver.invoke(BeanELResolver.java:338)
    at javax.el.api@2.0.0.Final//javax.el.CompositeELResolver.invoke(CompositeELResolver.java:198)
    at org.glassfish.jakarta.el@3.0.2//com.sun.el.parser.AstValue.getValue(AstValue.java:111)
    at org.glassfish.jakarta.el@3.0.2//com.sun.el.parser.AstValue.getValue(AstValue.java:179)
    at org.glassfish.jakarta.el@3.0.2//com.sun.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:202)
    at org.jboss.weld.core@3.1.2.Final//org.jboss.weld.module.web.el.WeldValueExpression.getValue(WeldValueExpression.java:50)
    at org.jboss.weld.core@3.1.2.Final//org.jboss.weld.module.web.el.WeldValueExpression.getValue(WeldValueExpression.java:50)
    at com.sun.jsf-impl@2.3.9.SP04//com.sun.faces.facelets.el.TagValueExpression.getValue(TagValueExpression.java:73)
    at javax.faces.api@3.0.0.Final//javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:170)
    at javax.faces.api@3.0.0.Final//javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:157)
    at javax.faces.api@3.0.0.Final//javax.faces.component.UIData.getValue(UIData.java:736)
    at javax.faces.api@3.0.0.Final//javax.faces.component.UIData.getDataModel(UIData.java:1849)
    at javax.faces.api@3.0.0.Final//javax.faces.component.UIData.setRowIndexWithoutRowStatePreserved(UIData.java:479)
    at javax.faces.api@3.0.0.Final//javax.faces.component.UIData.setRowIndex(UIData.java:468)
    at com.sun.jsf-impl@2.3.9.SP04//com.sun.faces.renderkit.html_basic.TableRenderer.encodeBegin(TableRenderer.java:57)
    at javax.faces.api@3.0.0.Final//javax.faces.component.UIComponentBase.encodeBegin(UIComponentBase.java:540)
    at javax.faces.api@3.0.0.Final//javax.faces.component.UIData.encodeBegin(UIData.java:1153)
    at javax.faces.api@3.0.0.Final//javax.faces.component.UIComponent.encodeAll(UIComponent.java:1644)
    at javax.faces.api@3.0.0.Final//javax.faces.component.UIComponent.encodeAll(UIComponent.java:1650)
    at javax.faces.api@3.0.0.Final//javax.faces.component.UIComponent.encodeAll(UIComponent.java:1650)
    at com.sun.jsf-impl@2.3.9.SP04//com.sun.faces.application.view.FaceletViewHandlingStrategy.renderView(FaceletViewHandlingStrategy.java:468)
    at com.sun.jsf-impl@2.3.9.SP04//com.sun.faces.application.view.MultiViewHandler.renderView(MultiViewHandler.java:170)
    at javax.faces.api@3.0.0.Final//javax.faces.application.ViewHandlerWrapper.renderView(ViewHandlerWrapper.java:132)
    at javax.faces.api@3.0.0.Final//javax.faces.application.ViewHandlerWrapper.renderView(ViewHandlerWrapper.java:132)
    at com.sun.jsf-impl@2.3.9.SP04//com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:102)
    at com.sun.jsf-impl@2.3.9.SP04//com.sun.faces.lifecycle.Phase.doPhase(Phase.java:76)
    at com.sun.jsf-impl@2.3.9.SP04//com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:199)
    at javax.faces.api@3.0.0.Final//javax.faces.webapp.FacesServlet.executeLifecyle(FacesServlet.java:708)
    ... 49 more

如果你有建议或意见，阅读它将是一种乐趣，因为每一个反馈都是受欢迎的。我刚刚开始学习这项技术。

首先，如果您想使用CDI，您可以避免使用静态工厂：

@PersistenceContext(unitName = "jpa")
private EntityManager em;

@Produces
public EntityManager getEntityManager(){
    return em;
}

将beans.xml文件放入WEB-INF目录：

<?xml version="1.0" encoding="UTF-8"?>
<beans xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/beans_1_0.xsd" 
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" >

</beans>

编辑

对于web应用程序，beans.xml部署描述符（如果存在）必须位于web-INF目录中。对于EJB模块或JAR文件，beans.xml部署描述符（如果存在）必须位于META-INF目录中

我试着做你告诉我的改变。但我也有同样的问题。我有Beam.xml，新的修改还不起作用=S。你添加了beans.xml吗？非常感谢你的快速回答你真是太好了。我要添加git存储库，答案是。是的，我有beams.xml。如果您能检查一下，看看是否一切正常，那么存储库将非常棒。谢谢您的评论和建议。有一个主要的类。。。您正在容器中部署应用程序，是吗？

@PersistenceContext(unitName = "jpa")
private EntityManager em;

@Produces
public EntityManager getEntityManager(){
    return em;
}

<?xml version="1.0" encoding="UTF-8"?>
<beans xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/beans_1_0.xsd" 
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" >

</beans>

@Inject
private EntityManager em;