我正在尝试用我的数据库中的客户填充一个下拉表，问题是我得到一个nullPointerException指向Facade中试图从数据库中检索信息的方法。下面是我的Facade和Customer类+ jsp.file和错误消息
门面课
package examples.facade.ics;
import java.util.ArrayList;
@Stateless
public class Facade implementes FacadeLocal{
@EJB private CustomerEAOLocal cusomterEAO;
public Facade () {
public ArrayList<Customer> getAllCustomers(){
return cusomterEAO.getAllCustomers();
客户类
@Entity
@NamedQueries({ @NamedQuery(name = "Customer.getAllCustomers",
query = "SELECT c FROM Customer c") })
@Table(name = "Customer")
public class Customer implements Serializable {
private String name;
private String phone;
private int custid;
private String mail;
private Set<Booking> bookings;
Index.jsp类文件
<h5>Customer</h5>
<div class="section_customer">
<select id="customer" onchange="change_customer(this.value)" class="frm-field required">
<c:forEach var="cust" items="$customers">
<option value=${cust.custid}>${cust.custid}</option>
</c:forEach>
<option value="null">Kaj</option>
</select>
</div>
错误消息
org.apache.jasper.JasperException: java.lang.NullPointerException
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:473)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:403)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:347)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
at io.undertow.servlet.handlers.ServletHandler.handleRequest(ServletHandler.java:85)
at io.undertow.servlet.handlers.security.ServletSecurityRoleHandler.handleRequest(ServletSecurityRoleHandler.java:62)
at io.undertow.jsp.JspFileHandler.handleRequest(JspFileHandler.java:32)
at io.undertow.servlet.handlers.ServletDispatchingHandler.handleRequest(ServletDispatchingHandler.java:36)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
at io.undertow.servlet.handlers.ServletInitialHandler.dispatchRequest(ServletInitialHandler.java:274)
at io.undertow.servlet.handlers.ServletInitialHandler.dispatchToPath(ServletInitialHandler.java:209)
at io.undertow.servlet.spec.RequestDispatcherImpl.forwardImpl(RequestDispatcherImpl.java:221)
at io.undertow.servlet.spec.RequestDispatcherImpl.forwardImplSetup(RequestDispatcherImpl.java:147)
at io.undertow.servlet.spec.RequestDispatcherImpl.forward(RequestDispatcherImpl.java:111)
at examples.examples.ics.BookingServlet.doGet(BookingServlet.java:44)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:687)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
at io.undertow.servlet.handlers.ServletHandler.handleRequest(ServletHandler.java:85)
at io.undertow.servlet.handlers.security.ServletSecurityRoleHandler.handleRequest(ServletSecurityRoleHandler.java:62)
at io.undertow.servlet.handlers.ServletDispatchingHandler.handleRequest(ServletDispatchingHandler.java:36)
at org.wildfly.extension.undertow.security.SecurityContextAssociationHandler.handleRequest(SecurityContextAssociationHandler.java:78)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
at io.undertow.servlet.handlers.security.SSLInformationAssociationHandler.handleRequest(SSLInformationAssociationHandler.java:131)
at io.undertow.servlet.handlers.security.ServletAuthenticationCallHandler.handleRequest(ServletAuthenticationCallHandler.java:57)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
at io.undertow.security.handlers.AbstractConfidentialityHandler.handleRequest(AbstractConfidentialityHandler.java:46)
at io.undertow.servlet.handlers.security.ServletConfidentialityConstraintHandler.handleRequest(ServletConfidentialityConstraintHandler.java:64)
at io.undertow.security.handlers.AuthenticationMechanismsHandler.handleRequest(AuthenticationMechanismsHandler.java:60)
at io.undertow.servlet.handlers.security.CachedAuthenticatedSessionHandler.handleRequest(CachedAuthenticatedSessionHandler.java:77)
at io.undertow.security.handlers.NotificationReceiverHandler.handleRequest(NotificationReceiverHandler.java:50)
at io.undertow.security.handlers.AbstractSecurityContextAssociationHandler.handleRequest(AbstractSecurityContextAssociationHandler.java:43)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
at org.wildfly.extension.undertow.security.jacc.JACCContextIdHandler.handleRequest(JACCContextIdHandler.java:61)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
at org.wildfly.extension.undertow.deployment.GlobalRequestControllerHandler.handleRequest(GlobalRequestControllerHandler.java:68)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
at io.undertow.servlet.handlers.ServletInitialHandler.handleFirstRequest(ServletInitialHandler.java:292)
at io.undertow.servlet.handlers.ServletInitialHandler.access$100(ServletInitialHandler.java:81)
at io.undertow.servlet.handlers.ServletInitialHandler$2.call(ServletInitialHandler.java:138)
at io.undertow.servlet.handlers.ServletInitialHandler$2.call(ServletInitialHandler.java:135)
at io.undertow.servlet.core.ServletRequestContextThreadSetupAction$1.call(ServletRequestContextThreadSetupAction.java:48)
at io.undertow.servlet.core.ContextClassLoaderSetupAction$1.call(ContextClassLoaderSetupAction.java:43)
at org.wildfly.extension.undertow.security.SecurityContextThreadSetupAction.lambda$create$0(SecurityContextThreadSetupAction.java:105)
at org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService$UndertowThreadSetupAction.lambda$create$0(UndertowDeploymentInfoService.java:1508)
at org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService$UndertowThreadSetupAction.lambda$create$0(UndertowDeploymentInfoService.java:1508)
at org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService$UndertowThreadSetupAction.lambda$create$0(UndertowDeploymentInfoService.java:1508)
at org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService$UndertowThreadSetupAction.lambda$create$0(UndertowDeploymentInfoService.java:1508)
at org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService$UndertowThreadSetupAction.lambda$create$0(UndertowDeploymentInfoService.java:1508)
at io.undertow.servlet.handlers.ServletInitialHandler.dispatchRequest(ServletInitialHandler.java:272)
at io.undertow.servlet.handlers.ServletInitialHandler.access$000(ServletInitialHandler.java:81)
at io.undertow.servlet.handlers.ServletInitialHandler$1.handleRequest(ServletInitialHandler.java:104)
at io.undertow.server.Connectors.executeRootHandler(Connectors.java:326)
at io.undertow.server.HttpServerExchange$1.run(HttpServerExchange.java:812)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.NullPointerException
at examples.facade.ics.Facade.getAllCustomers(Facade.java:88)
at org.apache.jsp.Index_jsp._jspService(Index_jsp.java:128)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:433)
... 57 more