问题是将数据插入数据库。使用 JPA、JBoss、MySQL。我做错了什么？这是一对多。我想在用户表中插入一些“用户”，并给他一些角色。我在 MySQL 5.2 Workbench 中创建了两个表，并在 Eclipse 中使用 JPA 生成了这个表。
表用户角色：
CREATE TABLE IF NOT EXISTS `virtual_trainer`.`user_roles` (
`role_name` VARCHAR(45) NOT NULL ,
`users_id` INT NOT NULL ,
`name` VARCHAR(45) NOT NULL ,
PRIMARY KEY (`users_id`) ,
CONSTRAINT `fk_user_roles_users1`
FOREIGN KEY (`users_id` )
REFERENCES `virtual_trainer`.`users` (`id` )
ON DELETE CASCADE
ON UPDATE CASCADE)
ENGINE = InnoDB
User.java 父实体：
@Entity
@Table(name="users")
public class User implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
@Column(insertable=false, updatable=false)
private int id;
private String name;
private String password;
//bi-directional many-to-one association to UserRole
@OneToMany(mappedBy="user", cascade={CascadeType.ALL})
private Set<UserRole> userRoles;
//getter,setter
UserRole.java 子实体：
@Entity
@Table(name="user_roles")
public class UserRole implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy=GenerationType.AUTO)
@Column(name="users_id")
private int usersId;
@Column(insertable=false, updatable=false)
private String name;
@Column(name="role_name")
private String roleName;
//bi-directional many-to-one association to User
@ManyToOne(cascade={CascadeType.ALL}, fetch=FetchType.LAZY)
@JoinColumn(name="users_id", insertable=false, updatable=false)
private User user;
//getter,setter
RegseterBeanService：（插入数据）
@ManagedBean(name="bean")
@Stateful
@LocalBean
public class RegisterUserService implements RegisterUsersInterface{
@PersistenceContext(unitName="virtual.trainer.entities")
private EntityManager em;
@Transactional
public void addUser() {
// TODO Auto-generated method stub
User u = new User();
u.setName("wojtek");
u.setPassword("jajco");
UserRole ur = new UserRole();
ur.setRoleName("user");
ur.setName("wojtek");
u.getUserRoles().add(ur);
em.persist(u);
em.close();
}
}
这是控制台中的错误：
19:35:06,666 WARNING [javax.enterprise.resource.webcontainer.jsf.lifecycle] (http-localhost-127.0.0.1-8080-1) #{bean.addUser}: java.lang.NullPointerException: javax.faces.FacesException: #{bean.addUser}: java.lang.NullPointerException
at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:118) [jsf-impl-2.1.7-jbossorg-2.jar:]
at javax.faces.component.UICommand.broadcast(UICommand.java:315) [jboss-jsf-api_2.1_spec-2.0.1.Final.jar:2.0.1.Final]
at javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:794) [jboss-jsf-api_2.1_spec-2.0.1.Final.jar:2.0.1.Final]
at javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:1259) [jboss-jsf-api_2.1_spec-2.0.1.Final.jar:2.0.1.Final]
at com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:81) [jsf-impl-2.1.7-jbossorg-2.jar:]
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101) [jsf-impl-2.1.7-jbossorg-2.jar:]
at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:118) [jsf-impl-2.1.7-jbossorg-2.jar:]
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:593) [jboss-jsf-api_2.1_spec-2.0.1.Final.jar:2.0.1.Final]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:329) [jbossweb-7.0.13.Final.jar:]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:248) [jbossweb-7.0.13.Final.jar:]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:275) [jbossweb-7.0.13.Final.jar:]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:161) [jbossweb-7.0.13.Final.jar:]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:397) [jbossweb-7.0.13.Final.jar:]
at org.jboss.as.jpa.interceptor.WebNonTxEmCloserValve.invoke(WebNonTxEmCloserValve.java:50) [jboss-as-jpa-7.1.1.Final.jar:7.1.1.Final]
at org.jboss.as.web.security.SecurityContextAssociationValve.invoke(SecurityContextAssociationValve.java:153) [jboss-as-web-7.1.1.Final.jar:7.1.1.Final]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:155) [jbossweb-7.0.13.Final.jar:]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) [jbossweb-7.0.13.Final.jar:]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) [jbossweb-7.0.13.Final.jar:]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:368) [jbossweb-7.0.13.Final.jar:]
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:877) [jbossweb-7.0.13.Final.jar:]
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:671) [jbossweb-7.0.13.Final.jar:]
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:930) [jbossweb-7.0.13.Final.jar:]
at java.lang.Thread.run(Unknown Source) [rt.jar:1.7.0_01]
Caused by: javax.faces.el.EvaluationException: java.lang.NullPointerException
at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:102) [jboss-jsf-api_2.1_spec-2.0.1.Final.jar:2.0.1.Final]
at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:102) [jsf-impl-2.1.7-jbossorg-2.jar:]
... 22 more
Caused by: java.lang.NullPointerException
at virtual.trainer.bean.RegisterUserService.addUser(RegisterUserService.java:30) [classes:]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) [rt.jar:1.7.0_01]
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) [rt.jar:1.7.0_01]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) [rt.jar:1.7.0_01]
at java.lang.reflect.Method.invoke(Unknown Source) [rt.jar:1.7.0_01]
at org.apache.el.parser.AstValue.invoke(AstValue.java:262) [jbossweb-7.0.13.Final.jar:]
at org.apache.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:278) [jbossweb-7.0.13.Final.jar:]
at com.sun.faces.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:105) [jsf-impl-2.1.7-jbossorg-2.jar:]
at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:88) [jboss-jsf-api_2.1_spec-2.0.1.Final.jar:2.0.1.Final]
... 23 more
19:35:06,724 ERROR [org.apache.catalina.core.ContainerBase.[jboss.web].[default-host].[/VirtualTrainer123].[Faces Servlet]] (http-localhost-127.0.0.1-8080-1) Servlet.service() for servlet Faces Servlet threw exception: java.lang.NullPointerException
at virtual.trainer.bean.RegisterUserService.addUser(RegisterUserService.java:30) [classes:]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) [rt.jar:1.7.0_01]
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) [rt.jar:1.7.0_01]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) [rt.jar:1.7.0_01]
at java.lang.reflect.Method.invoke(Unknown Source) [rt.jar:1.7.0_01]
at org.apache.el.parser.AstValue.invoke(AstValue.java:262) [jbossweb-7.0.13.Final.jar:]
at org.apache.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:278) [jbossweb-7.0.13.Final.jar:]
at com.sun.faces.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:105) [jsf-impl-2.1.7-jbossorg-2.jar:]
at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:88) [jboss-jsf-api_2.1_spec-2.0.1.Final.jar:2.0.1.Final]
at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:102) [jsf-impl-2.1.7-jbossorg-2.jar:]
at javax.faces.component.UICommand.broadcast(UICommand.java:315) [jboss-jsf-api_2.1_spec-2.0.1.Final.jar:2.0.1.Final]
at javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:794) [jboss-jsf-api_2.1_spec-2.0.1.Final.jar:2.0.1.Final]
at javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:1259) [jboss-jsf-api_2.1_spec-2.0.1.Final.jar:2.0.1.Final]
at com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:81) [jsf-impl-2.1.7-jbossorg-2.jar:]
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101) [jsf-impl-2.1.7-jbossorg-2.jar:]
at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:118) [jsf-impl-2.1.7-jbossorg-2.jar:]
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:593) [jboss-jsf-api_2.1_spec-2.0.1.Final.jar:2.0.1.Final]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:329) [jbossweb-7.0.13.Final.jar:]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:248) [jbossweb-7.0.13.Final.jar:]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:275) [jbossweb-7.0.13.Final.jar:]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:161) [jbossweb-7.0.13.Final.jar:]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:397) [jbossweb-7.0.13.Final.jar:]
at org.jboss.as.jpa.interceptor.WebNonTxEmCloserValve.invoke(WebNonTxEmCloserValve.java:50) [jboss-as-jpa-7.1.1.Final.jar:7.1.1.Final]
at org.jboss.as.web.security.SecurityContextAssociationValve.invoke(SecurityContextAssociationValve.java:153) [jboss-as-web-7.1.1.Final.jar:7.1.1.Final]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:155) [jbossweb-7.0.13.Final.jar:]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) [jbossweb-7.0.13.Final.jar:]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) [jbossweb-7.0.13.Final.jar:]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:368) [jbossweb-7.0.13.Final.jar:]
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:877) [jbossweb-7.0.13.Final.jar:]
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:671) [jbossweb-7.0.13.Final.jar:]
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:930) [jbossweb-7.0.13.Final.jar:]
at java.lang.Thread.run(Unknown Source) [rt.jar:1.7.0_01]