Jakarta ee 从普通类访问EJB
我使用Facade模式来访问数据库实体。我编写了一个包装器来访问FacadeEJB,如下所示。正如我从异常中了解到的,EJB似乎还没有初始化。在论坛上阅读了关于异常的内容后,我明白应该在@PostConstruct notation解决这个问题,但仍然没有任何帮助。也许我用错了,任何指点都将不胜感激Jakarta ee 从普通类访问EJB,jakarta-ee,ejb,Jakarta Ee,Ejb,我使用Facade模式来访问数据库实体。我编写了一个包装器来访问FacadeEJB,如下所示。正如我从异常中了解到的,EJB似乎还没有初始化。在论坛上阅读了关于异常的内容后,我明白应该在@PostConstruct notation解决这个问题,但仍然没有任何帮助。也许我用错了,任何指点都将不胜感激 public class PatientSearchHelper { @EJB private PatientFacade patientFacade; private f
public class PatientSearchHelper {
@EJB
private PatientFacade patientFacade;
private final Patient patient;
private ResponseHeader respHeader;
private SearchResponse searchResponse;
private List<Patient> resultSet;
public PatientSearchHelper (Patient patient) {
this.patient = patient;
}
@PostConstruct
public void initialize() {
this.respHeader = new ResponseHeader();
this.searchResponse = new SearchResponse();
}
public SearchResponse getById() {
System.out.println("Patient Id: " + patient.getPatientid());
//patientFacade = (PatientFacade) new InitialContext().lookup("java:global/Aarogayam2/PatientFacade!common.facades.PatientFacade");
resultSet = patientFacade.findById(patient.getPatientid());
if (resultSet.size() > 0) {
formatFoundResponse();
} else {
formatNotFoundResponse();
}
return searchResponse;
}
private void formatFoundResponse() {
searchResponse.setPayload(resultSet);
respHeader.setSuccess(true);
searchResponse.setHeader(respHeader);
}
private void formatNotFoundResponse() {
respHeader.setSuccess(false);
respHeader.setMessage("No Patient found");
searchResponse.setHeader(respHeader);
searchResponse.setPayload(null);
}
}
例外情况
SEVERE: java.lang.NullPointerException
at common.helpers.PatientSearchHelper.getById(PatientSearchHelper.java:48)
at common.services.PatientService.getById(PatientService.java:57)
at common.services.PatientService$Proxy$_$$_WeldSubclass.getById(Unknown Source)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
如果您想创建容器来创建EJB实例,则需要使用JNDI或@EJB注释进行访问。为了使上述代码正常工作,请使PatientSearchHelper类成为EJB,并在访问任何方法之前在客户端代码中使用@EJB来获取实例。您可以使用CDI bean,使用
@Named
注释,而不是创建新的无状态EJB来包装另一个实例(如果您的方法不需要事务支持)
@Named
public class PatientSearchHelper {
@EJB
private PatientFacade patientFacade;
private final Patient patient;
private ResponseHeader respHeader;
private SearchResponse searchResponse;
private List<Patient> resultSet;
...
@Named
公共类PatientSearchHelper{
@EJB
私人诊所;
私人最终病人;
私人负责人;
私人搜索响应搜索响应;
私有列表结果集;
...
另一种方法是使用以下通用代码在Beanmanger中查找bean,如果找到,只需返回所需类的实例:
private static <T> T lookUpClassInBeanManager(Class<T> clazz) {
BeanManager bm = CDI.current().getBeanManager();
Bean<T> bean = (Bean<T>) bm.getBeans(clazz).iterator().next();
CreationalContext<T> ctx = bm.createCreationalContext(bean);
return (T) bm.getReference(bean, clazz, ctx);
}
public static PatientFacade lookUpPatientFacade() {
return lookUpClassInBeanManager(PatientFacade.class);
}
private static T lookUpClassInBeanManager(类clazz){
BeanManager bm=CDI.current().getBeanManager();
Bean=(Bean)bm.getBeans(clazz.iterator().next();
CreationalContext ctx=bm.createCreationalContext(bean);
return(T)bm.getReference(bean、clazz、ctx);
}
公共静态PatientFacade lookUpPatientFacade(){
返回lookUpClassInBeanManager(PatientFacade.class);
}
通过这种方式,您可以始终获得EJB类的现有实例。例如,在
@FacesConverter
或任何其他不能声明为@Stateless
的类中,这非常方便。感谢IndowKnight!!将PatientSearchHelper设置为无状态解决了我的问题。
private static <T> T lookUpClassInBeanManager(Class<T> clazz) {
BeanManager bm = CDI.current().getBeanManager();
Bean<T> bean = (Bean<T>) bm.getBeans(clazz).iterator().next();
CreationalContext<T> ctx = bm.createCreationalContext(bean);
return (T) bm.getReference(bean, clazz, ctx);
}
public static PatientFacade lookUpPatientFacade() {
return lookUpClassInBeanManager(PatientFacade.class);
}