java - 为什么@PostConstruct 不起作用？

Question

我有一个简单的 EJB，当我通过我的独立客户端运行它时，一切都运行良好， 但是一旦我添加了拦截器，EJB 中的@PostConstruct 就会停止工作:

包拦截器；

public class LogInterceptor {

@PostConstruct
public void init(InvocationContext context) {
    System.out.println(new Date().toString() +" Entered interceptor");
}

@PreDestroy
public void aboutToBeRemoved(InvocationContext context) {
    System.out.println(new Date().toString() + " Leaving interceptor");
}

@AroundInvoke
public Object gettingToBusiness(InvocationContext context) {

    String methodName = context.getMethod().getName();
    System.out.println("The method name is: " +methodName);

    if (methodName.equals("add")) {

    }
    try {
        return context.proceed();
    } catch (Exception e) {
        e.printStackTrace();
    }
    return null;
}


}

我的测试客户端:

public class Test {

public static void main(String[] args){
    InitialContext ctx=getInitialContext();
    ListRemote stub=null;
    try {
        stub = (ListRemote)ctx.lookup("ejb:/Lab12/ListEJB!interceptor.ListRemote?stateful");
    } catch (NamingException e) {
        System.out.println("Lookup Failed");
        e.printStackTrace();
    }
    System.out.println("Adding data");
    stub.add("Hello");
    stub.add("-");
    stub.add("World");
    stub.add("!!!");
    System.out.println("Getting data :");
    for(Object o:stub.getAll()){
        System.out.print(o+" ");
    }
    System.out.println("Removing '-' element");
    stub.remove(1);
    System.out.println("Getting data again:");
    for(Object o:stub.getAll()){
        System.out.print(o+" ");
    }
    stub.destroy();
}

public static InitialContext getInitialContext(){
    Properties properties = new Properties();
    properties.put(Context.URL_PKG_PREFIXES , "org.jboss.ejb.client.naming");
            try {
        return new InitialContext(properties);
    } catch (NamingException e) {
        System.out.println("Cannot generate InitialContext");
        e.printStackTrace();
    }
    return null;
}
}

我的 EJB:

@Stateful(name="ListEJB")
@Interceptors({LogInterceptor.class})
public class ListBean implements ListRemote{
private ArrayList<Serializable> list;

@PostConstruct
public void init(){
    System.out.println("In it init ---------------------------------------------------");
    list=new ArrayList<Serializable>();
}
public void add(Serializable object){
    System.out.println("Currently in the list is: " +list);

    System.out.println("The object is: " +object);
    list.add(object);
    System.out.println("Added");
}
public Serializable get(int index){
    return list.get(index);
}
public void remove(int index){
    list.remove(index);
}
public Object[] getAll(){
    return list.toArray();
}
@Remove
public void destroy(){
    list=null;
}

}

为什么它会禁用我的 EJB @PostConstruct？

Answer 1

在这段代码中:

@PostConstruct
public void init(InvocationContext context) {
    System.out.println(new Date().toString() +" Entered interceptor");
}

您正在拦截原始 EJB 的 PostConstruct 并且不让它通过。如果要将其传递给目标 EJB，则需要调用 proceed:

@PostConstruct
public void init(InvocationContext context) {
    System.out.println(new Date().toString() +" Entered interceptor");
    context.proceed();
}

同样适用于您的 PreDestroy。基本上它适用于所有被拦截的方法。查看EJB3 specification , 第 12.5 节(第 308 页):

Interceptor methods must always call InvocationContext.proceed() or no subsequent interceptor methods or bean business method or lifecycle callback methods will be invoked.