是否可以从 POJO 访问 EJB?我试过了
@EJB MyClass obj
但这不起作用。
如果您使用可以将任何东西变成托管组件的 JSR-199(Java 上下文和依赖注入),则注入是可能的。因此,如果您的 POJO 是 CDI 托管 bean,您可以这样做:
@Inject MyEjb service
如果没有 CDI,您将不得不进行查找。
可以从 POJO 访问 EJB。您必须为此进行 JNDI 查找。
通常,依赖注入,就像您现在尝试的那样,仅在托管环境中有效 - 在 Servlet 和 EJB 中。
您正在使用的注释要求您的基础设施知道使用该注释进入该字段。您可能需要使用包装类或手动执行,这实际上取决于您的设置。
我会查看@Inject,因为这听起来像是我正在寻找的解决方案,但是当我尝试它时它不起作用。我确定我错过了一些东西,但我尝试了一段时间并没有得到任何结果。紧迫的最后期限使我实施了以下帮助程序类,我认为如果他们有类似的问题,我会发布给任何人使用。
感谢您的回复。
public class InjectionHelper {
private static final String DEPENDENCY_SEPERATOR = "/";
private static Logger logger = Logger.getLogger(InjectionHelper.class);
private static Map<Class<?>, Object> dependencies = null;
private static List<Object> dependenciesList = null;
private static Context baseContext = null;
/**
* Search for the dependency of the specified class.
*/
public static final <T> T injectDependency(Class<T> dependencyClass){
//initialise the dependencies
if(dependenciesList == null){
dependenciesList = new ArrayList<Object>();
dependencies = new HashMap<Class<?>, Object>();
try{
baseContext = new InitialContext();
populateDependencies(baseContext, new Stack<String>());
}
catch(Exception e){
logger.error("Error populating dependencies", e);
}
}
//We have seen this dependency before and can get it from the map
if(dependencies.containsKey(dependencyClass)){
return (T)dependencies.get(dependencyClass);
}
//Not seen the dependency so we must try and find it in the list
for(Object o: dependenciesList){
if(dependencyClass.isInstance(o)){
dependencies.put(dependencyClass, o);
return (T)o;
}
}
//We don't have the dependency
return null;
}
/**
* Traverse the InitialContext and extract all dependencies and store them in the map keyed by their class.
*
* @param lookupNameStack
*/
private static final void populateDependencies(Context ctx, Stack<String> lookupNameStack) {
try {
NamingEnumeration<Binding> list = ctx.listBindings("");
while (list.hasMore()) {
Binding item = list.next();
//Get the name and object for the binding
String lookupName = item.getName();
Object objectBinding = item.getObject();
//If a JavaGlobalJndiNamingObjectProxy this is a dependency we want to store
if(objectBinding instanceof JavaGlobalJndiNamingObjectProxy){
//Based on our current position in the tree get the string representation
Iterator<String> lookupNameIterator = lookupNameStack.iterator();
String lookupPrefix = "";
while(lookupNameIterator.hasNext()){
lookupPrefix += lookupNameIterator.next();
}
//lookup the object and store in the map
try{
Object obj = baseContext.lookup(lookupPrefix+lookupName);
dependenciesList.add(obj);
logger.info("Found [" + obj.getClass() + "] Lookup [" + lookupPrefix + lookupName +"]");
}
catch(Exception e){
logger.info("Failed to find Lookup [" + lookupPrefix+lookupName + "]", e);
}
}
lookupNameStack.push(lookupName+DEPENDENCY_SEPERATOR);
//If we find a context we can explore that branch
if (objectBinding instanceof Context) {
populateDependencies((Context) objectBinding, lookupNameStack);
}
//Now we have traversed the branch we need to remove the last leaf
lookupNameStack.pop();
}
} catch (NamingException ex) {
logger.info("JNDI failure: ", ex);
}
}
}