I have a Provider for a MongoDB connection. I would like to store the list
of nodes and access credentials in a properties file external to the module
so they're easy to updated. I have this working in one way, but failing in
another and I'm not sure why.
First, this is how I would like to do it, but the values mongoNode1 and
mongoNode2 are never set. I have stepped through my code and I know that
those values are loaded from the properties file and available when the
module loads, but they come through as null in this code:
public class MongoConnectionProvider implements Provider<Mongo> {
@Inject @Named("mongoNode1") private String mongoNode1;
@Inject @Named("mongoNode2") private String mongoNode2;
List<ServerAddress> mongoNodesDBAddresses;
MongoOptions options;
public MongoConnectionProvider() {
try {
// create addresses for each replicaset node
List<String> mongoNodes = getMongoNodes();
mongoNodesDBAddresses = new
ArrayList<ServerAddress>(mongoNodes.size());
for (String mongoNode : mongoNodes) {
mongoNodesDBAddresses.add(new DBAddress(mongoNode));
}
} catch (Exception e) {
throw new RuntimeException("Error initializing mongo db", e);
}
options = new MongoOptions();
options.setReadPreference(ReadPreference.nearest()); //
http://stackoverflow.com/questions/6520439/how-to-configure-mongodb-java-driver-mongooptions-for-production-use
}
@Override
public Mongo get() {
final Mongo mongo = new Mongo(mongoNodesDBAddresses, options);
return mongo;
}
protected List<String> getMongoNodes() {
List<String> mongoNodes = new ArrayList<String>();
mongoNodes.add(mongoNode1);
mongoNodes.add(mongoNode2);
return mongoNodes;
}
}
An option that does get me the properties is less than ideal since I have a
handful of subclasses that break or require duplicate code when the
constructor changes. Here's the code that works:
public class MongoConnectionProvider implements Provider<Mongo> {
private String mongoNode1;
private String mongoNode2;
List<ServerAddress> mongoNodesDBAddresses;
MongoOptions options;
@Inject
public MongoConnectionProvider(@Named("mongoNode1") String mongoNode1,
@Named("mongoNode2") String mongoNode2) {
this.mongoNode1 = mongoNode1;
this.mongoNode2 = mongoNode2;
try {
// create addresses for each replicaset node
List<String> mongoNodes = getMongoNodes();
mongoNodesDBAddresses = new
ArrayList<ServerAddress>(mongoNodes.size());
for (String mongoNode : mongoNodes) {
mongoNodesDBAddresses.add(new DBAddress(mongoNode));
}
} catch (Exception e) {
throw new RuntimeException("Error initializing mongo db", e);
}
options = new MongoOptions();
options.setReadPreference(ReadPreference.nearest()); //
http://stackoverflow.com/questions/6520439/how-to-configure-mongodb-java-driver-mongooptions-for-production-use
}
@Override
public Mongo get() {
final Mongo mongo = new Mongo(mongoNodesDBAddresses, options);
return mongo;
}
protected List<String> getMongoNodes() {
List<String> mongoNodes = new ArrayList<String>();
mongoNodes.add(mongoNode1);
mongoNodes.add(mongoNode2);
return mongoNodes;
}
}
Why am I able to inject these values into the constructor, but not the
class? I would like to make this second case work if possible.
By the way, I also tried injecting them directly into the function
getMongoNodes, but that produces the error "annotation type not applicable
to this kind of declaration".
protected List<String> getMongoNodes() {
@Inject @Named("mongoNode1") String mongoNode1;
@Inject @Named("mongoNode2") String mongoNode2;
List<String> mongoNodes = new ArrayList<String>();
mongoNodes.add(mongoNode1);
mongoNodes.add(mongoNode2);
return mongoNodes;
}
Any ideas how I can get these named properties into my provider without
including them in the constructor?
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