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継続的なクエリーの例
以下のコード例は、組み込みキャッシュを使用した単純な継続的なクエリーを示しています。
この例では、年齢が 21 歳未満の Person インスタンスがキャッシュに追加されると、リスナーは通知を受け取ります。これらの Person インスタンスも "matches" マップに追加されます。エントリーがキャッシュから削除されるか、その年齢が 21 以上になると、"matches" マップから削除されます。
継続的クエリーの登録
import org.infinispan.query.api.continuous.ContinuousQuery;
import org.infinispan.query.api.continuous.ContinuousQueryListener;
import org.infinispan.query.Search;
import org.infinispan.query.dsl.QueryFactory;
import org.infinispan.query.dsl.Query;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
[...]
// We have a cache of Person objects.
Cache<Integer, Person> cache = ...
// Create a ContinuousQuery instance on the cache.
ContinuousQuery<Integer, Person> continuousQuery = Search.getContinuousQuery(cache);
// Define a query.
// In this example, we search for Person instances under 21 years of age.
Query query = cache.query("FROM Person p WHERE p.age < 21");
final Map<Integer, Person> matches = new ConcurrentHashMap<Integer, Person>();
// Define the ContinuousQueryListener.
ContinuousQueryListener<Integer, Person> listener = new ContinuousQueryListener<Integer, Person>() {
@Override
public void resultJoining(Integer key, Person value) {
matches.put(key, value);
}
@Override
public void resultUpdated(Integer key, Person value) {
// We do not process this event.
}
@Override
public void resultLeaving(Integer key) {
matches.remove(key);
}
};
// Add the listener and the query.
continuousQuery.addContinuousQueryListener(query, listener);
[...]
// Remove the listener to stop receiving notifications.
continuousQuery.removeContinuousQueryListener(listener);
import org.infinispan.query.api.continuous.ContinuousQuery;
import org.infinispan.query.api.continuous.ContinuousQueryListener;
import org.infinispan.query.Search;
import org.infinispan.query.dsl.QueryFactory;
import org.infinispan.query.dsl.Query;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
[...]
// We have a cache of Person objects.
Cache<Integer, Person> cache = ...
// Create a ContinuousQuery instance on the cache.
ContinuousQuery<Integer, Person> continuousQuery = Search.getContinuousQuery(cache);
// Define a query.
// In this example, we search for Person instances under 21 years of age.
Query query = cache.query("FROM Person p WHERE p.age < 21");
final Map<Integer, Person> matches = new ConcurrentHashMap<Integer, Person>();
// Define the ContinuousQueryListener.
ContinuousQueryListener<Integer, Person> listener = new ContinuousQueryListener<Integer, Person>() {
@Override
public void resultJoining(Integer key, Person value) {
matches.put(key, value);
}
@Override
public void resultUpdated(Integer key, Person value) {
// We do not process this event.
}
@Override
public void resultLeaving(Integer key) {
matches.remove(key);
}
};
// Add the listener and the query.
continuousQuery.addContinuousQueryListener(query, listener);
[...]
// Remove the listener to stop receiving notifications.
continuousQuery.removeContinuousQueryListener(listener);
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