135 lines
3.5 KiB
Java
135 lines
3.5 KiB
Java
package org.gcube.common.clients.queries;
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import java.util.ArrayList;
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import java.util.HashMap;
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import java.util.List;
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import java.util.Map;
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import org.gcube.common.clients.delegates.ProxyPlugin;
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import org.gcube.common.clients.exceptions.DiscoveryException;
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/**
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* Partial implementation of {@link Query}s.
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*
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* @author Fabio Simeoni
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*
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* @param <A> the type of service addresses
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* @param <R> the type of query results
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*/
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public abstract class AbstractQuery<A,R> implements Query<A> {
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private final ProxyPlugin<A,?,?> plugin;
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private final Map<String,String> conditions = new HashMap<String, String>();
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//default matcher does not filter out any result
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private ResultMatcher<R> matcher = new ResultMatcher<R>() {
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@Override public boolean match(R doc) {
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return true;
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}
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};
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/**
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* Creates an instance with a {@link ISFacade}, a {@link PluginAdapter}, and a type of IS queries
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* @param facade the facade
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* @param plugin the plugin
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* @param queryClass the query type
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*/
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protected AbstractQuery(ProxyPlugin<A,?,?> plugin) {
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this.plugin = plugin;
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}
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/**
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* Adds a condition to the query.
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* @param property an expression that identifies a property of service endpoints
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* @param value the value of the property
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*/
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public void addCondition(String property, String value) {
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this.conditions.put(property,value);
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}
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/**
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* Sets an {@link ResultMatcher} for the query.
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* @param matcher the matcher.
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*/
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public void setMatcher(ResultMatcher<R> matcher) {
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this.matcher=matcher;
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}
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@Override
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public final List<A> fire() throws DiscoveryException {
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//delegate actual execution to subclass-specific mechanisms
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List<R> results = fire(conditions);
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//from results to addresses
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List<A> endpoints = new ArrayList<A>();
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for (R result : results)
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try {
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if (matcher.match(result)) //should we include this? ask matcher
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endpoints.add(address(result)); //extract address
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}
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catch(IllegalArgumentException e) {
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//skip result, this is just a signal from subclasses
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};
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return endpoints;
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}
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/**
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* Executes the query through implementation-specific means.
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* @param conditions the conditions to apply on the query prior to its execution
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* @return the query results
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* @throws DiscoveryException if the query could not be executed
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*/
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protected abstract List<R> fire(Map<String,String> conditions) throws DiscoveryException;
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/**
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* Returns an endpoint address from a query result.
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* @param result the result
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* @return the address
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* @throws IllegalArgumentException if an address cannot be derived from the result
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*/
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protected abstract A address(R result) throws IllegalArgumentException;
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/**
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* Returns the {@link ProxyPlugin}.
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* @return the plugin
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*/
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protected ProxyPlugin<A,?,?> plugin() {
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return plugin;
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}
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//queries are value objects based on properties
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@Override
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public final boolean equals(Object obj) {
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if (this == obj)
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return true;
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if (obj == null)
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return false;
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if (getClass() != obj.getClass())
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return false;
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AbstractQuery<?,?> other = (AbstractQuery<?,?>) obj;
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if (conditions == null) {
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if (other.conditions != null)
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return false;
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} else if (!conditions.equals(other.conditions))
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return false;
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return true;
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}
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@Override
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public final int hashCode() {
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final int prime = 31;
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int result = 1;
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result = prime * result + ((conditions == null) ? 0 : conditions.hashCode());
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return result;
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}
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@Override
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public final String toString() {
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return conditions.toString();
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}
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}
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