io.undertow.predicate.ExistsPredicate Maven / Gradle / Ivy
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* Copyright 2014 Red Hat, Inc., and individual contributors
* as indicated by the @author tags.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package io.undertow.predicate;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;
import io.undertow.attribute.ExchangeAttribute;
import io.undertow.server.HttpServerExchange;
/**
* Returns true if the given attribute is not null and not an empty string
*
* @author Stuart Douglas
*/
public class ExistsPredicate implements Predicate {
private final ExchangeAttribute attribute;
ExistsPredicate(final ExchangeAttribute attribute) {
this.attribute = attribute;
}
@Override
public boolean resolve(final HttpServerExchange value) {
final String att = attribute.readAttribute(value);
if(att == null) {
return false;
}
return !att.isEmpty();
}
public static class Builder implements PredicateBuilder {
@Override
public String name() {
return "exists";
}
@Override
public Map> parameters() {
final Map> params = new HashMap<>();
params.put("value", ExchangeAttribute.class);
return params;
}
@Override
public Set requiredParameters() {
return Collections.singleton("value");
}
@Override
public String defaultParameter() {
return "value";
}
@Override
public Predicate build(final Map config) {
ExchangeAttribute value = (ExchangeAttribute) config.get("value");
return new ExistsPredicate(value);
}
}
}