com.google.inject.spi.MembersInjectorLookup Maven / Gradle / Ivy
/**
* Copyright (C) 2009 Google Inc.
*
* 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 com.google.inject.spi;
import com.google.inject.Binder;
import com.google.inject.MembersInjector;
import com.google.inject.TypeLiteral;
import static com.google.inject.internal.util.Preconditions.checkNotNull;
import static com.google.inject.internal.util.Preconditions.checkState;
/**
* A lookup of the members injector for a type. Lookups are created explicitly in a module using
* {@link com.google.inject.Binder#getMembersInjector(Class) getMembersInjector()} statements:
*
* MembersInjector<PaymentService> membersInjector
* = getMembersInjector(PaymentService.class);
*
* @author [email protected] (Bob Lee)
* @since 2.0
*/
public final class MembersInjectorLookup implements Element {
private final Object source;
private final TypeLiteral type;
private MembersInjector delegate;
public MembersInjectorLookup(Object source, TypeLiteral type) {
this.source = checkNotNull(source, "source");
this.type = checkNotNull(type, "type");
}
public Object getSource() {
return source;
}
/**
* Gets the type containing the members to be injected.
*/
public TypeLiteral getType() {
return type;
}
public T acceptVisitor(ElementVisitor visitor) {
return visitor.visit(this);
}
/**
* Sets the actual members injector.
*
* @throws IllegalStateException if the delegate is already set
*/
public void initializeDelegate(MembersInjector delegate) {
checkState(this.delegate == null, "delegate already initialized");
this.delegate = checkNotNull(delegate, "delegate");
}
public void applyTo(Binder binder) {
initializeDelegate(binder.withSource(getSource()).getMembersInjector(type));
}
/**
* Returns the delegate members injector, or {@code null} if it has not yet been initialized.
* The delegate will be initialized when this element is processed, or otherwise used to create
* an injector.
*/
public MembersInjector getDelegate() {
return delegate;
}
/**
* Returns the looked up members injector. The result is not valid until this lookup has been
* initialized, which usually happens when the injector is created. The members injector will
* throw an {@code IllegalStateException} if you try to use it beforehand.
*/
public MembersInjector getMembersInjector() {
return new MembersInjector() {
public void injectMembers(T instance) {
checkState(delegate != null,
"This MembersInjector cannot be used until the Injector has been created.");
delegate.injectMembers(instance);
}
@Override public String toString() {
return "MembersInjector<" + type + ">";
}
};
}
}