com.google.inject.internal.DelegatingInvocationHandler.java Source code

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Here is the source code for com.google.inject.internal.DelegatingInvocationHandler.java

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/*
 * 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.internal;

import com.google.common.base.Preconditions;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

class DelegatingInvocationHandler<T> implements InvocationHandler {

    private volatile boolean initialized;

    private T delegate;

    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        try {
            // checking volatile field for synchronization
            Preconditions.checkState(initialized,
                    "This is a proxy used to support" + " circular references. The object we're"
                            + " proxying is not constructed yet. Please wait until after"
                            + " injection has completed to use this object.");
            Preconditions.checkNotNull(delegate,
                    "This is a proxy used to support" + " circular references. The object we're "
                            + " proxying is initialized to null." + " No methods can be called.");

            // TODO: method.setAccessible(true); ?
            // this would fix visibility errors when we proxy a
            // non-public interface.
            return method.invoke(delegate, args);
        } catch (IllegalAccessException e) {
            throw new RuntimeException(e);
        } catch (IllegalArgumentException e) {
            throw new RuntimeException(e);
        } catch (InvocationTargetException e) {
            throw e.getTargetException();
        }
    }

    void setDelegate(T delegate) {
        this.delegate = delegate;
        initialized = true;
    }
}