com.google.api.server.spi.config.ApiConfigLoader.java Source code

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Here is the source code for com.google.api.server.spi.config.ApiConfigLoader.java

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/*
 * Copyright 2016 Google Inc. All Rights Reserved.
 *
 * 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.api.server.spi.config;

import com.google.api.server.spi.ServiceContext;
import com.google.api.server.spi.TypeLoader;
import com.google.api.server.spi.config.annotationreader.ApiConfigAnnotationReader;
import com.google.api.server.spi.config.model.ApiConfig;
import com.google.common.base.Preconditions;
import com.google.common.base.Predicates;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterables;
import com.google.common.collect.Lists;

import java.util.List;

/**
 * Loader for entire configurations for swarm endpoints.  The current implementation hardcodes two
 * configuration sources.  First annotation configuration is read, then if requested by the config
 * so far, datastore configuration is read, overriding the annotation configurations.
 *
 * @author Eric Orth
 */
public class ApiConfigLoader {

    /**
     * The common API name to use for all internal-mechanism endpoint classes loaded through
     * {@code loadInternalConfiguration}.
     */
    public static final String INTERNAL_API_NAME = "_GoogleCloudEndpointsInternal";

    private final ApiConfig.Factory configFactory;
    private final TypeLoader typeLoader;

    private final ApiConfigAnnotationReader annotationSource;
    // Configuration sources.
    private final ImmutableList<ApiConfigSource> apiConfigSources;

    /**
     * Creates a {@link ApiConfigLoader}.
     *
     * @param configFactory Factory class in charge of creating {@link ApiConfig}s.
     * @param typeLoader Utility class for dealing with types in endpoint config generation.
     * @param annotationSource Config source which reads annotations in endpoint classes.
     * @param apiConfigSources Additional config sources, if any, to operate on endpoints.
     * @throws IllegalArgumentException if {@code apiConfigSources} includes another instance
     *         of ApiConfigAnnotationReader.
     */
    public ApiConfigLoader(ApiConfig.Factory configFactory, TypeLoader typeLoader,
            ApiConfigAnnotationReader annotationSource, ApiConfigSource... apiConfigSources) {
        this.configFactory = Preconditions.checkNotNull(configFactory);
        this.typeLoader = Preconditions.checkNotNull(typeLoader);
        this.annotationSource = Preconditions.checkNotNull(annotationSource);
        this.apiConfigSources = ImmutableList.copyOf(apiConfigSources);
        Preconditions.checkArgument(
                !Iterables.any(this.apiConfigSources, Predicates.instanceOf(ApiConfigAnnotationReader.class)),
                "Multiple instances of the of ApiConfigAnnotationReader were passed in");
    }

    /**
     * Constructor with basic defaults suitable for unit tests.
     */
    public ApiConfigLoader() throws ClassNotFoundException {
        this(new ApiConfig.Factory(), new TypeLoader(ApiConfigLoader.class.getClassLoader()),
                new ApiConfigAnnotationReader());
    }

    public ApiConfig loadConfiguration(ServiceContext serviceContext, Class<?> endpointClass)
            throws ApiConfigException {
        ApiConfig config = configFactory.create(serviceContext, typeLoader, endpointClass);

        annotationSource.loadEndpointClass(serviceContext, endpointClass, config);
        for (ApiConfigSource apiConfigSource : apiConfigSources) {
            apiConfigSource.loadEndpointClass(serviceContext, endpointClass, config);
        }

        annotationSource.loadEndpointMethods(serviceContext, endpointClass,
                config.getApiClassConfig().getMethods());
        for (ApiConfigSource apiConfigSource : apiConfigSources) {
            apiConfigSource.loadEndpointMethods(serviceContext, endpointClass,
                    config.getApiClassConfig().getMethods());
        }

        return config;
    }

    /**
     * Only used for internal-mechanism Apis.  Loads default values for class-wide configuration.
     * Most validation is skipped/ignored as these Apis are not configurable and often follow
     * different rules anyway.
     */
    public ApiConfig loadInternalConfiguration(ServiceContext serviceContext, Class<?> endpointClass)
            throws ApiConfigException {
        ApiConfig config = configFactory.create(serviceContext, typeLoader, endpointClass);
        config.setName(INTERNAL_API_NAME);
        annotationSource.loadEndpointMethods(serviceContext, endpointClass,
                config.getApiClassConfig().getMethods());
        return config;
    }

    public boolean isStaticConfig(ApiConfig config) {
        for (ApiConfigSource apiConfigSource : apiConfigSources) {
            if (!apiConfigSource.isStaticConfig(config)) {
                return false;
            }
        }
        // ApiConfigAnnotationReader is static.
        return true;
    }

    public ApiConfig reloadConfiguration(ServiceContext serviceContext, Class<?> endpointClass, ApiConfig oldConfig)
            throws ApiConfigException {
        ApiConfig config = configFactory.copy(oldConfig);

        // ApiConfigAnnotationReader is static, so ignore.
        List<ApiConfigSource> apiMethodConfigSources = Lists.newArrayList();
        for (ApiConfigSource apiConfigSource : apiConfigSources) {
            if (!apiConfigSource.isStaticConfig(config)) {
                apiConfigSource.loadEndpointClass(serviceContext, endpointClass, config);
                apiMethodConfigSources.add(apiConfigSource);
            }
        }

        for (ApiConfigSource apiConfigSource : apiMethodConfigSources) {
            apiConfigSource.loadEndpointMethods(serviceContext, endpointClass,
                    config.getApiClassConfig().getMethods());
        }

        return config;
    }
}