[Cronet] Create Builders, rename UrlRequestContext to CronetEngine

components/cronet/android/java/src/org/chromium/net/UrlRequestContext.java

-// Copyright 2014 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-package org.chromium.net;
-
-import android.content.Context;
-import android.util.Log;
-
-import java.lang.reflect.Constructor;
-import java.util.concurrent.Executor;
-
-/**
- * A context for {@link UrlRequest}'s, which uses the best HTTP stack
- * available on the current platform.
- */
-public abstract class UrlRequestContext {
-    private static final String TAG = "UrlRequestFactory";
-    private static final String CRONET_URL_REQUEST_CONTEXT =
-            "org.chromium.net.CronetUrlRequestContext";
-
-    /**
-     * Creates a {@link UrlRequest} object. All callbacks will
-     * be called on {@code executor}'s thread. {@code executor} must not run
-     * tasks on the current thread to prevent blocking networking operations
-     * and causing exceptions during shutdown. Request is given medium priority,
-     * see {@link UrlRequest#REQUEST_PRIORITY_MEDIUM}. To specify other
-     * priorities see {@link #createRequest(String, UrlRequestListener,
-     * Executor, int priority)}.
-     *
-     * @param url {@link java.net.URL} for the request.
-     * @param listener callback class that gets called on different events.
-     * @param executor {@link Executor} on which all callbacks will be called.
-     * @return new request.
-     */
-    public abstract UrlRequest createRequest(String url,
-            UrlRequestListener listener, Executor executor);
-
-    /**
-     * Creates a {@link UrlRequest} object. All callbacks will
-     * be called on {@code executor}'s thread. {@code executor} must not run
-     * tasks on the current thread to prevent blocking networking operations
-     * and causing exceptions during shutdown.
-     *
-     * @param url {@link java.net.URL} for the request.
-     * @param listener callback class that gets called on different events.
-     * @param executor {@link Executor} on which all callbacks will be called.
-     * @param priority priority of the request which should be one of the
-     *         {@link UrlRequest#REQUEST_PRIORITY_IDLE REQUEST_PRIORITY_*}
-     *         values.
-     * @return new request.
-     */
-    public abstract UrlRequest createRequest(String url,
-            UrlRequestListener listener, Executor executor, int priority);
-
-    /**
-     * @return {@code true} if the context is enabled.
-     */
-    abstract boolean isEnabled();
-
-    /**
-     * @return a human-readable version string of the context.
-     */
-    public abstract String getVersionString();
-
-    /**
-     * Shuts down the {@link UrlRequestContext} if there are no active requests,
-     * otherwise throws an exception.
-     *
-     * Cannot be called on network thread - the thread Cronet calls into
-     * Executor on (which is different from the thread the Executor invokes
-     * callbacks on). May block until all the {@code UrlRequestContext}'s
-     * resources have been cleaned up.
-     */
-    public abstract void shutdown();
-
-    /**
-     * Starts NetLog logging to a file. The NetLog is useful for debugging.
-     * The file can be viewed using a Chrome browser navigated to
-     * chrome://net-internals/#import
-     * @param fileName the complete file path. It must not be empty. If the file
-     *            exists, it is truncated before starting. If actively logging,
-     *            this method is ignored.
-     * @param logAll {@code true} to include basic events, user cookies,
-     *            credentials and all transferred bytes in the log.
-     *            {@code false} to just include basic events.
-     */
-    public abstract void startNetLogToFile(String fileName, boolean logAll);
-
-    /**
-     * Stops NetLog logging and flushes file to disk. If a logging session is
-     * not in progress, this call is ignored.
-     */
-    public abstract void stopNetLog();
-
-    /**
-     * Creates a {@link UrlRequestContext} with the given
-     * {@link UrlRequestContextConfig}.
-     * @param context Android {@link Context}.
-     * @param config context configuration.
-     */
-    public static UrlRequestContext createContext(Context context,
-            UrlRequestContextConfig config) {
-        UrlRequestContext urlRequestContext = null;
-        if (config.userAgent().isEmpty()) {
-            config.setUserAgent(UserAgent.from(context));
-        }
-        if (!config.legacyMode()) {
-            urlRequestContext = createCronetContext(context, config);
-        }
-        if (urlRequestContext == null) {
-            // TODO(mef): Fallback to stub implementation. Once stub
-            // implementation is available merge with createCronetFactory.
-            urlRequestContext = createCronetContext(context, config);
-        }
-        Log.i(TAG, "Using network stack: "
-                + urlRequestContext.getVersionString());
-        return urlRequestContext;
-    }
-
-    private static UrlRequestContext createCronetContext(Context context,
-            UrlRequestContextConfig config) {
-        UrlRequestContext urlRequestContext = null;
-        try {
-            Class<? extends UrlRequestContext> contextClass =
-                    UrlRequestContext.class.getClassLoader()
-                            .loadClass(CRONET_URL_REQUEST_CONTEXT)
-                            .asSubclass(UrlRequestContext.class);
-            Constructor<? extends UrlRequestContext> constructor =
-                    contextClass.getConstructor(
-                            Context.class, UrlRequestContextConfig.class);
-            UrlRequestContext cronetContext =
-                    constructor.newInstance(context, config);
-            if (cronetContext.isEnabled()) {
-                urlRequestContext = cronetContext;
-            }
-        } catch (ClassNotFoundException e) {
-            // Leave as null.
-        } catch (Exception e) {
-            throw new IllegalStateException(
-                    "Cannot instantiate: " + CRONET_URL_REQUEST_CONTEXT,
-                    e);
-        }
-        return urlRequestContext;
-    }
-}