JavaScriptBridge.java
/*
* Copyright (C) 2015 The Android Open Source Project
*
* 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 androidx.test.espresso.web.bridge;
import static androidx.test.internal.util.Checks.checkState;
import android.os.Build;
import android.os.Looper;
import android.util.Log;
import androidx.concurrent.futures.ResolvableFuture;
import java.util.concurrent.atomic.AtomicInteger;
/**
* Provides a gateway for Java and Javascript code to communicate to eachother.
*/
public final class JavaScriptBridge {
private static final AtomicInteger tokenGenerator = new AtomicInteger(0);
static final String TAG = "JS_BRIDGE";
static final String JS_BRIDGE_NAME = "__g_wd_jsb";
private static volatile boolean initialized = false;
private static JavaScriptBoundBridge boundBridge;
/**
* Creates a Conduit object which allows Java to wrap Javascript code within a handler that will
* forward evaluation results back to the Java process.
*
* <p>Conduits can be used for only 1 evaluation. Creating new ones is relatively cheap.
*/
public static Conduit makeConduit() {
checkState(initialized, "Install bridge not called!");
checkState(null != boundBridge, "Bridge not configured; chromium webviews do not need bridge");
Conduit conduit =
new Conduit.Builder()
.withBridgeName(JS_BRIDGE_NAME)
.withToken(String.valueOf(tokenGenerator.incrementAndGet()))
.withSuccessMethod("setResult")
.withErrorMethod("setError")
.withJsResult(ResolvableFuture.<String>create())
.build();
boundBridge.addConduit(conduit);
return conduit;
}
/**
* Sets up Java / Javascript bridging on every WebView in the app.
*
* <p>This method must be called very early (eg: before webviews are loaded in your app).
* GoogleInstrumentation invokes this method if this library is present on your classpath.
*
* <p>This method must be called from the main thread. It'll return immedately if the bridge
* is already installed.
*/
public static void installBridge() {
checkState(Looper.getMainLooper() == Looper.myLooper(), "Must be on main thread!");
if (initialized) {
return;
}
try {
if (Build.VERSION.SDK_INT < 19) {
boundBridge = new AndroidJavaScriptBridgeInstaller().install();
}
} catch (JavaScriptBridgeInstallException e) {
Log.e(TAG, "Unable to bridge web views!", e);
}
initialized = true;
}
}