Add Java integration for the Google Wallet API

java/app/build.gradle.kts

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+plugins {
+    id("com.android.application")
+}
+
+android {
+    namespace = "com.google.android.gms.samples.wallet"
+    compileSdk = 34
+
+    defaultConfig {
+        applicationId = "com.google.android.gms.samples.wallet"
+        minSdk = 26
+        targetSdk = 34
+        versionCode = 1
+        versionName = "1.0"
+
+        testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
+        vectorDrawables {
+            useSupportLibrary = true
+        }
+    }
+
+    buildTypes {
+        release {
+            isMinifyEnabled = false
+            proguardFiles(
+                getDefaultProguardFile("proguard-android-optimize.txt"),
+                "proguard-rules.pro"
+            )
+        }
+    }
+
+    compileOptions {
+        sourceCompatibility = JavaVersion.VERSION_1_8
+        targetCompatibility = JavaVersion.VERSION_1_8
+    }
+
+    viewBinding {
+        enable = true
+    }
+
+    packaging {
+        resources {
+            excludes += "/META-INF/{AL2.0,LGPL2.1}"
+        }
+    }
+}
+
+dependencies {
+
+    // Google Wallet dependencies
+    implementation("com.google.android.gms:play-services-pay:16.4.0")
+
+    implementation("androidx.appcompat:appcompat:1.6.1")
+
+    val lifecycle_version = "2.5.1"
+    implementation("androidx.lifecycle:lifecycle-viewmodel-ktx:$lifecycle_version")
+    implementation("androidx.lifecycle:lifecycle-livedata-ktx:$lifecycle_version")
+
+    testImplementation("junit:junit:4.13.2")
+    androidTestImplementation("androidx.test.ext:junit:1.1.5")
+    androidTestImplementation("androidx.test.espresso:espresso-core:3.5.1")
+    androidTestImplementation("androidx.compose.ui:ui-test-junit4:1.5.4")
+}

java/app/proguard-rules.pro

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+# Add project specific ProGuard rules here.
+# You can control the set of applied configuration files using the
+# proguardFiles setting in build.gradle.
+#
+# For more details, see
+#   http://developer.android.com/guide/developing/tools/proguard.html
+
+# If your project uses WebView with JS, uncomment the following
+# and specify the fully qualified class name to the JavaScript interface
+# class:
+#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
+#   public *;
+#}
+
+# Uncomment this to preserve the line number information for
+# debugging stack traces.
+#-keepattributes SourceFile,LineNumberTable
+
+# If you keep the line number information, uncomment this to
+# hide the original source file name.
+#-renamesourcefileattribute SourceFile

java/app/src/androidTest/java/com/google/android/gms/samples/wallet/ExampleInstrumentedTest.kt

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+package com.google.android.gms.samples.wallet
+
+import androidx.test.platform.app.InstrumentationRegistry
+import androidx.test.ext.junit.runners.AndroidJUnit4
+
+import org.junit.Test
+import org.junit.runner.RunWith
+
+import org.junit.Assert.*
+
+/**
+ * Instrumented test, which will execute on an Android device.
+ *
+ * See [testing documentation](http://d.android.com/tools/testing).
+ */
+@RunWith(AndroidJUnit4::class)
+class ExampleInstrumentedTest {
+    @Test
+    fun useAppContext() {
+        // Context of the app under test.
+        val appContext = InstrumentationRegistry.getInstrumentation().targetContext
+        assertEquals("com.google.android.gms.samples.wallet", appContext.packageName)
+    }
+}

java/app/src/main/AndroidManifest.xml

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+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools">
+
+    <application
+        android:allowBackup="true"
+        android:dataExtractionRules="@xml/data_extraction_rules"
+        android:fullBackupContent="@xml/backup_rules"
+        android:icon="@mipmap/ic_launcher"
+        android:label="@string/app_name"
+        android:roundIcon="@mipmap/ic_launcher_round"
+        android:supportsRtl="true"
+        android:theme="@style/Theme.GoogleWalletSample">
+        <activity
+            android:name=".MainActivity"
+            android:exported="true"
+            android:label="@string/app_name"
+            android:theme="@style/Theme.GoogleWalletSample">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+        </activity>
+    </application>
+
+</manifest>

java/app/src/main/java/com/google/android/gms/samples/wallet/MainActivity.java

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+/*
+ * Copyright 2023 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.android.gms.samples.wallet;
+
+import android.content.Intent;
+import android.os.Bundle;
+import android.view.View;
+import android.widget.Toast;
+
+import androidx.activity.ComponentActivity;
+import androidx.activity.result.ActivityResultLauncher;
+import androidx.activity.result.IntentSenderRequest;
+import androidx.activity.result.contract.ActivityResultContracts;
+import androidx.annotation.Nullable;
+import androidx.lifecycle.ViewModelProvider;
+
+import com.google.android.gms.pay.PayClient;
+import com.google.android.gms.samples.wallet.databinding.ActivitySavePassBinding;
+import com.google.android.gms.samples.wallet.viewmodel.WalletViewModel;
+
+public class MainActivity extends ComponentActivity {
+
+    private WalletViewModel model;
+
+    private static final int ADD_TO_GOOGLE_WALLET_REQUEST_CODE = 999;
+
+    private View addToGoogleWalletButtonContainer;
+    private View addToGoogleWalletButton;
+
+  /**
+   * Initialize the Google Pay API on creation of the activity
+   *
+   * @see android.app.Activity#onCreate(android.os.Bundle)
+   */
+  @Override
+  protected void onCreate(Bundle savedInstanceState) {
+    super.onCreate(savedInstanceState);
+    initializeUi();
+
+    // Check Google Pay availability
+    model = new ViewModelProvider(this).get(WalletViewModel.class);
+
+    // Check out Google Wallet availability
+    model.canAddPasses.observe(this, this::setAddToGoogleWalletAvailable);
+  }
+
+  private void initializeUi() {
+
+    // Use view binding to access the UI elements
+    ActivitySavePassBinding layoutBinding = ActivitySavePassBinding.inflate(getLayoutInflater());
+    setContentView(layoutBinding.getRoot());
+
+    addToGoogleWalletButton = layoutBinding.addToGoogleWalletButton.getRoot();
+    addToGoogleWalletButtonContainer = layoutBinding.passContainer;
+    addToGoogleWalletButton.setOnClickListener(v -> {
+      addToGoogleWalletButton.setClickable(false);
+      model.savePassesJwt(model.genericObjectJwt, this, ADD_TO_GOOGLE_WALLET_REQUEST_CODE);
+    });
+  }
+
+  /**
+   * If getPayApiAvailabilityStatus returned {@code true}, show the "Add to Google Wallet" button.
+   * Otherwise, notify the user that Google Wallet is not available. Please adjust to fit in with
+   * your current user flow. You are not required to explicitly let the user know if isReadyToPay
+   * returns {@code false}.
+   *
+   * @param available isReadyToPay API response.
+   */
+  private void setAddToGoogleWalletAvailable(boolean available) {
+    if (available) {
+      addToGoogleWalletButtonContainer.setVisibility(View.VISIBLE);
+    } else {
+      Toast.makeText(
+          this,
+          R.string.google_wallet_status_unavailable,
+          Toast.LENGTH_LONG).show();
+    }
+  }
+
+  @Override
+  protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
+    super.onActivityResult(requestCode, resultCode, data);
+
+    if (requestCode == ADD_TO_GOOGLE_WALLET_REQUEST_CODE) {
+      switch (resultCode) {
+        case RESULT_OK: {
+          Toast
+              .makeText(this, getString(R.string.add_google_wallet_success), Toast.LENGTH_LONG)
+              .show();
+          break;
+        }
+
+        case RESULT_CANCELED: {
+          // TODO Handle save canceled
+          break;
+        }
+
+        case PayClient.SavePassesResult.SAVE_ERROR: {
+          if (data != null) {
+            String apiErrorMessage = data.getStringExtra(PayClient.EXTRA_API_ERROR_MESSAGE);
+            // TODO Handle API error
+          }
+          break;
+        }
+
+        default: // TODO Handle other outcomes
+      }
+
+      addToGoogleWalletButton.setClickable(true);
+    }
+  }
+}

java/app/src/main/java/com/google/android/gms/samples/wallet/viewmodel/WalletViewModel.java

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+/*
+ * Copyright 2023 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.android.gms.samples.wallet.viewmodel;
+
+import android.app.Activity;
+import android.app.Application;
+import androidx.lifecycle.AndroidViewModel;
+import androidx.lifecycle.LiveData;
+import androidx.lifecycle.MutableLiveData;
+import com.google.android.gms.pay.Pay;
+import com.google.android.gms.pay.PayApiAvailabilityStatus;
+import com.google.android.gms.pay.PayClient;
+
+public class WalletViewModel extends AndroidViewModel {
+
+    // A client to interact with the Google Wallet API
+    private final PayClient walletClient;
+
+    // LiveData with the result of whether the user can save passes with Google Wallet
+    private final MutableLiveData<Boolean> _canAddPasses = new MutableLiveData<>();
+    public final LiveData<Boolean> canAddPasses = _canAddPasses;
+
+    public WalletViewModel(Application application) {
+        super(application);
+        walletClient = Pay.getClient(application);
+
+        fetchCanAddPassesToGoogleWallet();
+    }
+
+    /**
+     * Determine whether the API to save passes to Google Pay is available on the device.
+     */
+    private void fetchCanAddPassesToGoogleWallet() {
+        walletClient
+            .getPayApiAvailabilityStatus(PayClient.RequestType.SAVE_PASSES)
+            .addOnSuccessListener(
+                status -> _canAddPasses.setValue(status == PayApiAvailabilityStatus.AVAILABLE))
+            // If the API is not available, we recommend to either:
+            // 1) Hide the save button
+            // 2) Fall back to a different Save Passes integration (e.g. JWT link)
+            // Note that a user might become eligible in the future.
+
+            // Google Play Services is too old. API availability can't be verified.
+            .addOnFailureListener(exception -> _canAddPasses.setValue(false));
+    }
+
+    /**
+     * Exposes the `savePassesJwt` method in the wallet client
+     */
+    public void savePassesJwt(String jwtString, Activity activity, int requestCode) {
+        walletClient.savePassesJwt(jwtString, activity, requestCode);
+    }
+
+    /**
+     * Exposes the `savePasses` method in the wallet client
+     */
+    public void savePasses(String objectString, Activity activity, int requestCode) {
+        walletClient.savePasses(objectString, activity, requestCode);
+    }
+
+    // Test generic object used to be created against the API
+    // See https://developers.google.com/wallet/tickets/boarding-passes/web#json_web_token_jwt for more details
+    public final String genericObjectJwt = "eyJ0eXAiOiJKV1QiLCJhbGciOiJSUzI1NiJ9.eyJhdWQiOiJnb29nbGUiLCJwYXlsb2FkIjp7ImdlbmVyaWNPYmplY3RzIjpbeyJpZCI6IjMzODgwMDAwMDAwMjIwOTUxNzcuZjUyZDRhZjYtMjQxMS00ZDU5LWFlNDktNzg2ZDY3N2FkOTJiIn1dfSwiaXNzIjoid2FsbGV0LWxhYi10b29sc0BhcHBzcG90LmdzZXJ2aWNlYWNjb3VudC5jb20iLCJ0eXAiOiJzYXZldG93YWxsZXQiLCJpYXQiOjE2NTA1MzI2MjN9.ZURFHaSiVe3DfgXghYKBrkPhnQy21wMR9vNp84azBSjJxENxbRBjqh3F1D9agKLOhrrflNtIicShLkH4LrFOYdnP6bvHm6IMFjqpUur0JK17ZQ3KUwQpejCgzuH4u7VJOP_LcBEnRtzZm0PyIvL3j5-eMRyRAo5Z3thGOsKjqCPotCAk4Z622XHPq5iMNVTvcQJaBVhmpmjRLGJs7qRp87sLIpYOYOkK8BD7OxLmBw9geqDJX-Y1zwxmQbzNjd9z2fuwXX66zMm7pn6GAEBmJiqollFBussu-QFEopml51_5nf4JQgSdXmlfPrVrwa6zjksctIXmJSiVpxL7awKN2w";
+}

java/app/src/main/res/drawable-v21/add_to_google_wallet_button_background.xml

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+<?xml version="1.0" encoding="utf-8"?>
+<ripple xmlns:android="http://schemas.android.com/apk/res/android"
+    android:color="@color/accent_alpha26">
+    <item>
+        <shape>
+            <size android:width="270dp" android:height="48dp"/>
+            <solid android:color="#1f1f1f"/>
+            <stroke android:color="#747775" android:width="1dp"/>
+            <corners android:radius="24dp"/>
+        </shape>
+    </item>
+</ripple>

java/app/src/main/res/drawable/add_to_google_wallet_button_background.xml

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+<?xml version="1.0" encoding="utf-8"?>
+<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
+    <item>
+        <shape>
+            <size android:width="270dp" android:height="48dp"/>
+            <solid android:color="#1f1f1f"/>
+            <stroke android:color="#747775" android:width="1dp"/>
+            <corners android:radius="24dp"/>
+        </shape>
+    </item>
+</layer-list>