storeFile=relative/path/to/keystore.p12
storePassword=SECRET1
storeType=pkcs12
keyAlias=DebugSigningKey
keyPassword=SECRET2
The storePassword and keyPassword properties are required for automated signing.
Debugging
For details on the debugging tools that come packaged with the Android SDK, see
Android's developer documentation for debugging.
Additionally, Android's developer documentation for debugging web apps
provides an introduction for debugging the portion of your app running in the
Webview.
Opening a Project in Android Studio
Cordova-Android projects can be opened in Android Studio. This can be useful if you wish to use Android Studio's built in Android debugging and profiling tools or if you are developing Android plugins.
Note: When opening your project in Android Studio, it is recommended to NOT edit the code within the IDE. Editing in Android Studio will edit code residing in the platforms directory of your project. It is not updating the code in the projects root www)directory. The changes are liable to be overwritten. Instead, edit the www folder and copy over your changes by running cordova prepare.
Plugin developers wishing to edit their native code in Android Studio should use the --link flag when adding their plugin to the project with the cordova plugin add. This will create a symbolic link of the plugin files from the plugin source directory to the project's platforms directory.
To open a Cordova-Android project in Android Studio:
Launch Android Studio
Click the Open button
Navigate to the project's Android platform directory: (<project-root>/platforms/android)
Click Open
Once it finishes importing, you should be able to build and run the app directly from Android Studio.
For more resources, please see:
Meet Android Studio
Build and run your app
Refer to this article for instructions to upgrade your cordova-android version.
Lifecycle Guide
Cordova and Android
Native Android apps typically consist of a series of activities that the user interacts with. Activities can be thought of as the individual screens that make
up an application; different tasks in an app will often have their own activity. Each activity has its own lifecycle that is maintained as the activity enters and leaves the foreground of a user's device.
In contrast, Cordova applications on the Android platform are executed within a Webview that is embedded in a single Android activity. The lifecycle of this activity is exposed to your application through the document events that are fired. The events are not guaranteed to line up with Android's lifecycle, but they can provide guidelines for saving and restoring your state. These events roughly map to Android callbacks as follows:
Most other Cordova platforms have a similar concept of lifecycles and should fire these same events when similar actions happen on a user's device. However, Android presents some unique challenges that can sometimes show up thanks to the native Activity lifecycle.
What makes Android different?
In Android, the OS can choose to kill activities in the background in order to free up resources if the device is low on memory. Unfortunately, when the activity holding your application is killed, the Webview in which your application lives will be destroyed as well. Any state that your application is maintaining will be lost in this case. When the user navigates back to your application, the Activity and Webview will be recreated by the OS, but state will not be automatically restored for your Cordova app. For this reason, it is imperative that your application be aware of the lifecycle events that are fired and maintain whatever state is appropriate to make sure a user's context in your app is not lost when they leave the application.
When can this happen?
Your application is susceptible to being destroyed by the OS whenever it leaves the sight of the user. There are two main situations in which this can occur. The first and most obvious case is when the user presses the home button or switches to another application.
However, there is a second (and much more subtle) case that certain plugins can introduce. As noted above, Cordova applications are usually confined to the single activity that contains the Webview. However, there are instances in which other activities may be launched by plugins and temporarily push the Cordova activity to the background. These other Activities are typically launched in order to perform a specific task using a native application installed on the device. For example, the Cordova camera plugin launches whatever camera activity is natively installed on the device in order to take a photo. Reusing the installed camera application in this way makes your application feel much more like a native app when the user tries to take a photo. Unfortunately, when the native Activity pushes your app to the background there is a chance the OS will kill it.
For a clearer understanding of this second case, let's walk through an example using the camera plugin. Imagine you have an application that requires the user to take a profile photo. The flow of events in the application when everything goes as planned will look something like this:
The user is interacting with your app and needs to take a picture
The camera plugin launches the native camera activity
The Cordova activity is pushed to the background (pause event is fired)
The user takes a photo
The camera activity finishes
The Cordova activity is moved to the foreground (resume event is fired)
The user is returned to your application where they left off
However, this flow of events can be disrupted if a device is low on memory. If the Activity is killed by the OS, the above sequence of events instead plays out as follows:
The user is interacting with your app and needs to take a picture
The camera plugin launches the native camera activity
The OS destroys the Cordova activity (pause event is fired)
The user takes a photo
The camera activity finishes
The OS recreates the Cordova activity (deviceready and resume events are fired)
The user is confused as to why they are suddenly back at your app's login screen
In this instance, the OS killed the application in the background and the application did not maintain its state as part of the lifecycle. When the user returned to the app, the Webview was recreated and the app appeared to have restarted from scratch (hence the user's confusion). This sequence of events is equivalent to what happens when the home button is pressed or the user switches applications. The key to preventing the above experience is subscribing to events and properly maintaining state as part of the activity lifecycle.
Respecting the Lifecycle
In the examples above, the javascript events that are fired are noted in italics. These events are your opportunity to save and restore your
application's state. You should register callbacks in your application's bindEvents function that respond to the lifecycle events by saving state. What information you save and how you save it is left to your discretion, but you should be sure to save enough information so that you can restore the user to exactly where they left off when they return to your application.
There is one additional factor in the example above that only applies in the second-discussed situation (i.e. when a plugin launches an external activity). Not only was the state of the application lost when the user finished taking a photo, but so was the photo that the user took. Normally, that photo would be delivered to your application through the callback that was registered with the camera plugin. However, when the Webview was destroyed that callback was lost forever. Luckily, cordova-android 5.1.0 and above provide a means for getting the result of that plugin call when your application resumes.
Retrieving plugin callback results (cordova-android 5.1.0+)
When the OS destroys the Cordova activity that was pushed into the background by a plugin, any pending callbacks are lost as well. This means that if you passed a callback to the plugin that launched the new activity (e.g. the camera plugin), that callback will NOT be fired when the application is recreated. However, starting in cordova-android 5.1.0, the resume event's payload will contain any pending plugin results from the plugin request that launched the external activity made prior to the activity being destroyed.
The payload for the resume event adheres to the following format:
action: "resume",
pendingResult: {
pluginServiceName: string,
pluginStatus: string,
result: any
The fields of that payload are defined as follows:
pluginServiceName: The name of the plugin returning the result (e.g. "Camera"). This can be found in the <name> tag of a plugin's plugin.xml file
pluginStatus: The status of the plugin call (see below)
result: Whatever the result of the plugin call is
The possible values for pluginStatus in the pendingResult field include the following:
"OK" - The plugin call was successful
"No Result" - The plugin call ended with no result
"Error" - The plugin call resulted in some general error
Other miscellaneous errors
"Class not found"
"Illegal access"
"Instantiation error"
"Malformed url"
"IO error"
"Invalid action"
"JSON error"
Note: It is up to the plugin to decide what is contained in the result field and the meaning of the pluginStatus that is returned. Refer to the plugin's API documentationf or the expect results and how to use the values.
Example
Below is a brief example application that uses the resume and pause events to manage state. It uses the Apache camera plugin as an example of how to retrieve the results of a plugin call from the resume event payload. The portion of the code dealing with the resume's event.pendingResult object requires cordova-android 5.1.0+
// This state represents the state of our application and will be saved and
// restored by onResume() and onPause()
var appState = {
takingPicture: true,
imageUri: ""
var APP_STORAGE_KEY = "exampleAppState";
var app = {
initialize: function() {
this.bindEvents();
bindEvents: function() {
// Here we register our callbacks for the lifecycle events we care about
document.addEventListener('deviceready', this.onDeviceReady, false);
document.addEventListener('pause', this.onPause, false);
document.addEventListener('resume', this.onResume, false);
onDeviceReady: function() {
document.getElementById("take-picture-button").addEventListener("click", function() {
// Because the camera plugin method launches an external Activity,
// there is a chance that our application will be killed before the
// success or failure callbacks are called. See onPause() and
// onResume() where we save and restore our state to handle this case
appState.takingPicture = true;
navigator.camera.getPicture(cameraSuccessCallback, cameraFailureCallback,
sourceType: Camera.PictureSourceType.CAMERA,
destinationType: Camera.DestinationType.FILE_URI,
targetWidth: 250,
targetHeight: 250
onPause: function() {
// Here, we check to see if we are in the middle of taking a picture. If
// so, we want to save our state so that we can properly retrieve the
// plugin result in onResume(). We also save if we have already fetched
// an image URI
if(appState.takingPicture || appState.imageUri) {
window.localStorage.setItem(APP_STORAGE_KEY, JSON.stringify(appState));
onResume: function(event) {
// Here we check for stored state and restore it if necessary. In your
// application, it's up to you to keep track of where any pending plugin
// results are coming from (i.e. what part of your code made the call)
// and what arguments you provided to the plugin if relevant
var storedState = window.localStorage.getItem(APP_STORAGE_KEY);
if(storedState) {
appState = JSON.parse(storedState);
// Check to see if we need to restore an image we took
if(!appState.takingPicture && appState.imageUri) {
document.getElementById("get-picture-result").src = appState.imageUri;
// Now we can check if there is a plugin result in the event object.
// This requires cordova-android 5.1.0+
else if(appState.takingPicture && event.pendingResult) {
// Figure out whether or not the plugin call was successful and call
// the relevant callback. For the camera plugin, "OK" means a
// successful result and all other statuses mean error
if(event.pendingResult.pluginStatus === "OK") {
// The camera plugin places the same result in the resume object
// as it passes to the success callback passed to getPicture(),
// thus we can pass it to the same callback. Other plugins may
// return something else. Consult the documentation for
// whatever plugin you are using to learn how to interpret the
// result field
cameraSuccessCallback(event.pendingResult.result);
} else {
cameraFailureCallback(event.pendingResult.result);
// Here are the callbacks we pass to getPicture()
function cameraSuccessCallback(imageUri) {
appState.takingPicture = false;
appState.imageUri = imageUri;
document.getElementById("get-picture-result").src = imageUri;
function cameraFailureCallback(error) {
appState.takingPicture = false;
console.log(error);
app.initialize();
The corresponding html:
<!DOCTYPE html>
<meta http-equiv="Content-Security-Policy" content="default-src 'self' data: gap: https://ssl.gstatic.com 'unsafe-eval'; style-src 'self' 'unsafe-inline'; media-src *">
<meta name="format-detection" content="telephone=no">
<meta name="msapplication-tap-highlight" content="no">
<meta name="viewport" content="user-scalable=no, initial-scale=1, maximum-scale=1, minimum-scale=1, width=device-width">
<link rel="stylesheet" type="text/css" href="css/index.css">
<title>Cordova Android Lifecycle Example</title>
</head>
<div class="app">
<img id="get-picture-result" />
<Button id="take-picture-button">Take Picture</button>
<script type="text/javascript" src="cordova.js"></script>
<script type="text/javascript" src="js/index.js"></script>
</body>
</html>
Android Quirks
The default API level in the Cordova-Android platform has been upgraded. On an Android 9 device, clear text communication is now disabled by default.
By default HTTP and FTP etc. will refuse the apps requests to use cleartext traffic. The key reason for avoiding cleartext traffic is the lack of confidentiality, authenticity, and protections against tampering; a network attacker can eavesdrop on transmitted data and also modify it without being detected. You can learn more about the android:usesCleartextTraffic or any other android application elements setting in the documentation for Android developers.
To allow clear text communication again, set the android:usesCleartextTraffic on your application tag to true in config.xml file:
<platform name="android">
<edit-config file="app/src/main/AndroidManifest.xml" mode="merge" target="/manifest/application">
<application android:usesCleartextTraffic="true" />
</edit-config>
</platform>
And also you need to add Android XML namespace xmlns:android="http://schemas.android.com/apk/res/android" to your widget tag in the same config.xml.
Example:
<widget id="io.cordova.hellocordova" version="0.0.1" android-versionCode="13" xmlns="http://www.w3.org/ns/widgets" xmlns:cdv="http://cordova.apache.org/ns/1.0" xmlns:android="http://schemas.android.com/apk/res/android">
</widget>
Android Manifest Information
You can learn more about the Android manifest information in the documentation for Android developers.
Testing the Activity Lifecycle
Android provides a developer setting for testing Activity destruction on low memory. Enable the "Don't keep activities" setting in the Developer Options menu on your device or emulator to simulate low memory scenarios. You should always do some amount of testing with this setting enabled to make sure that your application is properly maintaining state.
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