Launch android from browser

You can change your_uri_scheme to the URI scheme that you’d like. Ideally, you want this to be unique. If it overlaps with another app’s URI scheme, the user will see an Android chooser when clicking on the link. You see this often when you have multiple browsers installed, as they all register for the http URI.

Next, you’ll want to confirm that your app was opened from the URI scheme. To handle the deep link in the app, you simply need to grab the intent data string in the Activity that was opened via the click. Below is an example:

From here, you’ll need to do string parsing to read the values appended the URI scheme that will be very specific to your use case and implementation.

Adding Javascript to Your Website to Open Your App

Now that your Android app is ready to be triggered from a URI scheme, the next part is simple. You merely need to add some Javascript to your website that will auto trigger your app open. The function below, triggerAppOpen , will attempt to open your app’s URI scheme once you replace your_uri_scheme with the one you added in the manifest above.

You could call triggerAppOpen into window.onload if you wanted to do it on page load, or you could make it the onclick of a link somewhere on your site. Either works and the you’ll get the intended results.

Android is incredibly complicated, and there are edge cases everywhere. You’ll think everything is going well until you get that one user complaining that his links aren’t working on Facebook while running Android 4.4.4. That’s why you should use a tool like Branch—to save you this nightmare and ensure that your links work everywhere. Be sure to request a Branch demo if you’re interested in learning more.

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Launching the Browser From Your Android Applications — The Easy Way

This quick tip shows you how to launch the built-in Browser application in three ways. First, you learn how to launch the browser to a specific URL. Second, you learn how to create text with links. Third, you learn how to launch a Google web search and specify the search criteria. You will achieve these goals by creating and configuring the appropriate Intents within your application’s Activity class.

Step 1: Create an Android Application

Begin by creating an Android project. Implement your Android application as normal. Once you have a project set up and the application running, decide under what circumstances you want to launch the browser. Will this occur when Button controls are pressed? Implement the necessary controls that will trigger to web browsing or searching features of the application, including any click handling. Once you have completed these tasks, you have places to drop in the code to launch the browser or web search. Now you are ready to proceed with this quick tip.

You can follow along with our project: HelloWorldWideWeb, which is available as open source.

Step 2: Working with URIs

Android uses Uri (Uniform Resource Identifier) objects to identify the unique location of a piece of data. Uri objects are often used to specify the data that an Intent is supposed to use. In this case, we will create a Uri object from a web URL using the parse() method:

Step 3: Creating the Intent

You can view HTML content using the following Intent: android.content.Intent.ACTION_VIEW. Begin by creating an Intent of this type and specifying the URI you created above, as follows, within your Button click handler:

Step 4: Launching the Intent

When you launch this Intent, any applications that can display web will be able to handle this request. Once you have set the type data for the Intent, you can call the startActivity() method, passing in your Intent:

When you click on this button, the Browser application (which generally handles HTML content display) is launched to the website you provided.

When you hit the back button, you return to the previous Activity, which happens to be your application.

Step 5: Using Links in Text

Another easy way to launch in to the browser is simply by including links within text on the screen. The TextView object can be configured to find these and turn then in to clickable links, like in a web browser, such that when the user clicks on them they launch the browser to the appropriate spot. For instance, the following TextView does just that:

The following screenshot shows what this looks like.

The text for @string/contains_links is verbatim for what you see on the screen. No special formatting commands or tags are needed within the string.

Step 6: Enabling Web Searches

When you want to provide the user with the ability to perform a web search, you could still use the ACTION_VIEW intent and set up the query strings appropriate to a specific search engine, or if you are content with a Google search, you can simply use the web search Intent: android.content.Intent.ACTION_WEB_SEARCH. Begin by creating an Intent of this type, as follows, within your second Button click handler:

Step 7: Supplying Search Criteria

Often, you want to supply some criteria to search on. You can do this by supplying this information as part of the Intent’s extras. The ACTION_WEB_SEARCH Intent specifically uses the SearchManager.QUERY extra field for the search criteria. For example, to perform the Google search on pygmy goats, you configure the SearchManager.QUERY extra and launch the Browser as follows:

When you click on this button, the Browser application (which generally handles HTML content display) is launched to the website you provided.

A Note on Permissions: Although your application is leveraging browser capabilities on the device, it is not required to have any such permissions. This is because the application is not directly displaying web content. Instead, it’s just leveraging other applications’ capabilities to do so.

Becoming a Browser

For more fine control over web content within your applications, you’ll want to use the WebView control. This special view allows fine control over rendering of web content. However, this control will require your application to have the appropriate permissions to do so, and that, friends, is discussed in a tutorial right here on Mobiletuts+!

Conclusion

In this quick tip you have learned how to configure an Intent to launch the Browser as well as perform a search query. This feature can be very useful for applications wishing to web content within their applications.

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Android Application Launch explained: from Zygote to your Activity.onCreate()

Apr 30, 2018 · 6 min read

This article explains how Android launches your application when a user clicks an app icon. The Android system does a lot of heavy lifting behind the curtains to make your launch activity visible to a user. This article covers this process in detail by highlighting the important phases and call sequences.

Android applications are unique in two ways:

1. Multiple Entry points: Android apps are composed of different components and they can invoke the components owned by other apps. These components roughly correspond to multiple entry points for any application. Hence, they differ from traditional applications which have a single entry point like main() method.
2. Own Little World: Every Android application lives in its own world, it runs in a separate process, it has its own Dalvik VM instance and is assigned a unique user ID.

When does Android process start?

An Android process is started whenever it is required.

Any time a user or some other sys t em component requests a component (could be a service, an activity or an intent receiver) that belongs to your application be executed, the Android system spins off a new process for your app if it’s not already running. Generally processes keep running until killed by the system. Application processes are created on demand and a lot of things happen before you see your application’s launch activity up and running.

Every app runs in its own process: By default, every Android app runs in its own Android process which is nothing but a Linux process which gets one execution thread to start with. For example, when you click on a hyper-link in your e-mail, a web page opens in a browser window. Your mail client and the browser are two separate apps and they run in their two separate individual processes. The click event causes Android platform to launch a new process so that it can instantiate the browser activity in the context of its own process. The same holds good for any other component in an application.

Zygote : Spawning new life, new process

Let’s step back for a moment and have a quick look on system start-up process. Like the most Linux based systems, at startup, the boot loader loads the kernel and starts the init process. The init then spawns the low level Linux processes called “daemons” e.g. android debug daemon, USB daemon etc. These daemons typically handle the low level hardware interfaces including radio interface.

Init process then starts a very interesting process called ‘ Zygote ’.

As the name implies it’s the very beginning for the rest of the Android application. This is the process which initializes a very first instance of Dalvik virtual machine. It also pre-loads all common classes used by Android application framework and various apps installed on a system. It thus prepares itself to be replicated. It stats listening on a socket interface for future requests to spawn off new virtual machines (VM)for managing new application processes. On receiving a new request, it forks itself to create a new process which gets a pre-initialized VM instance.

After zygote, init starts the runtime process.

The zygote then forks to start a well managed process called system server. System server starts all core platform services e.g activity manager service and hardware services in its own context.

At this point the full stack is ready to launch the first app process — Home app which displays the home screen also known as Launcher application.

When a user clicks an app icon in Launcher …

The click event gets translated into startActivity(intent) and it is routed to ActivityManagerService via Binder IPC. The ActvityManagerService performs multiple steps

1. The first step is to collect information about the target of the intent object. This is done by using resolveIntent() method on PackageManager object. PackageManager.MATCH_DEFAULT_ONLY and PackageManager.GET_SHARED_LIBRARY_FILES flags are used by default.
2. The target information is saved back into the intent object to avoid re-doing this step.
3. Next important step is to check if user has enough privileges to invoke the target component of the intent. This is done by calling grantUriPermissionLocked() method.
4. If user has enough permissions, ActivityManagerService checks if the target activity requires to be launched in a new task. The task creation depends on Intent flags such as FLAG_ACTIVITY_NEW_TASK and other flags such as FLAG_ACTIVITY_CLEAR_TOP.
5. Now, it’s the time to check if the ProcessRecord already exists for the process.If the ProcessRecord is null, the ActivityManager has to create a new process to instantiate the target component.

As you saw above many things happen behind the scene when a user clicks on an icon and a new application gets launched. Here is the full picture :

There are three distinct phases of process launch :

1. Process Creation
2. Binding Application
3. Launching Activity / Starting Service / Invoking intent receiver …

ActivityManagerService creates a new process by invoking startProcessLocked() method which sends arguments to Zygote process over the socket connection. Zygote forks itself and calls ZygoteInit.main() which then instantiates ActivityThread object and returns a process id of a newly created process.

Every process gets one thread by default. The main thread has a Looper instance to handle messages from a message queue and it calls Looper.loop() in its every iteration of run() method. It’s the job of a Looper to pop off the messages from message queue and invoke the corresponding methods to handle them. ActivityThread then starts the message loop by calling Looper.prepareLoop() and Looper.loop() subsequently.

The following sequence captures the call sequence in detail —

The next step is to attach this newly created process to a specific application. This is done by calling bindApplication() on the thread object. This method sends BIND_APPLICATION message to the message queue. This message is retrieved by the Handler object which then invokes handleMessage() method to trigger the message specific action — handleBindApplication(). This method invokes makeApplication() method which loads app specific classes into memory.

This call sequence is depicted in following figure.

Launching an Activity:

After the previous step, the system contains the process responsible for the application with application classes loaded in process’s private memory. The call sequence to launch an activity is common between a newly created process and an existing process.

The actual process of launching starts in realStartActivity() method which calls sheduleLaunchActivity() on the application thread object. This method sends LAUNCH_ACTIVITY message to the message queue. The message is handled by handleLaunchActivity() method as shown below.

Assuming that user clicks on Video Browser application. the call sequence to launch the activity is as shown in the figure.

The Activity starts its managed lifecycle with onCreate() method call. The activity comes to foreground with onRestart() call and starts interacting with the user with onStart() call.

Thanks for reading through 🙌🏼. If you found this post useful, please applaud using the 👏 button and share it through your circles.

This article was initially published as two part series (Part 1 and Part 2) on my blog ./ mult-core-dump in 2010. These articles have been cited in multiple documents including the very famous Introduction to the Android Graphics Pipeline

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