JarCasting
Conductor
A small, yet full-featured framework that allows building View-based Android applications. Conductor provides a light-weight wrapper around standard Android Views that does just about everything you'd want:
| Conductor | |
|---|---|
| |
Easy integration |
| |
Single Activity apps without using Fragments |
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Simple but powerful lifecycle management |
| |
Navigation and backstack handling |
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Beautiful transitions between views |
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State persistence |
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Callbacks for onActivityResult, onRequestPermissionsResult, etc |
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MVP / MVVM / VIPER / MVC ready |
Conductor is architecture-agnostic and does not try to force any design decisions on the developer. We here at Lalafo tend to use MVP, but it would work equally well with standard MVVM, MVC or whatever else you want to throw at it.
Installation
def conductorVersion = '1.0.0'
implementation "com.lalafo.conductor:conductor:$conductorVersion"
// If you want Conductor Dagger2 codegen support add
// Annotations:
implementation "com.lalafo.conductor:conductor-codegen-annotations:$conductorVersion"
// Annotations processor:
annotationProcessor "com.lalafo.conductor:conductor-codegen-compiler:$conductorVersion"
// Or in case of using Kotlin
kapt "com.lalafo.conductor:conductor-codegen-compiler:$conductorVersion"
// If you want Controllers that are Lifecycle-aware (architecture components):
implementation "com.lalafo.conductor:conductor-archlifecycle:$conductorVersion"
// If you want Glide support Controller lifecycle:
implementation "com.lalafo.conductor:conductor-glide:$conductorVersion"
SNAPSHOT builds
Just use 1.0.0-SNAPSHOT as your version number in any of the dependencies above and add the url to the snapshot repository:
allprojects {
repositories {
maven { url "https://oss.sonatype.org/content/repositories/snapshots/" }
}
}
Components to Know
| Conductor Components | |
|---|---|
| Controller | The Controller is the View wrapper that will give you all of your lifecycle management features. Think of it as a lighter-weight and more predictable Fragment alternative with an easier to manage lifecycle. |
| Router | A Router implements navigation and backstack handling for Controllers. Router objects are attached to Activity/containing ViewGroup pairs. Routers do not directly render or push Views to the container ViewGroup, but instead defer this responsibility to the ControllerChangeHandler specified in a given transaction. |
| ControllerChangeHandler | ControllerChangeHandlers are responsible for swapping the View for one Controller to the View of another. They can be useful for performing animations and transitions between Controllers. Several default ControllerChangeHandlers are included. |
| RouterTransaction | Transactions are used to define data about adding Controllers. RouterTransactions are used to push a Controller to a Router with specified ControllerChangeHandlers, while ChildControllerTransactions are used to add child Controllers. |
| ControllerFactory | Controller factory is used to instance the controllers with your own logic. It could be useful if you want to pass custom parameters on Controller instantiation during app running normally or after process death. |
Getting Started
Minimal Activity implementation
public class MainActivity extends Activity {
private Router router;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ViewGroup container = (ViewGroup) findViewById(R.id.controller_container);
router = Conductor.attachRouter(this, container, savedInstanceState);
if (!router.hasRootController()) {
router.setRoot(RouterTransaction.with(new HomeController()));
}
}
@Override
public void onBackPressed() {
if (!router.handleBack()) {
super.onBackPressed();
}
}
}
Minimal Controller implementation
public class HomeController extends Controller {
@Override
protected View onCreateView(@NonNull LayoutInflater inflater, @NonNull ViewGroup container) {
View view = inflater.inflate(R.layout.controller_home, container, false);
((TextView) view.findViewById(R.id.tv_title)).setText("Hello World");
return view;
}
}
Sample Project
Demo app - Shows how to use all basic and most advanced functions of Conductor.
Controller Lifecycle
The lifecycle of a Controller is significantly simpler to understand than that of a Fragment. A lifecycle diagram is shown below:
Advanced Topics
ControllerFactory
Controller factory could be useful if you want to instance the Controller on your own. Just like Fragments, by default Conductor require you to have public empty constructor or public constructor with a single Bundle args argument, so it will be able to instantiate the given Controller by calling one of these constructors via reflection. This means by default you can't just pass anything into your own Controller constructor.
This is the situation when ControllerFactory could be handy. First, create your own factory:
public class AppFactory extends ControllerFactory {
@NonNull @Override public Controller newInstance(@NonNull ClassLoader classLoader, @NonNull String className, @Nullable Object args) {
Class<? extends Controller> klass = loadControllerClass(classLoader, className);
if (klass == HomeController.class) {
return new HomeController("your controller creation", "goes here", 42, args);
} else {
return super.newInstance(classLoader, className, args);
}
}
}
Then set it to Conductor before starting any transaction.
Router router = Conductor.attachRouter(MainActivity.this, container, savedInstanceState);
Conductor.setControllerFactory(new AppFactory());
Finally, create the transaction:
if (!router.hasRootController()) {
// Create transaction with class so the Conductor will use
// your Controller to instantiate it.
router.setRoot(RouterTransaction.with(HomeController.class, null));
}
As you saw you should use another method to create the transaction:
RouterTransaction.with(@NonNull Class<? extends Controller> controllerClass, @Nullable Object arguments);
The arguments passed to RouterTransaction.with(...) are the exact arguments that will be passed to your ControllerFactory here:
Controller newInstance(@NonNull ClassLoader classLoader, @NonNull String className, @Nullable Object args) { ... }
So you will be able to pass the arguments manually while creating the new transaction.
NOTE: the passed arguments are not saved in the ControllerTransaction. They do not survive after the process death. Keep this gotcha in mind, because that's when conductor-codegen is useful.
Dagger2 Codegen
If you are using Dagger2 you are probably using Daggers MemebersInjector pattern, that's looks like this in Java:
public class HomeController extends Controller {
@Inject
public String injectedData;
// Code...
}
and even worse in Kotlin:
class HomeController: Controller() {
@Inject
lateinit var injectedData: String
// Code...
}
and this still requires to inject Controllers manually using components:
// Inject things to controller
Component component = ...; // Getting your dagger component
component.inject(this);
// And only after you could use injected objects
Ideally we want to inject things using the constructor injection. This gives us some goodies:
- All the data is present in the object at any moment
- No need to care about manual injection
- Clean looking class without public and late initialization or nullable fields.
As you have ControllerFactory you could it in 3 ways.
- Write your own
ControllerFactoryimplementation and maintain it, using@Injecton Controllers constructors. - Use
AssistedInjectto pass the data to Controllers mixing injections and params data. It's a good approach but you still will got to manage the saving of passed controller params over constructor. - Use
conductor-codegenpackage from our repo in couple withControllerArgs.
conductor-codegen is highly inspired with AssistedInject from Square. So if you used AssistedInject before you will probably get it right fast.
Case 1: Controller constructor injection without arguments
1. Create controller with Injection Constructor
class HomeController @InjectController constructor(
private val injectedData: String
): Controller() {
// More code ...
}
2. Create your AppControllerFactory
@ConductorFactory
open class AppControllerFactory: ControllerFactory()
NOTE: Make sure to make it non final.
3. Declare you Dagger2 module for conductor-codegen bindings
@ConductorBindingModule
@Module(includes = ConductorModule_ConductorBindingModule.class)
public abstract class ConductorModule {}
NOTE: Make sure to add includes = YOURCLASSNAME_ConductorBindingModule.class to @Module so the Dagger would be able to pick up all the bindings.
4. Register your AppControllerFactory to Conductor in you Activity or App class
class MainActivity: AppCompatActivity() {
@Inject lateinit var appControllerFactory: AppControllerFactory
override fun onCreate(savedInstanceState: Bundle?) {
// Inject all the objects
// ...
Conductor.setControllerFactory(appControllerFactory)
// Execute yout transactions safely after that
}
}
5. All done! Just make sure to create transactions using RouterTransaction.with(ControllerClassName.class, null) method.
Case 2: Controller constructor injection with ControllerArgs
It's nice to have constructor injection. You know what is nicer? Having your arguments in the constructor too. Now you are bundling your arguments to Bundle args so they survive the Controller recreation. But this is kinda messy, and you probably already know why. So we decided to move further and to add ControllerArgs.
ControllerArgs is an interface, that extends Parcelable. Controller has public constructor, that takes your implementation of ControllerArgs and stores it internally, so the args are saved between Controller recreation.
And don't be scared about the Parcelable and all this stuff you have to write to make class a Parcelable one. If you are using Kotlin, you already have @Parcelize, or if you stick to Java, you could use just as useful AutoValue: Parcel extensions.
1. Create your args
@Parcelize
data class StringArgs(val value: String): ControllerArgs
2. Add them to the Controller injection constructor
class HomeController @InjectController constructor(
@ControllerBundle private val args: StringArgs,
private val injectedMeme: Thermosiphon
) : Controller(args) {
// Blah blah blah ...
}
3. Make sure to setup factory and module
Just make sure to execute all steps in Case 1 from 2 to 4.
4. Put arguments to your transaction
RouterTransaction.with(HomeController.class, new StringArgs("Subscribe for r/mAndroidDev on Reddit!");
5. Done! Now you have both constructor injection and constructor arguments!
Notes
- Only one or none
ControllerArgsimplementing classes are allowed in the controller injection constructor for now. @ControllerBundleis an optional annotation. The codegen will detect the your "controller bundle" without it, but it's bad for the code style. Just add it so you recognize them fast in the constuctor.- You can add
@InjectController.Factoryto your Controller, if you want to in analogue toAssistedInjectlibrary. But it's optional, so you better add them if you really need one. - Conductor already bundled with some lint rules for the
codegenthat are experimental and not really stable or tested for now. So if you find the bugs for the lint - report it to us. - Only one
@ConductorFactoryannotated factory and one@ConductorBindingModuleannotated Dagger module are allowed per project for now.
Retain View Modes
setRetainViewMode can be called on a Controller with one of two values: RELEASE_DETACH, which will release the Controller's view as soon as it is detached from the screen (saves memory), or RETAIN_DETACH, which will ensure that a Controller holds on to its view, even if it's not currently shown on the screen (good for views that are expensive to re-create).
Custom Change Handlers
ControllerChangeHandler can be subclassed in order to perform different functions when changing between two Controllers. Two convenience ControllerChangeHandler subclasses are included to cover most basic needs: AnimatorChangeHandler, which will use an Animator object to transition between two views, and TransitionChangeHandler, which will use Lollipop's Transition framework for transitioning between views.
Child Routers & Controllers
getChildRouter can be called on a Controller in order to get a nested Router into which child Controllers can be pushed. This enables creating advanced layouts, such as Master/Detail.
Glide Lifecycle
If the Glide dependency has been added, you need to setup Glide:
public class GlideControllerSupport extends BaseGlideControllerSupport<GlideRequests> {
public GlideControllerSupport(Controller controller) {
super(controller);
}
@Override protected GlideRequests getGlideRequest(@NonNull ControllerLifecycle lifecycle, RequestManagerTreeNode requestManagerTreeNode) {
Context context = App.getInstance().getApplicationContext();
return new GlideRequests(Glide.get(context), lifecycle, requestManagerTreeNode, context);
}
}
public class HomeController extends Controller implements GlideProvider<GlideRequests>{
private GlideControllerSupport glideControllerSupport = new GlideControllerSupport(this);
@Override public GlideRequests getGlide() {
return glideControllerSupport.getGlide();
}
@NonNull @Override protected View onCreateView(@NonNull LayoutInflater inflater, @NonNull ViewGroup container) {
getGlide().load("url")
.centerCrop()
.into(new SimpleTarget<Drawable>() {
@Override public void onResourceReady(@NonNull Drawable resource, @Nullable Transition<? super Drawable> transition) {
}
});
return null;
}
}
License
Copyright (c) 2020 Lalafo.
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.