Droidux is "predictable state container" implementation, inspired by Redux.
Droidux is influenced by Three principles of Redux.
- Single source of truth
- The state of your whole application is stored in an object tree inside a single store.
- State is read-only
- The only way to mutate the state is to emit an action, an object describing what happened.
- Mutations are written as pure functions
- To specify how the state tree is transformed by actions, you write pure reducers.
Features of Droidux are following:
- All mutations can be observed via Flowable from RxJava
- All mutations are automatically notified to views via Data Binding
see also: Introduction to Redux // Speaker Deck (in Japanese)
Droidux depends on RxJava and Data Binding. Add to your project build.gradle file:
apply plugin: 'com.android.application'
dependencies {
compile 'info.izumin.android:droidux:0.6.0'
compile 'io.reactivex.rxjava2:rxjava:2.1.8'
compile 'io.reactivex.rxjava2:rxandroid:2.0.1'
annotationProcessor 'info.izumin.android:droidux-processor:0.6.0'
}And also you need to setup Data Binding.
When you use AsyncAction, you need to add droidux-thunk.
compile 'info.izumin.android:droidux-thunk:0.3.0'/**
* This is a state class.
* It can be as simple as possible implementation, like POJO, or immutable object.
*/
public class Counter {
private final int count;
public Counter(int count) {
this.count = count;
}
public int getCount() {
return count;
}
}
/**
* This is a reducer class.
* It should be applied @Reducer annotation is given a state class as an argument.
* It describe whether the reducer should handle which actions.
*/
@Reducer(Counter.class)
public class CounterReducer {
/**
* This is a method to handle actions.
* It should be applied @Dispatchable annotation is given an action class as an parameter.
* It describe how to transform the state into the next state when dispatched actions.
* It should return the next state instance, and it is preferred instantiate the new state.
*
* This example handle IncrementCountAction,
+ and it returns new counter instance that state is incremented.
*/
@Dispatchable(IncrementCountAction.class)
public Counter increment(Counter state) {
return new Counter(state.getCount() + 1);
}
@Dispatchable(DecrementCountAction.class)
public Counter decrement(Counter state) {
return new Counter(state.getCount() - 1);
}
@Dispatchable(ClearCountAction.class)
public Counter clear() {
return new Counter(0);
}
}
/**
* This is a store interface.
* It should be applied @Store annotation and passing reducer classes as parameters.
* Droidux generates an implementation of getter method, observe method and dispatch method from user-defined interface.
*/
@Store(CounterReducer.class)
public interface CounterStore extends BaseStore {
Counter getCounter();
Flowable<Counter> observeCounter();
}
/**
* They are action classes. They should extend Action class.
*/
public class IncrementCountAction implements Action {}
public class DecrementCountAction implements Action {}
public class ClearCountAction implements Action {}
// Instantiate a Droidux store holding the state of your app.
// Its class is generated automatically from Reducer class.
//
// The instantiating should use Builder class,
// and it should register a reducer instance and an initial state.
//
// Its APIs in this example are following:
// - Flowable<Action> dispatch(Action action)
// - Flowable<Counter> observeCounter()
// - Counter getCounter()
CounterStore store = DroiduxCounterStore.builder()
.setReducer(new CounterReducer(), new Counter(0))
.build(); // Counter: 0
// You can observe to the updates using RxJava interface.
store.observe((counter) -> Log.d(TAG, counter.toString()));
// The only way to mutate the internal state is to dispatch an action.
store.dispatch(new IncrementCountAction()).subscribe(); // Counter: 1
store.dispatch(new IncrementCountAction()).subscribe(); // Counter: 2
store.dispatch(new IncrementCountAction()).subscribe(); // Counter: 3
store.dispatch(new DecrementCountAction()).subscribe(); // Counter: 2
store.dispatch(new ClearCountAction()).subscribe(); // Counter: 0// If you use databinding, yor store interface must extend `android.databinding.Observable`.
@Store(CounterReducer.class)
public interface CounterStore extends BaseStore, android.databinding.Observable {
// You should annotate the getter method with @Bindable
@Bindable Counter getCounter();
}
CounterStore store = DroiduxCounterStore.builder()
// Pass the field id generated by DataBinding annotation processor.
.setReducer(new CounterReducer(), new Counter(0), BR.counter)
.build();Layout file is following:
<layout>
<data>
<variable android:name="store" android:type="CounterStore" />
</data>
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent" >
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:text="@{store.counter}" />
</RelativeLayout>
</layout>@Store({CounterReducer.class, TodoListReducer.class})
class RootStore extends BaseStore {
Counter getCounter();
Flowable<Counter> observeCounter();
TodoList getTodoList();
Flowable<TodoList> observeTodoList();
}
RootStore store = DroiduxRootStore.builder()
.setReducer(new CounterReducer(), new Counter(0))
.setReducer(new TodoListReducer(), new TodoList())
.addMiddleware(new Logger())
.build();
store.dispatch(new IncrementCountAction()).subscribe(); // Counter: 1, Todo: 0
store.dispatch(new AddTodoAction("new task")).subscribe(); // Counter: 1, Todo: 1class Logger extends Middleware<CounterStore> {
@Override
public Flowable<Action> beforeDispatch(Action action) {
Log.d("[prev counter]", String.valueOf(getStore().count()));
Log.d("[action]", action.getClass().getSimpleName());
return Flowable.just(action);
}
@Override
public Flowable<Action> afterDispatch(Action action) {
Log.d("[next counter]", String.valueOf(getStore().count()));
return Flowable.just(action);
}
}
// Instantiate store class
CounterStore store = DroiduxCounterStore.builder()
.setReducer(new CounterReducer(), new Counter(0))
.addMiddleware(new Logger()) // apply logger middleware
.build(); // Counter: 0
store.dispatch(new IncrementCountAction()).subscribe();
// logcat:
// [prev counter]: 0
// [action]: IncrementCountAction
// [next counter]: 1
store.dispatch(new IncrementCountAction()).subscribe();
// logcat:
// [prev counter]: 1
// [action]: IncrementCountAction
// [next counter]: 2
store.dispatch(new ClearCountAction()).subscribe();
// logcat:
// [prev counter]: 2
// [action]: ClearCountAction
// [next counter]: 0class TodoList extends ArrayList<TodoList.Todo> implements UndoableState<TodoList> {
@Override
public TodoList clone() {
// ...
}
public static Todo {
// ...
}
}
@Undoable
@Reducer(TodoList.class)
class TodoListReducer {
@Dispatchable(AddTodoAction.class)
public TodoList add(TodoList state, AddTodoAction action) {
// ...
}
@Dispatchable(CompleteTodoAction.class)
public TodoList complete(TodoList state, CompleteTodoAction action) {
// ...
}
}
@Store(TodoListReducer.class)
public interface TodoListStore {
TodoList todoList();
Flowable<TodoList> observeTodoList();
}
class AddTodoAction implements Action {
// ...
}
class CompleteTodoAction implements Action {
// ...
}
TodoListStore store = DroiduxTodoListStore.builder()
.setReducer(new TodoListReducer(), new TodoList())
.build();
store.dispatch(new AddTodoAction("item 1")).subscribe(); // ["item 1"]
store.dispatch(new AddTodoAction("item 2")).subscribe(); // ["item 1", "item 2"]
store.dispatch(new AddTodoAction("item 3")).subscribe(); // ["item 1", "item 2", "item 3"]
store.dispatch(new CompleteTodoAction("item 2")).subscribe(); // ["item 1", "item 3"]
store.dispatch(new AddTodoAction("item 4")).subscribe(); // ["item 1", "item 3", "item 4"]
store.dispatch(new UndoAction(TodoList.class)).subscribe();
// => ["item 1", "item 3"]
store.dispatch(new UndoAction(TodoList.class)).subscribe();
// => ["item 1", "item 2", "item 3"]
store.dispatch(new RedoAction(TodoList.class)).subscribe();
// => ["item 1", "item 3"]Use droidux-thunk.
class FetchTodoListAction implements AsyncAction {
private final TodoListApi client;
public FetchTodoListAction(TodoListApi client) {
this.client = client;
}
public Flowable<ReceiveTodoListAction> call(Dispatcher dispatcher) {
return dispatcher.dispatch(new DoingFetchAction())
.flatMap(_action -> client.fetch())
.map(todoList -> {
this.todoList = todoList;
return new ReceiveTodoListAction(todoList);
});
}
}
class ReceiveTodoListAction implements Action {
private final TodoList todoList;
public ReceiveTodoListAction(TodoList todoList) {
this.todoList = todoList;
}
public TodoList getTodoList() {
return todoList;
}
}
TodoListStore store = DroiduxTodoListStore.builder()
.setReducer(new TodoListReducer(), new TodoList())
.addMiddleware(new ThunkMiddleware())
.build();
store.dispatch(new FetchTodoListAction(client)).subscribe();Copyright 2015 izumin5210
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