程序包 ohos.aafwk.abilityjet.databinding

类 DataBinding

java.lang.Object

ohos.aafwk.abilityjet.databinding.DataBinding

public abstract class DataBinding
extends Object

A base class of automatically generated binding code that implements binding between ComponentContainer and ActiveData objects.

When a ComponentContainer or ActiveData object is modified, the DataBinding object automatically modifies the object bound to the ComponentContainer or ActiveData. For example, if you modified the attribute of a ComponentContainer, DataBinding will synchronize the attribute value to the ActiveData object bound to the ComponentContainer. Similarly, if the attribute value of an ActiveData object is changed, the attribute value of the bound ComponentContainer will also be updated.

To enable the data binding feature, you must first add "dataBindingEnable true" to the build.gradle file of the current module as follows:

 
 ohos {
     ...
     buildTypes {
         debug {
             dataBindingEnabled true
         }
         ...
     }
 }
 
 

Before using the DataBinding class, use an ActiveData object to define the data to observe, the data type to bind, and the set() and get() methods. The sample code snippet is as follows:

 
 import ohos.aafwk.abilityjet.activedata.ActiveData;

 public class FruitComponentModel {
     private ActiveData<String> price;

     public ActiveData<String> getPrice() {
         return price;
     }

     public void setPrice(ActiveData<String> price) {
         this.price = price;
     }
 }
 
 

Then, declare the data to be bound by DataBinding in the layout file. Example declaration:

In this example, a binding is declared in fruit.xml and the system will automatically generate a FruitBinding class after the compilation. You can call the DataBindingUtil#createBinding(int, Context, String) method to obtain a FruitBinding object and call initComponent(ohos.agp.components.ComponentContainer) and setLifecycle(ohos.aafwk.ability.Lifecycle) to initialize the object. The obtained FruitBinding object then calls the method defined in FruitComponentModel to bind it to an ActiveData object. Example code:

 

 public class FruitSlice extends AbilitySlice {
     private static final HiLogLabel LABEL_LOG = new HiLogLabel(3, 0xD001100, "FruitSlice");

     private FruitBinding binding;

     @Override
     public onStart(Intent intent) {
         super.onStart(intent);
         ComponentContainer componentContainer =
             (ComponentContainer) LayoutScatter.getInstance(this).parse(ResourceTable.Layout_fruit, null, false);
         if (!(componentContainer instanceof ComponentContainer)) {
             return;
         }
         super.setUIContent(componentContainer);

         try {
             binding = DataBindingUtil.createBinding(ResourceTable.Layout_fruit, getContext(), "ohos.myapplication");
         } catch (IllegalArgumentException | IOException exception) {
             HiLog.info(LABEL_LOG, exception.toString());
         }

         if(binding != null) {
             binding.initComponent(componentContainer);
             binding.setLifecycle(getLifecycle());
             ActiveData<String> price = new ActiveData<>();
             price.setData("7.23");
             FruitComponentModel apple = new FruitComponentModel();
             apple.setPrice(price);
             binding.setApple(apple);
         }
     }
 }
 
 

从以下版本开始:

1

另请参阅:

ComponentContainer, ActiveData

SystemCapability

SystemCapability.Aafwk#ABILITYJET

构造器概要

构造器

构造器	说明
DataBinding()

方法概要

限定符和类型	方法	说明
Lifecycle	getLifecycle()	Obtains the lifecycle of the bound object.
abstract void	initComponent(ComponentContainer componentContainer)	Initializes the bound components by using ComponentContainer.
void	setLifecycle(Lifecycle lifecycle)	Sets the lifecycle of the bound object.

从类继承的方法 java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

构造器详细资料

DataBinding

public DataBinding()

方法详细资料

setLifecycle

public void setLifecycle(Lifecycle lifecycle)

Sets the lifecycle of the bound object.

The lifecycle of the bound object is required because the data of the object can be updated only when it is visible (either in the ACTIVE or INACTIVE state). You are advised to set the lifecycle when initializing the ability slice that hosts the bound object.

参数:

lifecycle - Indicates the lifecycle of the bound object.

抛出:

IllegalStateException - Lifecycle can't set twice.

从以下版本开始:

1

getLifecycle

public Lifecycle getLifecycle()

Obtains the lifecycle of the bound object.

You can use Lifecycle to query the lifecycle state of the bound object and listens for its lifecycle changes.

返回:

Returns the lifecycle of the bound object.

从以下版本开始:

1

initComponent

public abstract void initComponent(ComponentContainer componentContainer)

Initializes the bound components by using ComponentContainer.

参数:

componentContainer - Indicates the group of components to initialize.

从以下版本开始:

4