[Context](../reference/apis/js-apis-inner-application-context.md) is the context of an object in an application. It provides basic information about the application, for example, **resourceManager**, **applicationInfo**, **dir** (application development path), and **area** (encrypted area). It also provides basic methods such as **createBundleContext()** and **getApplicationContext()**. The UIAbility component and ExtensionAbility derived class components have their own **Context** classes, for example, the base class **Context**, **ApplicationContext**, **AbilityStageContext**, **UIAbilityContext**, **ExtensionContext**, and **ServiceExtensionContext**.
- The figure below illustrates the inheritance relationship of contexts.
- The following describes the information provided by different contexts.
-[UIAbilityContext](../reference/apis/js-apis-inner-application-uiAbilityContext.md): Each UIAbility has the **Context** attribute, which provides APIs to operate the ability, obtain the ability configuration, and more.
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@@ -89,7 +91,8 @@ The following table describes the application development paths obtained from co
The capability of obtaining the application development path is provided by the base class **Context**. This capability is also provided by **ApplicationContext**, **AbilityStageContext**, **UIAbilityContext**, and **ExtensionContext**. However, the paths obtained from different contexts may differ, as shown below.
**Figure 1** Application development paths obtained from context
- Obtain the application-level path through **ApplicationContext**. It is recommended that global application information be stored in this path. Files stored in this path will be deleted only when the application is uninstalled.
| Name| Path|
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@@ -174,7 +177,7 @@ The base class **Context** provides the [createBundleContext(bundleName:string)]
>
> - Request the **ohos.permission.GET_BUNDLE_INFO_PRIVILEGED** permission. For details, see [Permission Application Guide](../security/accesstoken-guidelines.md#declaring-permissions-in-the-configuration-file).
>
> - This is a system API and cannot be called by third-party applications.
> - This is a system API and cannot be called by third-party applications.
For example, application information displayed on the home screen includes the application name and icon. The home screen application calls the foregoing method to obtain the context information, so as to obtain the resource information including the application name and icon.
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@@ -189,7 +192,7 @@ The base class **Context** provides the [createBundleContext(bundleName:string)]
// ...
}
}
```
```
- Call **createModuleContext(bundleName:string, moduleName:string)** to obtain the context of a specified module of another application. After obtaining the context, you can obtain the resource information of that module.
> **NOTE**
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@@ -198,7 +201,7 @@ The base class **Context** provides the [createBundleContext(bundleName:string)]
>
> - Request the **ohos.permission.GET_BUNDLE_INFO_PRIVILEGED** permission. For details, see [Permission Application Guide](../security/accesstoken-guidelines.md#declaring-permissions-in-the-configuration-file).
>
> - This is a system API and cannot be called by third-party applications.
> - This is a system API and cannot be called by third-party applications.
@@ -67,7 +67,7 @@ Users often need to share data (such as a text or an image) from one application
For example, when **"ability.picker.type"** is **"application/pdf"**, **"ability.picker.fileNames"** is **"["APIs.pdf"]"**, and **"ability.picker.fileSizes"** is **"[350 \* 1024]"**, the application selector is displayed as follows:
In the preceding code, the **ability.want.params.INTENT** field is nested Want. In this field, **action** and **type** are used for implicit matching by the application selector. For details about implicit matching, see [Matching Rules of Implicit Want](explicit-implicit-want-mappings.md#matching-rules-of-implicit-want). After the user selects an application, the nested Want of the **ability.want.params.INTENT** field is passed to that application.
@@ -61,7 +61,8 @@ The system matches the [action](../reference/apis/js-apis-ability-wantConstant.m
- If **action** in the passed **want** parameter is specified, and **actions** under **skills** of an ability is specified but does not contain **action** in the passed **want** parameter, the matching fails.
**Figure 1** Matching rules of action in the want parameter
### Matching Rules of entities in the want Parameter
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@@ -78,8 +79,9 @@ The system matches the [entities](../reference/apis/js-apis-ability-wantConstant
- If **entities** in the passed **want** parameter is specified, and **entities** under **skills** of an ability is specified but does not contain **entities** in the passed **want** parameter, the matching fails.
Figure 2 Matching rule of entities in the want parameter
Figure 2 Matching rule of entities in the want parameter
### Matching Rules of uri and type in the want Parameter
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@@ -87,7 +89,8 @@ The system matches the [entities](../reference/apis/js-apis-ability-wantConstant
When the **uri** and **type** parameters are specified in the **want** parameter to initiate a component startup request, the system traverses the list of installed components and matches the **uris** array under **skills** of the abilities one by one. If one of the **uris** arrays under **skills** matches the **uri** and **type** in the passed **want**, the matching is successful.
Figure 3 Matching rules when uri and type are specified in the want parameter
- Cross-device migration task management: The initiator accepts a migration request from the user, provides a migration entry, and displays the migration result. (This capability is unavailable yet.)
@@ -92,7 +92,8 @@ Before using EventHub, you must obtain an EventHub object, which is provided by
**globalThis** is a global object inside the [ArkTS engine instance](thread-model-stage.md) and can be used by UIAbility, ExtensionAbility, and Page inside the engine. Therefore, you can use **globalThis** for data synchronization.
**Figure 1** Using globalThis for data synchronization
The following describes how to use **globalThis** in three scenarios. Precautions are provided as well.
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@@ -209,6 +210,7 @@ To implement data synchronization between the UIAbility and ExtensionAbility com
### Precautions for Using globalThis
**Figure 2** Precautions for globalThis
- In the stage model, all the UIAbility components in a process share one ArkTS engine instance. When using **globalThis**, do not store objects with the same name. For example, if AbilityA and AbilityB use **globalThis** to store two objects with the same name, the object stored earlier will be overwritten.
- The caller ability uses **startAbilityByCall** to obtain a caller object and uses **call()** of the caller object to send data to the callee ability.
For example, there are EntryAbility and SpecifiedAbility, and the launch type of SpecifiedAbility is set to **specified**. You are required to start SpecifiedAbility from EntryAbility.
After the UIAbility instance is created but before it enters the **Foreground** state, the system creates a WindowStage instance and triggers the **onWindowStageCreate()** callback. You can set UI loading and WindowStage event subscription in the callback.
**Figure 2** WindowStageCreate and WindowStageDestory
In the **onWindowStageCreate()** callback, use [loadContent()](../reference/apis/js-apis-window.md#loadcontent9-2) to set the page to be loaded, and call [on('windowStageEvent')](../reference/apis/js-apis-window.md#onwindowstageevent9) to subscribe to [WindowStage events](../reference/apis/js-apis-window.md#windowstageeventtype9), for example, having or losing focus, or becoming visible or invisible.
[Want](../reference/apis/js-apis-app-ability-want.md) is used as the carrier to transfer information between application components. It is used as a parameter of **startAbility()** to specify the startup target and information that needs to be carried during startup, for example, **bundleName** and **abilityName**, which respectively indicate the bundle name of the target ability and the ability name in the bundle. For example, when UIAbilityA starts UIAbilityB and needs to transfer some data to UIAbilityB, it can use Want to transfer the data.
The COM port whose **type** is **cmd** corresponds to the AT command serial port on the board. The port is used to send commands to the device. In the example, the **ChA(COM20)** serial port is used.
IP camera devices have two connection modes. One is to connect through the local serial port, and the other is to connect through the IP address of the local area network.
Add an NFS sharing path, for example, **D:\HS\NFS_Share_File -public –alldirs**. Note that the FTP IP address 192.168.1.10 is the IP address of the development board.
<img src="figures/NFS-2.PNG" style="zoom:75%;" />
3. Stop the NFS server and restart the NFS server to make the added sharing path take effect.
