update zh-cn/application-dev/reference/apis/js-apis-data-preferences.md.

Signed-off-by: N葛亚芳 <geyafang@huawei.com>

zh-cn/application-dev/reference/apis/js-apis-data-preferences.md

@@ -69,9 +69,9 @@ Stage模型示例：
 
 ```ts
 // 获取context
-import Ability from '@ohos.application.Ability';
+import UIAbility from '@ohos.app.ability.UIAbility';
 let context = null;
-class MainAbility extends Ability{
+class EntryAbility extends UIAbility {
     onWindowStageCreate(windowStage){
         context = this.context;
     }
@@ -139,9 +139,9 @@ Stage模型示例：
 
 ```ts
 // 获取context
-import Ability from '@ohos.application.Ability';
+import UIAbility from '@ohos.app.ability.UIAbility';
 let context = null;
-class MainAbility extends Ability{
+class EntryAbility extends UIAbility {
     onWindowStageCreate(windowStage){
         context = this.context;
     }
@@ -215,9 +215,9 @@ Stage模型示例：
 
 ```ts
 // 获取context
-import Ability from '@ohos.application.Ability';
+import UIAbility from '@ohos.app.ability.UIAbility';
 let context = null;
-class MainAbility extends Ability{
+class EntryAbility extends UIAbility {
     onWindowStageCreate(windowStage){
         context = this.context;
     }
@@ -294,9 +294,9 @@ Stage模型示例：
 
 ```ts
 // 获取context
-import Ability from '@ohos.application.Ability';
+import UIAbility from '@ohos.app.ability.UIAbility';
 let context = null;
-class MainAbility extends Ability{
+class EntryAbility extends UIAbility {
     onWindowStageCreate(windowStage){
         context = this.context;
     }
@@ -358,9 +358,9 @@ Stage模型示例：
 
 ```ts
 // 获取context
-import Ability from '@ohos.application.Ability';
+import UIAbility from '@ohos.app.ability.UIAbility';
 let context = null;
-class MainAbility extends Ability{
+class EntryAbility extends UIAbility {
     onWindowStageCreate(windowStage){
         context = this.context;
     }
@@ -428,9 +428,9 @@ Stage模型示例：
 
 ```ts
 // 获取context
-import Ability from '@ohos.application.Ability';
+import UIAbility from '@ohos.app.ability.UIAbility';
 let context = null;
-class MainAbility extends Ability{
+class EntryAbility extends UIAbility {
     onWindowStageCreate(windowStage){
         context = this.context;
     }