1# 启动指定页面
2
3
4当PageAbility的启动模式设置为单例时（具体设置方法和典型场景示例见[PageAbility的启动模式](pageability-launch-type.md)，缺省情况下是单实例模式），若PageAbility已被拉起，再次启动PageAbility会触发onNewWant回调（即非首次拉起）。应用开发者可以通过want传递启动参数，例如开发者希望指定页面启动PageAbility，可以通过want中的parameters参数传递pages信息，具体示例代码如下：
5
6
7调用方PageAbility的app.ets中或者page中，使用startAbility再次拉起PageAbility，通过want中的uri参数传递页面信息：
8
9```ts
10import featureAbility from '@ohos.ability.featureAbility';
11import Want from '@ohos.app.ability.Want';
12import hilog from '@ohos.hilog';
13
14const TAG: string = 'PagePageAbilityFirst';
15const domain: number = 0xFF00;
16```
17```ts
18(async (): Promise<void> => {
19  let wantInfo: Want = {
20    bundleName: 'com.samples.famodelabilitydevelop',
21    abilityName: 'com.samples.famodelabilitydevelop.PageAbilitySingleton',
22    parameters: { page: 'pages/second' }
23  };
24  featureAbility.startAbility({ want: wantInfo }).then((data) => {
25    hilog.debug(domain, TAG, `restartAbility success : ${data}`);
26  });
27})()
28```
29
30
31在目标端PageAbility的onNewWant回调中获取包含页面信息的want参数：
32
33```ts
34// GlobalContext.ts 构造单例对象
35export class GlobalContext {
36  private constructor() {
37  }
38
39  private static instance: GlobalContext;
40  private _objects = new Map<string, Object>();
41
42  public static getContext(): GlobalContext {
43    if (!GlobalContext.instance) {
44      GlobalContext.instance = new GlobalContext();
45    }
46    return GlobalContext.instance;
47  }
48
49  getObject(value: string): Object | undefined {
50    return this._objects.get(value);
51  }
52
53  setObject(key: string, objectClass: Object): void {
54    this._objects.set(key, objectClass);
55  }
56}
57```
58
59```ts
60import Want from '@ohos.app.ability.Want';
61import featureAbility from '@ohos.ability.featureAbility';
62import { GlobalContext } from '../utils/GlobalContext';
63
64class PageAbilitySingleton {
65  onNewWant(want: Want) {
66    featureAbility.getWant().then((want) => {
67      GlobalContext.getContext().setObject('newWant', want);
68    })
69  }
70}
71
72export default new PageAbilitySingleton();
73```
74
75
76在目标端页面的自定义组件中获取包含页面信息的want参数并根据uri做路由处理：
77
78```ts
79import Want from '@ohos.app.ability.Want';
80import router from '@ohos.router';
81import { GlobalContext } from '../../utils/GlobalContext';
82
83@Entry
84@Component
85struct First {
86  onPageShow() {
87    let newWant = GlobalContext.getContext().getObject('newWant') as Want;
88    if (newWant) {
89      if (newWant.parameters) {
90        if (newWant.parameters.page) {
91          router.pushUrl({ url: newWant.parameters.page as string});
92          GlobalContext.getContext().setObject("newWant", undefined)
93        }
94      }
95    }
96  }
97
98  build() {
99    Column() {
100      Row() {
101        Text('singleton_first_title')
102          .fontSize(24)
103          .fontWeight(FontWeight.Bold)
104          .textAlign(TextAlign.Start)
105          .margin({ top: 12, bottom: 11, right: 24, left: 24 })
106      }
107      .width('100%')
108      .height(56)
109      .justifyContent(FlexAlign.Start)
110
111      Image('pic_empty')
112        .width(120)
113        .height(120)
114        .margin({ top: 224 })
115
116      Text('no_content')
117        .fontSize(14)
118        .margin({ top: 8, bottom: 317, right: 152, left: 152 })
119        .fontColor('text_color')
120        .opacity(0.4)
121    }
122    .width('100%')
123    .height('100%')
124    .backgroundColor('backGrounding')
125  }
126}
127```
128
129
130当PageAbility的启动模式设置为多实例模式或为首次启动单例模式的PageAbility时（具体设置方法和典型场景示例见[PageAbility的启动模式](pageability-launch-type.md)），在调用方PageAbility中，通过want中的parameters参数传递要启动的指定页面的pages信息，调用startAbility()方法启动PageAbility。被调用方可以在onCreate中使用featureAbility的getWant方法获取want，再通过调用router.pushUrl实现启动指定页面。
131
132
133调用方的页面中实现按钮点击触发startAbility方法启动目标端PageAbility，startAbility方法的入参want中携带指定页面信息，示例代码如下：
134
135```ts
136import featureAbility from '@ohos.ability.featureAbility';
137import Want from '@ohos.app.ability.Want';
138import { BusinessError } from '@ohos.base';
139import fs from '@ohos.file.fs';
140import promptAction from '@ohos.promptAction';
141import worker from '@ohos.worker';
142import hilog from '@ohos.hilog';
143
144const TAG: string = 'PagePageAbilityFirst';
145const domain: number = 0xFF00;
146
147@Entry
148@Component
149struct PagePageAbilityFirst {
150  build() {
151    Column() {
152      //...
153      List({ initialIndex: 0 }) {
154        //...
155        ListItem() {
156          Flex({ justifyContent: FlexAlign.SpaceBetween, alignContent: FlexAlign.Center }) {
157          //...
158          }
159          .onClick(() => {
160            let want: Want = {
161              bundleName: 'com.samples.famodelabilitydevelop',
162              abilityName: 'com.samples.famodelabilitydevelop.PageAbilityStandard',
163              parameters: { page: 'pages/first' }
164            };
165            featureAbility.startAbility({ want: want }).then((data) => {
166              hilog.info(domain, TAG, `startAbility finish:${data}`);
167            }).catch((err: BusinessError) => {
168              hilog.info(domain, TAG, `startAbility failed errcode:${err.code}`);
169            })
170          })
171        }
172        //...
173        ListItem() {
174          Flex({ justifyContent: FlexAlign.SpaceBetween, alignContent: FlexAlign.Center }) {
175          //...
176          }
177          .onClick(() => {
178            let want: Want = {
179              bundleName: 'com.samples.famodelabilitydevelop',
180              abilityName: 'com.samples.famodelabilitydevelop.PageAbilityStandard',
181              parameters: { page: 'pages/second' }
182            };
183            featureAbility.startAbility({ want: want }).then((data) => {
184              hilog.info(domain, TAG, `startAbility finish:${data}`);
185            }).catch((err: BusinessError) => {
186              hilog.info(domain, TAG, `startAbility failed errcode:${err.code}`);
187            })
188          })
189        }
190        //...
191      }
192      //...
193    }
194    //...
195  }
196}
197```
198
199
200目标端PageAbility的onCreate生命周期回调中通过featureAbility的getWant方法获取want，并对参数进行解析，实现指定页面拉起：
201
202```ts
203import featureAbility from '@ohos.ability.featureAbility';
204import router from '@ohos.router';
205
206class PageAbilityStandard {
207  onCreate() {
208    featureAbility.getWant().then((want) => {
209      if (want.parameters) {
210        if (want.parameters.page) {
211          router.pushUrl({ url: want.parameters.page as string });
212        }
213      }
214    })
215  }
216}
217
218export default new PageAbilityStandard();
219```
220