@ohos.app.ability.Want (Want)

Want是对象间信息传递的载体，可以用于应用组件间的信息传递。Want的使用场景之一是作为startAbility的参数，其包含了指定的启动目标，以及启动时需携带的相关数据，例如bundleName和abilityName字段分别指明目标Ability所在应用的包名以及对应包内的Ability名称。当UIAbilityA需要启动UIAbilityB并传入一些数据时，可使用Want作为载体将这些数据传递给UIAbilityB。

说明：

本模块首批接口从API version 9 开始支持。后续版本的新增接口，采用上角标单独标记接口的起始版本。

导入模块

import Want from '@ohos.app.ability.Want';

属性

系统能力：SystemCapability.Ability.AbilityBase

名称 类型 必填 说明
deviceId string 否 表示运行指定Ability的设备ID。如果未设置该字段，则表明指定本设备。
bundleName string 否 表示待启动Ability所在的应用Bundle名称。
moduleName string 否 表示待启动的Ability所属的模块名称。
abilityName string 否 表示待启动Ability名称。如果在Want中该字段同时指定了BundleName和AbilityName，则Want可以直接匹配到指定的Ability。AbilityName需要在一个应用的范围内保证唯一。
action string 否 表示要执行的通用操作（如：查看、分享、应用详情）。在隐式Want中，您可以定义该字段，配合uri或parameters来表示对数据要执行的操作。隐式Want定义及匹配规则请参见显式Want与隐式Want匹配规则。
entities Array<string> 否 表示目标Ability额外的类别信息（如：浏览器、视频播放器）。在隐式Want中是对action字段的补充。在隐式Want中，您可以定义该字段，来过滤匹配Ability类型。
uri string 否 表示携带的数据，一般配合type使用，指明待处理的数据类型。如果在Want中指定了uri，则Want将匹配指定的Uri信息，包括scheme、schemeSpecificPart、authority和path信息。
type string 否 表示MIME type类型描述，打开文件的类型，主要用于文管打开文件。比如：'text/xml' 、 'image/*'等，MIME定义请参见https://www.iana.org/assignments/media-types/media-types.xhtml?utm_source=ld246.com。
parameters {[key: string]: any} 否 表示WantParams描述，由开发者自行决定传入的键值对。默认会携带以下key值：
- ohos.aafwk.callerPid：表示拉起方的pid。
- ohos.aafwk.param.callerBundleName：表示拉起方的Bundle Name。
- ohos.aafwk.param.callerToken：表示拉起方的token。
- ohos.aafwk.param.callerUid：表示BundleInfo中的uid，应用包里应用程序的uid。
- component.startup.newRules：表示是否启用新的管控规则。
- moduleName：表示拉起方的模块名，该字段的值即使定义成其他字符串，在传递到另一端时会被修改为正确的值。
- ohos.dlp.params.sandbox：表示dlp文件才会有。
- ability.params.backToOtherMissionStack：表示是否支持跨任务链返回。
flags number 否 表示处理Want的方式。默认传数字。
例如通过wantConstant.Flags.FLAG_ABILITY_CONTINUATION表示是否以设备间迁移方式启动Ability。

示例：

  • 基础用法：在UIAbility对象中调用，示例中的context的获取方式请参见获取UIAbility的上下文信息。

    import common from '@ohos.app.ability.common';
import Want from '@ohos.app.ability.Want';
import { BusinessError } from '@ohos.base';

let context = getContext(this) as common.UIAbilityContext; // UIAbilityContext
let want: Want = {
  deviceId: '', // deviceId为空表示本设备
  bundleName: 'com.example.myapplication',
  abilityName: 'FuncAbility',
  moduleName: 'entry' // moduleName非必选
};

context.startAbility(want, (err: BusinessError) => {
  if (err.code) {
    // 显式拉起Ability，通过bundleName、abilityName和moduleName可以唯一确定一个Ability
    console.error(`Failed to startAbility. Code: ${err.code}, message: ${err.message}`);
  }
});

  • 目前支持的数据类型有：字符串、数字、布尔、对象、数组和文件描述符等。

    • 字符串（String）
      import common from '@ohos.app.ability.common';
import Want from '@ohos.app.ability.Want';
import { BusinessError } from '@ohos.base';

let context = getContext(this) as common.UIAbilityContext; // UIAbilityContext
let want: Want = {
  bundleName: 'com.example.myapplication',
  abilityName: 'FuncAbility',
  parameters: {
    keyForString: 'str',
  },
};

context.startAbility(want, (err: BusinessError) => {
  if (err.code) {
    console.error(`Failed to startAbility. Code: ${err.code}, message: ${err.message}`);
  }
});
    • 数字（Number）
      import common from '@ohos.app.ability.common';
import Want from '@ohos.app.ability.Want';
import { BusinessError } from '@ohos.base';

let context = getContext(this) as common.UIAbilityContext; // UIAbilityContext
let want: Want = {
  bundleName: 'com.example.myapplication',
  abilityName: 'FuncAbility',
  parameters: {
    keyForInt: 100,
    keyForDouble: 99.99,
  },
};

context.startAbility(wan, (err) => {
  console.error(`Failed to startAbility. Code: ${err.code}, message: ${err.message}`);
});
    • 布尔（Boolean）
      import common from '@ohos.app.ability.common';
import Want from '@ohos.app.ability.Want';
import { BusinessError } from '@ohos.base';

let context = getContext(this) as common.UIAbilityContext; // UIAbilityContext
let want: Want = {
  bundleName: 'com.example.myapplication',
  abilityName: 'FuncAbility',
  parameters: {
    keyForBool: true,
  },
};

context.startAbility(want, (err: BusinessError) => {
  if (err.code) {
    console.error(`Failed to startAbility. Code: ${err.code}, message: ${err.message}`);
  }
});
    • 对象（Object）
      import common from '@ohos.app.ability.common';
import Want from '@ohos.app.ability.Want';
import { BusinessError } from '@ohos.base';

let context = getContext(this) as common.UIAbilityContext; // UIAbilityContext
let want: Want = {
  bundleName: 'com.example.myapplication',
  abilityName: 'FuncAbility',
  parameters: {
    keyForObject: {
      keyForObjectString: 'str',
      keyForObjectInt: -200,
      keyForObjectDouble: 35.5,
      keyForObjectBool: false,
    },
  },
};

context.startAbility(want, (err: BusinessError) => {
  if (err.code) {
    console.error(`Failed to startAbility. Code: ${err.code}, message: ${err.message}`);
  }
});
    • 数组（Array）
      import common from '@ohos.app.ability.common';
import Want from '@ohos.app.ability.Want';
import { BusinessError } from '@ohos.base';

let context = getContext(this) as common.UIAbilityContext; // UIAbilityContext
let want: Want = {
  bundleName: 'com.example.myapplication',
  abilityName: 'FuncAbility',
  parameters: {
    keyForArrayString: ['str1', 'str2', 'str3'],
    keyForArrayInt: [100, 200, 300, 400],
    keyForArrayDouble: [0.1, 0.2],
    keyForArrayObject: [{ obj1: 'aaa' }, { obj2: 100 }],
  },
};

context.startAbility(want, (err: BusinessError) => {
  if (err.code) {
    console.error(`Failed to startAbility. Code: ${err.code}, message: ${err.message}`);
  }
});
    • 文件描述符（FD）
        import fs from '@ohos.file.fs';
  import common from '@ohos.app.ability.common';
  import Want from '@ohos.app.ability.Want';
  import { BusinessError } from '@ohos.base';

  let context = getContext(this) as common.UIAbilityContext; // UIAbilityContext

  let fd: number = 0;
  try {
    fd = fs.openSync('/data/storage/el2/base/haps/pic.png').fd;
  } catch(err) {
    let code = (err as BusinessError).code;
    let message = (err as BusinessError).message;
    console.error(`Failed to openSync. Code: ${code}, message: ${message}`);
  }
  let want: Want = {
    deviceId: '', // deviceId为空表示本设备
    bundleName: 'com.example.myapplication',
    abilityName: 'FuncAbility',
    moduleName: 'entry', // moduleName非必选
    parameters: {
      'keyFd': { 'type': 'FD', 'value': fd } // {'type':'FD', 'value':fd}是固定用法，用于表示该数据是FD
    }
  };

  context.startAbility(want, (err: BusinessError) => {
    if (err.code) {
      console.error(`Failed to startAbility. Code: ${err.code}, message: ${err.message}`);
    }
  });

    • parameter参数用法：

      • 以ability.params.backToOtherMissionStack为例，ServiceExtension在拉起UIAbility的时候，可以支持跨任务链返回。
        // (1) UIAbility1启动一个ServiceExtension
  import common from '@ohos.app.ability.common';
  import Want from '@ohos.app.ability.Want';
  import { BusinessError } from '@ohos.base';

  let context = getContext(this) as common.UIAbilityContext; // UIAbilityContext
  let want: Want = {
    bundleName: 'com.example.myapplication1',
    abilityName: 'ServiceExtensionAbility',
  };
  context.startAbility(want, (err: BusinessError) => {
    if (err.code) {
      console.error(`Failed to startAbility. Code: ${err.code}, message: ${err.message}`);
    }
  });

        // (2) 该ServiceExtension去启动另一个UIAbility2，并在启动的时候携带参数ability.params.backToOtherMissionStack为true
  import common from '@ohos.app.ability.common';
  import Want from '@ohos.app.ability.Want';
  import { BusinessError } from '@ohos.base';

  let context = getContext(this) as common.ServiceExtensionContext; // ServiceExtensionContext
  let want: Want = {
    bundleName: 'com.example.myapplication2',
    abilityName: 'MainAbility',
    parameters: {
      "ability.params.backToOtherMissionStack": true,
    },
  };

  context.startAbility(want, (err: BusinessError) => {
    if (err.code) {
      console.error(`Failed to startAbility. Code: ${err.code}, message: ${err.message}`);
    }
  });

      说明：上例中，如果ServiceExtension启动UIAbility2时不携带ability.params.backToOtherMissionStack参数，或者携带的ability.params.backToOtherMissionStack参数为false，则UIAbility1和UIAbility2不在同一个任务栈里面，在UIAbility2的界面点back键，不会回到UIAbility1的界面。如果携带的ability.params.backToOtherMissionStack参数为true，则表示支持跨任务链返回，此时在UIAbility2的界面点back键，会回到UIAbility1的界面。

      • parameter携带开发者自定义参数，由UIAbilityA传递给UIAbilityB，并在UIAbilityB中进行获取。
        // (1) UIAbilityA通过startability启动UIAbilityB
  import common from '@ohos.app.ability.common';
  import Want from '@ohos.app.ability.Want';
  import { BusinessError } from '@ohos.base';

  let context = getContext(this) as common.UIAbilityContext; // UIAbilityContext
  let want: Want = {
    bundleName: 'com.example.myapplication',
    abilityName: 'UIAbilityB',
    parameters: {
      developerParameters: 'parameters',
    },
  };
  context.startAbility(want, (err: BusinessError) => {
    if (err.code) {
      console.error(`Failed to startAbility. Code: ${err.code}, message: ${err.message}`);
    }
  });

        // (2) 以UIAbilityB实例首次启动为例，会进入到UIAbilityB的onCreate生命周期
  import UIAbility from '@ohos.app.ability.UIAbility';
  import AbilityConstant from '@ohos.app.ability.AbilityConstant';
  import Want from '@ohos.app.ability.Want';

  class UIAbilityB extends UIAbility {
    onCreate(want: Want, launchParam: AbilityConstant.LaunchParam) {
      console.log(`onCreate, want parameters: ${want.parameters?.developerParameters}`);
    }
  }