harmony 鸿蒙@ohos.app.ability.Want (Want)

  • 2022-12-13
  • 浏览 (1341)

@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:以下各项对应的系统能力均为SystemCapability.Ability.AbilityBase

名称 类型 必填 说明
deviceId string 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 表示待启动Ability所在的应用Bundle名称。
moduleName string 表示待启动的Ability所属的模块名称。
abilityName string 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 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> 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 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schemeschemeSpecificPartauthoritypath信息。
type string 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} 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 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:

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

  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) => {
    // 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';
      
      
      let context = getContext(this) as common.UIAbilityContext; // UIAbilityContext
      let want: Want = {
        bundleName: 'com.example.myapplication',
        abilityName: 'FuncAbility',
        parameters: {
          keyForString: 'str',
        },
      };
      
      
      context.startAbility(want, (err) => {
        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';
      
      
      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(want, (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';
      
      
      let context = getContext(this) as common.UIAbilityContext; // UIAbilityContext
      let want: Want = {
        bundleName: 'com.example.myapplication',
        abilityName: 'FuncAbility',
        parameters: {
          keyForBool: true,
        },
      };
      
      
      context.startAbility(want, (err) => {
        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';
      
      
      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) => {
        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';
      
      
      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) => {
        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) => {
        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';
    
    
        let context = getContext(this) as common.UIAbilityContext; // UIAbilityContext
        let want: Want = {
          bundleName: 'com.example.myapplication1',
          abilityName: 'ServiceExtensionAbility',
        };
        context.startAbility(want, (err) => {
          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';
    
    
        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) => {
          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';
    
    
        let context = getContext(this) as common.UIAbilityContext; // UIAbilityContext
        let want: Want = {
          bundleName: 'com.example.myapplication',
          abilityName: 'UIAbilityB',
          parameters: {
            developerParameters: 'parameters',
          },
        };
        context.startAbility(want, (err) => {
          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}`);
            }
        }
    

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