harmony 鸿蒙Want

2022-12-22
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Want

Want is a carrier for information transfer between objects (application components). Want can be used as a parameter of startAbility to specify a 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. When ability A needs to start ability B and transfer some data to ability B, it can use Want a carrier to transfer the data.

NOTE

The APIs of this module are supported since API version 6 and deprecated since API version 9. You are advised to use @ohos.app.ability.Want instead. Newly added APIs will be marked with a superscript to indicate their earliest API version.

Modules to Import

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

Attributes

System capability: SystemCapability.Ability.AbilityBase

Name	Type	Mandatory	Description
deviceId	string	No	ID of the device running the ability. If this field is unspecified, the local device is used.
bundleName	string	No	Bundle name.
abilityName	string	No	Name of the ability. If both bundleName and abilityName are specified in a Want object, the Want object can match a specific ability. The value of abilityName must be unique in an application.
uri	string	No	URI. If uri is specified in a Want object, the Want object will match the specified URI information, including scheme, schemeSpecificPart, authority, and path.
type	string	No	MIME type, that is, the type of the file to open, for example, ‘text/xml’ and *‘image/’**. For details about the MIME type definition, see https://www.iana.org/assignments/media-types/media-types.xhtml?utm_source=ld246.com.
flags	number	No	How the Want object will be handled. By default, numbers are passed in. For details, see flags.
action	string	No	Action to take, such as viewing and sharing application details. In implicit Want, you can define this field and use it together with uri or parameters to specify the operation to be performed on the data. For details, see action. For details about the definition and matching rules of implicit Want, see Matching Rules of Explicit Want and Implicit Want.
parameters	{[key: string]: Object}	No	Want parameters in the form of custom key-value (KV) pairs. By default, the following keys are carried: - ohos.aafwk.callerPid: PID of the caller. - ohos.aafwk.param.callerToken: token of the caller. - ohos.aafwk.param.callerUid: UID in bundleInfo, that is, the application UID in the bundle information. - component.startup.newRules: whether to enable the new control rule. - moduleName: module name of the caller. No matter what this field is set to, the correct module name will be sent to the peer. - ohos.dlp.params.sandbox: available only for DLP files.
entities	Array<string>	No	Additional category information (such as browser and video player) of the target ability. It is a supplement to action in implicit Want and is used to filter ability types. For details, see entity.

Example

Basic usage (called in a UIAbility object, where context in the example is the context object of the UIAbility).

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

  let want: Want = {
    deviceId: '', // An empty deviceId indicates the local device.
    bundleName: 'com.example.myapplication',
    abilityName: 'EntryAbility',
    moduleName: 'entry', // moduleName is optional.
  };
  this.context.startAbility(want, (error: BusinessError) => {
      // Start an ability explicitly. The bundleName, abilityName, and moduleName parameters work together to uniquely identify an ability.
      console.error('error.code = ${error.code}');
  });

Passing a file descriptor (FD) (called in the UIAbility object, where context in the example is the context object of the UIAbility):

  import fs from '@ohos.file.fs';
  import Want from '@ohos.app.ability.Want';
  import { BusinessError } from '@ohos.base';
  // ...
  let fd: number = 0;
  try {
      fd = fs.openSync('/data/storage/el2/base/haps/pic.png').fd;
  } catch(e) {
      console.error(`openSync fail: ${JSON.stringify(e)}`);
  }
  let want: Want = {
    deviceId: '', // An empty deviceId indicates the local device.
    bundleName: 'com.example.myapplication',
    abilityName: 'EntryAbility',
    moduleName: 'entry', // moduleName is optional.
    parameters: {
          'keyFd':{'type':'FD', 'value':fd}
      }
  };
  this.context.startAbility(want, (error: BusinessError) => {
      // Start an ability explicitly. The bundleName, abilityName, and moduleName parameters work together to uniquely identify an ability.
      console.error(`error.code = ${error.code}`);
  });
  // ...