查询关键资产(ArkTS)

接口介绍

接口文档链接：

query(query: AssetMap): Promise<Array<AssetMap>>

参数列表：

代码示例

查询单条关键资产明文

查询别名是demo_alias的关键资产明文。

import { asset } from '@kit.AssetStoreKit';
import { util } from '@kit.ArkTS';
import { BusinessError } from '@kit.BasicServicesKit';

function stringToArray(str: string): Uint8Array {
  let textEncoder = new util.TextEncoder();
  return textEncoder.encodeInto(str);
}

function arrayToString(arr: Uint8Array): string {
  let textDecoder = util.TextDecoder.create("utf-8", { ignoreBOM: true });
  let str = textDecoder.decodeWithStream(arr, { stream: false })
  return str;
}

let query: asset.AssetMap = new Map();
query.set(asset.Tag.ALIAS, stringToArray('demo_alias')); // 指定了关键资产别名，最多查询到一条满足条件的关键资产
query.set(asset.Tag.RETURN_TYPE, asset.ReturnType.ALL);  // 此处表示需要返回关键资产的所有信息，即属性+明文
try {
  asset.query(query).then((res: Array<asset.AssetMap>) => {
    for (let i = 0; i < res.length; i++) {
      // parse the secret.
      let secret: Uint8Array = res[i].get(asset.Tag.SECRET) as Uint8Array;
      // parse uint8array to string
      let secretStr: string = arrayToString(secret);
    }
  }).catch ((err: BusinessError) => {
    console.error(`Failed to query Asset. Code is ${err.code}, message is ${err.message}`);
  });
} catch (error) {
  let err = error as BusinessError;
  console.error(`Failed to query Asset. Code is ${err.code}, message is ${err.message}`);
}

查询单条关键资产属性

查询别名是demo_alias的关键资产属性。

import { asset } from '@kit.AssetStoreKit';
import { util } from '@kit.ArkTS';
import { BusinessError } from '@kit.BasicServicesKit';

function stringToArray(str: string): Uint8Array {
  let textEncoder = new util.TextEncoder();
  return textEncoder.encodeInto(str);
}

let query: asset.AssetMap = new Map();
query.set(asset.Tag.ALIAS, stringToArray('demo_alias'));       // 指定了关键资产别名，最多查询到一条满足条件的关键资产
query.set(asset.Tag.RETURN_TYPE, asset.ReturnType.ATTRIBUTES); // 此处表示仅返回关键资产属性，不包含关键资产明文
try {
  asset.query(query).then((res: Array<asset.AssetMap>) => {
    for (let i = 0; i < res.length; i++) {
      // parse the attribute.
      let accessibility: number = res[i].get(asset.Tag.ACCESSIBILITY) as number;
    }
  }).catch ((err: BusinessError) => {
    console.error(`Failed to query Asset. Code is ${err.code}, message is ${err.message}`);
  });
} catch (error) {
  let err = error as BusinessError;
  console.error(`Failed to query Asset. Code is ${err.code}, message is ${err.message}`);
}

批量查询关键资产属性

批量查询标签1是demo_label的关键资产属性，从第5条满足条件的结果开始返回，一共返回10条，且返回结果以DATA_LABEL_NORMAL_1属性内容排序。

import { asset } from '@kit.AssetStoreKit';
import { util } from '@kit.ArkTS';
import { BusinessError } from '@kit.BasicServicesKit';

function stringToArray(str: string): Uint8Array {
  let textEncoder = new util.TextEncoder();
  return textEncoder.encodeInto(str);
}

let query: asset.AssetMap = new Map();
query.set(asset.Tag.RETURN_TYPE, asset.ReturnType.ATTRIBUTES); // 此处表示仅返回关键资产属性，不包含关键资产明文
query.set(asset.Tag.DATA_LABEL_NORMAL_1, stringToArray('demo_label'));
query.set(asset.Tag.RETURN_OFFSET, 5); // 此处表示查询结果的偏移量，即从满足条件的第5条关键资产开始返回
query.set(asset.Tag.RETURN_LIMIT, 10); // 此处表示查询10条满足条件的关键资产
query.set(asset.Tag.RETURN_ORDERED_BY, asset.Tag.DATA_LABEL_NORMAL_1); // 此处查询结果以DATA_LABEL_NORMAL_1属性内容排序
try {
  asset.query(query).then((res: Array<asset.AssetMap>) => {
    for (let i = 0; i < res.length; i++) {
      // parse the attribute.
      let accessibility: number = res[i].get(asset.Tag.ACCESSIBILITY) as number;
    }
  }).catch ((err: BusinessError) => {
    console.error(`Failed to query Asset. Code is ${err.code}, message is ${err.message}`);
  });
} catch (error) {
  let err = error as BusinessError;
  console.error(`Failed to query Asset. Code is ${err.code}, message is ${err.message}`);
}

约束和限制

• 批量查询关键资产

批量查询出的关键资产需要通过IPC通道传输给业务，受IPC缓冲区大小限制，建议对查询超过40条关键资产时，进行分批查询，且每次查询数量不超过40条。