harmony-utils之KvUtil，键值型数据库工具类

harmony-utils 简介与说明

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harmony-utils 一款功能丰富且极易上手的HarmonyOS工具库，借助众多实用工具类，致力于助力开发者迅速构建鸿蒙应用。其封装的工具涵盖了APP、设备、屏幕、授权、通知、线程间通信、弹框、吐司、生物认证、用户首选项、拍照、相册、扫码、文件、日志、异常捕获、字符、字符串、数字、集合、日期、随机、base64、加密、解密、JSON等一系列的功能和作，能够满足各种不同的开发需求。
picker_utils 是harmony-utils拆分出来的一个子库，包含 PickerUtil、PhotoHelper、ScanUtil。

下载安装
ohpm i @pura/harmony-utils
ohpm i @pura/picker_utils

//全局初始化方法，在UIAbility的onCreate方法中初始化 AppUtil.init()
 onCreate(want: Want, launchParam: AbilityConstant.LaunchParam): void {
   AppUtil.init(this.context);
 }

API方法与使用

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put 添加指定类型的键值对到数据库

KvUtil.put("name", "张三叁");
KvUtil.put("id", 10018);
KvUtil.put("sex", RandomUtil.getRandomBoolean());
KvUtil.put("info", RandomUtil.getRandomUint8Array(8));

get 获取指定键的值

let kv1 = await KvUtil.get("name");

getString 获取指定键的值，string类型

let kv2 = await KvUtil.getString('name');

getNumber 获取指定键的值，number类型

let kv3 = await KvUtil.getNumber("id");

getBoolean 获取指定键的值，boolean类型

let kv4 = await KvUtil.getBoolean('sex');

getUint8Array 获取指定键的值，uint8Array类型

let kv5 = await KvUtil.getUint8Array('info');

delete 从数据库中删除指定键值的数据

KvUtil.delete("name");
ToastUtil.showToast('删除缓存成功');

putBatch 批量插入键值对到SingleKVStore数据库中

let entries: distributedKVStore.Entry[] = [];
for (let i = 0; i < 10; i++) {
  let key = 'batch_test_string_key';
  let entry: distributedKVStore.Entry = {
    key: key + i,
    value: {
      type: distributedKVStore.ValueType.STRING,
      value: 'batch_test_string_value'
    }
  }
  entries.push(entry);
}
KvUtil.putBatch(entries).then(() = > {
  ToastUtil.showToast('批量插入成功');
}).catch((err: BusinessError) = > {
  ToastUtil.showToast('批量插入异常！');
});

deleteBatch 批量删除SingleKVStore数据库中的键值对

let keys = ["batch_test_string_key0","batch_test_string_key1","batch_test_string_key2","batch_test_string_key3"];
KvUtil.deleteBatch(keys).then(() = > {
  ToastUtil.showToast('批量删除成功');
}).catch((err: BusinessError) = > {
  ToastUtil.showToast('批量删除异常！');
});

getEntries 获取匹配指定键前缀的所有键值对

let keyPrefix = "batch_test_string_key";
KvUtil.getEntries(keyPrefix).then((entries: distributedKVStore.Entry[]) = > {
  Utils.showSheetText(JSON.stringify(entries, null, 2))
}).catch((err: BusinessError) = > {
  ToastUtil.showToast(`异常信息：${err.message}`);
});

backup 以指定名称备份数据库

let backupFile = "BK001";
KvUtil.backup(backupFile, (err: BusinessError) = > {
  if (err) {
    console.error(`Failed to backup.code is ${err.code},message is ${err.message} `);
  } else {
    console.info(`Succeeded in backupping data`);
  }
});

deleteBackup 根据指定名称删除备份文件

let files = ["BK001", "BK002"];
KvUtil.deleteBackup(files, (err: BusinessError, data: [string, number][]) = > {
  if (err) {
    console.error(`Failed to delete Backup.code is ${err.code},message is ${err.message}`);
  } else {
    console.info(`Succeed in deleting Backup.data=${data}`);
  }
});

restore 从指定的数据库文件恢复数据库

let backupFile = "BK001";
KvUtil.restore(backupFile, (err: BusinessError) = > {
  if (err) {
    console.error(`Failed to backup.code is ${err.code},message is ${err.message} `);
  } else {
    console.info(`Succeeded in backupping data`);
  }
});

onDataChange 订阅指定类型的数据变更通知

private callBack: Callback< distributedKVStore.ChangeNotification > = (change) = > {
    let pStr = JSON.stringify(change, null, 2);
    LogUtil.info(pStr);
  }
  
  KvUtil.onDataChange(distributedKVStore.SubscribeType.SUBSCRIBE_TYPE_ALL, callBack);

offDataChange 取消订阅数据变更通知

KvUtil.offDataChange(callBack);
ToastUtil.showToast('取消订阅数据变更通知');

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审核编辑 黄宇