HarmonyOS基础技术赋能之分布式数据服务功能
系统运维 2025-10-08 06:11:46
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想了解更多内容，基据服请访问：
和华为官方合作共建的础技鸿蒙技术社区
https://harmonyos.51cto.com
引言
分布式数据服务(Distributed Data Service，DDS) 为应用程序提供不同设备间数据库数据分布式的术赋式数能力。通过调用分布式数据接口，分布应用程序将数据保存到分布式数据库中。基据服通过结合帐号、础技应用和数据库三元组，术赋式数分布式数据服务对属于不同应用的分布数据进行隔离，保证不同应用之间的基据服数据不能通过分布式数据服务互相访问。在通过可信认证的础技设备间，分布式数据服务支持应用数据相互同步，术赋式数为用户提供在多种终端设备上最终一致的分布数据访问体验。
功能介绍
此次通过HarmonyOS的基据服分布式数据服务能力，一方面可以实现自身应用界面的础技数据实时更新;另一方面也可以实现不同设备之间的数据实时更新。前提是术赋式数在不同设备之间，要实现分布式数据服务的同步能力，需要同一个华为账号登录、网站模板并一个应用包名、同一个网络之间进行，也可以两个设备同时开启蓝牙。
开发指南
1. 在config.json中添加permisssion权限。
// 添加在abilities同一目录层级 "reqPermissions": [ { "name": "ohos.permission.DISTRIBUTED_DATASYNC" } ]2. 在MainAbility中添加权限
@Override public void onStart(Intent intent) { super.onStart(intent); super.setMainRoute(MainAbilitySlice.class.getName()); //实现Ability的代码中显式声明需要使用多设备协同访问的权限 requestPermissionsFromUser(new String[]{ "ohos.permission.DISTRIBUTED_DATASYNC"}, 0); }3. 根据配置构造分布式数据库管理类实例KvManager以及创建分布式数据库对象SingleKvStore。
//实现数据库的初始化 // 初入的参数context: Context context = getApplicationContext()获得；storeId为分布式数据库id,String类型，可自行定义，例如“testApp”。 public static SingleKvStore initOrGetDB(Context context, String storeId) { KvManagerConfig kvManagerConfig = new KvManagerConfig(context); kvManager = KvManagerFactory.getInstance().createKvManager(kvManagerConfig); Options options = new Options(); options.setCreateIfMissing(true) .setEncrypt(false) .setKvStoreType(KvStoreType.SINGLE_VERSION) //数据库类型：单版本分布式数据库 .setAutoSync(true);//设置数据为自动同步 singleKvStore = kvManager.getKvStore(options, storeId); return singleKvStore; }4. 将数据写入单版本分布式数据库。
//以key-value形式存储到分布式数据库 try { long id = System.currentTimeMillis(); singleKvStore.putString("key", "{ \"id\":" + id + ",\"temp\":" + temperature + ",\"humidity\":" + humidity + ",\"NH4\":" + 0.0 + ",\"H2S\":" + 0.0 + ",\"other\":" + gas + "}"); } catch (KvStoreException e) { e.printStackTrace(); }5.订阅分布式数据变化。客户端需要实现KvStoreObserver接口，监听数据变化。
try { //订阅类型SubscribeType.SUBSCRIBE_TYPE_ALL意思可以同步到本机和其他外围设备 innerKvStoreObserver = new InnerKvStoreObserver(); singleKvStore.subscribe(SubscribeType.SUBSCRIBE_TYPE_ALL, innerKvStoreObserver); } catch (KvStoreException e) { e.printStackTrace(); } public class InnerKvStoreObserver implements KvStoreObserver { @Override public void onChange(ChangeNotification changeNotification) { //刷新页面上的数据，同样有一个坑，onChange方法实质上，在一个子线程里执行 MainAbilitySlice.taskDispatcher.asyncDispatch(() -> { //在这里执行页面ui组件的显示刷新 flushUIData(); }); } }6.获取分布式数据库数据
private void flushUIData() { //查询分布式数据的数据，获取数据可以通过get（String key）/ getEntries(String key)方法获取数据 List<Entry> entries = singleKvStore.getEntries(“key”); if (entries.size() > 0) { ZSONObject zsonObject = ZSONObject.stringToZSON(entries.get(0).getValue().getString()); int temp = zsonObject.getIntValue("temp"); int humidity = zsonObject.getIntValue("humidity"); int other = zsonObject.getIntValue("other"); tvTemp.setText(temp+"℃"); tvHumi.setText(humidity+"% RH"); tvGas.setText(other+"% LEL"); }7. 解除订阅。一般在页面销毁时调用，也就是MainAbilitySlice的云南idc服务商onStop()中调用
if (singleKvStore != null) { singleKvStore.unSubscribe(innerKvStoreObserver); }8. 同步数据到其他设备。获取已连接的设备列表，选择同步方式进行数据同步
List<DeviceInfo> deviceInfoList = kvManager.getConnectedDevicesInfo(DeviceFilterStrategy.NO_FILTER); List<String> deviceIdList = new ArrayList<>(); for (DeviceInfo deviceInfo : deviceInfoList) { deviceIdList.add(deviceInfo.getId()); } singleKvStore.sync(deviceIdList, SyncMode.PUSH_ONLY);项目中采用在后台service中开启定时任务，实时保存数据到分布式数据库，然后在主界面，监听数据变化，实时更新数据。
结果演示
1.刚开始安装完成后效果：
2.每隔3秒，界面数据都会发生变化：
附上源码：
1.MainAbilitySlice
public class MainAbilitySlice extends AbilitySlice { private SingleKvStore singleKvStore; private Text tvTemp; private Text tvHumi; private Text tvGas; private Intent serviceIntent; private InnerKvStoreObserver innerKvStoreObserver; @Override public void onStart(Intent intent) { super.onStart(intent); super.setUIContent(ResourceTable.Layout_ability_main); tvTemp=(Text)findComponentById(ResourceTable.Id_tvTemp); tvHumi=(Text)findComponentById(ResourceTable.Id_tvHumi); tvGas=(Text)findComponentById(ResourceTable.Id_tvGas); initService(); try { //获取数据库 singleKvStore = DBUtils.initOrGetDB(this, DBUtils.STORE_ID); innerKvStoreObserver = new InnerKvStoreObserver(); singleKvStore.subscribe(SubscribeType.SUBSCRIBE_TYPE_ALL, innerKvStoreObserver); } catch (KvStoreException e) { e.printStackTrace(); } } public class InnerKvStoreObserver implements KvStoreObserver { @Override public void onChange(ChangeNotification changeNotification) { //刷新页面上的数据，同样有一个坑，onChange方法实质上，在一个子线程里执行 getUITaskDispatcher().asyncDispatch(() -> { //在这里执行页面ui组件的显示刷新 flushUIData(); }); } } private void flushUIData() { //查询分布式数据的数据 List<Entry> entries = singleKvStore.getEntries("key"); if (entries.size() > 0) { ZSONObject zsonObject = ZSONObject.stringToZSON(entries.get(0).getValue().getString()); int temp = zsonObject.getIntValue("temp"); int humidity = zsonObject.getIntValue("humidity"); int other = zsonObject.getIntValue("other"); tvTemp.setText(temp+"℃"); tvHumi.setText(humidity+"% RH"); tvGas.setText(other+"% LEL"); } } private void initService() { //启动ServiceAbility serviceIntent = new Intent(); Operation operation = new Intent.OperationBuilder() .withDeviceId("") .withBundleName("com.isoftstone.kvstoreapp") .withAbilityName("com.isoftstone.kvstoreapp.ServiceAbility") .build(); serviceIntent.setOperation(operation); startAbility(serviceIntent); } @Override public void onActive() { super.onActive(); } @Override public void onForeground(Intent intent) { super.onForeground(intent); } @Override protected void onStop() { super.onStop(); //销毁service stopAbility(serviceIntent); //删除数据库 DBUtils.clearDB(); //解除订阅 if (singleKvStore != null) { singleKvStore.unSubscribe(innerKvStoreObserver); } } }2.ServiceAbility
public class ServiceAbility extends Ability { private static final HiLogLabel LABEL_LOG = new HiLogLabel(3, 0xD001100, "Demo"); private SingleKvStore singleKvStore; private Timer timer; private MyTimerTask myTimerTask; private int temperature; private int humidity; private int gas; @Override public void onStart(Intent intent) { super.onStart(intent); singleKvStore = DBUtils.initOrGetDB(this, DBUtils.STORE_ID); timer=new Timer(); myTimerTask=new MyTimerTask(); timer.schedule(myTimerTask,0,3000); } @Override public void onBackground() { super.onBackground(); HiLog.info(LABEL_LOG, "ServiceAbility::onBackground"); } @Override public void onStop() { super.onStop(); if(myTimerTask!=null){ myTimerTask.cancel(); } if(timer!=null){ timer.cancel(); } } @Override public void onCommand(Intent intent, boolean restart, int startId) { } @Override public IRemoteObject onConnect(Intent intent) { return null; } @Override public void onDisconnect(Intent intent) { } private class MyTimerTask extends TimerTask{ @Override public void run() { temperature++; humidity++; gas++; try { long id = System.currentTimeMillis(); singleKvStore.putString("key", "{ \"id\":" + id + ",\"temp\":" + temperature + ",\"humidity\":" + humidity + ",\"NH4\":" + 0.0 + ",\"H2S\":" + 0.0 + ",\"other\":" + gas + "}"); } catch (KvStoreException e) { e.printStackTrace(); } } } }3.DBUtils
public class DBUtils { //分布式数据库storeId public static final String STORE_ID="kvStoreDB"; private static KvManager kvManager; private static SingleKvStore singleKvStore; //具体的实现数据库的初始化 public static SingleKvStore initOrGetDB(Context context, String storeId) { KvManagerConfig kvManagerConfig = new KvManagerConfig(context); kvManager = KvManagerFactory.getInstance().createKvManager(kvManagerConfig); Options options = new Options(); options.setCreateIfMissing(true) .setEncrypt(false) .setKvStoreType(KvStoreType.SINGLE_VERSION) .setAutoSync(true);//设置数据为自动同步 singleKvStore = kvManager.getKvStore(options, storeId); return singleKvStore; } // 如果数据库中的字段有修改，只能先关闭，后删除，然后重新创建才生效 public static void clearDB() { kvManager.closeKvStore(singleKvStore); kvManager.deleteKvStore(STORE_ID); } }4. MainAbility
public class MainAbility extends Ability { @Override public void onStart(Intent intent) { super.onStart(intent); super.setMainRoute(MainAbilitySlice.class.getName()); //实现Ability的代码中显式声明需要使用多设备协同访问的权限 requestPermissionsFromUser(new String[]{ "ohos.permission.DISTRIBUTED_DATASYNC"}, 0); } }5. MyApplication
public class MyApplication extends AbilityPackage { @Override public void onInitialize() { super.onInitialize(); } }6. config.json 文件
{ "app": { "bundleName": "com.isoftstone.healthdata", "vendor": "isoftstone", "version": { "code": 1000000, "name": "1.0" }, "apiVersion": { "compatible": 4, "target": 5, "releaseType": "Release" } }, "deviceConfig": { }, "module": { "package": "com.isoftstone.kvstoreapp", "name": ".MyApplication", "deviceType": [ "phone" ], "distro": { "deliveryWithInstall": true, "moduleName": "entry", "moduleType": "entry" }, "reqPermissions": [ { "name": "ohos.permission.DISTRIBUTED_DATASYNC" } ], "abilities": [ { "skills": [ { "entities": [ "entity.system.home" ], "actions": [ "action.system.home" ] } ], "orientation": "unspecified", "name": "com.isoftstone.kvstoreapp.MainAbility", "icon": "$media:icon", "description": "$string:mainability_description", "label": "$string:app_name", "type": "page", "launchType": "standard" }, { "name": "com.isoftstone.kvstoreapp.ServiceAbility", "icon": "$media:icon", "description": "$string:serviceability_description", "type": "service" } ] } }7.xml布局文件
<?xml version="1.0" encoding="utf-8"?> <DirectionalLayout xmlns:ohos="http://schemas.huawei.com/res/ohos" ohos:height="match_parent" ohos:orientation="vertical" ohos:width="match_parent"> <DirectionalLayout ohos:padding="20vp" ohos:height="match_content" ohos:width="match_parent" ohos:orientation="horizontal"> <Text ohos:width="match_content" ohos:height="match_content" ohos:text_size="20vp" ohos:text="温度："/> <Text ohos:id="$+id:tvTemp" ohos:width="0" ohos:height="match_content" ohos:text_size="22vp" ohos:text_color="#00ff00" ohos:text="待采集..." ohos:weight="1"/> </DirectionalLayout> <DirectionalLayout ohos:height="1vp" ohos:width="match_parent" ohos:background_element="#cccccc"/> <DirectionalLayout ohos:padding="20vp" ohos:height="match_content" ohos:width="match_parent" ohos:orientation="horizontal"> <Text ohos:width="match_content" ohos:height="match_content" ohos:text_size="20vp" ohos:text="湿度："/> <Text ohos:id="$+id:tvHumi" ohos:width="0" ohos:height="match_content" ohos:text_size="22vp" ohos:text_color="#00ff00" ohos:text="待采集..." ohos:weight="1"/> </DirectionalLayout> <DirectionalLayout ohos:height="1vp" ohos:width="match_parent" ohos:background_element="#cccccc"/> <DirectionalLayout ohos:padding="20vp" ohos:height="match_content" ohos:width="match_parent" ohos:orientation="horizontal"> <Text ohos:width="match_content" ohos:height="match_content" ohos:text_size="20vp" ohos:text="可燃气体："/> <Text ohos:id="$+id:tvGas" ohos:width="0" ohos:height="match_content" ohos:text_size="22vp" ohos:text_color="#00ff00" ohos:text="待采集..." ohos:weight="1"/> </DirectionalLayout> <DirectionalLayout ohos:height="1vp" ohos:width="match_parent" ohos:background_element="#cccccc"/> </DirectionalLayout>想了解更多内容，请访问：
和华为官方合作共建的鸿蒙技术社区
https://harmonyos.51cto.com
