鸿蒙软总线跨设备访问该怎么玩——小总结 精华

 重点撸代码：

1、跨设备启动FA、跨设备迁移、回迁

（1）权限

ohos.permission.DISTRIBUTED_DEVICE_STATE_CHANGE：用于允许监听分布式组网内的设备状态变化。
ohos.permission.GET_DISTRIBUTED_DEVICE_INFO：用于允许获取分布式组网内的设备列表和设备信息。
ohos.permission.GET_BUNDLE_INFO：用于查询其他应用的信息。
ohos.permission.DISTRIBUTED_DATASYNC：用于允许不同设备间的数据交换。

"reqPermissions": [
    {"name": "ohos.permission.DISTRIBUTED_DATASYNC"},
    {"name": "ohos.permission.DISTRIBUTED_DEVICE_STATE_CHANGE"}, 
    {"name": "ohos.permission.GET_DISTRIBUTED_DEVICE_INFO" }, 
   {"name": "ohos.permission.GET_BUNDLE_INFO"} 
]

//主动申明，要多设备协同，让用户选择允许还是禁止
requestPermissionsFromUser(new String[]{"ohos.permission.DISTRIBUTED_DATASYNC"}, 0);

（2）界面：ability_main.xml

<?xml version="1.0" encoding="utf-8"?>
<DirectionalLayout
    xmlns:ohos="http://schemas.huawei.com/res/ohos"
    ohos:height="match_parent"
    ohos:width="match_parent"
    ohos:orientation="vertical">

    <Button
        ohos:id="$+id:main_start_fa_btn"
        ohos:height="match_content"
        ohos:width="300vp"
        ohos:text="1.启动远程设备的FA"
        ohos:text_size="20fp"
        ohos:text_color="#ffffff"
        ohos:background_element="$graphic:button_bg"
        ohos:layout_alignment="horizontal_center"
        ohos:top_padding="8vp"
        ohos:bottom_padding="8vp"
        ohos:left_padding="40vp"
        ohos:right_padding="40vp"
        ohos:top_margin="20vp"
        />

    <Button
        ohos:id="$+id:main_migration_btn"
        ohos:height="match_content"
        ohos:width="300vp"
        ohos:text="2.迁移到远程设备"
        ohos:text_size="20fp"
        ohos:text_color="#ffffff"
        ohos:background_element="$graphic:button_bg"
        ohos:layout_alignment="horizontal_center"
        ohos:top_padding="8vp"
        ohos:bottom_padding="8vp"
        ohos:left_padding="40vp"
        ohos:right_padding="40vp"
        ohos:top_margin="20vp"
        />
    
</DirectionalLayout>

button_bg.xml

<?xml version="1.0" encoding="utf-8"?>
<shape  xmlns:ohos="http://schemas.huawei.com/res/ohos"
        ohos:shape="rectangle">
    <solid ohos:color="#007DFF"/>
    <corners ohos:radius="40"/>
</shape>

另外我们需要的Page Abiltiy：MigrationAbility、RemoveAbility
 
MainAbilitySlice:

public class MainAbilitySlice extends AbilitySlice {
   private Button mainStartFABtn,mainMigrationBtn;

    @Override
    public void onStart(Intent intent) {
        super.onStart(intent);
        super.setUIContent(ResourceTable.Layout_ability_main);
        mainStartFABtn = (Button)findComponentById(ResourceTable.Id_main_start_fa_btn);
        mainMigrationBtn = (Button)findComponentById(ResourceTable.Id_main_migration_btn);
        
        mainStartFABtn.setClickedListener(mClickListener);
        mainMigrationBtn.setClickedListener(mClickListener);
    }

    private Component.ClickedListener mClickListener = new Component.ClickedListener() {
        @Override
        public void onClick(Component component) {
            int compoentId = component.getId();
            switch (compoentId){
                case ResourceTable.Id_main_start_fa_btn:
                    //点击后跨设备打开Fa
                    //第一种写法
                    Intent intent = new Intent();
                    Operation op = new Intent.OperationBuilder()
                            .withDeviceId(Common.getOnLineDeviceId())
                            .withBundleName("com.ybzy.demo")
                            .withAbilityName("com.ybzy.demo.RemoveAbility")
                            .withFlags(Intent.FLAG_ABILITYSLICE_MULTI_DEVICE)
                            .build();
                    intent.setOperation(op);
                    intent.setParam("msg","我夸设备把你这个FA拉起来了！");
                    startAbility(intent);

                    //第二钟写法
                    intent.setElement(new ElementName(Common.getOnLineDeviceId()
                                            ,"com.ybzy.demo","com.ybzy.demo.RemoveAbility"));
                    intent.setFlags(Intent.FLAG_ABILITYSLICE_MULTI_DEVICE);
                    intent.setParam("msg","我夸设备把你这个FA拉起来了！");
                    startAbility(intent);

                    break;
                case ResourceTable.Id_main_migration_btn:
                    //点击后进入要迁移的Ability页面
                    Intent migrationIntent = new Intent();
                    migrationIntent.setElement(new ElementName("","com.ybzy.demo"
                                                    ,"com.ybzy.demo.MigrationAbility"));
                    startAbility(migrationIntent);
                    break;
                default:
                    break;
            }
        }
    };

    @Override
    public void onActive() {
        super.onActive();
    }

    @Override
    public void onForeground(Intent intent) {
        super.onForeground(intent);
    }
}

ability_migration.xml

<?xml version="1.0" encoding="utf-8"?>
<DirectionalLayout
    xmlns:ohos="http://schemas.huawei.com/res/ohos"
    ohos:height="match_parent"
    ohos:width="match_parent"
    ohos:background_element="#00ffff"
    ohos:orientation="vertical">

    <Text
        ohos:id="$+id:migration_text"
        ohos:height="match_content"
        ohos:width="250vp"
        ohos:background_element="#0088bb"
        ohos:layout_alignment="horizontal_center"
        ohos:text="下面是一个可编辑的文本框"
        ohos:text_size="50"
        ohos:padding="5vp"
        ohos:top_margin="30vp"
        />

    <TextField
        ohos:id="$+id:migration_textfield"
        ohos:height="250vp"
        ohos:width="250vp"
        ohos:hint="请输入..."
        ohos:layout_alignment="horizontal_center"
        ohos:background_element="#ffffff"
        ohos:text_color="#888888"
        ohos:text_size="20fp"
        ohos:padding="5vp"
        />
    <Button
        ohos:id="$+id:migration_migration_btn"
        ohos:height="match_content"
        ohos:width="match_content"
        ohos:text="点击迁移"
        ohos:text_size="20fp"
        ohos:text_color="#ffffff"
        ohos:background_element="$graphic:button_bg"
        ohos:top_padding="8vp"
        ohos:bottom_padding="8vp"
        ohos:left_padding="50vp"
        ohos:right_padding="50vp"
        ohos:layout_alignment="horizontal_center"
        ohos:top_margin="30vp"
        />

    <Button
        ohos:id="$+id:migration_migration_back_btn"
        ohos:height="match_content"
        ohos:width="match_content"
        ohos:text="点击迁移回来"
        ohos:text_size="20fp"
        ohos:text_color="#ffffff"
        ohos:background_element="$graphic:button_bg"
        ohos:top_padding="8vp"
        ohos:bottom_padding="8vp"
        ohos:left_padding="50vp"
        ohos:right_padding="50vp"
        ohos:layout_alignment="horizontal_center"
        ohos:top_margin="30vp"
        />
</DirectionalLayout>

RemoveAbility...把接收到的值显示到页面就行，setText()

（3）工具类

public class Common{
    public static String getDeviceId(){
        List<DeviceInfo> deviceList = DeviceManager.getDeviceList(DeviceInfo.FLAG_GET_ONLINE_DEVICE);
        if(deviceList.isEmpty()){
            return null;
        }
        int deviceNum = deviceList.size();
        List<String> deviceIds = new ArrayList<>(deviceNum);
        List<String> deviceNames = new ArrayList<>(deviceNum);
        deviceList.forEach((device)->{
            deviceIds.add(device.getDeviceId());
            deviceNames.add(device.getDeviceName());
        });

        //我们这里的实验环境，就两部手机，组件还没讲
        //我就直接使用deviceIds的第一个元素，做为启动远程设备的目标id
        String devcieIdStr = deviceIds.get(0);
        return devcieIdStr;
    }


    public static void myShowTip(Context context,String msg){
        //提示框的核心组件文本
        Text text = new Text(context);
        text.setWidth(MATCH_CONTENT);
        text.setHeight(MATCH_CONTENT);
        text.setTextSize(16, Text.TextSizeType.FP);
        text.setText(msg);
        text.setPadding(30,20,30,20);
        text.setMultipleLine(true);
        text.setMarginLeft(30);
        text.setMarginRight(30);
        text.setTextColor(Color.WHITE);
        text.setTextAlignment(TextAlignment.CENTER);
    
        //给上面的文本设置一个背景样式
        ShapeElement style = new ShapeElement();
        style.setShape(ShapeElement.RECTANGLE);
        style.setRgbColor(new RgbColor(77,77,77));
        style.setCornerRadius(15);
        text.setBackground(style);
    
        //构建存放上面的text的布局
        DirectionalLayout mainLayout = new DirectionalLayout(context);
        mainLayout.setWidth(MATCH_PARENT);
        mainLayout.setHeight(MATCH_CONTENT);
        mainLayout.setAlignment(LayoutAlignment.CENTER);
        mainLayout.addComponent(text);
    
        //最后要让上面的组件绑定dialog
        ToastDialog toastDialog = new ToastDialog(context);
        toastDialog.setSize(MATCH_PARENT,MATCH_CONTENT);
        toastDialog.setDuration(1500);
        toastDialog.setAutoClosable(true);
        toastDialog.setTransparent(true);
        toastDialog.setAlignment(LayoutAlignment.CENTER);
        toastDialog.setComponent((Component) mainLayout);
        toastDialog.show();
    }
    
}

（4）实现功能
MigrationAbilitySlice：

public class MigrationAbilitySlice extends AbilitySlice implements IAbilityContinuation {
    TextField migrationTextField;
    Button migrationMigrationBtn,migrationMigrationBackBtn;
    String msg = "";

    @Override
    public void onStart(Intent intent) {
        super.onStart(intent);
        super.setUIContent(ResourceTable.Layout_ability_migration);

        migrationTextField = (TextField)findComponentById(ResourceTable.Id_migration_textfield);
        migrationTextField.setText(msg);
        migrationMigrationBtn = (Button)findComponentById(ResourceTable.Id_migration_migration_btn);
        migrationMigrationBtn.setClickedListener(component -> {
            //1、要进行迁移的Ability实现接口 IAbilityContinuation，实现的方法返回值改成true
            //2、要进行迁移的Ability下面关联的所有AbilitySlice都要实现接口 IAbilityContinuation，
            //  实现的方法上处理数据
            //3、进行迁移
            String deviceId = Common.getOnLineDeviceId();
            if(deviceId != null){
//                continueAbility(deviceId); 
                continueAbilityReversibly(deviceId);
            }
        });

        migrationMigrationBackBtn = (Button) findComponentById(ResourceTable
                                                                    .Id_migration_migration_back_btn);
        migrationMigrationBackBtn.setClickedListener(component -> {
            reverseContinueAbility();
        });
    }

    @Override
    public void onActive() {
        super.onActive();
    }

    @Override
    public void onForeground(Intent intent) {
        super.onForeground(intent);
    }

    @Override
    public boolean onStartContinuation() {
        return true;
    }

    @Override
    public boolean onSaveData(IntentParams intentParams) {
        intentParams.setParam("msg",migrationTextField.getText());
        return true;
    }

    @Override
    public boolean onRestoreData(IntentParams intentParams) {
        msg = intentParams.getParam("msg").toString();
//        getUITaskDispatcher().asyncDispatch(() -> {
//            migrationTextField.setText(intentParams.getParam("msg").toString());
//        });
        return true;
    }

    @Override
    public void onCompleteContinuation(int i) {

    }

}

2、跨设备连接Service

启动远程设备Service的代码示例如下：
添加按钮：

<Button
    ohos:id="$+id:main_start_removeService_btn"
    ohos:height="match_content"
    ohos:width="300vp"
    ohos:text="远程启动ServiceAbility"
    ohos:text_size="20fp"
    ohos:text_color="#ffffff"
    ohos:background_element="$graphic:button_bg"
    ohos:layout_alignment="horizontal_center"
    ohos:top_padding="8vp"
    ohos:bottom_padding="8vp"
    ohos:left_padding="40vp"
    ohos:right_padding="40vp"
    ohos:top_margin="20vp"
    />
    
    <Button
    ohos:id="$+id:main_stop_removeService_btn"
    ohos:height="match_content"
    ohos:width="300vp"
    ohos:text="远程关闭ServiceAbility"
    ohos:text_size="20fp"
    ohos:text_color="#ffffff"
    ohos:background_element="$graphic:button_bg"
    ohos:layout_alignment="horizontal_center"
    ohos:top_padding="8vp"
    ohos:bottom_padding="8vp"
    ohos:left_padding="40vp"
    ohos:right_padding="40vp"
    ohos:top_margin="20vp"
    />

新建RemoteServiceAbility：

public class RemoteServiceAbility extends Ability {
    private static final HiLogLabel LABEL_LOG = new HiLogLabel(3, 0xD001100, "Demo");
    private Source sVideoSource;
    private Player sPlayer;

    @Override
    public void onStart(Intent intent) {
        HiLog.error(LABEL_LOG, "RmoteServiceAbility::onStart");
        super.onStart(intent);
        Common.myShowTip(this,"remote onstart");
        sPlayer = new Player(RemoteServiceAbility.this);
        new PlayerThread().start();
    }
    class PlayerThread extends Thread {
        @Override
        public void run() {
            try {
                File mp3FilePath = getExternalFilesDir(Environment.DIRECTORY_MUSIC);
                if (!mp3FilePath.exists()) {
                    mp3FilePath.mkdirs();
                }
                File mp3File = new File(mp3FilePath.getAbsolutePath() + "/" + "bj.mp3");

                Resource res = getResourceManager()
                        .getRawFileEntry("resources/rawfile/bj.mp3").openRawFile();
                byte[] buf = new byte[4096];
                int count = 0;
                FileOutputStream fos = new FileOutputStream(mp3File);
                while ((count = res.read(buf)) != -1) {
                    fos.write(buf, 0, count);
                }
                FileDescriptor fileDescriptor = new FileInputStream(mp3File).getFD();
                sVideoSource = new Source(fileDescriptor);
                sPlayer.setSource(sVideoSource);
                sPlayer.prepare();
                sPlayer.setVolume(0.3f);
                sPlayer.enableSingleLooping(true);
                sPlayer.play();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    @Override
    public void onStop() {
        super.onStop();
        Common.myShowTip(RemoteServiceAbility.this,"remote onStop");
        sPlayer.stop();
    }

    @Override
    public IRemoteObject onConnect(Intent intent) {
        return null;
    }
    @Override
    public void onDisconnect(Intent intent) {
    }
}

启动：

case ResourceTable.Id_main_start_remoteService_btn:

    Common.myShowTip(MainAbilitySlice.this,deviceId);
    Intent startRemoteServiceIntent = new Intent();
    startRemoteServiceIntent.setElement(new ElementName(
            deviceId,
            "com.ybzy.demo",
            "com.ybzy.demo.RemoteServiceAbility"
    ));
    startRemoteServiceIntent.setFlags(Intent.FLAG_ABILITYSLICE_MULTI_DEVICE);
    startAbility(startRemoteServiceIntent);
    break;

关闭远程设备Service：

case ResourceTable.Id_main_stop_remoteService_btn:
    Common.myShowTip(MainAbilitySlice.this,deviceId);
    Intent stopRemoteServiceIntent = new Intent();
    stopRemoteServiceIntent.setElement(new ElementName(
            deviceId,
            "com.ybzy.demo",
            "com.ybzy.demo.RemoteServiceAbility"
    ));
    stopRemoteServiceIntent.setFlags(Intent.FLAG_ABILITYSLICE_MULTI_DEVICE);
    stopAbility(stopRemoteServiceIntent);
    break;

仅通过启动和停止Service Ability两种方式对Service进行调度无法应对需长期交互的场景，
简单地说，信息就是只能去，回不来！
因此，分布式任务调度平台向开发者提供了跨设备Service连接及断开连接的能力。
链接上了，信息可去可回！
 
链接是使用connectAbility()方法，需要传入目标Service的Intent与接口IAbilityConnection的实例对象。
 
接口IAbilityConnection提供了两个方法供开发者实现：
（1）onAbilityConnectDone()用来处理连接的回调。
（2）onAbilityDisconnectDone()用来处理断开连接的回调。
 
我们可以在onAbilityConnectDone()中获取管理链接的代理，进一步为了使用该代理跨设备调度Service，
开发者需要在本地及远端分别实现对外接口一致的代理，这个接口是IRemoteBroker。
 
添加按钮：

<Button
    ohos:id="$+id:main_connect_remoteService_btn"
    ohos:height="match_content"
    ohos:width="300vp"
    ohos:text="远程链接ServiceAbility"
    ohos:text_size="20fp"
    ohos:text_color="#ffffff"
    ohos:background_element="$graphic:button_bg"
    ohos:layout_alignment="horizontal_center"
    ohos:top_padding="8vp"
    ohos:bottom_padding="8vp"
    ohos:left_padding="40vp"
    ohos:right_padding="40vp"
    ohos:top_margin="20vp"
    />

<Button
    ohos:id="$+id:main_use_remoteService_btn"
    ohos:height="match_content"
    ohos:width="300vp"
    ohos:text="使用远程ServiceAbility"
    ohos:text_size="20fp"
    ohos:text_color="#ffffff"
    ohos:background_element="$graphic:button_bg"
    ohos:layout_alignment="horizontal_center"
    ohos:top_padding="8vp"
    ohos:bottom_padding="8vp"
    ohos:left_padding="40vp"
    ohos:right_padding="40vp"
    ohos:top_margin="20vp"
    />

<Button
    ohos:id="$+id:main_disconnect_remoteService_btn"
    ohos:height="match_content"
    ohos:width="300vp"
    ohos:text="远程断开ServiceAbility"
    ohos:text_size="20fp"
    ohos:text_color="#ffffff"
    ohos:background_element="$graphic:button_bg"
    ohos:layout_alignment="horizontal_center"
    ohos:top_padding="8vp"
    ohos:bottom_padding="8vp"
    ohos:left_padding="40vp"
    ohos:right_padding="40vp"
    ohos:top_margin="20vp"
    />

发起连接的本地侧的代理示例如下：

public class MyRemoteProxy implements IRemoteBroker {
    //IRemoteBroker:获取远程代理对象的持有者
    private static final int ERR_OK = 0;
    //COMMAND_PLUS表示有效消息进行通信的约定的标记，MIN_TRANSACTION_ID是这个标记可以用的最小值：1
    private static final int COMMAND_PLUS = IRemoteObject.MIN_TRANSACTION_ID;

    //IRemoteObject:此接口
    // 可用于查询或获取接口描述符、
    // 添加或删除死亡通知、
    // 将对象状态转储到特定文件以及发送消息。
    private final IRemoteObject remote;
    public MyRemoteProxy(IRemoteObject remote) {
        this.remote = remote;
    }

    @Override
    public IRemoteObject asObject() {//获取远程代理对象的方法
        return remote;
    }

    public int plus(int a,int b) throws RemoteException {
        //MessageParcel:这个类提供了读写对象、接口标记、文件描述符和大数据的方法。
        MessageParcel data = MessageParcel.obtain();
        //obtain()创建索引为0的空MessageParcel对象
        MessageParcel reply = MessageParcel.obtain();

        //MessageOption:定义与sendRequest一起发送消息的选项。
        // option不同的取值，决定采用同步或异步方式跨设备调用Service
        // 这个例子我们需要同步获取对端Service执行加法运算后的结果，同步模式调用sendRequest接口，即MessageOption.TF_SYNC
        // 对应的是异步：TF_ASYNC
        MessageOption option = new MessageOption(MessageOption.TF_SYNC);
        data.writeInt(a);
        data.writeInt(b);

        try {
            remote.sendRequest(COMMAND_PLUS, data, reply, option);
            //第1个参数：约定通信双方确定的消息标记。
            //第2个参数：发送到对等端侧的数据包裹MessageParcel对象。
            //第3个参数：对等端侧返回的数据包裹MessageParcel对象。
            //第4个参数：设置发送消息，用同步还是异步模式。
            int ec = reply.readInt(); //返回通信成不成功，约定的标记ERR_OK
            if (ec != ERR_OK) {
                throw new RemoteException();
            }
            int result = reply.readInt();
            return result;
        } catch (RemoteException e) {
            throw new RemoteException();
        } finally {
            data.reclaim(); //reclaim()清除不再使用的MessageParcel对象。
            reply.reclaim();
        }
    }
}

等待连接的远端侧的代理示例如下：

public class MyRemote extends RemoteObject implements IRemoteBroker{
    private static final int ERR_OK = 0;
    private static final int ERROR = -1;
    private static final int COMMAND_PLUS = IRemoteObject.MIN_TRANSACTION_ID;
 
    public MyRemote() {
        super("MyService_Remote");
    }
 
    @Override
    public IRemoteObject asObject() {
        return this;
    }
 
    @Override
    public boolean onRemoteRequest(int code, MessageParcel data, MessageParcel reply, MessageOption option) {
        if (code != COMMAND_PLUS) {
            reply.writeInt(ERROR);
            return false;
        }
        int value1 = data.readInt();
        int value2 = data.readInt();
        int sum = value1 + value2;
        reply.writeInt(ERR_OK);
        reply.writeInt(sum);
        return true;
    }
}

等待连接侧还需要作如下修改：

// 绑定前面定义的代理，实例化出发起链接侧需要的代理
private MyRemote remote = new MyRemote();
@Override
public IRemoteObject onConnect(Intent intent) {
    //链接成功的时候，给发起链接侧返回去
    return remote.asObject();
}

完成上述步骤后，可以通过点击事件实现连接、利用连接关系控制PA以及断开连接等行为，代码示例如下：

private MyRemoteProxy mProxy = null;
// 创建连接回调实例
private IAbilityConnection conn = new IAbilityConnection() {
    // 连接到Service的回调
    @Override
    public void onAbilityConnectDone(ElementName elementName, IRemoteObject iRemoteObject, int resultCode) {
        // 在这里开发者可以拿到服务端传过来IRemoteObject对象，从中解析出服务端传过来的信息
        mProxy = new MyRemoteProxy(iRemoteObject);
        UIUtils.showTip(MainAbilitySlice.this,"拿到remoteObject：" + mProxy);
    }

    // 意外断开连接才会回调
    @Override
    public void onAbilityDisconnectDone(ElementName elementName, int resultCode) {
    }
};



// 连接远程
case ResourceTable.Id_main_connect_remoteService_btn:
    //1、实现连接的本地侧的代理
    //2、实现等待连接的远端侧的代理
    //3、修改等待连接侧的Service
    //4、在本地(发起链接侧)获取远端(被链接侧)返回过来的链接代理，创建链接后的回调函数
    //5、实现链接，通过代理对象使用Service的服务
    if (deviceId != null) {
        Intent connectServiceIntent = new Intent();
        connectServiceIntent.setElement(new ElementName(
                deviceId,
                "com.ybzy.demo",
                "com.ybzy.demo.RemoteServiceAbility"
        ));
        connectServiceIntent.setFlags(Intent.FLAG_ABILITYSLICE_MULTI_DEVICE);
        connectAbility(connectServiceIntent, iAbilityConnection);
    }
    break;
    
    
// 链接后使用
case ResourceTable.Id_main_use_remoteService_btn:
    if (mProxy != null) {
        int ret = -1;
        try {
            ret = mProxy.plus(10, 20);
        } catch (RemoteException e) {
            e.printStackTrace();
        }
        Common.myShowTip(MainAbilitySlice.this, "获取的结果：" + ret);
    }
    break;
    
// 用完断开
case ResourceTable.Id_main_disconnect_remoteService_btn:
    disconnectAbility(iAbilityConnection);
    break;