要解决在Android Wear设备上无法发送DataItem到手机的问题，你可以使用以下代码示例：

在Android Wear应用中，发送DataItem到手机：

private void sendDataItemToPhone() {
    PutDataMapRequest dataMap = PutDataMapRequest.create("/data_item_path");
    dataMap.getDataMap().putString("key", "value");

    PutDataRequest request = dataMap.asPutDataRequest();
    PendingResult pendingResult = Wearable.DataApi.putDataItem(mGoogleApiClient, request);

    pendingResult.setResultCallback(new ResultCallback() {
        @Override
        public void onResult(@NonNull DataApi.DataItemResult dataItemResult) {
            if (dataItemResult.getStatus().isSuccess()) {
                Log.d(TAG, "DataItem sent successfully");
            } else {
                Log.d(TAG, "Failed to send DataItem");
            }
        }
    });
}

在手机应用中，接收来自Android Wear设备的DataItem：

public class MainActivity extends AppCompatActivity implements DataApi.DataListener, GoogleApiClient.ConnectionCallbacks, GoogleApiClient.OnConnectionFailedListener {
    private static final String TAG = "MainActivity";
    private GoogleApiClient mGoogleApiClient;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        mGoogleApiClient = new GoogleApiClient.Builder(this)
                .addApi(Wearable.API)
                .addConnectionCallbacks(this)
                .addOnConnectionFailedListener(this)
                .build();
    }

    @Override
    protected void onStart() {
        super.onStart();
        mGoogleApiClient.connect();
    }

    @Override
    protected void onStop() {
        if (mGoogleApiClient != null && mGoogleApiClient.isConnected()) {
            Wearable.DataApi.removeListener(mGoogleApiClient, this);
            mGoogleApiClient.disconnect();
        }
        super.onStop();
    }

    @Override
    public void onConnected(@Nullable Bundle bundle) {
        Wearable.DataApi.addListener(mGoogleApiClient, this);
    }

    @Override
    public void onConnectionSuspended(int i) {
        Wearable.DataApi.removeListener(mGoogleApiClient, this);
    }

    @Override
    public void onConnectionFailed(@NonNull ConnectionResult connectionResult) {
        Log.d(TAG, "onConnectionFailed: " + connectionResult.getErrorMessage());
    }

    @Override
    public void onDataChanged(DataEventBuffer dataEventBuffer) {
        for (DataEvent event : dataEventBuffer) {
            if (event.getType() == DataEvent.TYPE_CHANGED && event.getDataItem().getUri().getPath().equals("/data_item_path")) {
                DataMap dataMap = DataMapItem.fromDataItem(event.getDataItem()).getDataMap();
                String value = dataMap.getString("key");
                Log.d(TAG, "Received DataItem value: " + value);
            }
        }
    }
}

这些代码示例演示了如何在Android Wear设备上发送DataItem，并在手机应用中接收。确保手机和Android Wear设备都已连接到同一个Google账号，并且已经添加了相应的权限和依赖项。