我试图构建一个必须在后台运行的应用程序。因此，为此我使用ForegroundService，但是当我在CommunicateViewModel类中编写“ this”时，其下划线并显示给我：
“无法解析构造函数 'Intent（com.harrysoft.androidbluetoothserial.demoapp.CommunicateViewModel， java.lang.Class）'“
和下一个：
“第一个参数类型错误。找到： 'com.harrysoft.androidbluetoothserial.demoapp.CommunicateViewModel'， 必需：“ android.content.Context”少...检查信息： startForegroundService（android.content.Context，Intent）在 ContextCompat无法应用于 （com.harrysoft.androidbluetoothserial.demoapp.CommunicateViewModel， 意向）
我该如何解决这个问题？
CommunicateViewModel：
package com.harrysoft.androidbluetoothserial.demoapp;
import android.app.Application;
import android.arch.lifecycle.AndroidViewModel;
import android.arch.lifecycle.LiveData;
import android.arch.lifecycle.MutableLiveData;
import android.content.Intent;
import android.os.CountDownTimer;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.annotation.StringRes;
import android.support.v4.content.ContextCompat;
import android.text.TextUtils;
import android.util.Log;
import android.view.View;
import android.widget.Toast;
import com.harrysoft.androidbluetoothserial.BluetoothManager;
import com.harrysoft.androidbluetoothserial.SimpleBluetoothDeviceInterface;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import io.reactivex.android.schedulers.AndroidSchedulers;
import io.reactivex.disposables.CompositeDisposable;
import io.reactivex.schedulers.Schedulers;
public class CommunicateViewModel extends AndroidViewModel {
// A CompositeDisposable that keeps track of all of our asynchronous tasks
private CompositeDisposable compositeDisposable = new CompositeDisposable();
// Our BluetoothManager!
private BluetoothManager bluetoothManager;
// Our Bluetooth Device! When disconnected it is null, so make sure we know that we need to deal with it potentially being null
@Nullable
private SimpleBluetoothDeviceInterface deviceInterface;
// The messages feed that the activity sees
private MutableLiveData<String> messagesData = new MutableLiveData<>();
// The connection status that the activity sees
private MutableLiveData<ConnectionStatus> connectionStatusData = new MutableLiveData<>();
// The device name that the activity sees
private MutableLiveData<String> deviceNameData = new MutableLiveData<>();
// The message in the message box that the activity sees
private MutableLiveData<String> messageData = new MutableLiveData<>();
// Our modifiable record of the conversation
private StringBuilder messages = new StringBuilder();
// Our configuration
private String deviceName;
private String mac;
// A variable to help us not double-connect
private boolean connectionAttemptedOrMade = false;
// A variable to help us not setup twice
private boolean viewModelSetup = false;
// Called by the system, this is just a constructor that matches AndroidViewModel.
public CommunicateViewModel(@NonNull Application application) {
super(application);
}
// Called in the activity's onCreate(). Checks if it has been called before, and if not, sets up the data.
// Returns true if everything went okay, or false if there was an error and therefore the activity should finish.
public boolean setupViewModel(String deviceName, String mac) {
// Check we haven't already been called
if (!viewModelSetup) {
viewModelSetup = true;
// Setup our BluetoothManager
bluetoothManager = BluetoothManager.getInstance();
if (bluetoothManager == null) {
// Bluetooth unavailable on this device :( tell the user
toast(R.string.bluetooth_unavailable);
// Tell the activity there was an error and to close
return false;
}
// Remember the configuration
this.deviceName = deviceName;
this.mac = mac;
// Tell the activity the device name so it can set the title
deviceNameData.postValue(deviceName);
// Tell the activity we are disconnected.
connectionStatusData.postValue(ConnectionStatus.DISCONNECTED);
}
// If we got this far, nothing went wrong, so return true
return true;
}
// Called when the user presses the connect button
public void toconnect(){
Intent serviceIntent = new Intent(this, TimeService.class);
serviceIntent.putExtra("inputExtra", "this can be set invissable");
ContextCompat.startForegroundService(this, serviceIntent);
connect();
}
public void connect() {
// Check we are not already connecting or connected
if (!connectionAttemptedOrMade) {
// Connect asynchronously
compositeDisposable.add(bluetoothManager.openSerialDevice(mac)
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(device -> onConnected(device.toSimpleDeviceInterface()), t -> {
toast(R.string.connection_failed);
connectionAttemptedOrMade = false;
connectionStatusData.postValue(ConnectionStatus.DISCONNECTED);
}));
// Remember that we made a connection attempt.
connectionAttemptedOrMade = true;
// Tell the activity that we are connecting.
connectionStatusData.postValue(ConnectionStatus.CONNECTING);
}
}
// Called when the user presses the disconnect button
public void disconnect() {
// Check we were connected
if (connectionAttemptedOrMade && deviceInterface != null) {
connectionAttemptedOrMade = false;
// Use the library to close the connection
bluetoothManager.closeDevice(deviceInterface);
// Set it to null so no one tries to use it
deviceInterface = null;
// Tell the activity we are disconnected
connectionStatusData.postValue(ConnectionStatus.DISCONNECTED);
}
}
// Called once the library connects a bluetooth device
private void onConnected(SimpleBluetoothDeviceInterface deviceInterface) {
this.deviceInterface = deviceInterface;
if (this.deviceInterface != null) {
// We have a device! Tell the activity we are connected.
connectionStatusData.postValue(ConnectionStatus.CONNECTED);
// Setup the listeners for the interface
this.deviceInterface.setListeners(this::onMessageReceived, this::onMessageSent, t -> toast(R.string.message_send_error));
// Tell the user we are connected.
toast(R.string.connected);
// Reset the conversation
messages = new StringBuilder();
messagesData.postValue(messages.toString());
} else {
// deviceInterface was null, so the connection failed
toast(R.string.connection_failed);
connectionStatusData.postValue(ConnectionStatus.DISCONNECTED);
}
getCurrentTime();
}
// Adds a received message to the conversation
private void onMessageReceived(String message) {
messages.append(deviceName).append(": ").append(message).append('\n');
messagesData.postValue(messages.toString());
}
// Adds a sent message to the conversation
private void onMessageSent(String message) {
// Add it to the conversation
messages.append(getApplication().getString(R.string.you_sent)).append(": ").append(message).append('\n');
messagesData.postValue(messages.toString());
// Reset the message box
messageData.postValue("");
}
// Send a message
public void sendMessage(String message) {
new CountDownTimer(1000, 1000) {
public void onTick(long millisUntilFinished) {
if (deviceInterface != null && !TextUtils.isEmpty(message)) {
Log.i("info", "sendMessage: send");
}
deviceInterface.sendMessage(message);
}
public void onFinish() {
disconnect();
timer();
}
}.start();
// Check we have a connected device and the message is not empty, then send the message -----------------
}
//---------------------------------------------------------------------------MY Code
//timer
public void timer(){
new CountDownTimer(28000, 1000) {
public void onTick(long millisUntilFinished) {
Log.i("INFO", "onTick: ");
}
public void onFinish() {
connect();
}
}.start();
}
// Get Time
public void getCurrentTime() {
Calendar calendar = Calendar.getInstance();
SimpleDateFormat mdformat = new SimpleDateFormat("HHmm");
SimpleDateFormat seconds = new SimpleDateFormat("ss");
String strSec = seconds.format(calendar.getTime());
String strDate = "Time" + mdformat.format(calendar.getTime());
//if ((strSec == "29") || (strSec == "59")) {
sendMessage(strDate);
//}
}
// Called when the activity finishes - clear up after ourselves.
@Override
protected void onCleared() {
// Dispose any asynchronous operations that are running
compositeDisposable.dispose();
// Shutdown bluetooth connections
bluetoothManager.close();
}
// Helper method to create toast messages.
private void toast(@StringRes int messageResource) { Toast.makeText(getApplication(), messageResource, Toast.LENGTH_LONG).show(); }
// Getter method for the activity to use.
public LiveData<String> getMessages() { return messagesData; }
// Getter method for the activity to use.
public LiveData<ConnectionStatus> getConnectionStatus() { return connectionStatusData; }
// Getter method for the activity to use.
public LiveData<String> getDeviceName() { return deviceNameData; }
// Getter method for the activity to use.
public LiveData<String> getMessage() { return messageData; }
// An enum that is passed to the activity to indicate the current connection status
enum ConnectionStatus {
DISCONNECTED,
CONNECTING,
CONNECTED
}
}
TimeService：
package com.harrysoft.androidbluetoothserial.demoapp;
import android.app.Notification;
import android.app.PendingIntent;
import android.app.Service;
import android.content.Intent;
import android.os.IBinder;
import android.support.v4.app.*;
import io.reactivex.annotations.Nullable;
import static com.harrysoft.androidbluetoothserial.demoapp.App.CHANNEL_ID;
public class TimeService extends Service {
@Override
public void onCreate() {
super.onCreate();
}
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
String input = intent.getStringExtra("inputExtra");
Intent notificationIntent = new Intent(this, MainActivity.class);
PendingIntent pendingIntent = PendingIntent.getActivity(this,
0, notificationIntent, 0);
Notification notification = new NotificationCompat.Builder(this, CHANNEL_ID)
.setContentTitle("Example Service")
.setContentText(input)
.setSmallIcon(R.drawable.ic_android)
.setContentIntent(pendingIntent)
.build();
startForeground(1, notification);
//do heavy work on a background thread
//stopSelf();
return START_NOT_STICKY;
}
@Override
public void onDestroy() {
super.onDestroy();
}
@Nullable
@Override
public IBinder onBind(Intent intent) {
return null;
}
}
答案 0 :(得分：0)
您必须传递Context作为Intent构造函数的第一个参数。您可以借助application对象来检索它。
Intent serviceIntent = new Intent(getApplication().getApplicationContext(), TimeService.class);