Question

我需要从后台进程发送通知。在这个项目中，我试图每10秒发送一次简单的通知。它运行但没有发送通知！

public class MainActivity extends ActionBarActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Long previousDate = new Long(System.currentTimeMillis());
        NotificationManager manager = (NotificationManager)getSystemService(Context.NOTIFICATION_SERVICE);
        new GetMethodEx1().execute(previousDate);
    }

    class GetMethodEx1 extends AsyncTask<Long,Void,Void>{

        private Context mContext;
        private int NOTIFICATION_ID = 1;
        private Notification mNotification;
        private NotificationManager mNotificationManager;

        @Override
        protected Void doInBackground(Long... params){
            Long previousDate = params[0];
            Long Intervall = new Long(System.currentTimeMillis());
            while ( true ){
                if ((Intervall - previousDate) > 10000 ){
                    String title = "Title";
                    String body = "Hi, I am the body";
                    createNotification( title, body);
                    previousDate = Intervall;
                }
            }
            return null;
        }

        private void createNotification(String contentTitle, String contentText) {

            //Build the notification using Notification.Builder
            Notification.Builder builder = new Notification.Builder(mContext)
            .setSmallIcon(android.R.drawable.stat_sys_download)
            .setAutoCancel(true)
            .setContentTitle(contentTitle)
            .setContentText(contentText);

            //Get current notification
            mNotification = builder.getNotification();

            //Show the notification
            mNotificationManager.notify(NOTIFICATION_ID, mNotification);
        }
  // [ ... ]
  }

它不会崩溃但不起作用！

Answer 1

在createNotification()方法中，您需要将代码修改为

private void createNotification(String contentTitle, String contentText) {

    mNotificationManager = (NotificationManager)getSystemService(Context.NOTIFICATION_SERVICE);
    //Build the notification using Notification.Builder
    Notification.Builder builder = new Notification.Builder(mContext)
    .setSmallIcon(android.R.drawable.stat_sys_download)
    .setAutoCancel(true)
    .setContentTitle(contentTitle)
    .setContentText(contentText);


    //Show the notification
    mNotificationManager.notify(NOTIFICATION_ID, builder.build());
}

在您的onCreate中，您不需要此行

NotificationManager manager = (NotificationManager)getSystemService(Context.NOTIFICATION_SERVICE);

请删除以上行。

修改

当您在getSystemService方法内调用createNotification()而不是onCreate()时，您需要将Context作为参数传递给方法createNotification()，因为getSystemService是类Context的一种方法，所以您需要在上下文中运行它。

private void createNotification(String contentTitle, String contentText,Context context) { mNotificationManager = (NotificationManager)context.getSystemService(Context.NOTIFICATION_SERVICE); //Build the notification using Notification.Builder Notification.Builder builder = new Notification.Builder(mContext) .setSmallIcon(android.R.drawable.stat_sys_download) .setAutoCancel(true) .setContentTitle(contentTitle) .setContentText(contentText); //Show the notification mNotificationManager.notify(NOTIFICATION_ID, builder.build()); }

在调用方法createNotification()时使用

createNotification( c, b,MainActivity.this);

Answer 2

鉴于Gabrio的问题和Sash_KP的答案，我想在这里提供清理代码的概念：

https://github.com/tks423/glendale-case-detail-app

public class MainActivity extends AppCompatActivity {

private EditText respText;
private static final String siteUrlSansActivityId = "https://csi.glendaleca.gov/csipropertyportal/jsp/frameContent.jsp?actStatus=Case&actId=";
private String siteUrl;
private EditText activityId;
private Context mContext  = MainActivity.this;
private int NOTIFICATION_ID = 1;
private Notification noti;
private NotificationManager nm;
PendingIntent contentIntent;

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

    StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
    StrictMode.setThreadPolicy(policy);

    activityId = (EditText) findViewById(R.id.edtURL);

    activityId.addTextChangedListener(new TextWatcher() {

        public void afterTextChanged(Editable s) {

            siteUrl = siteUrlSansActivityId + activityId.getText().toString();
        }

        public void beforeTextChanged(CharSequence s, int start, int count, int after) {}

        public void onTextChanged(CharSequence s, int start, int before, int count) {}
    });

    Button btnGo = (Button) findViewById(R.id.btnGo);
    respText = (EditText) findViewById(R.id.edtResp);
    btnGo.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {

            try {

                Log.d("JSwa", "Connecting to [" + siteUrl + "]");
                Document doc  = Jsoup.connect(siteUrl).get();
                // Get document (HTML page) title
                String title = doc.title();
                Log.d("JSwA", "Title ["+title+"]");

                Elements topicList = doc.select("td.tabletext");

                String status = topicList.get(1).text();

                respText.setText(status);
            }
            catch(Throwable t) {
                t.printStackTrace();
            }

        }
    });

    nm = (NotificationManager)getSystemService(Context.NOTIFICATION_SERVICE);

    ( new ParseURLLoop() ).execute(siteUrl);
}


@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();
    if (id == R.id.action_settings) {
        return true;
    }
    return super.onOptionsItemSelected(item);
}

private class ParseURLLoop extends AsyncTask<String, Void, Void> {

    @Override
    protected Void doInBackground(String... params) {

        //String siteUrl = params[0];

        Long previousDate = new Long(System.currentTimeMillis());
        Log.d("doInBackground", "PreviousDate [" + previousDate + "]");
        Long intervall = new Long(System.currentTimeMillis());
        Log.d("doInBackground", "intervall [" + intervall + "]");

        Boolean a = false;
        while ( a == false){
            if ((intervall - previousDate) > 1000 * 60 ){

                StringBuffer buffer = new StringBuffer();
                try {
                    Log.d("JSwa", "In here");

                    Log.d("JSwa", "Connecting to [" + siteUrl + "]");
                    Document doc  = Jsoup.connect(siteUrl).get();
                    Log.d("JSwa", "Connected to [" + siteUrl + "]");
                    // Get document (HTML page) title
                    String title = doc.title();
                    Log.d("JSwA", "Title ["+title+"]");

                    Elements topicList = doc.select("td.tabletext");

                    if(!"In Process".equals(topicList.get(1).text())){
                        Log.d("Status", "status is [" + topicList.get(1).text() +"]");

                        createNotification( "Glendale AE" , topicList.get(1).text() , MainActivity.this);

                        Intent notificationIntent = new Intent(mContext.getApplicationContext(), MainActivity.class);
                        contentIntent = PendingIntent.getActivity(mContext.getApplicationContext(),
                                0, notificationIntent,
                                PendingIntent.FLAG_CANCEL_CURRENT);
                    }
                }
                catch(Throwable t) {
                    t.printStackTrace();
                }

                previousDate = intervall;
            }
            intervall = new Long(System.currentTimeMillis());
        }

        return null;
    }

    private void createNotification(String contentTitle, String contentText,Context context) {

        Log.d("createNotification", "title is [" + contentTitle +"]");

        nm = (NotificationManager)context.getSystemService(Context.NOTIFICATION_SERVICE);
        //Build the notification using Notification.Builder
        Notification.Builder builder = new Notification.Builder(mContext)
                .setSmallIcon(android.R.drawable.stat_sys_download)
                .setAutoCancel(true)
                .setContentTitle(contentTitle)
                .setContentText(contentText);


        //Show the notification
        nm.notify(NOTIFICATION_ID, builder.build());
    }



    @Override
    protected void onPreExecute() {
        super.onPreExecute();
    }

}

}

从Asynctask进程获取通知

2 个答案: