安卓通知栏的用法

通知栏简介：

Notification can display some information for user. Some users use Android Wear platform, which work with notification better and use wear devices you can do some actions and work with application better. As example user can delay reminder without use smartphone.

创建一个通知栏步骤：

Building a notification
Better way build a new notification use NotificationCompat.Builder object. We can add to notification many attributes, like title, description, icon, additional action, etc.

NotificationCompat.Builder mBuilder =
    new NotificationCompat.Builder(this)
        .setSmallIcon(R.drawable.notification_icon)
        .setContentTitle("My notification")
        .setContentText("Hello World!");

添加通知栏对应的点击跳转页面：

We also can add intent to our notification.

Intent resultIntent = new Intent(this, ResultActivity.class);
PendingIntent resultPendingIntent =
    PendingIntent.getActivity(
    this,
    0,
    resultIntent,
    PendingIntent.FLAG_UPDATE_CURRENT
);
mBuilder.setContentIntent(resultPendingIntent);

如果有附加的活动，必须添加intent

If we have additional action we must add intent for this action.

mBuilder.addAction(
R.drawable.ic_notification,
"ACTION_TITLE",
resultPendingIntent);

发送通知栏状态：

Latest step send created notification

// Sets an ID for the notification
int mNotificationId = 001;
// Gets an instance of the NotificationManager service
NotificationManager mNotifyMgr =
(NotificationManager) getSystemService(NOTIFICATION_SERVICE);
// Builds the notification and issues it.
mNotifyMgr.notify(mNotificationId, mBuilder.build());

Pending intent flags

Type	Name	Description
int	FLAG_CANCEL_CURRENT	Flag indicating that if the described PendingIntent already exists, the current one should be canceled before generating a new one.
int	FLAG_NO_CREATE	Flag indicating that if the described PendingIntent does not already exist, then simply return null instead of creating it.
int	FLAG_ONE_SHOT	Flag indicating that this PendingIntent can be used only once.
int	FLAG_UPDATE_CURRENT	Flag indicating that if the described PendingIntent already exists, then keep it but replace its extra data with what is in this new Intent.

App Description

Application has 2 activities, which display information about notes. Application can send notification and user can choose some actions. These actions depend on user behavior with notification.

Create a project

First step is create a project (File / New Project…)

After this need to create project with Activity and Fragment.

添加依赖：
Add dependences

Need add dependencies tobuild.gradle file:

dependencies {
    compile fileTree(dir: ‘libs‘, include: [‘*.jar‘])
    compile ‘com.android.support:appcompat-v7:22.0.0‘
    compile ‘com.android.support:recyclerview-v7:21.0.3‘
    compile ‘com.android.support:cardview-v7:21.0.3‘
}

Add strings and an array to strings.xml and arrays.xml

We will use string constant and array constant. We must add these constant to strings.xml and arrays.xml

strings.xml

<resources>
    <string name="app_name">NotificationDemo</string>
    <string name="action_notification">Notification</string>
    <string name="action_all_notes">All notes</string>
    <string name="action_settings">Settings</string>
    <string name="title_activity_detail">DetailActivity</string>
</resources>

arrays.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <array name="list_values">
        <item>First item</item>
        <item>Second item</item>
        <item>Third item</item>
        <item>Fourth item</item>
    </array>
</resources>

Add icon for notifications

We also will be use icon for additional action in notification. We must add this icon to our project (File / New… / Image Asset) and choose asset type – Notification icon.

Update fragment_main.xml.

This project has fragment_main.xml file with layout to main fragment. We must update this file.

fragment_main.xml

<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.alexzh.tutorial.notificationdemo.ListFragment">

    <android.support.v7.widget.RecyclerView
        android:id="@+id/list"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

</LinearLayout>

Create ListFragment and delete this fragment from MainActivity.java

When we use Wizard（向导） for creating Activity with Fragment. Fragment was created in MainActivity class. I move this fragment to a new class, which called ListFragment.

package com.alexzh.tutorial.notificationdemo;

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v7.widget.DefaultItemAnimator;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.StaggeredGridLayoutManager;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

public class ListFragment extends Fragment {
    private String[] list;

    public ListFragment() {

    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
    Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_main, container, false);
        list = getResources().getStringArray(R.array.list_values);

        StaggeredGridLayoutManager mGridLayoutManager =
            new StaggeredGridLayoutManager(1, StaggeredGridLayoutManager.VERTICAL);
        RecyclerView mRecyclerView = (RecyclerView) rootView.findViewById(R.id.list);
        mRecyclerView.setHasFixedSize(true);
        mRecyclerView.setLayoutManager(mGridLayoutManager);
        mRecyclerView.setItemAnimator(new DefaultItemAnimator());
        return rootView;
    }
}

Creating an adapter
Next step is creating an adapter with notes.
First step is creating layout for this adapter, which called item_text.xml.

<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.CardView
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:card_view="http://schemas.android.com/apk/res-auto"
    android:orientation="horizontal"
    android:layout_width="match_parent"
    android:layout_marginLeft="8dp"
    android:layout_marginRight="8dp"
    android:layout_marginTop="10dp"
    android:layout_marginBottom="10dp"
    card_view:cardCornerRadius="4dp"
    android:layout_height="wrap_content">

    <LinearLayout
        android:id="@+id/background"
        android:orientation="horizontal"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:paddingLeft="12dp"
        android:paddingRight="12dp"
        android:paddingTop="8dp"
        android:paddingBottom="8dp">

        <TextView
            android:id="@+id/text"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:textSize="18sp"
            android:paddingTop="8dp"
            android:paddingRight="12dp"
            android:paddingLeft="12dp"
            android:paddingBottom="8dp"/>

        <ImageView
            android:id="@+id/image"
            android:layout_width="24dp"
            android:layout_height="24dp"
            android:src="@mipmap/ic_launcher" />

    </LinearLayout>
</android.support.v7.widget.CardView>

Second step is creating a class with Adapter. For this situation we will extend our class from RecyclerView.ViewHolder class.

public class NotesAdapter extends RecyclerView.Adapter<NotesAdapter.ViewHolder> {
    private Context mContext;
    private String[] mList;

    public NotesAdapter(Context context, String[] list) {
        mContext = context;
        mList = list;
    }

    @Override
    public ViewHolder onCreateViewHolder(ViewGroup viewGroup, int i) {
        View view = LayoutInflater.from(viewGroup.getContext()).inflate(
                R.layout.item_text,
                viewGroup,
                false);
        return new ViewHolder(mContext, view);
    }

    @Override
    public void onBindViewHolder(ViewHolder viewHolder, int position) {
        viewHolder.mNoteText.setText(mList[position]);
    }

    @Override
    public int getItemCount() {
        return mList.length;
    }

    public static class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
        private Context mContext;
        private TextView mNoteText;
        private ImageView mNotificationImage;

        public ViewHolder(Context context, View itemView) {
            super(itemView);
            mContext = context;
            mNoteText = (TextView) itemView.findViewById(R.id.text);
            mNotificationImage = (ImageView) itemView.findViewById(R.id.image);
            mNotificationImage.setOnClickListener(this);
            itemView.setOnClickListener(this);
            itemView.setTag(itemView);
        }

        @Override
        public void onClick(View v) {
            if (v.getId() == R.id.image) {
                Intent allNotesIntent = new Intent(mContext, MainActivity.class);
                Intent detailNoteIntent = new Intent(mContext, DetailActivity.class);
                allNotesIntent.putExtra(MainActivity.NOTIFICATION_ID_STR, MainActivity.NOTIFICATION_ID);
                detailNoteIntent.putExtra(DetailActivity.TEXT_MESSAGE, mNoteText.getText());
                PendingIntent detailPendingIntent = PendingIntent.getActivity(mContext, 0, detailNoteIntent, PendingIntent.FLAG_CANCEL_CURRENT);
                PendingIntent allNotesPendingIntent = PendingIntent.getActivity(mContext, 0, allNotesIntent, PendingIntent.FLAG_CANCEL_CURRENT);
                NotificationCompat.Builder mBuilder = new NotificationCompat.Builder(mContext);
                mBuilder.setSmallIcon(R.mipmap.ic_launcher);
                mBuilder.setContentTitle(mContext.getString(R.string.action_notification));
                mBuilder.setContentText(mNoteText.getText());
                mBuilder.addAction(
                        R.drawable.ic_notification,
                        mContext.getString(R.string.action_all_notes),
                        allNotesPendingIntent);
                mBuilder.setAutoCancel(true);
                mBuilder.setContentIntent(detailPendingIntent);

                NotificationManager mNotificationManager = (NotificationManager)
                            mContext.getSystemService(Context.NOTIFICATION_SERVICE);

                mNotificationManager.notify(MainActivity.NOTIFICATION_ID, mBuilder.build());
            } else {
                Intent detailNoteIntent = new Intent(mContext, DetailActivity.class);
                detailNoteIntent.putExtra(DetailActivity.TEXT_MESSAGE, mNoteText.getText());
                mContext.startActivity(detailNoteIntent);
            }
        }
    }
}

After it need create adapter and add this adapter to mRecyclerView object. It’s need do in ListFragment class.

NotesAdapter mAdapter = new NotesAdapter(getActivity(), list);
mRecyclerView.setAdapter(mAdapter);

Update mainActivity and add constant for NOTIFICATIONS
Next step is create constant which used to notifications. These constant was created in MainActivity class.

public static int NOTIFICATION_ID = 100;
public static String NOTIFICATION_ID_STR = "_id";

And create constant for sending text to detail activity. This constant need create in DetailActivity.

public static final String TEXT_MESSAGE = "text_message";

Add detailActivity with fragment
Need to add new Activity with a Fragment. For it need to click File / New… / Activity / Blank activity with a fragment.

Increase font for detail information
Next step is increase text size for displaying some note. We need to update layout file for detail fragment and to add this attributes for TextView .

android:textSize="24sp"

After it we can load note text from Intent.

TextView textView = (TextView) rootView.findViewById(R.id.textView);
if (getActivity().getIntent().getStringExtra(TEXT_MESSAGE) != null)
textView.setText(getActivity().getIntent().getStringExtra(TEXT_MESSAGE));

Full source code you can display on github.