实现常驻型音乐通知栏（逻辑清晰）

效果图：

利用广播来实现通知栏按钮的点击事件，并且动态设置按钮，下面是所有的代码。

MainActivity:

package com.example.notification;

import android.app.Activity;
import android.app.Notification;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.support.v4.app.NotificationCompat;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.RemoteViews;
import android.widget.Toast;

public class MainActivity extends Activity implements OnClickListener {
	public NotificationManager mNotificationManager;
	private RemoteViews mRemoteViews;
	private Button start;
	private boolean isPlay = false;

	/** TAG */
	private final static String TAG = "CustomActivity";
	/** Notification 的ID */
	int notifyId = 101;
	/** NotificationCompat 构造器 */
	NotificationCompat.Builder mBuilder;
	/** 通知栏按钮广播 */
	public ButtonBroadcastReceiver bReceiver;
	/** 通知栏按钮点击事件对应的ACTION */
	public final static String ACTION_BUTTON = "com.notifications.intent.action.ButtonClick";

	// 标识
	public final static String INTENT_BUTTONID_TAG = "ButtonId";
	/** 上一首 按钮点击 ID */
	public final static int BUTTON_PREV_ID = 1;
	/** 播放/暂停 按钮点击 ID */
	public final static int BUTTON_PALY_ID = 2;
	/** 下一首 按钮点击 ID */
	public final static int BUTTON_NEXT_ID = 3;

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

		start = (Button) findViewById(R.id.start);
		start.setOnClickListener(this);

		// 注册广播
		bReceiver = new ButtonBroadcastReceiver();
		IntentFilter intentFilter = new IntentFilter();
		intentFilter.addAction(ACTION_BUTTON);
		registerReceiver(bReceiver, intentFilter);

		mNotificationManager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
	}

	/**
	 * 带按钮的通知栏
	 */
	public void showButtonNotify() {
		mBuilder = new NotificationCompat.Builder(this);
		mRemoteViews = new RemoteViews(getPackageName(), R.layout.notification_layout);
		mRemoteViews.setImageViewResource(R.id.custom_song_icon, R.drawable.app_img_music);
		mRemoteViews.setTextViewText(R.id.tv_custom_song_singer, "歌名");
		mRemoteViews.setTextViewText(R.id.tv_custom_song_name, "作家");

		// API3.0 以上的时候显示按钮，否则消失
		// 如果版本号低于（3。0），那么不显示按钮
		if (BaseTools.getSystemVersion() <= 9) {
			mRemoteViews.setViewVisibility(R.id.ll_custom_button, View.GONE);
		} else {
			mRemoteViews.setViewVisibility(R.id.ll_custom_button, View.VISIBLE);
			if (isPlay) {
				mRemoteViews.setImageViewResource(R.id.btn_custom_play, R.drawable.btn_pause);
			} else {
				mRemoteViews.setImageViewResource(R.id.btn_custom_play, R.drawable.btn_play);
			}
		}

		// 点击的事件处理
		Intent buttonIntent = new Intent(ACTION_BUTTON);
		/* 上一首按钮 */
		buttonIntent.putExtra(INTENT_BUTTONID_TAG, BUTTON_PREV_ID);
		// 这里加了广播，所及INTENT的必须用getBroadcast方法
		PendingIntent intent_prev = PendingIntent.getBroadcast(this, 1, buttonIntent,
				PendingIntent.FLAG_UPDATE_CURRENT);
		mRemoteViews.setOnClickPendingIntent(R.id.btn_custom_prev, intent_prev);
		/* 播放/暂停 按钮 */
		buttonIntent.putExtra(INTENT_BUTTONID_TAG, BUTTON_PALY_ID);
		PendingIntent intent_paly = PendingIntent.getBroadcast(this, 2, buttonIntent,
				PendingIntent.FLAG_UPDATE_CURRENT);
		mRemoteViews.setOnClickPendingIntent(R.id.btn_custom_play, intent_paly);
		/* 下一首 按钮 */
		buttonIntent.putExtra(INTENT_BUTTONID_TAG, BUTTON_NEXT_ID);
		PendingIntent intent_next = PendingIntent.getBroadcast(this, 3, buttonIntent,
				PendingIntent.FLAG_UPDATE_CURRENT);
		mRemoteViews.setOnClickPendingIntent(R.id.btn_custom_next, intent_next);

		mBuilder.setContent(mRemoteViews).setWhen(System.currentTimeMillis())// 通知产生的时间，会在通知信息里显示
				.setTicker("正在播放").setPriority(Notification.PRIORITY_DEFAULT)// 设置该通知优先级
				.setOngoing(true).setSmallIcon(R.drawable.app_img_music);
		Notification notify = mBuilder.build();
		notify.flags = Notification.FLAG_ONGOING_EVENT;
		mNotificationManager.notify(200, notify);
	}

	/**
	 * 广播监听按钮点击事件
	 */
	public class ButtonBroadcastReceiver extends BroadcastReceiver {
		@Override
		public void onReceive(Context context, Intent intent) {
			// TODO Auto-generated method stub
			String action = intent.getAction();
			if (action.equals(ACTION_BUTTON)) {
				// 通过传递过来的ID判断按钮点击属性或者通过getResultCode()获得相应点击事件
				int buttonId = intent.getIntExtra(INTENT_BUTTONID_TAG, 0);
				switch (buttonId) {
				case BUTTON_PREV_ID:
					Log.d(TAG, "上一首");
					Toast.makeText(MainActivity.this, "上一首", Toast.LENGTH_SHORT).show();
					break;
				case BUTTON_PALY_ID:

					isPlay = !isPlay;
					if (isPlay) {
						Log.e("tag", "notifi>>>>>>>设置为播放");
						Toast.makeText(MainActivity.this, "播放", Toast.LENGTH_SHORT).show();
					} else {
						Log.e("tag", "notifi>>>>>>>设置为暂停");
						Toast.makeText(MainActivity.this, "暂停", Toast.LENGTH_SHORT).show();
					}
					showButtonNotify();
					break;
				case BUTTON_NEXT_ID:
					Log.d(TAG, "下一首");
					Toast.makeText(MainActivity.this, "下一首", Toast.LENGTH_SHORT).show();
					break;
				default:
					break;
				}
			}
		}
	}

	@Override
	public void onClick(View v) {
		if (v.getId() == R.id.start) {
			// 开启notifi
			showButtonNotify();
		}
	}

	@Override
	protected void onDestroy() {
		// TODO Auto-generated method stub
		if (bReceiver != null) {
			unregisterReceiver(bReceiver);
		}
		super.onDestroy();
	}
}

清除notification的方法：

mNotificationManager.cancelAll();

上面代码中会用到的一个计算sdk版本的工具类BaseTools：

package com.example.notification;


import android.content.Context;
import android.content.pm.PackageInfo;
import android.content.pm.PackageManager;

public class BaseTools {
	public static String getAppVersion(Context context) throws Exception {
		PackageManager packageManager = context.getPackageManager();
		PackageInfo packInfo = packageManager.getPackageInfo(context.getPackageName(),0);
		String versionName = packInfo.versionName;
		return versionName;
	}
	public static int getSystemVersion(){
		int version= android.os.Build.VERSION.SDK_INT;
		return version;
	}
}

notification的布局notification_layout.xml，其中的样式就是些高度宽度什么的：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical" >

    <ImageView
        android:id="@+id/custom_song_icon"
        android:layout_width="64dp"
        android:layout_height="64dp"
        android:layout_alignParentLeft="true"
        android:layout_centerVertical="true"
        android:src="@drawable/app_img_music" />

    <LinearLayout
        android:id="@+id/ll_custom_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentRight="true"
        android:layout_centerVertical="true"
        android:layout_marginLeft="5dip"
        android:gravity="center_vertical"
        android:orientation="horizontal" >

        <ImageButton
            android:id="@+id/btn_custom_prev"
            style="@style/btn_custom_style"
            android:src="@drawable/btn_prev" />

        <ImageButton
            android:id="@+id/btn_custom_play"
            style="@style/btn_custom_style"
            android:contentDescription="播放"
            android:src="@drawable/btn_play" />

        <ImageButton
            android:id="@+id/btn_custom_next"
            style="@style/btn_custom_style"
            android:contentDescription="下一首"
            android:src="@drawable/btn_next" />
    </LinearLayout>

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_marginBottom="5dip"
        android:layout_marginLeft="5dip"
        android:layout_marginTop="5dip"
        android:layout_toLeftOf="@id/ll_custom_button"
        android:layout_toRightOf="@id/custom_song_icon"
        android:orientation="vertical" >

        <TextView
            android:id="@+id/tv_custom_song_singer"
            style="@style/NotificationTitle"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignParentLeft="true"
            android:layout_alignParentTop="true"
            android:text="title"
            android:textSize="15sp" />

        <TextView
            android:id="@+id/tv_custom_song_name"
            style="@style/NotificationContent"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_alignParentBottom="true"
            android:layout_alignParentLeft="true"
            android:text="content"
            android:textSize="12sp" />
    </RelativeLayout>

</RelativeLayout>