Android应用图标在状态栏上显示实现原理

NotificationManager nm = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
Notification n = new Notification(
resId, "Floats Start!", System.currentTimeMillis());

// 将此通知放到通知栏的"Ongoing"即"正在运行"组中
n.flags |= Notification.FLAG_ONGOING_EVENT;
// 表明在点击了通知栏中的"清除通知"后，此通知不清除，
// 经常与FLAG_ONGOING_EVENT一起使用
n.flags |= Notification.FLAG_NO_CLEAR;

PendingIntent pi = PendingIntent.getActivity(this, 0, getIntent(), 0);
n.contentIntent = pi;
n.setLatestEventInfo(this, "FloatsWindow", "start!", pi);
nm.notify(NOTIFICATION_ID_ICON, n);

package com.chris.floats.window;
import android.os.Bundle;
import android.util.DisplayMetrics;
import android.view.Gravity;
import android.view.WindowManager;
import android.app.Activity;
import android.app.Notification;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.content.Context;
public class MainActivity extends Activity {
private static WindowManager mWindowMgr = null;
private WindowManager.LayoutParams mWindowMgrParams = null;
private static FloatsWindowView mFloatsWindowView = null;

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

@Override
protected void onStop() {
super.onStop();
deleteIconToStatusbar();
}
/*
* 显示应用主界面时，去除悬浮层
* 修改状态栏上的图标
*/
@Override
public void onWindowFocusChanged(boolean hasFocus) {
if(hasFocus){
if(mFloatsWindowView != null){
mWindowMgr.removeView(mFloatsWindowView);
mFloatsWindowView = null;
}
addIconToStatusbar(R.drawable.a0);
}else{
getWindowLayout();
addIconToStatusbar(R.drawable.ic_launcher);
}
}
private void initParams(){
DisplayMetrics dm = getResources().getDisplayMetrics();
mWindowMgrParams.x = dm.widthPixels - 136;
mWindowMgrParams.y = 300;
mWindowMgrParams.width = 136;
mWindowMgrParams.height = 136;
}
private void getWindowLayout(){
if(mFloatsWindowView == null){
mWindowMgr = (WindowManager)getBaseContext().getSystemService(Context.WINDOW_SERVICE);
mWindowMgrParams = new WindowManager.LayoutParams();

/*
* 2003 在指悬浮在所有界面之上
* (4.0+系统中，在下拉菜单下面，而在2.3中，在上拉菜单之上)
*/
mWindowMgrParams.type = 2003;
mWindowMgrParams.format = 1;

/*
* 代码实际是wmParams.flags |= FLAG_NOT_FOCUSABLE;
* 40的由来是wmParams的默认属性（32）+ FLAG_NOT_FOCUSABLE（8）
*/
mWindowMgrParams.flags = 40;
mWindowMgrParams.gravity = Gravity.LEFT | Gravity.TOP;
initParams();

mFloatsWindowView = new FloatsWindowView(this);
mWindowMgr.addView(mFloatsWindowView, mWindowMgrParams);
}
}

private final static int NOTIFICATION_ID_ICON = 0x10000;
/*
* 如果没有从状态栏中删除ICON，且继续调用addIconToStatusbar,
* 则不会有任何变化。除了：
* 如果，将notification中的resId设置不同的图标，则会显示不同
* 的图标
*/
private void addIconToStatusbar(int resId){
NotificationManager nm = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
Notification n = new Notification(
resId, "Floats Start!", System.currentTimeMillis());

// 将此通知放到通知栏的"Ongoing"即"正在运行"组中
n.flags |= Notification.FLAG_ONGOING_EVENT;
// 表明在点击了通知栏中的"清除通知"后，此通知不清除，
// 经常与FLAG_ONGOING_EVENT一起使用
n.flags |= Notification.FLAG_NO_CLEAR;

PendingIntent pi = PendingIntent.getActivity(this, 0, getIntent(), 0);
n.contentIntent = pi;
n.setLatestEventInfo(this, "FloatsWindow", "start!", pi);
nm.notify(NOTIFICATION_ID_ICON, n);
}

private void deleteIconToStatusbar(){
NotificationManager nm = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
nm.cancel(NOTIFICATION_ID_ICON);
}
}