有时需要监听到应用在前后台切换并做些处理,一般的做法可能是建立一个BaseActivity,然后全部的Activity都继承它,在BaseActivity的onStart和onStop中计数去处理。这样并不是最好的方式,不做详细介绍,有更好的方式,道理其实差不多,就是借助ActivityLifecycleCallbacks来实现。
一、写了个帮助类:
package com.dway.helper;
import android.app.Activity;
import android.app.Application;
import android.os.Bundle;
/**
* 应用前后台状态监听帮助类,仅在Application中使用
* Created by dway on 2018/1/30.
*/
public class AppFrontBackHelper {
private OnAppStatusListener mOnAppStatusListener;
public AppFrontBackHelper() {
}
/**
* 注册状态监听,仅在Application中使用
* @param application
* @param listener
*/
public void register(Application application, OnAppStatusListener listener){
mOnAppStatusListener = listener;
application.registerActivityLifecycleCallbacks(activityLifecycleCallbacks);
}
public void unRegister(Application application){
application.unregisterActivityLifecycleCallbacks(activityLifecycleCallbacks);
}
private Application.ActivityLifecycleCallbacks activityLifecycleCallbacks = new Application.ActivityLifecycleCallbacks() {
//打开的Activity数量统计
private int activityStartCount = 0;
@Override
public void onActivityCreated(Activity activity, Bundle savedInstanceState) {
}
@Override
public void onActivityStarted(Activity activity) {
activityStartCount++;
//数值从0变到1说明是从后台切到前台
if (activityStartCount == 1){
//从后台切到前台
if(mOnAppStatusListener != null){
mOnAppStatusListener.onFront();
}
}
}
@Override
public void onActivityResumed(Activity activity) {
}
@Override
public void onActivityPaused(Activity activity) {
}
@Override
public void onActivityStopped(Activity activity) {
activityStartCount--;
//数值从1到0说明是从前台切到后台
if (activityStartCount == 0){
//从前台切到后台
if(mOnAppStatusListener != null){
mOnAppStatusListener.onBack();
}
}
}
@Override
public void onActivitySaveInstanceState(Activity activity, Bundle outState) {
}
@Override
public void onActivityDestroyed(Activity activity) {
}
};
public interface OnAppStatusListener{
void onFront();
void onBack();
}
}
public class MyApp extends Application {
@Override
public void onCreate() {
super.onCreate();
AppFrontBackHelper helper = new AppFrontBackHelper();
helper.register(MyApp.this, new AppFrontBackHelper.OnAppStatusListener() {
@Override
public void onFront() {
//应用切到前台处理
}
@Override
public void onBack() {
//应用切到后台处理
}
});
}
}
也可以直接在Application里面写,但写成帮助类,是为了不用每次都去写,减轻Application的代码量