知識點
我們用當前程序的Application來監測統計Activity的個數,當個數從0->1時程序進入前臺,當個數從n->0時程序進入後臺,我們只需要在Application或者BaseActivity或者存在於生命週期裏的Activity裏註冊即可。
工具類代碼
import android.app.Activity;
import android.app.Application;
import android.os.Bundle;
public class AppForeBackUtil {
private AppForeBackExchangeListener appForeBackExchangeListener;
public AppForeBackUtil() {
}
/**
* 註冊狀態監聽
*
* @param application
* @param listener
*/
public void register(Application application, AppForeBackExchangeListener listener) {
appForeBackExchangeListener = listener;
application.registerActivityLifecycleCallbacks(activityLifecycleCallbacks);
}
public void unRegister(Application application) {
application.unregisterActivityLifecycleCallbacks(activityLifecycleCallbacks);
}
private Application.ActivityLifecycleCallbacks activityLifecycleCallbacks = new Application.ActivityLifecycleCallbacks() {
//打開的Activity數量統計
private int activityStartCount = 0;
@Override
public void onActivityCreated(Activity activity, Bundle savedInstanceState) {
}
@Override
public void onActivityStarted(Activity activity) {
activityStartCount++;
//數值從0變到1說明是從後臺切到前臺
if (activityStartCount == 1) {
//從後臺切到前臺
if (appForeBackExchangeListener != null) {
appForeBackExchangeListener.toFront();
}
}
}
@Override
public void onActivityResumed(Activity activity) {
}
@Override
public void onActivityPaused(Activity activity) {
}
@Override
public void onActivityStopped(Activity activity) {
activityStartCount--;
//數值從1到0說明是從前臺切到後臺
if (activityStartCount == 0) {
//從前臺切到後臺
if (appForeBackExchangeListener != null) {
appForeBackExchangeListener.toBack();
}
}
}
@Override
public void onActivitySaveInstanceState(Activity activity, Bundle outState) {
}
@Override
public void onActivityDestroyed(Activity activity) {
}
};
public interface AppForeBackExchangeListener {
void toFront();
void toBack();
}
}
使用代碼
AppForeBackUtil helper = new AppForeBackUtil ();
helper.register(getApplication(), new AppForeBackUtil .AppForeBackExchangeListener () {
@Override
public void toFront() {
//TODO 應用進入前臺後的操作
}
@Override
public void toBack() {
//TODO 應用進入後臺後的操作
}
});
注意事項
在Application裏使用時需要注意,Application裏不能操作UI,註冊時填入this即可。在Activity裏使用時需要通過getApplication()方法獲取Application對象。
總結
其實前後臺切換還有很多實現方法,這只是一種,可以實現切換後臺等一系列切換時的觸發。所以我比較傾向使用這個。大家有更好的方法也可以提出來,當然最優也是我個人認爲的,哈哈哈~