按後退鍵的時候，讓程式退出。
實作起來的思路：
1.捕獲後退鍵被按了這個事件。
Java代碼
@Override
publicbooleanonKeyDown(intkeyCode, KeyEvent event) {
if(keyCode == KeyEvent.KEYCODE_BACK ){
//DO SOMETHING
returntrue;
}
returnfalse;
}
@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
if(keyCode == KeyEvent.KEYCODE_BACK ){
//DO SOMETHING
return true;
}
return false;
}
2-1.通過intent傳回都主螢幕中
Java代碼
@Override
publicbooleanonKeyDown(intkeyCode, KeyEvent event) {
if(keyCode == KeyEvent.KEYCODE_BACK && event.getRepeatCount() ==0) {// 按下的如果是BACK，同時沒有重複
Intent home =newIntent(Intent.ACTION_MAIN);
home.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
home.addCategory(Intent.CATEGORY_HOME);
startActivity(home);
}
returnsuper.onKeyDown(keyCode, event);
}
@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
if (keyCode == KeyEvent.KEYCODE_BACK && event.getRepeatCount() == 0) { // 按下的如果是BACK，同時沒有重複
Intent home = new Intent(Intent.ACTION_MAIN);
home.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
home.addCategory(Intent.CATEGORY_HOME);
startActivity(home);
}
return super.onKeyDown(keyCode, event);
}
2-2.記錄所有打開的activity，關閉的時候将所有的activity關閉
使用單例模式建立一個Activity管理對象，該對象中有一個Activity容器專門負責存儲新開啟的每一個Activity
MyApplication類(儲存每一個Activity，并實作關閉所有Activity的操作
Java代碼
publicclassMyApplicationextendsApplication {
privateList activityList =newLinkedList();
privatestaticMyApplication instance;
privateMyApplication()
{
}
//單例模式中擷取唯一的MyApplication執行個體
publicstaticMyApplication getInstance()
{
if(null== instance)
{
instance =newMyApplication();
}
returninstance;
}
//添加Activity到容器中
publicvoidaddActivity(Activity activity)
{
activityList.add(activity);
}
//周遊所有Activity并finish
publicvoidexit()
{
for(Activity activity:activityList)
{
activity.finish();
}
System.exit(0);
}
}
public class MyApplication extends Application {
private List activityList = new LinkedList();
private static MyApplication instance;
private MyApplication()
{
}
//單例模式中擷取唯一的MyApplication執行個體
public static MyApplication getInstance()
{
if(null == instance)
{
instance = new MyApplication();
}
return instance;
}
//添加Activity到容器中
public void addActivity(Activity activity)
{
activityList.add(activity);
}
//周遊所有Activity并finish
public void exit()
{
for(Activity activity:activityList)
{
activity.finish();
}
System.exit(0);
}
}
在每一個Activity中的onCreate方法裡添加該Activity到MyApplication對象執行個體容器中
Java代碼
MyApplication.getInstance().addActivity(this);
MyApplication.getInstance().addActivity(this);
在需要結束所有Activity的時候調用exit方法
Java代碼
MyApplication.getInstance().exit();