按后退键的时候，让程序退出。
实现起来的思路：
1.捕获后退键被按了这个事件。
Java代码
@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.通过intent返回都主屏幕中
Java代码
@Override
publicbooleanonKeyDown(intkeyCode, KeyEvent event) {
if(keyCode == KeyEvent.KEYCODE_BACK && event.getRepeatCount() ==0) {// 按下的如果是BACK，同时没有重复
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，同时没有重复
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.记录所有打开的activity，关闭的时候将所有的activity关闭
使用单例模式创建一个Activity管理对象，该对象中有一个Activity容器专门负责存储新开启的每一个Activity
MyApplication类(储存每一个Activity，并实现关闭所有Activity的操作
Java代码
publicclassMyApplicationextendsApplication {
privateList activityList =newLinkedList();
privatestaticMyApplication instance;
privateMyApplication()
{
}
//单例模式中获取唯一的MyApplication实例
publicstaticMyApplication getInstance()
{
if(null== instance)
{
instance =newMyApplication();
}
returninstance;
}
//添加Activity到容器中
publicvoidaddActivity(Activity activity)
{
activityList.add(activity);
}
//遍历所有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()
{
}
//单例模式中获取唯一的MyApplication实例
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);
}
//遍历所有Activity并finish
public void exit()
{
for(Activity activity:activityList)
{
activity.finish();
}
System.exit(0);
}
}
在每一个Activity中的onCreate方法里添加该Activity到MyApplication对象实例容器中
Java代码
MyApplication.getInstance().addActivity(this);
MyApplication.getInstance().addActivity(this);
在需要结束所有Activity的时候调用exit方法
Java代码
MyApplication.getInstance().exit();