android launchmodel的使用
我们知道android中activity的启动模式有四种，分别为standard，singleTop，singleTask，singleTop。关于这四种启动模式的详细介绍请看<a target=_blank href="http://blog.csdn.net/congqingbin/article/details/7441789">http://blog.csdn.net/congqingbin/article/details/7441789</a>该博文介绍的非常详细，我就不在这里多说了。下面我们列举singleTop和singleTask的一个应用。就是我们应用程序的退出。
一、singleTop应用
我们在启动应用程序的时候，可以先用一个空的Activity来作为入口，并且在manifest文件中加入android:launchMode="singleTop"
<activity
android:name=".FlashActivity"
android:label="@string/app_name"
android:launchMode="singleTop" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
源代码如下：
HomeActivity：
public class FlashActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
Log.d("mm", "FlashActivity onCreate"+getTaskId());
Intent intent = new Intent(this,Main.class);
startActivity(intent);
super.onCreate(savedInstanceState);
}
@Override
protected void onNewIntent(Intent intent) {
Log.d("mm", "FlashActivity onNewIntent");
//当flag为<span style="font-family: 宋体, SimSun;">FLAG_ACTIVITY_CLEAR_TOP的时候，本Activity也要finish掉</span>
<span style="white-space:pre"> </span>if(intent.getFlags() == Intent.FLAG_ACTIVITY_CLEAR_TOP){
finish();
}
super.onNewIntent(intent);
}
@Override
protected void onDestroy() {
Log.d("mm", "FlashActivity ondes");
super.onDestroy();
}
}
MainActivity代码
public class Main extends Activity {
//微信申请时的ID
boolean isRun = true;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.view_stub);
final ArrayList<MyObject> list = new ArrayList<MyObject>();
final ArrayList<MyObject.InnerClassObj> list2 = new ArrayList<MyObject.InnerClassObj>();
if ((((int) (Math.random() * 100)) & 0x01) == 0) {
// to show text
// all you have to do is inflate the ViewStub for textview
ViewStub stub = (ViewStub) findViewById(R.id.viewstub_demo_text);
stub.inflate();
TextView text = (TextView) findViewById(R.id.viewstub_demo_textview);
text.setText("The tree of liberty must be refreshed from time to time" +
" with the blood of patroits and tyrants! Freedom is nothing but " +
"a chance to be better!");
text.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
startActivity();
}
});
} else {
// to show image
// all you have to do is inflate the ViewStub for imageview
ViewStub stub = (ViewStub) findViewById(R.id.viewstub_demo_image);
stub.inflate();
final ImageView image = (ImageView) findViewById(R.id.viewstub_demo_imageview);
image.setImageResource(R.drawable.icon);
image.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
startActivity();
}
});
}
public void startActivity(){
Intent intent = new Intent();
intent.setClass(this, MyActivity.class);
startActivity(intent);
}
@Override
protected void onDestroy() {
Log.d("mm", "MainActivity ondes");
super.onDestroy();
}
}MyActivity的代码
public class MyActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
ImageView image = new ImageView(this);
image.setBackgroundResource(android.R.color.darker_gray);
setContentView(image);
Intent intent = new Intent(this, MMService.class);
startService(intent);
Log.d("mm", "MyActivity onCreate"+getTaskId());
}
@Override
public void onBackPressed() {
Log.d("mm", "MyActivity onBackPressed");
//监听返回键，这时候我们要退出程序的话，要返回到FlashActivity
Intent intent = new Intent(this,FlashActivity.class);
//如果想通过把Task栈中的Activity全部给finish掉的话，就必须设置这个flag,
//不然的话FlashActivity就会又创建一个新的FlashActivity
intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(intent);
super.onBackPressed();
}
@Override
protected void onDestroy() {
Log.d("mm", "MyActivity ondes");
super.onDestroy();
}
}
这样就可以把Task中所有的Activity都能够finish掉了
二、singleTask
singleTask就是设置为singleTask的Activity，在栈中只有一个实例，无论该Activity是在栈顶还是栈底，只要有被召唤就从栈中提到栈顶，当然它以上的Activity都会被finish掉，所以我们可以把FlashActivity的launchmode改为singleTask的话也是可以的。
但是MyActivity中flag就不用在设置了
public class MyActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
ImageView image = new ImageView(this);
image.setBackgroundResource(android.R.color.darker_gray);
setContentView(image);
Intent intent = new Intent(this, MMService.class);
startService(intent);
Log.d("mm", "MyActivity onCreate"+getTaskId());
}
@Override
public void onBackPressed() {
Log.d("mm", "MyActivity onBackPressed");
//监听返回键，这时候我们要退出程序的话，要返回到FlashActivity
Intent intent = new Intent(this,FlashActivity.class);
//如果想通过把Task栈中的Activity全部给finish掉的话，就必须设置这个flag,
//不然的话FlashActivity就会又创建一个新的FlashActivity
//intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(intent);
super.onBackPressed();
}
@Override
protected void onDestroy() {
Log.d("mm", "MyActivity ondes");
super.onDestroy();
}
}
关于Activity的启动模式的应用还有很多，根据自己的业务的需要，来设置。