Android生命周期二——Task，DialogActivity

Task

Task是一个栈，有压，弹两个动作，顺序先进后出。可以把Task看作是一个应用程序所有Activity的一个容器，它把所有的Activity组织在一起，让用户感觉应用程序是一个整体。

应用程序启动第一个Activity后，该Activity会被压入到栈中，
点击第二个Activity后，该Activity会被压入到栈中……

记住一点，程序只会显示在栈顶的Activity。如果Activity调用了finish方法，则会被销毁，从栈中踢出去。

直接上代码：

package com.zhd.lc;import android.app.Activity;import android.content.Intent;import android.os.Bundle;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;public class FirstActivity extends Activity {/** Called when the activity is first created. */@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.firstactivity);Button btnFirst = (Button) findViewById(R.id.btnFirst);btnFirst.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View view) {Intent intent = new Intent();intent.setClass(FirstActivity.this, SecondActivity.class);FirstActivity.this.startActivity(intent);}});}@Overrideprotected void onStart() {super.onStart();System.out.println("FirstActivity---->onStart");}@Overrideprotected void onRestart() {super.onRestart();System.out.println("FirstActivity---->onRestart");}@Overrideprotected void onResume() {super.onResume();System.out.println("FirstActivity---->onResume");}@Overrideprotected void onPause() {super.onPause();System.out.println("FirstActivity---->onPause");}@Overrideprotected void onStop() {super.onStop();System.out.println("FirstActivity---->onStop");}@Overrideprotected void onDestroy() {super.onDestroy();System.out.println("FirstActivity---->onDestroy");}}

 

 

package com.zhd.lc;import android.app.Activity;import android.content.Intent;import android.os.Bundle;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;public class SecondActivity extends Activity {/** Called when the activity is first created. */@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.secondactivity);Button btnSecond = (Button) findViewById(R.id.btnSecond);btnSecond.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View view) {Intent intent = new Intent();intent.setClass(SecondActivity.this, ThirdActivity.class);SecondActivity.this.startActivity(intent);SecondActivity.this.finish();}});}protected void onStart() {super.onStart();System.out.println("SecondActivity---->onStart");}@Overrideprotected void onRestart() {super.onRestart();System.out.println("SecondActivity---->onRestart");}@Overrideprotected void onResume() {super.onResume();System.out.println("SecondActivity---->onResume");}@Overrideprotected void onPause() {super.onPause();System.out.println("SecondActivity---->onPause");}@Overrideprotected void onStop() {super.onStop();System.out.println("SecondActivity---->onStop");}@Overrideprotected void onDestroy() {super.onDestroy();System.out.println("SecondActivity---->onDestroy");}}

 

 

package com.zhd.lc;import android.app.Activity;import android.content.Intent;import android.os.Bundle;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;public class ThirdActivity extends Activity {/** Called when the activity is first created. */@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.thirdactivity);Button btnThird = (Button) findViewById(R.id.btnThird);btnThird.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View view) {Intent intent = new Intent();intent.setClass(ThirdActivity.this, FirstActivity.class);ThirdActivity.this.startActivity(intent);}});}protected void onStart() {super.onStart();System.out.println("ThirdActivity---->onStart");}@Overrideprotected void onRestart() {super.onRestart();System.out.println("ThirdActivity---->onRestart");}@Overrideprotected void onResume() {super.onResume();System.out.println("ThirdActivity---->onResume");}@Overrideprotected void onPause() {super.onPause();System.out.println("ThirdActivity---->onPause");}@Overrideprotected void onStop() {super.onStop();System.out.println("ThirdActivity---->onStop");}@Overrideprotected void onDestroy() {super.onDestroy();System.out.println("ThirdActivity---->onDestroy");}}

其他的布局文件等……就不上代码了，注意SecondActivity.this.finish(); 这句代码，会将SecondActivity从栈中踢出去，从而你在显示ThirdActivity，点击返回按钮时，会直接跳到FirstActivity去了，请看下面的方法调用顺序

03-07 09:52:48.897: INFO/System.out(312): FirstActivity---->onPause
03-07 09:52:49.127: INFO/System.out(312): SecondActivity---->onStart
03-07 09:52:49.136: INFO/System.out(312): SecondActivity---->onResume
03-07 09:52:49.516: INFO/System.out(312): FirstActivity---->onStop
03-07 09:52:50.837: INFO/System.out(312): SecondActivity---->onPause
03-07 09:52:50.938: INFO/System.out(312): ThirdActivity---->onStart
03-07 09:52:50.947: INFO/System.out(312): ThirdActivity---->onResume
03-07 09:52:51.307: INFO/System.out(312): SecondActivity---->onStop
03-07 09:52:51.315: INFO/System.out(312): SecondActivity---->onDestroy        
03-07 09:52:52.677: INFO/System.out(312): ThirdActivity---->onPause
03-07 09:52:52.775: INFO/System.out(312): FirstActivity---->onStart
03-07 09:52:52.775: INFO/System.out(312): FirstActivity---->onResume
03-07 09:52:53.156: INFO/System.out(312): ThirdActivity---->onStop
03-07 09:53:05.316: INFO/System.out(312): FirstActivity---->onPause             //可以看到并没有返回到SecondActivity
03-07 09:53:05.496: INFO/System.out(312): ThirdActivity---->onRestart
03-07 09:53:05.527: INFO/System.out(312): ThirdActivity---->onStart
03-07 09:53:05.527: INFO/System.out(312): ThirdActivity---->onResume
03-07 09:53:06.067: INFO/System.out(312): FirstActivity---->onStop
03-07 09:53:06.086: INFO/System.out(312): FirstActivity---->onDestroy

 

DialogActivity

对话框式的Activity，在代码编写上和普通的Activity没有区别，我们主要看一下他的生命周期
代码就不上了，DialogActivity实现主要就是在AndroidManifest.xml文件中指定一个属性即可：

<?xml version="1.0" encoding="utf-8"?><manifest xmlns:android="http://schemas.android.com/apk/res/android"package="com.zhd.lc" android:versionCode="1" android:versionName="1.0"><uses-sdk android:minSdkVersion="4" /><application android:icon="@drawable/icon" android:label="@string/app_name"><activity android:name=".FirstActivity" android:label="@string/app_name"><intent-filter><action android:name="android.intent.action.MAIN" /><category android:name="android.intent.category.LAUNCHER" /></intent-filter></activity><activity android:name=".SecondActivity" android:label="@string/app_name" /><activity android:name=".ThirdActivity" android:label="@string/app_name" /><activity android:name=".DialogActivity" android:label="@string/app_name"android:theme="@android:style/Theme.Dialog" /></application></manifest> 

.DialogActivity" android:label="@string/app_name" android:theme="@android:style/Theme.Dialog" />

android:theme="@android:style/Theme.Dialog"这一句就是DialogActivity对话框的实现，简单吧。当然这只是最简单的一个对话框，Android提供了一系列的对话框，后面系统学习。 

DialogActivity对话框的生命周期

03-10 07:09:29.203: INFO/System.out(237): FirstActivity---->onPause
03-10 07:09:29.443: INFO/System.out(237): SecondActivity---->onStart
03-10 07:09:29.453: INFO/System.out(237): SecondActivity---->onResume
03-10 07:09:29.802: INFO/System.out(237): FirstActivity---->onStop
03-10 07:09:35.782: INFO/System.out(237): SecondActivity---->onPause
03-10 07:09:35.983: INFO/System.out(237): ThirdActivity---->onStart
03-10 07:09:35.983: INFO/System.out(237): ThirdActivity---->onResume
03-10 07:09:36.323: INFO/System.out(237): SecondActivity---->onStop
03-10 07:09:38.282: INFO/System.out(237): ThirdActivity---->onPause  //可以看到这里并没有调用ThirdActivity的断Stop方法，因为ThirdActivity这个Activity并没有完全从界面上消失，所以不会调用Stop方法，这里需要注意。
03-10 07:09:38.402: INFO/System.out(237): DialogActivity---->onStart
03-10 07:09:38.402: INFO/System.out(237): DialogActivity---->onResume
03-10 07:09:42.872: INFO/System.out(237): DialogActivity---->onPause
03-10 07:09:43.211: INFO/System.out(237): ThirdActivity---->onStop
03-10 07:09:43.262: INFO/System.out(237): FirstActivity---->onStart
03-10 07:09:43.272: INFO/System.out(237): FirstActivity---->onResume
03-10 07:09:43.723: INFO/System.out(237): DialogActivity---->onStop

方法名

下一个将调用的方法

是否会被内存回收

 

onCreate()

onStart()

N 

onRestart()

onStart()

N 

onStart()

onResume() or onStop()

N 

onResume()

onPause()

N 

onPause()

onResume() or

onStop()

Y/N 

onStop()

onRestart() or

onDestroy()

Y 

onDestroy()

nothing

Y 

 

好了，今天就到这里，休息……休息……