android Task Activity launchMode="singleTask" singleInstance 代码分析

<?xml version="1.0" encoding="utf-8"?><manifest xmlns:android="http://schemas.android.com/apk/res/android"    package="com.example.testsinglainstance"    android:versionCode="1"    android:versionName="1.0" >    <uses-sdk        android:minSdkVersion="8"        android:targetSdkVersion="8" />    <application        android:allowBackup="true"        android:icon="@drawable/ic_launcher"        android:label="@string/app_name"        android:theme="@style/AppTheme" >        <activity            android:name="com.example.testsinglainstance.MainActivity"            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=".Activity2"            android:launchMode="singleInstance"            android:label="@string/app_name" >        </activity>        <activity            android:name=".Activity3"            android:launchMode="singleTask"            android:label="@string/app_name" >        </activity>    </application></manifest>

package com.example.testsinglainstance;import android.os.Bundle;import android.app.Activity;import android.content.Intent;import android.view.Menu;import android.view.View;import android.view.View.OnClickListener;import android.widget.TextView;public class MainActivity extends Activity {@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);TextView tv = (TextView) findViewById(R.id.tv);tv.setText("1");System.out.println("1-oncreate->TaskId:"+this.getTaskId()+",hashcode:"+this.hashCode());tv.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {MainActivity.this.startActivity(new Intent(MainActivity.this,Activity2.class));}});}@Overrideprotected void onDestroy() {System.out.println("1-onDestroy");super.onDestroy();}}

package com.example.testsinglainstance;import android.os.Bundle;import android.app.Activity;import android.content.Intent;import android.view.Menu;import android.view.View;import android.view.View.OnClickListener;import android.widget.TextView;public class Activity2 extends Activity {@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);TextView tv=(TextView) findViewById(R.id.tv);tv.setText("2");System.out.println("2-oncreate->TaskId:"+this.getTaskId()+",hashcode:"+this.hashCode());tv.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {Activity2.this.startActivity(new Intent(Activity2.this,Activity3.class));}});}@Overrideprotected void onDestroy() {System.out.println("2-onDestroy");super.onDestroy();}}

package com.example.testsinglainstance;import android.os.Bundle;import android.app.Activity;import android.content.Intent;import android.view.Menu;import android.view.View;import android.view.View.OnClickListener;import android.widget.TextView;public class Activity3 extends Activity {@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);TextView tv=(TextView) findViewById(R.id.tv);tv.setText("3");System.out.println("3-oncreate->TaskId:"+this.getTaskId()+",hashcode:"+this.hashCode());tv.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {Activity3.this.startActivity(new Intent(Activity3.this,MainActivity.class));}});}@Overrideprotected void onDestroy() {System.out.println("3-onDestroy");super.onDestroy();}}

点击几次按纽后log如下:

12-17 08:48:45.632: I/System.out(5499): 1-oncreate->TaskId:27,hashcode:107908842412-17 08:49:03.539: I/System.out(5499): 2-oncreate->TaskId:28,hashcode:107912816012-17 08:49:04.273: I/System.out(5499): 3-oncreate->TaskId:27,hashcode:107915454412-17 08:49:04.843: I/System.out(5499): 1-oncreate->TaskId:27,hashcode:107917891212-17 08:49:05.953: I/System.out(5499): 1-onDestroy12-17 08:49:06.242: I/System.out(5499): 1-oncreate->TaskId:27,hashcode:107921051212-17 08:49:07.289: I/System.out(5499): 1-onDestroy12-17 08:49:07.523: I/System.out(5499): 1-oncreate->TaskId:27,hashcode:107924192012-17 08:49:07.953: I/System.out(5499): 1-onDestroy12-17 08:49:08.179: I/System.out(5499): 1-oncreate->TaskId:27,hashcode:107927318412-17 08:49:08.531: I/System.out(5499): 1-onDestroy12-17 08:49:08.742: I/System.out(5499): 1-oncreate->TaskId:27,hashcode:1079304448

在3界面按返回键

12-17 08:53:26.968: I/System.out(5499): 3-onDestroy12-17 08:53:27.656: I/System.out(5499): 1-onDestroy12-17 08:53:28.687: I/System.out(5499): 2-onDestroy

在2界面按返回键 

12-17 08:52:04.882: I/System.out(5499): 2-onDestroy12-17 08:52:05.937: I/System.out(5499): 1-onDestroy12-17 08:52:09.601: I/System.out(5499): 3-onDestroy12-17 08:52:11.562: I/System.out(5499): 1-onDestroy

结论1

:singleInstance 不新建actvity实例 ，实例在新的Task内

singleTask 不新建actvity实例 ，实例在原Task内

默认每次调用都生成一个新的实例

返回的时候，先返回到当前Task的下个Activity,当前Task到底，再返回到其他TasK

<?xml version="1.0" encoding="utf-8"?><manifest xmlns:android="http://schemas.android.com/apk/res/android"    package="com.example.testsinglainstance"    android:versionCode="1"    android:versionName="1.0" >    <uses-sdk        android:minSdkVersion="8"        android:targetSdkVersion="8" />    <application        android:allowBackup="true"        android:icon="@drawable/ic_launcher"        android:label="@string/app_name"        android:theme="@style/AppTheme" >        <activity            android:name="com.example.testsinglainstance.MainActivity"            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=".Activity2"            android:launchMode="singleTask"            android:label="@string/app_name" >        </activity>        <activity            android:name=".Activity3"            android:launchMode="singleTask"            android:label="@string/app_name" >        </activity>    </application></manifest>

按文本框log如下:

12-17 08:59:01.054: I/System.out(5598): 1-oncreate->TaskId:31,hashcode:107909612012-17 08:59:08.070: I/System.out(5598): 2-oncreate->TaskId:31,hashcode:107913643212-17 08:59:08.375: I/System.out(5598): 3-oncreate->TaskId:31,hashcode:107916278412-17 08:59:09.406: I/System.out(5598): 1-oncreate->TaskId:31,hashcode:107918698412-17 08:59:09.867: I/System.out(5598): 3-onDestroy12-17 08:59:09.960: I/System.out(5598): 1-onDestroy12-17 08:59:10.320: I/System.out(5598): 3-oncreate->TaskId:31,hashcode:107921381612-17 08:59:10.765: I/System.out(5598): 1-oncreate->TaskId:31,hashcode:107923696012-17 08:59:11.171: I/System.out(5598): 3-onDestroy12-17 08:59:11.257: I/System.out(5598): 1-onDestroy12-17 08:59:11.585: I/System.out(5598): 3-oncreate->TaskId:31,hashcode:107926371212-17 08:59:12.070: I/System.out(5598): 1-oncreate->TaskId:31,hashcode:1079286912

停留在3界面返回

12-17 09:01:26.585: I/System.out(5667): 3-onDestroy12-17 09:01:27.351: I/System.out(5667): 2-onDestroy12-17 09:01:28.421: I/System.out(5667): 1-onDestroy

停留在2界面返回

12-17 09:02:09.914: I/System.out(5667): 2-onDestroy12-17 09:02:10.601: I/System.out(5667): 1-onDestroy

结论2：

singleTask 在原Tast内

1个Task内只保留一个singleTask 后面设置无效