android_42_activity的4种启动模式

来源：互联网发布：舍伍德算法理解编辑：程序博客网时间：2024/06/05 09:36

standard:没啥好说的

singleTop:只要是在stack top了,就不再有任何反应了

singleTask: 在stack中,只存在一个实例, 如果不在stack top,那么就会把它上方的全部pop掉

singleInstance: 为该activity单独分配一个stack,示意图如下:

清单:

<?xml version="1.0" encoding="utf-8"?><manifest xmlns:android="http://schemas.android.com/apk/res/android"    package="com.sg31.activitylaunchmode"    android:versionCode="1"    android:versionName="1.0" >    <uses-sdk        android:minSdkVersion="8"        android:targetSdkVersion="21" />    <application        android:allowBackup="true"        android:icon="@drawable/ic_launcher"        android:label="@string/app_name"        android:theme="@style/AppTheme" >        <activity            android:name=".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>                // 核心:lanchMode        <activity             android:launchMode="singleInstance"            android:name="com.sg31.activitylaunchmode.SecondActivity"            ></activity>            </application></manifest>

main布局:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:paddingBottom="@dimen/activity_vertical_margin"    android:paddingLeft="@dimen/activity_horizontal_margin"    android:paddingRight="@dimen/activity_horizontal_margin"    android:paddingTop="@dimen/activity_vertical_margin"    tools:context="com.sg31.activitylaunchmode.MainActivity"         android:orientation="vertical"     >    <TextView        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="这是主Activity"         android:textSize="18sp"        />    <Button         android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="启动Main"        android:onClick="startMainActivityBtnClicked"                />    <Button         android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="启动Second"        android:onClick="startSecondActivityBtnClicked"        /></LinearLayout>

Second布局:

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical" >        <TextView        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="这是第二个Activity"         android:textSize="18sp"        />    <Button         android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="启动Main"        android:onClick="startMainActivityBtnClicked"                />    <Button         android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="启动Second"        android:onClick="startSecondActivityBtnClicked"        /></LinearLayout>

主Activity代码:

package com.sg31.activitylaunchmode;import android.support.v7.app.ActionBarActivity;import android.content.Intent;import android.os.Bundle;import android.view.Menu;import android.view.MenuItem;import android.view.View;public class MainActivity extends ActionBarActivity {@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);}@Overridepublic boolean onCreateOptionsMenu(Menu menu) {// Inflate the menu; this adds items to the action bar if it is present.getMenuInflater().inflate(R.menu.main, menu);return true;}@Overridepublic boolean onOptionsItemSelected(MenuItem item) {// Handle action bar item clicks here. The action bar will// automatically handle clicks on the Home/Up button, so long// as you specify a parent activity in AndroidManifest.xml.int id = item.getItemId();if (id == R.id.action_settings) {return true;}return super.onOptionsItemSelected(item);}public void startMainActivityBtnClicked(View v) {Intent intent = new Intent(this, MainActivity.class);startActivity(intent);}public void startSecondActivityBtnClicked(View v) {Intent intent = new Intent(this, SecondActivity.class);startActivity(intent);}}

第2个Activity代码:

package com.sg31.activitylaunchmode;import android.content.Intent;import android.os.Bundle;import android.support.v7.app.ActionBarActivity;import android.view.View;public class SecondActivity extends ActionBarActivity {@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_second);}public void startMainActivityBtnClicked(View v) {Intent intent = new Intent(this, MainActivity.class);startActivity(intent);}public void startSecondActivityBtnClicked(View v) {Intent intent = new Intent(this, SecondActivity.class);startActivity(intent);}}

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