<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
  package="com.example.administrator.intentflags">
  <application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:supportsRtl="true"
    android:theme="@style/AppTheme">
    <activity android:name=".MainActivity">
      <intent-filter>
        <action android:name="android.intent.action.MAIN" />

        <category android:name="android.intent.category.LAUNCHER" />
      </intent-filter>
    </activity>
    //另外两个activity
    <activity android:name=".Main2Activity"> </activity>
    <activity android:name=".Main3Activity"></activity>
  </application>
</manifest>

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:tools="http://schemas.android.com/tools"
  android:id="@+id/activity_main"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:orientation="vertical"
  tools:context="com.example.administrator.intentflags.MainActivity">
  <Button
    android:text="第一个页面"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:onClick="click1" />
  <Button
    android:text="第二个页面"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:onClick="click2" />
  <Button
    android:text="第三个页面"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:onClick="click3" />
  <TextView
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    //其余两个仅文字不一样
    android:text="第一个页面"
    android:textSize="50sp"/>
</LinearLayout>

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
/**
 * Created by panchengjia on 2016/12/14.
 */
public class MainActivity extends AppCompatActivity {

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    //其他两个界面此处引用各自对应的layout文件
    setContentView(R.layout.activity_main);
  }
  public void click1(View view){
    Intent intent = new Intent(this,MainActivity.class);
    startActivity(intent);
    //记录Taskid用于实验说明
    Log.i("Tag","页面一taskId："+getTaskId());
  }
  public void click2(View view){
    Intent intent = new Intent(this,Main2Activity.class);
    startActivity(intent);
    Log.i("Tag","页面二taskId："+getTaskId());
  }
  public void click3(View view){
    Intent intent = new Intent(this,Main3Activity.class);
    startActivity(intent);
    Log.i("Tag","页面三taskId："+getTaskId());
  }
}

<activity android:name=".Main2Activity"
      android:launchMode="singleTop"> </activity>

  <activity android:name=".Main2Activity"
      android:launchMode="singleTask"> </activity>

<activity android:name=".Main2Activity"
       android:launchMode="singleInstance"> </activity>