activity启动模式之singleInstance

singleInstance 这个启动模式，是这个activity占有唯一的一个栈。

看如下demo

manifest.xml

 <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:logo="@drawable/action_mode_search_normal_white_p"
        android:theme="@style/AppTheme" >
        <activity
            android:name=".HeadSetActivity"
            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>
        <activity
            android:name=".MyActivity1"
            android:label="@string/app_name"
            android:launchMode="singleInstance" >
            <intent-filter>
                <action android:name="activity_one" />

                <category android:name="android.intent.category.DEFAULT" />
            </intent-filter>
        </activity>
        <activity
            android:name=".MyActivity2"
            android:label="@string/app_name"
            android:launchMode="standard" >
            <intent-filter>
                <action android:name="activity_two" />

                <category android:name="android.intent.category.DEFAULT" />
            </intent-filter>
        </activity>
    </application>

三个activity代码

HeadSetActivity.java

package com.example.alert;

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;
import android.widget.TextView;

public class HeadSetActivity extends Activity {
    private TextView textView;
    private Button button1;
    private Button button2;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        textView = (TextView) findViewById(R.id.tv);
        button1 = (Button) findViewById(R.id.bt1);
        button2 = (Button) findViewById(R.id.bt2);
        button1.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View arg0) {
                // TODO Auto-generated method stub
                //启动activity1
                Intent intent = new Intent("activity_one");
                startActivity(intent);
            }
        });
        button2.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View arg0) {
                // TODO Auto-generated method stub
                //启动activity2
                Intent intent = new Intent("activity_two");
                startActivity(intent);
                
            }
        });

    }
//这个方法主要是接受子activity返回的数据的
    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        // TODO Auto-generated method stub
        super.onActivityResult(requestCode, resultCode, data);
        //requestCode 这个是启动子activity的时候，父activity给予的标签，父分组管理
        //resultCode 这个是子activity返回来的标签，是子activity分组管理
        //data里面是子activity返回来的数据
        if (requestCode == 1) {
            if (resultCode == 10) {
                
                String string = data.getExtras().getString("activity_finish");
                textView.setText("com from activity 1 and finish"+" 
" + string);
                
            } else if (resultCode == 100) {
                
                String string = data.getExtras().getString("activity_no_finish");
                textView.setText("com from activity 1 and no finish"+" 
" + string);
            }
        } else if (requestCode == 2) {
            if (resultCode == 100) {
                textView.setText("com from activity 2 and finish");
            } else if (resultCode == 120) {
                textView.setText("com from activity 2 and no finish");
            }

        }
    }

}

MyActivity1.java

package com.example.alert;

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;
import android.widget.TextView;

public class MyActivity1 extends Activity {
    private TextView textView;
    private Button button1;
    private Button button2;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        textView = (TextView) findViewById(R.id.tv);
        textView.setText("i am activity1");
        button1 = (Button) findViewById(R.id.bt1);
        button1.setText("HeadSetActivity");
        button2 = (Button) findViewById(R.id.bt2);
        button2.setText("Activity2");
        button1.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View arg0) {
                // TODO Auto-generated method stub
                Intent intent = new Intent();
                intent.setClass(MyActivity1.this, HeadSetActivity.class);
                startActivity(intent);
                

            }
        });
        button2.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View arg0) {
                // TODO Auto-generated method stub
                Intent intent = new Intent("activity_two");
                startActivity(intent);
            }
        });

    }

}

MyActivity2.java

package com.example.alert;

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;
import android.widget.TextView;

public class MyActivity2 extends Activity {
    private TextView textView;
    private Button button1;
    private Button button2;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        textView = (TextView) findViewById(R.id.tv);
        textView.setText("i am activity2");
        button1 = (Button) findViewById(R.id.bt1);
        button1.setText("HeadSetActivity");
        button2 = (Button) findViewById(R.id.bt2);
        button2.setText("Activity1");
        button1.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View arg0) {
                // TODO Auto-generated method stub
                Intent intent = new Intent();
                intent.setClass(MyActivity2.this, HeadSetActivity.class);
                startActivity(intent);
                
            }
        });
        button2.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View arg0) {
                // TODO Auto-generated method stub
                Intent intent = new Intent("activity_one");
                startActivity(intent);
            }
        });

    }
}

下面我们按照如下的启动操作进行验证

HeadSetActivity->MyActivity1->MyActivity1->HeadSetActivity->MyActivity1

结果如下

 Running activities (most recent first):
      TaskRecord{4305f1b8 #34 A=com.example.alert U=0 sz=1}
        Run #3: ActivityRecord{4305eef8 u0 com.example.alert/.MyActivity1 t34}
      TaskRecord{430b5f38 #33 A=com.example.alert U=0 sz=3}
        Run #2: ActivityRecord{426026a0 u0 com.example.alert/.HeadSetActivity t33}
        Run #1: ActivityRecord{4261ed58 u0 com.example.alert/.MyActivity2 t33}
        Run #0: ActivityRecord{42546340 u0 com.example.alert/.HeadSetActivity t33}

可以发现，这个task里面就只有始终只有一个MyActivity1，而且，它启动的activity，也不会在这个task里面，再者，它不许要像singleTask那样，需要

taskAffinity 进行设定