android属性之clearTaskOnLaunch

clearTaskOnLaunch

有没有这样的需求，每次从桌面进入都启动根Activity？可以使用这个属性实现哦，下面通过一个实例来看一下效果：

1.MainActivity.java（根Activity）:

package com.example.administrator.myapplication;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;

public class MainActivity extends AppCompatActivity {
    public static final String TAG = "yayun";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Log.d(TAG, "onCreate: taskId" + getTaskId());
        setContentView(R.layout.activity_main);
    }

    public void launch(View view) {
        Intent intent = new Intent();
        intent.setAction("yayun");
        intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        startActivity(intent);
    }
}

2.ActivityTest.java：

package com.example.administrator.myapplication;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.widget.TextView;

/**
 * Created by Administrator on 2016/7/31.
 */
public class ActivityTest extends Activity {
    public static final String TAG = "yayun";
    private TextView mTextView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Log.d(TAG, "onCreate: taskId" + getTaskId());
        setContentView(R.layout.activity1_layout);
        mTextView = (TextView) findViewById(R.id.tv);
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        Log.d(TAG, "onDestroy: ");
    }
}

3.AndroidMainifest.xml：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.administrator.myapplication">

    <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"
            android:clearTaskOnLaunch="true">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity android:name=".ActivityTest">
            <intent-filter>
                <action android:name="yayun" />

                <category android:name="android.intent.category.DEFAULT" />

            </intent-filter>
        </activity>

    </application>

</manifest>

MainActivity中配置了clearTaskOnLaunch属性为true。

启动项目在MainActivity中点击按钮启动ActivityTest，然后点击Home键，这时候从桌面再次进入，可以看到ActivityTest的onDestroy方法运行了，我们也就看不到它而是看到了MainActivity。

也就是说它可以清清除根Activity以外的所有Activity，当然它也必须配置在根Activity中才有效果哦！