AppLaunchChecker

转载请注明出处：http://blog.csdn.net/crazy1235/article/details/51156116

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Android Support Library 23.3.0 是目前发布的最新版本。

主要修复了Support v4 library, AppCompat library, RecyclerView, MediaRouter library, Design Support Library以及v7 Preference library的若干bug。

详细的更新日志参考官方地址：23.3.0更新日志。

在Support V4包中添加了一个新API：AppLaunchChecker。

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下面看一下这个类。

官方解释就是可以查看app在过去是否已经被启动过。通过hasStartedFromLauncher()方法可以判断当前启动是否通过home screen进行启动的。

使用很简单：

在启动activity的onCreate()方法里，调用如下静态方法：

@Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        //        AppLaunchChecker.onActivityCreate(this);    }

然后可以在其他你相判断的地方进行判断即可：

 @Override    protected void onResume() {        super.onResume();        if (AppLaunchChecker.hasStartedFromLauncher(this)) {            Toast.makeText(this, "it's started from launcher", Toast.LENGTH_SHORT).show();        } else {            Toast.makeText(this, "it's not started from launcher", Toast.LENGTH_SHORT).show();        }    }

用法就如上面所写的那么简单。

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那么这个工具类有什么用呢？

我们平时启动app有两种形式，一种是点击屏幕上的图标启动app；另外一种就是通过web界面进行打开app。

通常会对两种形式做不同的操作。所以就需要判断是否是从主屏幕上启动的还是通过别的方式打开的。

package android.support.v4.app;import android.app.Activity;import android.content.Context;import android.content.ContextWrapper;import android.content.Intent;import android.content.SharedPreferences;import android.os.Bundle;import android.support.v4.content.IntentCompat;import android.support.v4.content.SharedPreferencesCompat;/** * This class provides APIs for determining how an app has been launched. * This can be useful if you want to confirm that a user has launched your * app through its front door activity from their launcher/home screen, rather * than just if the app has been opened in the past in order to view a link, * open a document or perform some other service for other apps on the device. */public class AppLaunchChecker {    private static final String SHARED_PREFS_NAME = "android.support.AppLaunchChecker";    private static final String KEY_STARTED_FROM_LAUNCHER = "startedFromLauncher";    /**     * Checks if this app has been launched by the user from their launcher or home screen     * since it was installed.     *     * <p>To track this state properly you must call {@link #onActivityCreate(Activity)}     * in your launcher activity's {@link Activity#onCreate(Bundle)} method.</p>     *     * @param context Context to check     * @return true if this app has been started by the user from the launcher at least once     */    public static boolean hasStartedFromLauncher(Context context) {        return context.getSharedPreferences(SHARED_PREFS_NAME, 0)                .getBoolean(KEY_STARTED_FROM_LAUNCHER, false);    }    /**     * Records the parameters of an activity's launch for later use by the other     * methods available on this class.     *     * <p>Your app should call this method in your launcher activity's     * {@link Activity#onCreate(Bundle)} method to track launch state.     * If the app targets API 23 (Android 6.0 Marshmallow) or later, this state will be     * eligible for full data backup and may be restored to the user's device automatically.</p>     *     *     * @param activity the Activity currently running onCreate     */    public static void onActivityCreate(Activity activity) {        final SharedPreferences sp = activity.getSharedPreferences(SHARED_PREFS_NAME, 0);        if (sp.getBoolean(KEY_STARTED_FROM_LAUNCHER, false)) {            return;        }        final Intent launchIntent = activity.getIntent();        if (launchIntent == null) {            return;        }        if (Intent.ACTION_MAIN.equals(launchIntent.getAction())                && (launchIntent.hasCategory(Intent.CATEGORY_LAUNCHER)                || launchIntent.hasCategory(IntentCompat.CATEGORY_LEANBACK_LAUNCHER))) {            SharedPreferencesCompat.EditorCompat.getInstance().apply(                    sp.edit().putBoolean(KEY_STARTED_FROM_LAUNCHER, true));        }    }}

通过查看该类的源码可以发现，调用onActivityCreate()方法就是通过判断Intent的action和category类型保存到SharedPreference一个boolean类型变量，然后在调用hasStartedFromLauncher()方法的时候去读取该Boolean值，进行判断。

但是如果sharedPreference中已经保存了true值，以后每次的hasStartedFromLauncher()判断都是返回true。

应为在保存变量的时候，它并没有把不是主屏幕启动的false放到SharedPreference中。

所以个人感觉这个设计不合理。（也许该类的真正用途不在于此。）

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最后，本人修改了一下这个工具类，从而可以每次正确的判断app是否是从主屏幕启动的，还是别的方式启动的。

代码如下：

public class AppLaunchChecker {    private static final String SHARED_PREFS_NAME = "android.support.AppLaunchChecker";    private static final String KEY_STARTED_FROM_LAUNCHER = "startedFromLauncher";    public static boolean hasStartedFromLauncher(Context context) {        return context.getSharedPreferences(SHARED_PREFS_NAME, 0)                .getBoolean(KEY_STARTED_FROM_LAUNCHER, false);    }    public static void onActivityCreate(Activity activity) {        final SharedPreferences sp = activity.getSharedPreferences(SHARED_PREFS_NAME, 0);        final Intent launchIntent = activity.getIntent();        if (launchIntent == null) {            return;        }        if (Intent.ACTION_MAIN.equals(launchIntent.getAction())                && (launchIntent.hasCategory(Intent.CATEGORY_LAUNCHER)                || launchIntent.hasCategory(IntentCompat.CATEGORY_LEANBACK_LAUNCHER))) {            SharedPreferencesCompat.EditorCompat.getInstance().apply(                    sp.edit().putBoolean(KEY_STARTED_FROM_LAUNCHER, true));        } else {            SharedPreferencesCompat.EditorCompat.getInstance().apply(                    sp.edit().putBoolean(KEY_STARTED_FROM_LAUNCHER, false));        }    }}

类名方法名均一致。使用方式也一致！
so easy~~

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博文到此结束！感谢大家支持！谢谢~