如何存取权限getSystemService在应用程序类 [英] How to acces getSystemService in Application class

问题描述

我要访问应用程序类的TELEPHONY_SERVICE系统服务，但我的应用程序崩溃时我运行它。

I want to access the TELEPHONY_SERVICE system service in the Application class, but my app crashes when I run it.

public class SimpleDhtApplication extends Application {


    TelephonyManager tel = (TelephonyManager) this.getSystemService(Context.TELEPHONY_SERVICE);
    String portStr = tel.getLine1Number().substring(tel.getLine1Number().length() -4);
    final String myPort = String.valueOf((Integer.parseInt(portStr) * 2));
}

我想我不能正确访问的背景下，可以有人帮助！

I think I am not accessing the context correctly, can somebody help!

推荐答案

首先重写应用程序类的onCreate方法。内的onCreate，把code你有那么它看起来像：

Override the onCreate method of the Application class first. Within the onCreate, put the code you have so it would look like:

public class SimpleDhtApplication extends Application {


    @Override
    public void onCreate() {
        super.onCreate();
        TelephonyManager tel = (TelephonyManager) this.getSystemService(Context.TELEPHONY_SERVICE);
        String portStr = tel.getLine1Number().substring(tel.getLine1Number().length() -4);
        final String myPort = String.valueOf((Integer.parseInt(portStr) * 2));
    }
}

更新：当心tel.getLine1Number（）;它可能会返回null作为解释<一个href=\"http://developer.android.com/reference/android/telephony/TelephonyManager.html#getLine1Number%28%29\"相对=nofollow>这里。

Update: Watch out for tel.getLine1Number(); it may return null as explained here.

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