Application在不能使用getApplicationContext()方法下的实例获取

private static IDamApplication mainApp;

public IDamApplication() {
    mainApp = this;
}

public static IDamApplication getInstance() {
    return mainApp;
}

或者是

private static IDamApplication mainApp;

@Override
public void onCreate() {
    super.onCreate();
    mainApp = this;
}

public static IDamApplication getInstance() {
    return mainApp;
}

使用时通过IDamApplication.getInstance()获取。