Android系统中位运算符的妙用

重点关注

PackageManager

    public static final int GET_ACTIVITIES              = 0x00000001;

    public static final int GET_RECEIVERS               = 0x00000002;


    public static final int GET_SERVICES                = 0x00000004;


    public static final int GET_PROVIDERS               = 0x00000008;


    public static final int GET_INSTRUMENTATION         = 0x00000010;


    public static final int GET_INTENT_FILTERS          = 0x00000020;


    public static final int GET_SIGNATURES          = 0x00000040;


    public static final int GET_RESOLVED_FILTER         = 0x00000040;


    public static final int GET_META_DATA               = 0x00000080;


    public static final int GET_GIDS                    = 0x00000100;


    public static final int MATCH_DISABLED_COMPONENTS = 0x00000200;


    public static final int GET_SHARED_LIBRARY_FILES    = 0x00000400;


    public static final int GET_URI_PERMISSION_PATTERNS  = 0x00000800;


    public static final int GET_PERMISSIONS               = 0x00001000;


    public static final int MATCH_UNINSTALLED_PACKAGES = 0x00002000;


    public static final int GET_CONFIGURATIONS = 0x00004000;


    public static final int MATCH_DISABLED_UNTIL_USED_COMPONENTS = 0x00008000;


    public static final int MATCH_DEFAULT_ONLY  = 0x00010000;


    public static final int MATCH_ALL = 0x00020000;


    public static final int MATCH_DIRECT_BOOT_UNAWARE = 0x00040000;


    public static final int MATCH_DIRECT_BOOT_AWARE = 0x00080000;


    public static final int MATCH_SYSTEM_ONLY = 0x00100000;


    public static final int MATCH_FACTORY_ONLY = 0x00200000;

找规律

十六进制
1        2        4        8 
10       20       40       80
100      200      400      800
1000     2000     4000     8000
10000    20000    40000    80000

对应的二进制
2^0^     2^1^     2^2^     2^3^
2^4^     2^5^     2^6^     2^7^
2^8^     2^9^     2^10^    2^11^
2^12^    2^13^    2^14^    2^15^

位运算

1)位运预算针对的是二进制
2)从十六进制对应到二进制，再理解使用"|"(与)位运算符，则一定会得出不一样值。这里不管怎么排列组合。
这种活用、易被采纳使用的做法，就是高级货。注意：我们在使用|或&目的为了判断，所以，不要太关注此值。