JAVA中Modifier类关于修饰符的设计技巧

1.Modifier类中对于修饰符设计是这样的，采用十六进制的数字表示1，2，4，8，16 

 public static final int PUBLIC           = 0x00000001;
    public static final int PRIVATE          = 0x00000002;
    public static final int PROTECTED        = 0x00000004;
    public static final int STATIC           = 0x00000008;
    public static final int FINAL            = 0x00000010;
    public static final int SYNCHRONIZED     = 0x00000020;
    public static final int VOLATILE         = 0x00000040;
    public static final int TRANSIENT        = 0x00000080;
    public static final int NATIVE           = 0x00000100;
    public static final int INTERFACE        = 0x00000200;
    public static final int ABSTRACT         = 0x00000400;
    public static final int STRICT           = 0x00000800;
    static final int BRIDGE    = 0x00000040;
    static final int VARARGS   = 0x00000080;
    static final int SYNTHETIC = 0x00001000;
    static final int ANNOTATION  = 0x00002000;
    static final int ENUM      = 0x00004000;
    static final int MANDATED  = 0x00008000;

2.解码方法 ，根据传进来的mod的不同做与运算获得到的修饰符集，举个例子

public：是0000 0000 0000 0000 0000 0000 0000 0001

abstract：是0000 0000 0000 0000 0000 0100 0000 0000

int类型一共32位，用某位是1来表示一个修饰符做与运算的时候，得到的结果>0代表包含该修饰符，将这个修饰符的字符串添加进来，最终返回。获得的就是修饰符字符串。

 public static String toString(int mod) {
        StringBuilder sb = new StringBuilder();
        int len;

        if ((mod & PUBLIC) != 0)        sb.append("public ");
        if ((mod & PROTECTED) != 0)     sb.append("protected ");
        if ((mod & PRIVATE) != 0)       sb.append("private ");

        /* Canonical order */
        if ((mod & ABSTRACT) != 0)      sb.append("abstract ");
        if ((mod & STATIC) != 0)        sb.append("static ");
        if ((mod & FINAL) != 0)         sb.append("final ");
        if ((mod & TRANSIENT) != 0)     sb.append("transient ");
        if ((mod & VOLATILE) != 0)      sb.append("volatile ");
        if ((mod & SYNCHRONIZED) != 0)  sb.append("synchronized ");
        if ((mod & NATIVE) != 0)        sb.append("native ");
        if ((mod & STRICT) != 0)        sb.append("strictfp ");
        if ((mod & INTERFACE) != 0)     sb.append("interface ");

        if ((len = sb.length()) > 0)    /* trim trailing space */
            return sb.toString().substring(0, len-1);
        return "";
    }