Java使用Unsafe接口操作数组Demo

public class unSafeArrayDemo {
	
    private static final sun.misc.Unsafe UNSAFE;
    private static final long TBASE;
    private static final int TSHIFT;
    
    static {
        int ts;
        try {
            UNSAFE = getUnsafe();
            TBASE = UNSAFE.arrayBaseOffset(String[].class);
            ts = UNSAFE.arrayIndexScale(String[].class);
        } catch (Exception e) {
            throw new Error(e);
        }
        TSHIFT = 31 - Integer.numberOfLeadingZeros(ts);
    }
	
	static Unsafe getUnsafe() throws NoSuchFieldException, SecurityException, IllegalArgumentException, IllegalAccessException {
    	Field f = Unsafe.class.getDeclaredField("theUnsafe");
    	f.setAccessible(true);
    	Unsafe unsafe = (Unsafe)f.get(null);
		return unsafe;
    }
	
	@SuppressWarnings("unchecked")
    static final String entryAt(String[] tab, int i) {
        return (String) UNSAFE.getObjectVolatile(tab, ((long)i << TSHIFT) + TBASE);
    }
	
	public static void main(String[] args) {
		int nLen = 37;
		String[] table = new String[nLen];
		for (int i = 0; i < nLen; i++) {
			table[i] = "数值为:  " + String.valueOf(i + 26);
		}
		String str = entryAt(table, 23);
		System.out.println(str);
	}

}