java bitmap实现

public  class BitArray {
        private int[] bits = null;
        private long length;
        private final  int[] bitValue = {
                0x80000000,
                0x40000000,
                0x20000000,
                0x10000000,
                0x08000000,
                0x04000000,
                0x02000000,
                0x01000000,
                0x00800000,
                0x00400000,
                0x00200000,
                0x00100000,
                0x00080000,
                0x00040000,
                0x00020000,
                0x00010000,
                0x00008000,
                0x00004000,
                0x00002000,
                0x00001000,
                0x00000800,
                0x00000400,
                0x00000200,
                0x00000100,
                0x00000080,
                0x00000040,
                0x00000020,
                0x00000010,
                0x00000008,
                0x00000004,
                0x00000002,
                0x00000001
        };

        public BitArray(long length){
                if(length<0){
                        throw new IllegalArgumentException("length must be above zero!");
                }
                bits = new int[(int) (length/32+((length%32)>0?1:0))];
                this.length = length;
        }

        public int getBit(long index){
                if(index<0 || index>length) {
                        throw new IllegalArgumentException("length value illegal!");
                }

                int intData=(int) bits[(int) (index/32)];
                return ((intData & bitValue[(int) (index%32)])>>>(32-index%32-1));
        }

        public void setBit(long index,int value) {
                if(index<0||index>length) {
                        throw new IllegalArgumentException("length value illegal!");
                }

                if(value!=1&&value!=0){
                        throw new IllegalArgumentException("value must be 1 or 0!");
                }

                int intData = (int) bits[(int) (index/32)];

                if(value==1) {
                        bits[(int) (index/32)] = intData | bitValue[(int) (index%32)];
                }else{
                        bits[(int) (index/32)] = intData & ~bitValue[(int) (index%32)];
                }
        }

        public long getLength() {
                return length;
        }

        public static void main(String[] args){
                BitArray bitArray = new BitArray(1100000000L);
                bitArray.setBit(1100000000L-1,1);
                System.out.println(bitArray.getBit(1100000000L-1));
        }
}