space.yizhu.record.template.io.IntegerWriter Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of kits Show documentation
工具类
There is a newer version: 1.3.2


package space.yizhu.record.template.io;

import java.io.IOException;

public class IntegerWriter {

    final static int[] sizeTable = {9, 99, 999, 9999, 99999, 999999, 9999999,
            99999999, 999999999, Integer.MAX_VALUE};

    final static char[] DigitOnes = {
            '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
            '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
            '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
            '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
            '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
            '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
            '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
            '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
            '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
            '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
    };

    final static char[] DigitTens = {
            '0', '0', '0', '0', '0', '0', '0', '0', '0', '0',
            '1', '1', '1', '1', '1', '1', '1', '1', '1', '1',
            '2', '2', '2', '2', '2', '2', '2', '2', '2', '2',
            '3', '3', '3', '3', '3', '3', '3', '3', '3', '3',
            '4', '4', '4', '4', '4', '4', '4', '4', '4', '4',
            '5', '5', '5', '5', '5', '5', '5', '5', '5', '5',
            '6', '6', '6', '6', '6', '6', '6', '6', '6', '6',
            '7', '7', '7', '7', '7', '7', '7', '7', '7', '7',
            '8', '8', '8', '8', '8', '8', '8', '8', '8', '8',
            '9', '9', '9', '9', '9', '9', '9', '9', '9', '9',
    };

    final static char[] digits = {
            '0', '1', '2', '3', '4', '5',
            '6', '7', '8', '9', 'a', 'b',
            'c', 'd', 'e', 'f', 'g', 'h',
            'i', 'j', 'k', 'l', 'm', 'n',
            'o', 'p', 'q', 'r', 's', 't',
            'u', 'v', 'w', 'x', 'y', 'z'
    };

    private static final byte[] minValueBytes = "-2147483648".getBytes();
    private static final char[] minValueChars = "-2147483648".toCharArray();

    public static void write(ByteWriter byteWriter, int i) throws IOException {
        if (i == Integer.MIN_VALUE) {
            byteWriter.out.write(minValueBytes, 0, minValueBytes.length);
            return;
        }

        int size = (i < 0) ? stringSize(-i) + 1 : stringSize(i);
        char[] chars = byteWriter.chars;
        byte[] bytes = byteWriter.bytes;
        getChars(i, size, chars);

        
        

        for (int j = 0; j < size; j++) {
            bytes[j] = (byte) chars[j];
        }
        byteWriter.out.write(bytes, 0, size);
    }

    public static void write(CharWriter charWriter, int i) throws IOException {
        if (i == Integer.MIN_VALUE) {
            charWriter.out.write(minValueChars, 0, minValueChars.length);
            return;
        }

        int size = (i < 0) ? stringSize(-i) + 1 : stringSize(i);
        char[] chars = charWriter.chars;
        getChars(i, size, chars);
        charWriter.out.write(chars, 0, size);
    }

    static int stringSize(int x) {
        for (int i = 0; ; i++)
            if (x <= sizeTable[i])
                return i + 1;
    }

    static void getChars(int i, int index, char[] buf) {
        int q, r;
        int charPos = index;
        char sign = 0;

        if (i < 0) {
            sign = '-';
            i = -i;
        }

        
        while (i >= 65536) {
            q = i / 100;
            
            r = i - ((q << 6) + (q << 5) + (q << 2));
            i = q;
            buf[--charPos] = DigitOnes[r];
            buf[--charPos] = DigitTens[r];
        }

        
        
        for (; ; ) {
            q = (i * 52429) >>> (16 + 3);
            r = i - ((q << 3) + (q << 1));  
            buf[--charPos] = digits[r];
            i = q;
            if (i == 0) break;
        }
        if (sign != 0) {
            buf[--charPos] = sign;
        }
    }
}