import java.math.BigDecimal;public class text {// 定义数组长度private static final int LEN = 64;public static void paddingString(double n, StringBuilder sb, int len) {if (len < 0) {return;}if (n > 1) {n = n - 1;paddingString(n, sb, len);} else if (n < 1) {n *= 2;}if (n > 1) {sb.append(1);paddingString(n, sb, --len);return;} else if (n < 1) {sb.append(0);paddingString(n, sb, --len);return;} else {sb.append(1);return;}}private static byte[] setBitArray(String s) {byte[] arr = new byte[LEN];int temp;for (int i = LEN; i > 0; i--) {temp = s.charAt(i - 1) - 48;arr[i - 1] = (byte) temp;}return arr;}public static double binaryToDouble(byte[] s) {BigDecimal two = new BigDecimal(2);BigDecimal bigDecimal = new BigDecimal(0);BigDecimal temp = BigDecimal.ONE;BigDecimal temp1;for (int i = 0; i < s.length; i++) {temp = temp.divide(two);if (s[i] > 0) {int a = s[i];temp1 = new BigDecimal(a);bigDecimal = bigDecimal.add(temp.multiply(temp1));}}return bigDecimal.doubleValue();}public static String doubleToBinary(double n) {StringBuilder stringBuffer = new StringBuilder(LEN);// 填充并得到二进制结果paddingString(n, stringBuffer, LEN);int len;if ((len = stringBuffer.length()) > LEN + 1) {return stringBuffer.toString().substring(0, LEN + 1);} else {return stringBuffer.toString().substring(0, len);}}public static byte[] bytesAdd(byte[] a, byte[] b) {byte[] arr = new byte[LEN];for (int i = LEN - 1; i > 0; i--) {arr[i] = (byte) (arr[i] + a[i] + b[i]);if (arr[i] > 1) {arr[i] -= 2;arr[i - 1] = 1;}}return arr;}public static void main(String[] args){String s = doubleToBinary(.1); // 转成二进制字符串//0.1转换成二进制字符串可以有限位数转换，位数小于64//0.00011001100110011001100110011001100110011001100110011010010101001byte[] bytes = setBitArray(s); // 转成二进制数组 (一)double d = binaryToDouble(bytes); // 在转double, 反向验证结果的准确性System.out.println("十进制: " + d);System.out.println("========下面同理=========");String s1 = doubleToBinary(.2);//0.2在字符串转换时，64位无法容纳，所以到了64位的时候会停止，但是当转换后的bate[]进行转化的时候，会出现精度缺失的问题//0.00110011001100110011001100110011001100110011001100110100101010010byte[] bytes1 = setBitArray(s1); // (二)double d1 = binaryToDouble(bytes1);System.out.println("十进制: " + d1);byte[] add = bytesAdd(bytes, bytes1); // 二进制数组累加 (三)System.out.println("result: " + binaryToDouble(add)); // 将数组转换为小数}
}