java与C#用protobuf通信--java如何转换protobuf-net中的bcl.Decimal对象

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公司内部有些C#服务使用proto-net，引入了bcl.proto中的bcl.Decimal、bcl.DateTime等。对于java的proto生成代码需要对bcl.Decimal、bcl.DateTime转换成本地支持的数据类型。
bcl.Decimal结构为32位int保存高位、64位long保存低位，signScale 保存符号（正负）及模数。转换过程如下：

　　bcl.Decimal --> BigDecimal
　　1. 将高32位的int以高位在前格式转换为4个长度的byte数组；
　　2. 将低64位的long以高位在前的格式转换为8个长度的byte数组；
　　3. 将两个数组组合为12长度的byte数组bigIntBytes，获取signScale的符号值sgin = (signScale & 1) == 1 ? -1 : 1; (参考bcl.Decimal 注释：the number of decimal digits (bits 1-16), and the sign (bit 0))
　　4. 根据bigIntBytes和sgin获取BigInteger对象bInt，new BigInteger(sgin，bigIntBytes);
　　5. 获取signScale的模数值scale = (signScale & 0b1111_1111_1111_1110) >> 1; (参考bcl.Decimal 注释：the number of decimal digits (bits 1-16), and the sign (bit 0))

6.根据bInt和scale获取BigDecimal对象，new BigDecimal(bint, scale);

  BigDecimal -->  bcl.Decimal
　　上述过程反之即可

代码如下：

/*JDK1.7*/
public class BclUtil {
	/**
	 * 
	 */
	private static final long TICKS_PER_MILLISECOND = 10000;

	private static final int SIGNSCALE_FLAG = 0b1111_1111_1111_1110;

	private BclUtil() {

	}

	/**
	 * 转换 bcl.Decimal，返回BigDecimal<br>
	 * 高位在前<br>
	 * 
	 * @param bclDecimal
	 * @return
	 */
	public final static BigDecimal bclDecimalToBigDecimal(Bcl.Decimal bclDecimal) {
		if (bclDecimal == null) {
			return BigDecimal.ZERO;
		}
		byte[] deBytes = new byte[12];
		int2byte(deBytes, 0, bclDecimal.getHi());
		long2byte(deBytes, 4, bclDecimal.getLo());
		int signScale = bclDecimal.getSignScale();
		BigInteger bint = new BigInteger(getSign(signScale), deBytes);
		return new BigDecimal(bint, getScale(signScale));
	}

	/**
	 * 转换BigDecimal，返回bcl.Decimal<br>
	 * 高位在前<br>
	 * 
	 * @param bigDecimal
	 * @return
	 */
	public final static Bcl.Decimal bigDecimalToBclDecimal(BigDecimal bigDecimal) {
		if (bigDecimal == null) {
			return null;
		}
		Bcl.Decimal.Builder b = Bcl.Decimal.newBuilder();
		// 获取BigInteger,必须是unscaledValue
		BigInteger bi = bigDecimal.unscaledValue();
		byte[] deBytes = new byte[12];
		byte[] bigIntegerBytes = bi.toByteArray();
		System.arraycopy(bigIntegerBytes, 0, deBytes, 12 - bigIntegerBytes.length, bigIntegerBytes.length);
		// 取高4位int
		int hi = Eutil.bytes2int(deBytes, 0);
		b.setHi(hi);
		// 取低8位long
		long lo = Eutil.bytes2long(deBytes, 4);
		b.setLo(lo);
		int signScale = getSignScale(bi.signum(), bigDecimal.scale());
		b.setSignScale(signScale);
		return b.build();
	}

	private static int getSignScale(int signum, int scale) {
		// 从BigInteger获取取标志位放在bit 0/从BigDecimal获取取标志位放在bit 1-16
		return getSignInSignScale(signum) | (scale << 1);
	}

	public final static Bcl.Decimal zeroOfBclDecimal() {
		Bcl.Decimal.Builder b = Bcl.Decimal.newBuilder();
		b.setHi(0);
		b.setLo(0);
		b.setSignScale(0);
		return b.build();
	}

	/**
	 * 填充值符号<br>
	 * 
	 * @param sign
	 * @return
	 */
	public final static byte getSignInSignScale(int sign) {
		byte signTemp = 0;
		if (sign < 0) {
			signTemp = 1;
		}
		return signTemp;
	}

	/**
	 * 获取值符号<br>
	 * 
	 * @param signScale
	 * @return
	 */
	public final static int getSign(int signScale) {
		// the number of decimal digits (bits 1-16), and the sign (bit 0)
		boolean isNegative = (signScale & 1) == 1;
		return isNegative ? -1 : 1;
	}

	/**
	 * 获取模数
	 * 
	 * @param signScale
	 * @return
	 */
	public final static int getScale(int signScale) {
		// the number of decimal digits (bits 1-16), and the sign (bit 0)
		return (signScale & SIGNSCALE_FLAG) >> 1;
	}

	/**
	 * 获取int的byte数组，高位在前
	 * 
	 * @param dst
	 * @param pos
	 * @param src
	 */
	public final static void int2byte(byte[] dst, int pos, int src) {
		int2byte(dst, pos, src, true);
	}

	public final static byte[] int2byte(byte[] dst, int pos, int src, boolean big_endian) {
		if (big_endian) {
			dst[pos + 3] = (byte) ((src >>> 0) & 0xff);
			dst[pos + 2] = (byte) ((src >>> 8) & 0xff);
			dst[pos + 1] = (byte) ((src >>> 16) & 0xff);
			dst[pos + 0] = (byte) ((src >>> 24) & 0xff);
		} else {
			dst[pos + 0] = (byte) ((src >>> 0) & 0xff);
			dst[pos + 1] = (byte) ((src >>> 8) & 0xff);
			dst[pos + 2] = (byte) ((src >>> 16) & 0xff);
			dst[pos + 3] = (byte) ((src >>> 24) & 0xff);
		}

		return dst;
	}

	public final static byte[] int2unSignByte(byte[] dst, int pos, int src, boolean big_endian) {
		if (big_endian) {
			dst[pos + 3] = (byte) ((src >>> 0) & 0xff + 128);
			dst[pos + 2] = (byte) ((src >>> 8) & 0xff + 128);
			dst[pos + 1] = (byte) ((src >>> 16) & 0xff + 128);
			dst[pos + 0] = (byte) ((src >>> 24) & 0xff + 128);
		} else {
			dst[pos + 0] = (byte) ((src >>> 0) & 0xff + 128);
			dst[pos + 1] = (byte) ((src >>> 8) & 0xff + 128);
			dst[pos + 2] = (byte) ((src >>> 16) & 0xff + 128);
			dst[pos + 3] = (byte) ((src >>> 24) & 0xff + 128);
		}

		return dst;
	}

	/**
	 * 获取long的byte数组，高位在前
	 * 
	 * @param dst
	 * @param pos
	 * @param src
	 */
	final static void long2byte(byte[] dst, int pos, long src) {
		long2byte(dst, pos, src, true);
	}

	final static void long2byte(byte[] dst, int pos, long src, boolean big_endian) {
		if (big_endian) {
			int2byte(dst, 4 + pos, (int) (src & 0xffffffff));
			int2byte(dst, 0 + pos, (int) ((src >>> 32) & 0xffffffff));
		} else {
			int2byte(dst, 0 + pos, (int) (src & 0xffffffff));
			int2byte(dst, 4 + pos, (int) ((src >>> 32) & 0xffffffff));
		}
	}
}