java 保存unsigned 数据方法

最新推荐文章于 2025-08-20 15:04:37 发布

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最新推荐文章于 2025-08-20 15:04:37 发布

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文章标签： java

原文链接：http://www.cnblogs.com/clarkchen/archive/2011/05/22/2053459.html

本文介绍了在Java中如何处理无符号数，由于Java不直接支持无符号类型，需要使用特定的方法来读取和存储无符号数据。文章通过示例代码详细解释了如何从字节流中提取无符号字节、短整型和整型数据，并将其转换为Java可识别的类型。

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java中没有unsiged的设置，必须用signed的数据存储，也就是要多用些存储空间。
use a short to hold an unsigned byte, use a long to hold an unsigned int.
use a char to hold an unsigned short.
('char' type, which is a 2 byte representation of unicode, instead of the
 C 'char' type, which is 1 byte ASCII. Java's 'char' also can be used as
 an unsigned short, i.e. it represents numbers from 0 up to 2^16.)

从字节流中提取unsigned 数据，保存unsigned数据到字节流

short anUnsignedByte = 0;
char anUnsignedShort = 0;
long anUnsignedInt = 0;

int firstByte = 0;
int secondByte = 0;
int thirdByte = 0;
int fourthByte = 0;

byte buf[] = getMeSomeData();
// Check to make sure we have enough bytes
if(buf.length < (1 + 2 + 4))
doSomeErrorHandling();
int index = 0;

firstByte = (0x000000FF & ((int)buf[index]))
index++;
anUnsignedByte = (short)firstByte;

firstByte = (0x000000FF & ((int)buf[index]))
secondByte = (0x000000FF & ((int)buf[index+1]))
index = index+2;
anUnsignedShort = (char) (firstByte << 8 | secondByte);

firstByte = (0x000000FF & ((int)buf[index]))
secondByte = (0x000000FF & ((int)buf[index+1]))
thirdByte = (0x000000FF & ((int)buf[index+2]))
fourthByte = (0x000000FF & ((int)buf[index+3]))
index = index+4;
anUnsignedInt = ((long) (firstByte << 24
| secondByte << 16
| thirdByte << 8
| fourthByte))
& 0xFFFFFFFFL;
// write it back as unsigned int, unsigned short, unsigned byte.
buf[0] = (anUnsignedInt & 0xFF000000L) >> 24;
buf[1] = (anUnsignedInt & 0x00FF0000L) >> 16;
buf[2] = (anUnsignedInt & 0x0000FF00L) >> 8;
buf[3] = (anUnsignedInt & 0x000000FFL);

buf[4] = (anUnsignedShort & 0xFF00) >> 8;
buf[5] = (anUnsignedShort & 0x00FF);

buf[6] = (anUnsignedByte & 0xFF);

转载于:https://www.cnblogs.com/clarkchen/archive/2011/05/22/2053459.html