java 接收无符号类型的(Long、int、short)
最近在做一个项目，需要和C++通讯，双方通讯没有采用JNI的方式进行，使用字节序的方式进行进行（字节序就是所谓双方把协议定义好，按顺序进行接收），刚开始测试的时候未注意C++的unsigned int 类型，当一次测试忽然想起，JAVA是有符号的数据类型，最高位表示符号类型那个，如果无符号类型接收有符号的类型int， 那就用LONG，然后发现是错误的，发现高位的32位存在值，低32位是无符号类型INT发过来的值，然后想到一个方法就是对字节进行与和位移的操作，希望以下代码能对大家有用：public static void main(String args[]){
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++;
anUnsignedByte = (short)firstByte;
firstByte = (0x000000FF & ((int)buf))
secondByte = (0x000000FF & ((int)buf))
index = index+2;
anUnsignedShort= (char) (firstByte << 8 | secondByte);
firstByte = (0x000000FF & ((int)buf))
secondByte = (0x000000FF & ((int)buf))
thirdByte = (0x000000FF & ((int)buf))
fourthByte = (0x000000FF & ((int)buf))
index = index+4;
anUnsignedInt= ((long) (firstByte << 24
| secondByte << 16
| thirdByte << 8
| fourthByte))
& 0xFFFFFFFFL;
System.out.println(anUnsignedInt ); //打印出无符号类型用long进行正确接收的值
}
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