long b=99999999999999999L轉(zhuǎn)換成byte[]后再轉(zhuǎn)回來對不上
public?class?Binary?{
????//將byte[]轉(zhuǎn)換成long
????public?long?byte2Long(byte[]?arr){
????????long?num?=?0;
????????for?(int?i=?0;?i?<?8;?i++)?{
????????????num?+=?(long)((arr[i]&0xff)<<i*8)?;
????????}
????????return?num;
????}
?????//將long轉(zhuǎn)換成byte[]
????public?byte[]?long2Byte(long?b){
????????byte[]?bytes=new?byte[8];
????????for?(int?i?=?0;?i?<?8;?i++)?{
????????????bytes[i]=(byte)((b>>i*8)&0xff);
????????}
????????return?bytes;
????}
????public?static?void?main(String[]?args)?{
????????Binary?test=new?Binary();
????????long?b=?99999999999999999L;
????????byte[]?bytes=test.long2Byte(b)?;
????????System.out.println(Arrays.toString(bytes));
????????System.out.println(test.byte2Long(bytes));
????}
}轉(zhuǎn)回來變成了1592608119
2018-11-30
long類型的數(shù)不是有值域范圍嘛，你這個明顯超出范圍了啊
2019-03-17
過了一段時間回過頭來看,在第7行與第8行之間插入 System.out.println(num);
發(fā)現(xiàn)打印出來的數(shù)據(jù)分別是:
255
65535
9043967
1569325055
1569325175
1569342839
1575830903
1592608119
然后我把第7行改成 num+=(long)(arr[i]&0xff)<<i*8;
結(jié)果就對了.
經(jīng)分析byte是4字節(jié)的,最多只能左移4位,超過4位就會造成數(shù)據(jù)丟失,要先轉(zhuǎn)換成long才能左移8位;