本文系摘抄：
a.txt 內容 01234567890
BufferedInputStream in = new BufferedInputStream(new FileInputStream(
new File("a.txt")),8);
int s = -1;
// String str = "";
int count = 0;
while ((s = in.read()) != -1) {
System.out.print((char) s);
if (count == 4) {
in.mark(12);
break;
}
s = -1;
count++;
}
System.out.println();
in.reset();
while ((s = in.read()) != -1) {
System.out.print((char) s);
}
System.out.println();
in.reset();
while ((s = in.read()) != -1) {
System.out.print((char) s);
}
System.out.println();
in.close();
mark(int readlimit);
在mark後再read，如果讀到的字節數大於BufferedInputStream緩衝區大小，那麼你就再不能回到標記的位置，而readlimit如果大於BufferedInputStream緩衝區大小，那麼BufferedInputStream會重置緩衝大小爲readlimit；
