我使用PushbackInputStream
向前查看流中的下一个字节(bufferedIn
,它是一个 BufferedInputStream
),因为我想 mark()
before 某个值,然后使用 reset()
倒回之前。
// Wrap input stream into a push back stream
PushbackInputStream pbBufferedIn = new PushbackInputStream(bufferedIn, 20);
boolean markDone = false; // Flag for mark
boolean resetDone = false; // Flag for reset
// Read each byte in the stream (some twice)
for (int i = pbBufferedIn.read(); i != -1; i = pbBufferedIn.read()) {
// Convert to byte
byte b = (byte) i;
// Check for marking before value -1
if (!markDone) {
if (b == -1) {
// Push character back
pbBufferedIn.unread(i);
// Mark for later rewind
pbBufferedIn.mark(20);
markDone = true;
System.out.print("[mark] ");
// Re-read
pbBufferedIn.read();
}
}
// Print the current byte
System.out.print(b + " ");
// Check for rewind after value 1
if (markDone && !resetDone && b == 1) {
pbBufferedIn.reset(); // <------ mark/reset not supported!
resetDone = true;
System.out.print("[reset] ");
}
}
讽刺的是,PushbackInputStream
不支持标记/重置...另一方面,支持标记/重置的BufferedInputStream
没有推回机制。 .我该怎么办?
最佳答案
BufferedInputStream
(流重放):
- 您立即标记(开始创建缓冲区),以便您稍后可以重播(在某个缓冲区位置)。
- 此外,您无法用其他内容替换缓冲的内容。
PushbackInputStream
(流校正重放):
- 始终有一个可用的缓冲区,您可以将其重置(在某个缓冲区位置)
- 您可以向该缓冲区提供重播内容。
为了简单起见,下面我提供了带有 length-1-buffers 的相应示例:
PushbackInputStream pbis =
new PushbackInputStream(new ByteArrayInputStream(new byte[]{'a','b','c'}));
System.out.println((char)pbis.read());
System.out.println((char)pbis.read());
pbis.unread('x'); //pushback after read
System.out.println((char)pbis.read());
System.out.println((char)pbis.read());
BufferedInputStream bis =
new BufferedInputStream(new ByteArrayInputStream(new byte[]{'a','b','c'}));
System.out.println((char)bis.read());
bis.mark(1);//mark before read
System.out.println((char)bis.read());
bis.reset();//reset after read
System.out.println((char)bis.read());
System.out.println((char)bis.read());
结果:
a
b
x //correction
c
a
b
b //replay
c
关于java - PushbackInputStream 和标记/重置,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/23848081/