J2Me学习输入流--InputStream

Java InputStream API
Method Summary
int available()
          Returns the number of bytes that can be read (or skipped over) from this input stream without blocking by the next caller of a method for this input stream.
void close()
          Closes this input stream and releases any system resources associated with the stream.
void mark(int readlimit)
          Marks the current position in this input stream.
boolean markSupported()
          Tests if this input stream supports the mark and reset methods.
abstract  int read()
          Reads the next byte of data from the input stream.
int read(byte[] b)
          Reads some number of bytes from the input stream and stores them into the buffer array b.
int read(byte[] b, int off, int len)
          Reads up to len bytes of data from the input stream into an array of bytes.
void reset()
          Repositions this stream to the position at the time the mark method was last called on this input stream.
long skip(long n)
          Skips over and discards n bytes of data from this input stream.


Java  InputStream  的mark 和reset操作
mark用于标记当前位置；在读取一定数量的数据(小于readlimit的数据)后使用reset可以回到mark标记的位置。
FileInputStream不支持mark/reset操作；BufferedInputStream支持此操作；

mark(readlimit)的含义是在当前位置作一个标记，制定可以重新读取的最大字节数，也就是说你如果标记后读取的字节数大于readlimit，你就再也回不到回来的位置了。

通常InputStream的read()返回-1后，说明到达文件尾，不能再读取。除非使用了mark/reset