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IBM JAVA NIO培训资料,有很好的实例

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<a name="navskip"></a><td height="25" colspan="4"><img alt="5.缓冲区内部细节 " src="imagemaster/titlebar5.jpg" border="0" height="25" width="562"></td>
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<td width="90%"><font size="4" face="Verdana, Arial, Helvetica"><b>Position</b></font></td><td width="200" align="right"><font size="1" face="Verdana, Arial, Helvetica"><nobr>   第 3 页（共17 页）</nobr></font></td>
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<p>您可以回想一下，缓冲区实际上就是美化了的数组。在从通道读取时，您将所读取的数据放到底层的数组中。 <code>position</code> 变量跟踪已经写了多少数据。更准确地说，它指定了下一个字节将放到数组的哪一个元素中。因此，如果您从通道中读三个字节到缓冲区中，那么缓冲区的 <code>position</code> 将会设置为3，指向数组中第四个元素。 </p>
<p>同样，在写入通道时，您是从缓冲区中获取数据。 <code>position</code> 值跟踪从缓冲区中获取了多少数据。更准确地说，它指定下一个字节来自数组的哪一个元素。因此如果从缓冲区写了5个字节到通道中，那么缓冲区的 <code>position</code> 将被设置为5，指向数组的第六个元素。 </p>
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