Question

FileInputStream读取方法有签名（是正确的术语吗？） -

     public int read(byte[] b) throws IOException

     // Reads up to b.length bytes of data from this input stream into an array of bytes. This method blocks until some input is available.
     // Returns: the total number of bytes read into the buffer, or -1 if there is no more data because the end of the file has been reached.

像这样的签名有什么好处 -

     public byte[] read(int numberOfBytes) throws IOException
     // Reads up to numberOfBytes bytes of data from this input stream into an array of bytes.
     // Returns- an array of bytes read. Array is empty if there is no more data because the end of the file has been reached.

Answer 1

第一种形式允许您为多次执行重用相同的byte[]数组。基本上你可以读取产生最小垃圾的整个流（低GC活动）。

后者显然更方便，但每次在byte[]方法内部执行时都需要创建read()的新实例。这意味着在读取10 GiB文件时（即使在100字节的块中），您的应用程序将总共分配10 GiB的内存 - 而不是同时，但垃圾收集器仍然会像疯了一样工作。

看看Collection.toArray(T[]) - 它遵循相同的原则。

FileInputStream读取方法的样式

1 个答案: