BinaryReader.Dispose（BOOL处置）创建一个本地引用流。为什么？

问题描述

我发现了整箱的代码不同寻常的样品

这是在System.IO.BinaryReader方式：

 受保护的虚拟无效的Dispose（BOOL处置）{
如果（处置）{
流copyOfStream = m_stream; 
 m_stream = NULL; 
如果（copyOfStream = NULL&放大器;！&安培;！m_leaveOpen）
 copyOfStream.Close（）; 
} 
 m_stream = NULL; 
 m_buffer = NULL; 
 m_decoder = NULL; 
 m_charBytes = NULL; 
 m_singleChar = NULL; 
 m_charBuffer = NULL; 
} 
  

在执行逻辑有什么影响copyOfStream？

解决方案

它的完成使m_stream将被设置为null即使 Stream.Close（）抛出异常。

在回应评论

When you close a stream, any buffered output is flushed, which can throw an exception, e.g. due to a network failure.

In the above, if Stream.Close() throws, then m_stream will already be null. With the following alternative, m_stream won't be set to null if Stream.Close() throws:

m_stream.Close(); // <== throws
m_stream = null;  // <== not executed if Close() throws

It won't throw a NullReferenceException because it tests for null:

if (copyOfStream != null && !m_leaveOpen)
        copyOfStream.Close();

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