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关闭BufferedReader而不关闭包装的流

[英]Closing BufferedReader without closing wrapped stream

原文 2016-01-22 12:28:33 4 1 java/ sockets/ memory-leaks/ stream

I'm currently writing a program that communicates with a server using TCP sockets. 我目前正在编写一个使用TCP套接字与服务器通信的程序。 Part of that requires sending information back and forth through several methods. 其中一部分需要通过几种方法来回发送信息。 However, I do not want to open up a new socket connection for each request, but I can't guarantee the number or the order of the requests. 但是，我不想为每个请求打开一个新的套接字连接，但是我不能保证请求的数量或顺序。 In order to handle this, I simply keep one socket instance that gets reused a lot. 为了解决这个问题，我只保留了一个可以大量重用的套接字实例。

However, in order to read the data I use BufferedReader wrapper classes. 但是，为了读取数据，我使用BufferedReader包装器类。 Because I reuse the same socket, I can't call close() on the reader, or I'll close the socket stream as well. 因为我重用了相同的套接字，所以无法在读取器上调用close() ，否则我也将关闭套接字流。

Do I need to call close() on the BufferedReader if I don't want to close the underlying stream? 如果我不想关闭基础流，是否需要在BufferedReader上调用close() ？ Will I cause a memory leak by not doing this? 不这样做会导致内存泄漏吗？ If I do need to call close() how can I return the memory without closing the socket's stream? 如果确实需要调用close()如何在不关闭套接字流的情况下返回内存？

Note: I will close the underlying stream at program termination, this question isn't about that. 注意：我将在程序终止时关闭基础流，这个问题与之无关。

1 个解决方案

Don't close the BufferedReade . 不要关闭BufferedReade 。 More important , don't discard the BufferedReader ; 更重要的是 ，不要丢弃BufferedReader ; instead, pass it around rather than the SocketInputStream . 而是传递它，而不是SocketInputStream 。

A BufferedReader , as its name implies, has an internal buffer. 顾名思义， BufferedReader具有内部缓冲区。 When you read from it, it tries to fill that buffer from the underlying Reader . 从中读取时，它会尝试从基础Reader填充该缓冲区。 Which means that, if you discard it, those bytes are gone. 这意味着，如果丢弃它，这些字节将丢失。

And now some unasked advice: 现在有一些未提出的建议：

Do you really want to use a Reader ? 您真的要使用Reader吗？ Most communication protocols are better implemented using a DataInputStream / DataOutputStream . 使用DataInputStream / DataOutputStream可以更好地实现大多数通信协议。 With a Reader you're limited to character data (and in the case of BR , lines of character data). 使用Reader您只能使用字符数据（对于BR ，是字符数据行）。
Are you paying attention to encoding? 您是否在注意编码？ The correct way to construct a Reader on top of an InputStream is to use the two-argument variant of InputStreamReader : new InputStreamReader(in, "UTF-8") (you can use an encoding other than UTF-8, but have a good reason ). 构建一个正确的方法Reader上的顶部InputStream是使用两个参数的变异体InputStreamReader ： new InputStreamReader(in, "UTF-8")您可使用UTF-8编码，但有一个良好的原因）。
It's generally better to use a BufferedInputStream rather than a BufferedReader , because the translation from stream to reader may involve multiple reads. 通常最好使用BufferedInputStream而不是BufferedReader ，因为从流到阅读器的转换可能涉及多次读取。 If you want readLine() , you can always use both. 如果需要readLine() ，则可以始终使用两者。
Be sure to close the socket in either a finally or try-with-resources. 确保在finally或try-with-resources中关闭套接字 。 See this for more info. 请参阅此以获取更多信息。