关闭 Java FileInputStream [英] Closing a Java FileInputStream

问题描述

好的，我一直在做以下事情(变量名已更改):

Alright, I have been doing the following (variable names have been changed):

FileInputStream fis = null;
try
{
    fis = new FileInputStream(file);

    ... process ...

}
catch (IOException e)
{
    ... handle error ...
}
finally
{
    if (fis != null)
        fis.close();
}

最近，我开始使用 FindBugs，这表明我没有正确关闭流.我决定看看是否有任何可以用 finally{} 块完成的事情，然后我看到，哦，是的，close() 可以抛出 IOException.人们应该在这里做什么?Java 库抛出太多已检查的异常.

Recently, I started using FindBugs, which suggests that I am not properly closing streams. I decide to see if there's anything that can be done with a finally{} block, and then I see, oh yeah, close() can throw IOException. What are people supposed to do here? The Java libraries throw too many checked exceptions.

推荐答案

对于 Java 7 及更高版本 try-with-resources 应该被使用:

For Java 7 and above try-with-resources should be used:

try (InputStream in = new FileInputStream(file)) {
  // TODO: work
} catch (IOException e) {
  // TODO: handle error
}

如果您坚持使用 Java 6 或更低版本...

If you're stuck on Java 6 or below...

这种模式避免了使用 null 的麻烦:

This pattern avoids mucking around with null:

    try {
        InputStream in = new FileInputStream(file);
        try {
            // TODO: work
        } finally {
            in.close();
        }
    } catch (IOException e) {
        // TODO: error handling
    }

<小时>

有关如何有效处理close的更多详细信息，请阅读这篇博文:Java:如何不把流处理弄得一团糟.它有更多示例代码、更深入，并涵盖了将 close 包装在 catch 块中的陷阱.

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For a more detail on how to effectively deal with close, read this blog post: Java: how not to make a mess of stream handling. It has more sample code, more depth and covers the pitfalls of wrapping close in a catch block.

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