关闭Java FileInputStream [英] Closing a Java FileInputStream

问题描述

好的，我一直在做以下（变量名已经改变）：

  
 FileInputStream fis =空值; 
 try 
 {
 fis = new FileInputStream（file）; 
 
 ...进程... 
 
} 
 catch（IOException e）
 {
 ...句柄错误... 
} 
 finally 
 {
 if（fis！= null）
 fis.close（）; 
} 
  
 

最近，我开始使用FindBugs，这表明我是没有正确关闭流。我决定看看是否有任何可以完成的最终{}块，然后我看到，哦，close（）可以抛出IOException。人们应该在这里做什么？ Java库引起太多的检查异常。

解决方案

对于Java 7及更高版本 try-with-resources ：

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

如果你坚持Java 6或更低版本...

此模式避免了使用 null ：

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

---

有关如何有效处理关闭的更多详细信息，请阅读此博文： Java：如何不让乱码流处理。它具有更多的示例代码，更深入的内容，并涵盖了关闭在 catch 块中的陷阱。

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();
}

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.

解决方案

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
}

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

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
    }

---

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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