java - 如何在读取属性文件时关闭 fileInputStream

Question

我有以下代码:

    // Read properties file.
     Properties properties = new Properties();
     try {
     properties.load(new FileInputStream("filename.properties"));
     } catch (FileNotFoundException e) {
     system.out.println("FileNotFound");
     }catch (IOException e) {
     system.out.println("IOEXCeption");
     }

是否需要关闭FileInputStream？如果是，我该怎么做？我的代码 list 中出现错误做法错误。要求它放入 finally block 。

Answer 1

您必须关闭 FileInputStream，因为 Properties 实例不会。来自 Properties.load() javadoc:

The specified stream remains open after this method returns.

将 FileInputStream 存储在一个单独的变量中，在 try 之外声明，并添加一个 finally block 来关闭 FileInputStream 如果打开:

Properties properties = new Properties();
FileInputStream fis = null;
try {
    fis = new FileInputStream("filename.properties");
    properties.load(fis);
} catch (FileNotFoundException e) {
    system.out.println("FileNotFound");
} catch (IOException e) {
    system.out.println("IOEXCeption");
} finally {
    if (null != fis)
    {
        try
        {
            fis.close();
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }
    }
}

---

使用try-with-resources从 Java 7 开始:

final Properties properties = new Properties();
try (final FileInputStream fis =
         new FileInputStream("filename.properties"))
{
    properties.load(fis);
} catch (FileNotFoundException e) {
    System.out.println("FileNotFound: " + e.getMessage());
} catch (IOException e) {
    System.out.println("IOEXCeption: " + e.getMessage());
}