我想知道为什么我会得到这个新的
eclipse Juno的警告,尽管我认为我正确地关闭了一切.你能告诉我为什么我在下面的代码中得到这个警告？
public static boolean copyFile(String fileSource,String fileDestination)
{
try
{
// Create channel on the source (the line below generates a warning unassigned closeable value)
FileChannel srcChannel = new FileInputStream(fileSource).getChannel();
// Create channel on the destination (the line below generates a warning unassigned closeable value)
FileChannel dstChannel = new FileOutputStream(fileDestination).getChannel();
// Copy file contents from source to destination
dstChannel.transferFrom(srcChannel,srcChannel.size());
// Close the channels
srcChannel.close();
dstChannel.close();
return true;
}
catch (IOException e)
{
return false;
}
}
解决方法
如果您在Java 7上运行,则可以使用像这样的新的try-with-resources块,并且您的流将被自动关闭：
public static boolean copyFile(String fileSource,String fileDestination)
{
try(
FileInputStream srcStream = new FileInputStream(fileSource);
FileOutputStream dstStream = new FileOutputStream(fileDestination) )
{
dstStream.getChannel().transferFrom(srcStream.getChannel(),srcStream.getChannel().size());
return true;
}
catch (IOException e)
{
return false;
}
}
您不需要明确地关闭底层渠道.但是,如果您不使用Java 7,则应该以繁琐的旧方式编写代码,最后是块：
public static boolean copyFile(String fileSource,String fileDestination)
{
FileInputStream srcStream=null;
FileOutputStream dstStream=null;
try {
srcStream = new FileInputStream(fileSource);
dstStream = new FileOutputStream(fileDestination)
dstStream.getChannel().transferFrom(srcStream.getChannel(),srcStream.getChannel().size());
return true;
}
catch (IOException e)
{
return false;
} finally {
try { srcStream.close(); } catch (Exception e) {}
try { dstStream.close(); } catch (Exception e) {}
}
}
看看Java 7版本好多了:)
