在Spring Integration Listener中，有一个类文件调用FileReadingMessageSource，有一个 boolean 变量，允许编码器通过其方法setScanEachPoll(boolean scanEachPoll)对其进行修改.
我设法做到了，监听器将在每个周期扫描目录。但是，我发现了一些错误，即 toBeReceived 队列每次扫描目录时都会将附加文件保留在其中。
例如文件a、b、c、d、e。
第一个周期，扫描，队列将有a,b,c,d,e --> 处理a，队列剩下b,c,d,e
第二个周期，扫描，队列将有b,c,d,e,b,c,d,e --> 处理b，队列剩下c,d,e,b,c,d,e 队列中将会有重复的文件名。
此处粘贴 FileReadingMessageSource 类中的 scanInputDirectory() 方法。
private void scanInputDirectory() {
List<File> filteredFiles = scanner.listFiles(directory);
Set<File> freshFiles = new LinkedHashSet<File>(filteredFiles);
if (!freshFiles.isEmpty()) {
toBeReceived.addAll(freshFiles);
if (logger.isDebugEnabled()) {
logger.debug("Added to queue: " + freshFiles);
}
}
}
有什么办法可以防止这种情况发生吗？
最佳答案
我仍然相信 AcceptOnceFileListFilter 不会让相同的文件从目标目录中提取:请参阅 DefaultDirectoryScanner.listFiles() 以及它如何使用 this.filter。
OTOH OOM 问题可以通过 FileReadingMessageSource 的 internalQueueCapacity ctor arg 修复:
/**
* Creates a FileReadingMessageSource with a bounded queue of the given
* capacity. This can be used to reduce the memory footprint of this
* component when reading from a large directory.
*
* @param internalQueueCapacity
* the size of the queue used to cache files to be received
* internally. This queue can be made larger to optimize the
* directory scanning. With scanEachPoll set to false and the
* queue to a large size, it will be filled once and then
* completely emptied before a new directory listing is done.
* This is particularly useful to reduce scans of large numbers
* of files in a directory.
*/
public FileReadingMessageSource(int internalQueueCapacity) {
this(null);
Assert.isTrue(internalQueueCapacity > 0,
"Cannot create a queue with non positive capacity");
this.scanner = new HeadDirectoryScanner(internalQueueCapacity);
}
然后查看该类的 JavaDocs:
* A custom scanner that only returns the first <code>maxNumberOfFiles</code>
* elements from a directory listing. This is useful to limit the number of File
* objects in memory and therefore mutually exclusive with {@code AcceptOnceFileListFilter}.
* It should not be used in conjunction with an {@code AcceptOnceFileListFilter}.
但是它不能与 AcceptOnceFileListFilter 一起使用，并且最终必须删除已处理的文件，以避免在下次轮询中出现它们。
另请参阅 Reference Manual 中的更多信息.
关于java - Spring Integration Listener 中 FileReadingMessageSource 中的 scanEachPoll，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/48940071/