Question

在Spring Integration Listener中，有一个类文件调用FileReadingMessageSource，有一个布尔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文件追加到文件中。

例如，文件a，b，c，d，e。

第1个周期，扫描，队列将有a，b，c，d，e - ＆gt;处理a，队列左b，c，d，e

第二个周期，扫描，队列将有b，c，d，e，b，c，d，e - ＆gt;进程b，队列左c，d，e，b，c，d，e 它在队列中将有重复的文件名。

此处粘贴scanInputDirectory()类中的FileReadingMessageSource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);
        }
    }
}

任何想法如何防止这种情况？

Answer 1

我仍然认为AcceptOnceFileListFilter不允许从目标目录中提取相同的文件：请参阅DefaultDirectoryScanner.listFiles()以及它如何使用this.filter。

OTOH可以通过internalQueueCapacity的{{1}} ctor arg修复OOM问题：

FileReadingMessageSource

然后查看该类的JavaDocs：

/**
 * 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);
}

但是它不能与* 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}.一起使用，最后必须删除已处理的文件，以避免在下次轮询时使用。

另请参阅Reference Manual。

中的更多信息

Spring Integration Listener中的FileReadingMessageSource中的scanEachPoll

1 个答案: