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我正在使用 Univocity-Parser 的 bean 迭代器来读取文件的每一行并获取 bean。当我尝试多次读取同一个文件时，我在库中观察到一种奇怪的行为。

将 File 对象传递给 CsvParser 实例时的代码： private static void testBeanIterator() throws Exception {

        try {

            File sampleFile = generateFile(0);
            /*
            System.out.println("Sample file content = " + FileUtils.readFileToString(sampleFile,
                    Charset.defaultCharset()));
                    */
            for (int i = 0; i < 1000; i++) {

                BufferedReader reader =
                        new BufferedReader(new InputStreamReader(new FileInputStream(sampleFile),
                                StandardCharsets.UTF_8));

                AtomicInteger atomicInteger = new AtomicInteger();

                final BeanProcessor<CustomerSegmentMapping> rowProcessor =
                        new BeanProcessor<CustomerSegmentMapping>(CustomerSegmentMapping.class) {

                    @Override
                    public void beanProcessed(@Nonnull final CustomerSegmentMapping customerSegmentMapping,
                            @Nonnull final ParsingContext context) {

                        try {

                            System.out.println(OBJECT_MAPPER.writeValueAsString(customerSegmentMapping));
                            atomicInteger.getAndAdd(1);

                        } catch (Exception ex) {
                            throw new RuntimeException("error");
                        }
                    }
                };
                rowProcessor.setStrictHeaderValidationEnabled(true);

                final CsvParserSettings parserSettings = new CsvParserSettings();
                parserSettings.setRowProcessor(rowProcessor);
                parserSettings.setHeaderExtractionEnabled(true);

                final CsvParser parser = new CsvParser(parserSettings);
                //parser.parse(reader);
                parser.parse(sampleFile);

                System.out.println("Finished parser");

                if (atomicInteger.get() != 10) {
                    throw new Exception("mismatch");
                }

                reader.close();
            }
        } catch (Exception ex) {

            throw new RuntimeException("exception = " + ex.getMessage(), ex);
        } finally {

        }
}

执行代码时，控制台输出如下：

{"customerId":"6bc12a7a-2c28-4aea-a7be-6be45e16ffb2","segmentId":"S1"}
{"customerId":"da736310-e508-47ff-92b8-59d490e37a72","segmentId":"S1"}
{"customerId":"9a5d4454-e6d4-49a5-bb04-8354154d0493","segmentId":"S1"}
{"customerId":"ec2ed5cc-cd18-443b-bd69-e56fc09ba0f5","segmentId":"S1"}
{"customerId":"94ea24b0-0c83-4039-a391-1d2439c88be8","segmentId":"S1"}
{"customerId":"2baef5f9-d8cd-451d-b579-a626cb58b284","segmentId":"S1"}
{"customerId":"022a184b-1b06-49aa-b1c4-b94a6f343b04","segmentId":"S1"}
{"customerId":"bcb3984c-0495-4da8-b146-9af3983cc158","segmentId":"S1"}
{"customerId":"feef62de-1aaf-43d4-a83b-afe053db97cf","segmentId":"S1"}
{"customerId":"5825c924-55d5-4fd6-8468-ca36d47a7cae","segmentId":"S1"}

Finished parser

{"customerId":"6bc12a7a-2c28-4aea-a7be-6be45e16ffb2","segmentId":"S1"}
{"customerId":"da736310-e508-47ff-92b8-59d490e37a72","segmentId":"S1"}
{"customerId":"9a5d4454-e6d4-49a5-bb04-8354154d0493","segmentId":"S1"}
{"customerId":"ec2ed5cc-cd18-443b-bd69-e56fc09ba0f5","segmentId":"S1"}
{"customerId":"94ea24b0-0c83-4039-a391-1d2439c88be8","segmentId":"S1"}
{"customerId":"2baef5f9-d8cd-451d-b579-a626cb58b284","segmentId":"S1"}
{"customerId":"022a184b-1b06-49aa-b1c4-b94a6f343b04","segmentId":"S1"}
{"customerId":"bcb3984c-0495-4da8-b146-9af3983cc158","segmentId":"S1"}
{"customerId":"feef62de-1aaf-43d4-a83b-afe053db97cf","segmentId":"S1"}
{"customerId":"5825c924-55d5-4fd6-8468-ca36d47a7cae","segmentId":"S1"}

Finished parser

{"customerId":"6bc12a7a-2c28-4aea-a7be-6be45e16ffb2","segmentId":"S1"}
{"customerId":"da736310-e508-47ff-92b8-59d490e37a72","segmentId":"S1"}
{"customerId":"9a5d4454-e6d4-49a5-bb04-8354154d0493","segmentId":"S1"}
{"customerId":"ec2ed5cc-cd18-443b-bd69-e56fc09ba0f5","segmentId":"S1"}
{"customerId":"94ea24b0-0c83-4039-a391-1d2439c88be8","segmentId":"S1"}
{"customerId":"2baef5f9-d8cd-451d-b579-a626cb58b284","segmentId":"S1"}
{"customerId":"022a184b-1b06-49aa-b1c4-b94a6f343b04","segmentId":"S1"}
{"customerId":"bcb3984c-0495-4da8-b146-9af3983cc158","segmentId":"S1"}
{"customerId":"feef62de-1aaf-43d4-a83b-afe053db97cf","segmentId":"S1"}
{"customerId":"5825c924-55d5-4fd6-8468-ca36d47a7cae","segmentId":"S1"}

Finished parser

Exception in thread "main" java.lang.RuntimeException: exception = Could not find fields [CustomerId]' in input. Names found: [ustomerId, SegmentId]
Internal state when error was thrown: line=2, column=0, record=1, charIndex=60, headers=[ustomerId, SegmentId]
    at com.poppins.cube.common.UnivocityNahiHatanaHai.testBeanIterator(UnivocityNahiHatanaHai.java:95)
    at com.poppins.cube.common.UnivocityNahiHatanaHai.main(UnivocityNahiHatanaHai.java:37)
Caused by: com.univocity.parsers.common.DataProcessingException: Could not find fields [CustomerId]' in input. Names found: [ustomerId, SegmentId]
Internal state when error was thrown: line=2, column=0, record=1, charIndex=60, headers=[ustomerId, SegmentId]
    at com.univocity.parsers.common.processor.core.BeanConversionProcessor.mapFieldIndexes(BeanConversionProcessor.java:414)
    at com.univocity.parsers.common.processor.core.BeanConversionProcessor.mapValuesToFields(BeanConversionProcessor.java:340)
    at com.univocity.parsers.common.processor.core.BeanConversionProcessor.createBean(BeanConversionProcessor.java:508)
    at com.univocity.parsers.common.processor.core.AbstractBeanProcessor.rowProcessed(AbstractBeanProcessor.java:54)
    at com.univocity.parsers.common.Internal.process(Internal.java:21)
    at com.univocity.parsers.common.AbstractParser.rowProcessed(AbstractParser.java:596)
    at com.univocity.parsers.common.AbstractParser.parse(AbstractParser.java:133)
    at com.univocity.parsers.common.AbstractParser.parse(AbstractParser.java:605)
    at com.poppins.cube.common.UnivocityNahiHatanaHai.testBeanIterator(UnivocityNahiHatanaHai.java:83)
    ... 1 more

Process finished with exit code 1

以下是该文件的内容：

CustomerId,SegmentId
6bc12a7a-2c28-4aea-a7be-6be45e16ffb2,S1
da736310-e508-47ff-92b8-59d490e37a72,S1
9a5d4454-e6d4-49a5-bb04-8354154d0493,S1
ec2ed5cc-cd18-443b-bd69-e56fc09ba0f5,S1
94ea24b0-0c83-4039-a391-1d2439c88be8,S1
2baef5f9-d8cd-451d-b579-a626cb58b284,S1
022a184b-1b06-49aa-b1c4-b94a6f343b04,S1
bcb3984c-0495-4da8-b146-9af3983cc158,S1
feef62de-1aaf-43d4-a83b-afe053db97cf,S1
5825c924-55d5-4fd6-8468-ca36d47a7cae,S1

据我所知，问题的出现是因为我将 File 对象传递给 CsvParser。CsvParser 在内部创建一个未关闭的 InputStream 对象。如果我传递的是 Buffered reader 对象而不是 File 对象，则不会出现问题。

我无法理解这是否是 Univocity-Parsers 的一个已知问题，还是我在理解中遗漏了什么。

4

1 回答 1

1

图书馆的作者在这里。我可以看到你的异常显示它有 headerustomerId而不是CustomerId.

如果我没记错的话，这看起来像是 2.5.0 版本中引入的错误，该错误已在 2.5.6 版本中修复。这困扰了我一段时间，因为这是一个难以追踪的内部并发问题。基本上，当您传递一个没有显式编码的文件时，它会尝试在输入中找到一个 UTF BOM 标记（有效地消耗第一个字符）来自动确定编码。这仅发生在 InputStreams 和 Files 上。

无论如何，这已得到修复，因此只需更新到最新版本即可为您解决问题（如果您没有使用 2.5 版，请告诉我。某事）

如果您想保留当前版本，如果您致电，错误将消失

parser.parse(sampleFile, Charset.defaultCharset());

这将阻止解析器尝试发现您的文件中是否存在 BOM 标记，从而避免该讨厌的错误。

希望这可以帮助

于 2018-07-03T22:51:38.487 回答