XMLEntityScanner.peekChar 从 HttpRequest 读取 XML 时出现 ArrayIndexOutOfBoundsException
我正在从 Servlet doPost() 中的 HttpServletRequest 读取 XML 数据，并将 Reader 从 req.getReader() 传递到 JAXB 解组器。 我尝试了几种不同的输入 XML，但总是遇到此异常。
SEVERE: Servlet.service() for servlet RESTPhotoAdmin threw exception
java.lang.ArrayIndexOutOfBoundsException: 8192
at com.sun.org.apache.xerces.internal.impl.XMLEntityScanner.peekChar(XMLEntityScanner.java:491)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl$FragmentContentDriver.next(XMLDocumentFragmentScannerImpl.java:2672)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(XMLDocumentScannerImpl.java:647)
at com.sun.org.apache.xerces.internal.impl.XMLNSDocumentScannerImpl.next(XMLNSDocumentScannerImpl.java:140)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(XMLDocumentFragmentScannerImpl.java:508)
at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:807)
at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:737)
at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(XMLParser.java:107)
at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.parse(AbstractSAXParser.java:1205)
at com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl$JAXPSAXParser.parse(SAXParserImpl.java:522)
at com.sun.xml.internal.bind.v2.runtime.unmarshaller.UnmarshallerImpl.unmarshal0(UnmarshallerImpl.java:195)
at com.sun.xml.internal.bind.v2.runtime.unmarshaller.UnmarshallerImpl.unmarshal(UnmarshallerImpl.java:168)
at javax.xml.bind.helpers.AbstractUnmarshallerImpl.unmarshal(AbstractUnmarshallerImpl.java:137)
at javax.xml.bind.helpers.AbstractUnmarshallerImpl.unmarshal(AbstractUnmarshallerImpl.java:194)
at com.cantorva.gigcalendar.servlets.rest.RESTPhotoAdmin.doPost(RESTPhotoAdmin.java:41)
这仅发生在我的 Live Web 服务器上，而不发生在本地开发计算机上。 无论输入是什么（尽管我只尝试了大约 90k 个输入），堆栈跟踪的消息部分始终显示“8192”。 我查找了 XMLEntityScanner.java 第 491 行，可以看到正在读取一个缓冲区，并且该缓冲区确实是一个数组。 对我来说，无法使用从零开始的索引 8192 读取 8k 缓冲区是有道理的，所以这一定是一个错误 - 但原因是什么，我能做什么？
我问这个问题已经通过大量的侦探工作找到了答案。 我想为下一个可怜的家伙省去麻烦，因为 Apache 已经拒绝修复它。
I'm reading XML data from the HttpServletRequest in my servlets doPost() and passing the Reader from req.getReader() to a JAXB unmarshaller. I've tried a couple of different input XMLs but I always get this exception.
SEVERE: Servlet.service() for servlet RESTPhotoAdmin threw exception
java.lang.ArrayIndexOutOfBoundsException: 8192
at com.sun.org.apache.xerces.internal.impl.XMLEntityScanner.peekChar(XMLEntityScanner.java:491)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl$FragmentContentDriver.next(XMLDocumentFragmentScannerImpl.java:2672)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(XMLDocumentScannerImpl.java:647)
at com.sun.org.apache.xerces.internal.impl.XMLNSDocumentScannerImpl.next(XMLNSDocumentScannerImpl.java:140)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(XMLDocumentFragmentScannerImpl.java:508)
at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:807)
at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:737)
at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(XMLParser.java:107)
at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.parse(AbstractSAXParser.java:1205)
at com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl$JAXPSAXParser.parse(SAXParserImpl.java:522)
at com.sun.xml.internal.bind.v2.runtime.unmarshaller.UnmarshallerImpl.unmarshal0(UnmarshallerImpl.java:195)
at com.sun.xml.internal.bind.v2.runtime.unmarshaller.UnmarshallerImpl.unmarshal(UnmarshallerImpl.java:168)
at javax.xml.bind.helpers.AbstractUnmarshallerImpl.unmarshal(AbstractUnmarshallerImpl.java:137)
at javax.xml.bind.helpers.AbstractUnmarshallerImpl.unmarshal(AbstractUnmarshallerImpl.java:194)
at com.cantorva.gigcalendar.servlets.rest.RESTPhotoAdmin.doPost(RESTPhotoAdmin.java:41)
This only happens on my Live web server not on the local development machine. Whatever the input is (though I only tried approx 90k inputs) the message portion of the stack trace always reads "8192". I looked up XMLEntityScanner.java line 491 and can see a buffer being read, and the buffer is indeed an array. It makes sense to me that an 8k buffer can't be read using a zero based index of 8192 so this must be a bug - but what's the cause and what can I do?
I'm asking this having already found the answer through lots of detective work. I wanted to save the next poor guy the hassle since Apache have already refused to fix it.
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我发现了一个不起眼的错误 XERCESJ-1275 它本身是 XERCESJ-1015。 该报告没有提到我的堆栈跟踪，但提到了 ArrayIndexOutOfBoundsException。 线索是关于 0 是来自 Reader 的 read 方法的有效（或有些有效）响应的注释，但根据 JavaDoc，它不是来自 InputStream 的响应。 XMLEntityScanner 假定 0 永远不会出现 - 因此会出现错误。
Michael Glavassevich 对文档的解释不同，并将缺陷标记为无效，但解决方法只是使用
req.getInputStream()为 Unmarshaller 提供一个 InputStream，而不是 Reader，然后祈祷某些晦涩难懂的部分实现更完美地履行了不同的接口契约 - 他们确实做到了。I found an obscure bug XERCESJ-1275 which is itself a duplicate of XERCESJ-1015. The report doesn't mention my stack trace, but does mention a
ArrayIndexOutOfBoundsException. The clue was the comment about 0 being a valid (or somewhat valid) response from a Reader's read method, but not from an InputStream according to the JavaDoc. XMLEntityScanner assumes that 0 can never occur - thus the error.Michael Glavassevich interprets the documentation differently and marks the defect invalid, but the work around is simply to supply the Unmarshaller an InputStream using
req.getInputStream()rather than a Reader and cross your fingers that some obscure part of the implementation is fulfilling the different interface contracts more perfectly - which they do.