java XSD 验证：此解析器不支持规范“null”版本“null”
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XSD Validation: This parser does not support specification "null" version "null"
提问by peter.murray.rust
I am trying to validate XML files using standard Java libraries and get the above error. My XSD file test1.xsdis
我正在尝试使用标准 Java 库验证 XML 文件并收到上述错误。我的 XSD 文件test1.xsd是
<?xml version="1.0"?>
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<xsd:complexType name="foo">
<xsd:attribute name="bar" type="xsd:string" />
</xsd:complexType>
</xsd:schema>
with code (running as Junit test in Eclipse):
使用代码（在 Eclipse 中作为 Junit 测试运行）：
@Test
public void testValidatingParser1() throws Exception {
String SCHEMA_PATH = "test1.xsd";
InputStream SCHEMA_STREAM = getClass().getResourceAsStream(SCHEMA_PATH);
StreamSource SCHEMA_SOURCE = new StreamSource(SCHEMA_STREAM);
SchemaFactory sf = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
Schema schema = sf.newSchema(SCHEMA_SOURCE);
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
factory.setSchema(schema);
}
The error is:
错误是：
java.lang.UnsupportedOperationException: This parser does not support specification "null" version "null"
at javax.xml.parsers.DocumentBuilderFactory.setSchema(Unknown Source)
at org.xmlcml.graphics.misc.SchemaTest.testValidatingParser1(SchemaTest.java:123)
This error seems to arise from incompatibilities with XML parsers (such as Xerces) see this postbut I have no frameworks (other than Eclipse and Junit). I do not have xerces explicitly in my POM. Is there a simple workround (I don't mind what parser I use as long as it validates).
这个错误似乎是由于与 XML 解析器（例如 Xerces）的不兼容引起的，请参阅这篇文章，但我没有框架（Eclipse 和 Junit 除外）。我的 POM 中没有明确的 xerces。是否有一个简单的解决方法（我不介意我使用什么解析器，只要它通过验证）。
回答by peter.murray.rust
I tracked it down to incompatible versions of Xerces, included from other software. Forcing the later versions of Xerces cures the problem.
我将其追溯到其他软件中包含的不兼容版本的 Xerces。强制使用更高版本的 Xerces 可以解决问题。
回答by Yogendra Singh
I think that your XSD file is not getting accessible through InputStream SCHEMA_STREAM = getClass().getResourceAsStream(SCHEMA_PATH);. accessible.
我认为您的 XSD 文件无法通过InputStream SCHEMA_STREAM = getClass().getResourceAsStream(SCHEMA_PATH);. 无障碍。
I validate the your code and XSDfile with only changed line as below. It ran without any issues in JDK 1.6and JDK 1.7.
我XSD仅使用如下更改的行验证您的代码和文件。它在JDK 1.6和 中运行没有任何问题JDK 1.7。
InputStream SCHEMA_STREAM = new FileInputStream(new File(SCHEMA_PATH));
When file was not accessible, I got the NullPointerExceptionlittle different as below:
当文件无法访问时，我得到的NullPointerException有点不同，如下所示：
Exception in thread "main" org.xml.sax.SAXParseException:
schema_reference.4: Failed to read schema document 'null'
回答by Ozgur
Did you try this in xsd?
你在 xsd 中试过这个吗？
For attributes use the attribute use="optional"
对于属性使用属性 use="optional"
For elements use the attribute nillable="true"or use the attribute minOccurs="0"
对于元素使用属性nillable="true"或使用属性minOccurs="0"
