Question

我的简单Web服务接收XML文档的Zip文件，我尝试使用XSD架构文件验证XML。以下是代码段

        Schema schema = BlahSchemaFactory.newSchema("Blah.xsd");
        Validator validator = schema.newValidator();
        BlahErrorHandler eh = new BlahErrorHandler();
        validator.setErrorHandler(eh);

        ZipInputStream zis = new ZipInputStream(new ByteArrayInputStream(zipFileContentAsBytes));
        zis.getNextEntry(); 

        Source xmlSource = new StreamSource(zis);
        validator.validate(xmlSource);

BlahSchemaFactory 是一个单例，每个传递的XSD文件只帮助创建一次Schema对象。现在，当几个HTTP线程通过上面的代码传递时出现问题。它们在validate（）方法的代码深处相互阻塞。

以下是从HP Diagnostic工具获取的堆栈跟踪。

    "blah_thread_77" Id=472 in BLOCKED on lock=org.apache.xerces.impl.xpath.regex.RegularExpression@3c9d97f9
         owned by d1_thread_237 Id=21648
        at org.apache.xerces.impl.xpath.regex.RegularExpression.matches(Unknown Source)
        at org.apache.xerces.impl.xpath.regex.RegularExpression.matches(Unknown Source)
        at org.apache.xerces.impl.dv.xs.XSSimpleTypeDecl.getActualValue(Unknown Source)
        at org.apache.xerces.impl.dv.xs.XSSimpleTypeDecl.validate(Unknown Source)
        at org.apache.xerces.impl.xs.XMLSchemaValidator.processOneAttribute(Unknown Source)
        at org.apache.xerces.impl.xs.XMLSchemaValidator.processAttributes(Unknown Source)
        at org.apache.xerces.impl.xs.XMLSchemaValidator.handleStartElement(Unknown Source)
        at org.apache.xerces.impl.xs.XMLSchemaValidator.emptyElement(Unknown Source)
        at org.apache.xerces.impl.XMLNSDocumentScannerImpl.scanStartElement(Unknown Source)
        at org.apache.xerces.impl.XMLDocumentFragmentScannerImpl$FragmentContentDispatcher.dispatch(Unknown Source)
        at org.apache.xerces.impl.XMLDocumentFragmentScannerImpl.scanDocument(Unknown Source)
        at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
        at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
        at org.apache.xerces.jaxp.validation.StreamValidatorHelper.validate(Unknown Source)
        at org.apache.xerces.jaxp.validation.ValidatorImpl.validate(Unknown Source)
        at javax.xml.validation.Validator.validate(Validator.java:124)
        at BlahPackage.BlahClass.uploadSaveFileRecord(BlahRecord.java:77)
        at sun.reflect.GeneratedMethodAccessor210.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:601)
        at org.jboss.ws.common.invocation.AbstractInvocationHandlerJSE.invoke(AbstractInvocationHandlerJSE.java:111)
        at org.jboss.wsf.stack.cxf.JBossWSInvoker._invokeInternal(JBossWSInvoker.java:181)
        at org.jboss.wsf.stack.cxf.JBossWSInvoker.invoke(JBossWSInvoker.java:127)
        at org.apache.cxf.interceptor.ServiceInvokerInterceptor$1.run(ServiceInvokerInterceptor.java:58)
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)

问题：有什么方法可以避免线程上的阻塞吗？请提出建议！

Answer 1

以下是在尝试使用XSD架构验证XML时解决线程阻塞问题的代码段。你需要：

确保为每个线程创建一个新的架构
确保在SchemaFactory上调用newSchema时同步打电话（如图所示）

而不是打电话 BlahObject.class.getClassLoader（）的getResource（schemaFileOnClassPath）使用某种类型的Singleton来获取XSD的URL一次，否则你会遇到线程阻塞，类加载器试图找到它资源（这是使用HP诊断工具识别的）

    SchemaFactory schemaFactory = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
    URL schemaURL = BlahSchemaSingleton.getSchemaURL("Blah.xsd");
    Schema schema = null; 

    synchronized(schemaFactory) {
        schema = schemaFactory.newSchema(schemaURL);
    }

    Validator validator = schema.newValidator();
    BlahErrorHandler eh = new BlahErrorHandler();
    validator.setErrorHandler(eh);

    ZipInputStream zis = new ZipInputStream(new ByteArrayInputStream(zipFileContentAsBytes));
    zis.getNextEntry(); 

    Source xmlSource = new StreamSource(zis);
    validator.validate(xmlSource);

使用javax.xml.validation.Validator执行XML验证时阻止HTTP Web服务线程

1 个答案: