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My webservice receives an xml from a third-party source, which contains a !DOCTYPE declaration. Therefore I must use the second method in my controller to parse the xml document, the first one gives me this exception: Failed to read HTTP message: org.springframework.http.converter.HttpMessageNotReadableException: Could not unmarshal to [class com.example.MeterBusXml]: null; nested exception is javax.xml.bind.UnmarshalException - with linked exception: [org.xml.sax.SAXParseException; lineNumber: 1; columnNumber: 48; DOCTYPE is disallowed when the feature "http://apache.org/xml/features/disallow-doctype-decl" set to true.]

I have no control over the application which posts the xml, so I must adapt my webservice to parse it with the dtd.

My question is, what is the spring framework's way of injecting the EntityResolver into every XMLReader instance?

@RestController
public class MeterBusDataController {

  @RequestMapping (
    consumes = APPLICATION_XML_VALUE,
    method = POST,
    path = "/meterbus1"
  )
  public void method1(@RequestBody MeterBusXml xml) {
    System.out.println(xml);
  }

  @RequestMapping(
    method = POST,
    path = "/meterbus2"
  )
  public void method2(HttpServletRequest rq) throws IOException, ParserConfigurationException, SAXException, JAXBException {
    JAXBContext jc = newInstance(MeterBusXml.class);
    Unmarshaller um = jc.createUnmarshaller();
    SAXParserFactory spf = SAXParserFactory.newInstance();
    spf.setNamespaceAware(true);
    spf.setValidating(true);
    SAXParser sp = spf.newSAXParser();
    XMLReader xr = sp.getXMLReader();
    xr.setEntityResolver(new EntityResolver() {
      @Override
      public InputSource resolveEntity(String publicId, String systemId) throws SAXException, IOException {
        return new InputSource(new StringReader(""));
      }
    });
    BufferedReader reader = rq.getReader();
    InputSource inputSource = new InputSource(reader);
    SAXSource saxSource = new SAXSource(xr, inputSource);
    MeterBusXml xml = (MeterBusXml)um.unmarshal(saxSource);
    System.out.println(xml);
  }
}

See the following document for an example of the mbus.xml I'm trying to unmarshal. http://prevodniky.sk/products/product_EthMBus_common/download/Ethernet_converters_exports_v1_02_EN.pdf

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1 回答 1

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我找到了问题的根源。首先，我尝试创建和配置一个 Jaxb2Marshaller bean，但没有成功。然后我意识到，我需要一个 HttpMessageConverter，所以我必须重写类extendMessageConverters中的方法WebMvcConfigurerAdapter，并在Jaxb2RootElementHttpMessageConverter. 这个消息转换器不使用 a Jaxb2Marshaller，但它的内部工作原理非常相似。

setSupportDtd(true) 是必需的，以强制解析器接受 !DOCTYPE 声明。

setProcessExternalEntities(false) 是必需的，因为如果此属性为 false，则转换器使用空白EntityResolver，就像我在方法 2 中所做的那样。

@Configuration
public class WebConfiguration extends WebMvcConfigurerAdapter {

  @Override
  public void extendMessageConverters(List<HttpMessageConverter<Jaxb2RootElementHttpMessageConverter?>> converters) {
    for (final Iterator<HttpMessageConverter<?>> iterator = converters.iterator(); iterator.hasNext();) {
      HttpMessageConverter<?> next = iterator.next();
      if (next instanceof Jaxb2RootElementHttpMessageConverter) {
        Jaxb2RootElementHttpMessageConverter jaxbConverter = (Jaxb2RootElementHttpMessageConverter) next;
        jaxbConverter.setProcessExternalEntities(false);
        jaxbConverter.setSupportDtd(true);
      }
    }
  }
}
于 2016-03-31T18:50:41.960 回答