spring-获取 Document

@Override
public Document loadDocument(InputSource inputSource, EntityResolver entityResolver,
                      ErrorHandler errorHandler, int validationMode, boolean namespaceAware) throws Exception {

   DocumentBuilderFactory factory = createDocumentBuilderFactory(validationMode, namespaceAware);
   if (logger.isTraceEnabled()) {
      logger.trace("Using JAXP provider [" + factory.getClass().getName() + "]");
   }
   DocumentBuilder builder = createDocumentBuilder(factory, entityResolver, errorHandler);
   return builder.parse(inputSource);
}

@Override
@Nullable
public InputSource resolveEntity(@Nullable String publicId, @Nullable String systemId) throws IOException {
   if (logger.isTraceEnabled()) {
      logger.trace("Trying to resolve XML entity with public ID [" + publicId +
            "] and system ID [" + systemId + "]");
   }

   if (systemId != null && systemId.endsWith(DTD_EXTENSION)) {
      int lastPathSeparator = systemId.lastIndexOf('/');
      int dtdNameStart = systemId.indexOf(DTD_NAME, lastPathSeparator);
      if (dtdNameStart != -1) {
         String dtdFile = DTD_NAME + DTD_EXTENSION;
         if (logger.isTraceEnabled()) {
            logger.trace("Trying to locate [" + dtdFile + "] in Spring jar on classpath");
         }
         try {
            Resource resource = new ClassPathResource(dtdFile, getClass());
            InputSource source = new InputSource(resource.getInputStream());
            source.setPublicId(publicId);
            source.setSystemId(systemId);
            if (logger.isTraceEnabled()) {
               logger.trace("Found beans DTD [" + systemId + "] in classpath: " + dtdFile);
            }
            return source;
         }
         catch (FileNotFoundException ex) {
            if (logger.isDebugEnabled()) {
               logger.debug("Could not resolve beans DTD [" + systemId + "]: not found in classpath", ex);
            }
         }
      }
   }

   // Fall back to the parser's default behavior.
   return null;
}