java/src/main/com/google/apphosting/utils/config/XmlUtils.java

   1 package com.google.apphosting.utils.config;
   2
   3 import com.google.common.base.Charsets;
   4 import com.google.common.io.Files;
   5
   6 import org.mortbay.xml.XmlParser;
   7 import org.mortbay.xml.XmlParser.Node;
   8 import org.xml.sax.SAXException;
   9
  10 import java.io.ByteArrayInputStream;
  11 import java.io.File;
  12 import java.io.IOException;
  13 import java.io.InputStream;
  14 import java.util.logging.Level;
  15 import java.util.logging.Logger;
  16
  17 import javax.xml.XMLConstants;
  18 import javax.xml.transform.stream.StreamSource;
  19 import javax.xml.validation.SchemaFactory;
  20
  21 /**
  22  * Utility functions for processing XML.
  23  */
  24 public class XmlUtils {
  25   private static final Logger logger = Logger.getLogger(XmlUtils.class.getName());
  26
  27   static String getText(XmlParser.Node node) throws AppEngineConfigException{
  28     Object child = node.get(0);
  29     String value;
  30     if (child == null) {
  31       value = "";
  32     } else {
  33       if (!(child instanceof String)) {
  34         String msg = "Invalid XML: String content expected in node '" + node.getTag() + "'.";
  35         logger.log(Level.SEVERE, msg);
  36         throw new AppEngineConfigException(msg);
  37       }
  38       value = (String) child;
  39     }
  40
  41     return value.trim();
  42   }
  43
  44   /**
  45    * Parses the input stream and returns the {@link Node} for the root element.
  46    *
  47    * @throws AppEngineConfigException If the input stream cannot be parsed.
  48    */
  49   static Node parse(InputStream is) {
  50     XmlParser xmlParser = new XmlParser();
  51     try {
  52       return xmlParser.parse(is);
  53     } catch (IOException e) {
  54       String msg = "Received IOException parsing the input stream.";
  55       logger.log(Level.SEVERE, msg, e);
  56       throw new AppEngineConfigException(msg, e);
  57     } catch (SAXException e) {
  58       String msg = "Received SAXException parsing the input stream.";
  59       logger.log(Level.SEVERE, msg, e);
  60       throw new AppEngineConfigException(msg, e);
  61     }
  62   }
  63
  64   /**
  65    * Validates a given XML document against a given schema.
  66    *
  67    * @param xmlFilename filename with XML document.
  68    * @param schema XSD schema to validate with.
  69    *
  70    * @throws AppEngineConfigException for malformed XML, or IO errors
  71    */
  72   public static void validateXml(String xmlFilename, File schema) {
  73     File xml = new File(xmlFilename);
  74     if (!xml.exists()) {
  75       throw new AppEngineConfigException("Xml file: " + xml.getPath() + " does not exist.");
  76     }
  77     if (!schema.exists()) {
  78       throw new AppEngineConfigException("Schema file: " + schema.getPath() + " does not exist.");
  79     }
  80     try {
  81       validateXmlContent(Files.toString(xml, Charsets.UTF_8), schema);
  82     } catch (IOException ex) {
  83       throw new AppEngineConfigException(
  84           "IO error validating " + xmlFilename + " against " + schema.getPath(), ex);
  85     }
  86   }
  87
  88   /**
  89    * Validates a given XML document against a given schema.
  90    *
  91    * @param content a String containing the entire XML to validate.
  92    * @param schema XSD schema to validate with.
  93    *
  94    * @throws AppEngineConfigException for malformed XML, or IO errors
  95    */
  96   public static void validateXmlContent(String content, File schema) {
  97     if (!schema.exists()) {
  98       throw new AppEngineConfigException("Schema file: " + schema.getPath() + " does not exist.");
  99     }
 100     try {
 101       SchemaFactory factory = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
 102       try {
 103         factory
 104             .newSchema(schema)
 105             .newValidator()
 106             .validate(new StreamSource(new ByteArrayInputStream(content.getBytes(Charsets.UTF_8))));
 107       } catch (SAXException ex) {
 108         throw new AppEngineConfigException(
 109             "XML error validating " + content + " against " + schema.getPath(), ex);
 110       }
 111     } catch (IOException ex) {
 112       throw new AppEngineConfigException(
 113           "IO error validating " + content + " against " + schema.getPath(), ex);
 114     }
 115   }
 116 }