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

   1 // Copyright 2008 Google Inc. All Rights Reserved.
   2 package com.google.apphosting.utils.config;
   3
   4 import java.io.File;
   5 import java.io.FileInputStream;
   6 import java.io.FileNotFoundException;
   7 import java.io.IOException;
   8 import java.io.InputStream;
   9 import java.util.logging.Level;
  10 import java.util.logging.Logger;
  11
  12 /**
  13  * Creates an {@link AppEngineWebXml} instance from
  14  * <appdir>WEB-INF/appengine-web.xml.  If you want to read the configuration
  15  * from something that isn't a file, subclass and override
  16  * {@link #getInputStream()}.
  17  *
  18  */
  19 public class AppEngineWebXmlReader {
  20   private static final Logger logger =
  21       Logger.getLogger(AppEngineWebXmlReader.class.getName());
  22
  23   private static final String CONCURRENT_REQUESTS_URL =
  24       "http://code.google.com/appengine/docs/java/config/appconfig.html#Using_Concurrent_Requests";
  25
  26   private static final String DATASTORE_AUTO_IDS_URL =
  27       "http://developers.google.com/appengine/docs/java/datastore/entities#Kinds_and_Identifiers";
  28
  29   private static final String APPCFG_AUTO_IDS_URL =
  30       "http://developers.google.com/appengine/docs/java/config/appconfig#auto_id_policy";
  31
  32   public static final String DEFAULT_RELATIVE_FILENAME = "WEB-INF/appengine-web.xml";
  33
  34   private final String filename;
  35
  36   /**
  37    * Creates a reader for appengine-web.xml.
  38    *
  39    * @param appDir The directory in which the config file resides.
  40    * @param relativeFilename The path to the config file, relative to
  41    * {@code appDir}.
  42    */
  43   public AppEngineWebXmlReader(String appDir, String relativeFilename) {
  44     if (appDir.length() > 0 && appDir.charAt(appDir.length() - 1) != File.separatorChar) {
  45       appDir += File.separatorChar;
  46     }
  47     this.filename = appDir + relativeFilename;
  48   }
  49
  50   /**
  51    * Creates a reader for appengine-web.xml.
  52    *
  53    * @param appDir The directory in which the config file resides.  The
  54    * path to the config file relative to the directory is assumed to be
  55    * {@link #DEFAULT_RELATIVE_FILENAME}.
  56    */
  57   public AppEngineWebXmlReader(String appDir) {
  58     this(appDir, DEFAULT_RELATIVE_FILENAME);
  59   }
  60
  61   /**
  62    * @return A {@link AppEngineWebXml} config object derived from the
  63    * contents of <appdir>WEB-INF/appengine-web.xml.
  64    *
  65    * @throws AppEngineConfigException If <appdir>WEB-INF/appengine-web.xml does
  66    * not exist.  Also thrown if we are unable to parse the xml.
  67    */
  68   public AppEngineWebXml readAppEngineWebXml() {
  69     InputStream is = null;
  70     AppEngineWebXml appEngineWebXml;
  71     try {
  72       is = getInputStream();
  73       appEngineWebXml = processXml(is);
  74       logger.fine("Successfully processed " + getFilename());
  75       if (!appEngineWebXml.getThreadsafeValueProvided()) {
  76         if (allowMissingThreadsafeElement()) {
  77           logger.warning("appengine-web.xml does not contain a <threadsafe> element. This will "
  78               + "be treated as an error the next time you deploy.\nSee " + CONCURRENT_REQUESTS_URL
  79               + " for more information.\nYou probably want to enable concurrent requests.");
  80         } else {
  81           throw new AppEngineConfigException("appengine-web.xml does not contain a <threadsafe> "
  82               + "element.\nSee " + CONCURRENT_REQUESTS_URL + " for more information.\nYou probably "
  83               + "want to enable concurrent requests.");
  84         }
  85       }
  86       if ("legacy".equals(appEngineWebXml.getAutoIdPolicy())) {
  87         logger.warning("You have set the datastore auto id policy to 'legacy'. It is recommended "
  88             + "that you select 'default' instead.\nLegacy auto ids are deprecated. You can "
  89             + "continue to allocate legacy ids manually using the allocateIds() API functions.\n"
  90             + "For more information see:\n"
  91             + APPCFG_AUTO_IDS_URL + "\n" + DATASTORE_AUTO_IDS_URL + "\n");
  92       }
  93     } catch (Exception e) {
  94       String msg = "Received exception processing " + getFilename();
  95       logger.log(Level.SEVERE, msg, e);
  96       if (e instanceof AppEngineConfigException) {
  97         throw (AppEngineConfigException) e;
  98       }
  99       throw new AppEngineConfigException(msg, e);
 100     } finally {
 101       close(is);
 102     }
 103     return appEngineWebXml;
 104   }
 105
 106   protected boolean allowMissingThreadsafeElement() {
 107     return false;
 108   }
 109
 110   public String getFilename() {
 111     return filename;
 112   }
 113
 114   private void close(InputStream is) {
 115     if (is != null) {
 116       try {
 117         is.close();
 118       } catch (IOException e) {
 119         throw new AppEngineConfigException(e);
 120       }
 121     }
 122   }
 123
 124   protected AppEngineWebXml processXml(InputStream is) {
 125     return new AppEngineWebXmlProcessor().processXml(is);
 126   }
 127
 128   protected InputStream getInputStream() {
 129     try {
 130       return new FileInputStream(getFilename());
 131     } catch (FileNotFoundException fnfe) {
 132       throw new AppEngineConfigException(
 133           "Could not locate " + new File(getFilename()).getAbsolutePath(), fnfe);
 134     }
 135   }
 136 }