java/src/main/com/google/appengine/tools/util/ApiVersionFinder.java

   1 // Copyright 2009 Google Inc. All Rights Reserved.
   2
   3 package com.google.appengine.tools.util;
   4
   5 import java.io.File;
   6 import java.io.IOException;
   7 import java.util.jar.JarFile;
   8 import java.util.jar.Manifest;
   9 import java.util.jar.Attributes;
  10
  11 /**
  12  * {@code ApiVersionFinder} extracts the {@code Specification-Version}
  13  * from the Jar manifest of the specified jar file.
  14  *
  15  */
  16 public class ApiVersionFinder {
  17   private static final String DESIRED_VENDOR_ID = "com.google";
  18   private static final String API_PACKAGE_NAME = "com/google/appengine/api/";
  19
  20   public static void main(String[] args) throws IOException {
  21     ApiVersionFinder finder = new ApiVersionFinder();
  22     String apiVersion = finder.findApiVersion(args[0]);
  23     if (apiVersion == null) {
  24       System.exit(1);
  25     }
  26
  27     System.out.println(apiVersion);
  28     System.exit(0);
  29   }
  30
  31   public String findApiVersion(String fileName) throws IOException {
  32     return findApiVersion(new File(fileName));
  33   }
  34
  35   public String findApiVersion(File inputJar) throws IOException {
  36     JarFile jarFile = new JarFile(inputJar);
  37     try {
  38       Manifest manifest = jarFile.getManifest();
  39
  40       if (manifest != null) {
  41         Attributes attr = manifest.getAttributes(API_PACKAGE_NAME);
  42         if (attr != null) {
  43           String vendorId = attr.getValue(Attributes.Name.IMPLEMENTATION_VENDOR_ID);
  44           if (!DESIRED_VENDOR_ID.equals(vendorId)) {
  45             return null;
  46           }
  47
  48           return attr.getValue(Attributes.Name.SPECIFICATION_VERSION);
  49         }
  50       }
  51       return null;
  52     } finally {
  53       try {
  54         jarFile.close();
  55       } catch (IOException ex) {
  56       }
  57     }
  58   }
  59 }