src/components/cronet/android/java/src/org/chromium/net/UserAgent.java

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 package org.chromium.net;
   6
   7 import android.content.Context;
   8 import android.content.pm.PackageInfo;
   9 import android.content.pm.PackageManager;
  10 import android.content.pm.PackageManager.NameNotFoundException;
  11 import android.os.Build;
  12
  13 import java.util.Locale;
  14
  15 /**
  16  * Constructs a User-Agent string.
  17  */
  18 public final class UserAgent {
  19     private static final Object sLock = new Object();
  20
  21     private static int sVersionCode;
  22
  23     private UserAgent() {
  24     }
  25
  26     public static String from(Context context) {
  27         StringBuilder builder = new StringBuilder();
  28
  29         // Our package name and version.
  30         builder.append(context.getPackageName());
  31         builder.append('/');
  32         builder.append(versionFromContext(context));
  33
  34         // The platform version.
  35         builder.append(" (Linux; U; Android ");
  36         builder.append(Build.VERSION.RELEASE);
  37         builder.append("; ");
  38         builder.append(Locale.getDefault().toString());
  39
  40         String model = Build.MODEL;
  41         if (model.length() > 0) {
  42             builder.append("; ");
  43             builder.append(model);
  44         }
  45
  46         String id = Build.ID;
  47         if (id.length() > 0) {
  48             builder.append("; Build/");
  49             builder.append(id);
  50         }
  51
  52         builder.append("; Cronet/");
  53         builder.append(Version.CRONET_VERSION);
  54
  55         builder.append(')');
  56
  57         return builder.toString();
  58     }
  59
  60     private static int versionFromContext(Context context) {
  61         synchronized (sLock) {
  62             if (sVersionCode == 0) {
  63                 PackageManager packageManager = context.getPackageManager();
  64                 String packageName = context.getPackageName();
  65                 try {
  66                     PackageInfo packageInfo = packageManager.getPackageInfo(
  67                             packageName, 0);
  68                     sVersionCode = packageInfo.versionCode;
  69                 } catch (NameNotFoundException e) {
  70                     throw new IllegalStateException(
  71                             "Cannot determine package version");
  72                 }
  73             }
  74             return sVersionCode;
  75         }
  76     }
  77 }