Scott Main | 604e4ed | 2011-12-13 18:24:34 -0800 | [diff] [blame] | 1 | page.title=Manipulating Broadcast Receivers On Demand |
Scott Main | 580f014 | 2011-12-15 16:47:26 -0800 | [diff] [blame] | 2 | parent.title=Optimizing Battery Life |
Scott Main | 604e4ed | 2011-12-13 18:24:34 -0800 | [diff] [blame] | 3 | parent.link=index.html |
| 4 | |
| 5 | trainingnavtop=true |
| 6 | |
| 7 | previous.title=Determining and Monitoring the Connectivity Status |
| 8 | previous.link=connectivity-monitoring.html |
| 9 | |
| 10 | @jd:body |
| 11 | |
| 12 | <div id="tb-wrapper"> |
| 13 | <div id="tb"> |
| 14 | |
| 15 | <h2>This lesson teaches you to</h2> |
| 16 | <ol> |
| 17 | <li><a href="ToggleReceivers">Toggle and Cascade State Change Receivers to Improve |
| 18 | Efficiency</a></li> |
| 19 | </ol> |
| 20 | |
| 21 | |
| 22 | <h2>You should also read</h2> |
| 23 | <ul> |
| 24 | <li><a href="{@docRoot}guide/topics/intents/intents-filters.html">Intents and Intent Filters</a> |
| 25 | </ul> |
| 26 | |
| 27 | </div> |
| 28 | </div> |
| 29 | |
| 30 | <p>The simplest way to monitor device state changes is to create a {@link |
| 31 | android.content.BroadcastReceiver} for each state you're monitoring and register each of them in |
| 32 | your application manifest. Then within each of these receivers you simply reschedule your recurring |
| 33 | alarms based on the current device state.</p> |
| 34 | |
| 35 | <p>A side-effect of this approach is that your app will wake the device each time any of these |
| 36 | receivers is triggered—potentially much more frequently than required.</p> |
| 37 | |
| 38 | <p>A better approach is to disable or enable the broadcast receivers at runtime. That way you can |
| 39 | use the receivers you declared in the manifest as passive alarms that are triggered by system events |
| 40 | only when necessary.</p> |
| 41 | |
| 42 | |
| 43 | <h2 id="ToggleReceivers">Toggle and Cascade State Change Receivers to Improve Efficiency </h2> |
| 44 | |
| 45 | <p>Use can use the {@link android.content.pm.PackageManager} to toggle the enabled state on any |
| 46 | component defined in the manifest, including whichever broadcast receivers you wish to enable or |
| 47 | disable as shown in the snippet below:</p> |
| 48 | |
| 49 | <pre>ComponentName receiver = new ComponentName(context, myReceiver.class); |
| 50 | |
| 51 | PackageManager pm = context.getPackageManager(); |
| 52 | |
| 53 | pm.setComponentEnabledSetting(receiver, |
| 54 | PackageManager.COMPONENT_ENABLED_STATE_ENABLED, |
| 55 | PackageManager.DONT_KILL_APP)</pre> |
| 56 | |
| 57 | <p>Using this technique, if you determine that connectivity has been lost, you can disable all of |
| 58 | your receivers except the connectivity-change receiver. Conversely, once you are connected you can |
| 59 | stop listening for connectivity changes and simply check to see if you're online immediately before |
| 60 | performing an update and rescheduling a recurring update alarm.</p> |
| 61 | |
| 62 | <p>You can use the same technique to delay a download that requires higher bandwidth to complete. |
| 63 | Simply enable a broadcast receiver that listens for connectivity changes and initiates the |
| 64 | download only after you are connected to Wi-Fi.</p> |