android開源項目之OTTO事件匯流排（二）官方demo解說

注意自己該編譯版本為2.3以上，預設的1.6不支援match_parent屬性，導致布局檔案出錯。 另外需要手動添加android-support-v4和otto到自己的libs檔案夾。   主要代碼邏輯： 1，在首頁面點clear按鈕，發布兩個事件並傳遞對象。 2，然後LocationHistoryFragment接收事件對象，並處理。   1，BusProvider提供一個全域唯一的Bus執行個體對象 調用的時候使用MyProvider.getBusInstance()    1 /* 2  * Copyright (C) 2012 Square, Inc. 3  * 4  * Licensed under the Apache License, Version 2.0 (the "License"); 5  * you may not use this file except in compliance with the License. 6  * You may obtain a copy of the License at 7  * 8  * http://www.apache.org/licenses/LICENSE-2.0 9  *10  * Unless required by applicable law or agreed to in writing, software11  * distributed under the License is distributed on an "AS IS" BASIS,12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.13  * See the License for the specific language governing permissions and14  * limitations under the License.15  */16 17 package com.squareup.otto.sample;18 19 import com.squareup.otto.Bus;20 21 /**22  * Maintains a singleton instance for obtaining the bus. Ideally this would be replaced with a more efficient means23  * such as through injection directly into interested classes.24  */25 public final class BusProvider {26   private static final Bus BUS = new Bus();27 28   public static Bus getInstance() {29     return BUS;30   }31 32   private BusProvider() {33     // No instances.34   }35 }  2，LocationActivity為首頁面 點擊clear按鈕會發布兩個事件對象，LocationClearEvent和LocationChangedEvent  複製代碼  findViewById(R.id.clear_location).setOnClickListener(new OnClickListener() {      @Override public void onClick(View v) {        // Tell everyone to clear their location history.          //清除位置        BusProvider.getInstance().post(new LocationClearEvent());         // Post new location event for the default location.        //重新載入預設的位置        lastLatitude = DEFAULT_LAT;        lastLongitude = DEFAULT_LON;        BusProvider.getInstance().post(produceLocationEvent());      }    });     複製代碼 1   @Override protected void onResume() { 2     super.onResume(); 3  4     // Register ourselves so that we can provide the initial value. 5     BusProvider.getInstance().register(this); 6   } 7  8   @Override protected void onPause() { 9     super.onPause();10 11     // Always unregister when an object no longer should be on the bus.12     BusProvider.getInstance().unregister(this);13   }         3，上文提到的事件發送時要傳遞的兩個對象LocationChangedEvent對象和LocationClearEvent 可以根據自己喜好，任意設定對象。代碼見demo   4，LocationHistoryFragment裡接收事件對象 同樣需要註冊和反註冊。有時我們在服務裡發布事件，則無需註冊  複製代碼  @Subscribe public void onLocationChanged(LocationChangedEvent event) {    locationEvents.add(0, event.toString());    if (adapter != null) {      adapter.notifyDataSetChanged();    }  }   @Subscribe public void onLocationCleared(LocationClearEvent event) {    locationEvents.clear();    if (adapter != null) {      adapter.notifyDataSetChanged();    }