android開源項目之OTTO事件總線（二）官方demo解說

注意自己該編譯版本為2.3以上，默認的1.6不支持match_parent屬性，導致布局文件出錯。   另外需要手動添加android-support-v4和otto到自己的libs文件夾。       主要代碼邏輯：   1，在主頁面點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提供一個全局唯一的Bus實例對象   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, software 11  * 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 and 14  * 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 means 23  * 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為主頁面   點擊clear按鈕會發布兩個事件對象，LocationClearEvent和LocationChangedEvent     復制代碼   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.         //重新加載默認的位置         lastLatitude = DEFAULT_LAT;         lastLongitude = DEFAULT_LON;         BusProvider.getInstance().post(produceLocationEvent());       }     });           復制代碼  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，任意設置對象。代碼見demo       4，LocationHistoryFragment裡接收事件對象   同樣需要注冊和反注冊。有時我們在服務裡發布事件，則無需注冊     復制代碼   @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();     }