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android开源项目之OTTO事件总线(二)官方demo解说
官方demo见 https://github.com/square/otto
注意自己该编译版本为2.3以上,默认的1.6不支持match_parent属性,导致布局文件出错。
另外需要手动添加android-support-v4和otto到自己的libs文件夹。
主要代码逻辑:
1,在主页面点clear按钮,发布两个事件并传递对象。
2,然后LocationHistoryFragment接收事件对象,并处理。
1,BusProvider提供一个全局唯一的Bus实例对象
调用的时候使用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为主页面
点击clear按钮会发布两个事件对象,LocationClearEvent和LocationChangedEvent
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. //重新加载默认的位置 lastLatitude = DEFAULT_LAT; lastLongitude = DEFAULT_LON; BusProvider.getInstance().post(produceLocationEvent()); } });
要使用事件总线别忘了注册和反注册
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,上文提到的事件发送时要传递的两个对象LocationChangedEvent对象和LocationClearEvent
可以根据自己喜好,任意设置对象。代码见demo
4,LocationHistoryFragment里接收事件对象
同样需要注册和反注册。有时我们在服务里发布事件,则无需注册
@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(); }
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