今天来分享一下 项目中view刷新相关的核心功能。

android里线程之间消息的传递都是借助Handler来实现的

用到的场景主要是是Activity、Fragment、Application 、Service、Thread之间的消息互相传递

此实现必须借助抽象类来实现即

BaseActivity BaseFragment PhoebeApp (现在不讨论Service之间的消息传递)

先来看一下BaseActivity的实现

      public abstract class BaseActivity extends Activity implements Handler.Callback{
        @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        ActivityMgr.push(this);
        findViewById();
    }
        @Override
        public boolean handleMessage(Message msg) {
        return false;
    }
        @Override
    protected void onDestroy() {
        super.onDestroy();
        ActivityMgr.remove(this);
    }
}
 
    

其中BaseFragment的实现类似。省略

接下来看一下核心类

      /**
 * app中用于UI/非UI线程通信的核心工具类<br>
 * 可以再"UI/非UI线程"往"UI线程"中发信息, 最终接收方为 {@link BaseActivity} {@link BaseFragment} {@link PhoebeApp}
 * 
 * @author coffee<br>
 *         2015-12-26下午4:36:26
 */
public class HandlerMgr {
    public static void sendMessage(int what) {
        int delayMillis = 0;
        final Message msg = Message.obtain();
        msg.what = what;
        sendMessage(msg, delayMillis);
    }
    /**
     * 将消息发往Application、Activity、Fragment
     * 
     * @param orig
     * @param delayMillis
     */
    public static void sendMessage(Message orig, int delayMillis) {
        // 发往application
        Message appMessage = Message.obtain(orig);
        PhoebeApp.getHandler().sendMessage(appMessage);
        // 发往Activity
        ArrayList<?> activities = ActivityMgr.getAllActivities();
        for (final Object activity : activities) {
            boolean result = handle(activity, orig, delayMillis);
            if (result == true) {
                break;// 停止继续分发该Message
            } else {
                continue;
            }
        }
        // 发往Fragment
        // ArrayList<?> fragments = FragmentMgr.getAllFragments();
        // for (final Object fragment : fragments) {
        // boolean result = handle(fragment, orig, delayMillis);
        // if (result == true) {
        // break;// 停止继续分发该Message
        // } else {
        // continue;
        // }
        // }
    }
<span style="white-space:pre">  </span>
    private static boolean handle(final Object activityOrFragment, Message orig, int delayMillis) {
        final Message msg = Message.obtain(orig);
        if (delayMillis == 0) {
            boolean result = false;
            if (activityOrFragment instanceof Handler.Callback) {
                ((Handler.Callback) activityOrFragment).handleMessage(msg);
            }
            return result;
        } else {
            PhoebeApp.getHandler().postDelayed(new Runnable() {
                @Override
                public void run() {
                    if (activityOrFragment instanceof Handler.Callback) {
                        ((Handler.Callback) activityOrFragment).handleMessage(msg);
                    }
                }
            }, delayMillis);
        }
        return false;
    }
}
    

如果Thread发送的http请求 。请求完成以后

                  public void run(){
              // ...处理网络请求
              Message msg = Message.obtain();
              msg.what = 123;
              msg.obj = "{json字符串}";
              HandlerMgr.sendMessage(msg, 0);
            }
 
    

这个时候如果你Activity需要接收返回的结果

      @Override
    public boolean handleMessage(Message msg) {
        switch (msg.what) {
          case 123:
                  String json = msg.obj + "";
                  //处理json数据
                  break;
                }
        }
 
    

如果你想在多个Activity处理该http返回的结果。只需要在Activity的handleMessage中加一个case就行了

如果需要在多个Activity中接收，这里需要注意一下handlerMessage的返回值

如果返回true 只会有一个Activity 接收到。剩下的都接收不到了。

       for (final Object activity : activities) {
            boolean result = handle(activity, orig, delayMillis);
            if (result == true) {
                break;// 停止继续分发该Message
            } else {
                continue;
            }
        }