Best Practices for Interaction and Engagement

Planning Screens and Their Relationships
- 实体关系图（Entity-relationship diagram），数据、用户之间的关系、操作
- 详尽的用例场景
- 界面关系图
Planning for Multiple Touchscreen Sizes
- 界面组合技术，在平板电脑、电视上，屏幕很大，可以把列表界面和详情界面左右排布一起显示
Providing Descendant and Lateral Navigation
- Descendant，父界面前往子界面
- Lateral，兄弟界面之间的跳转
- list和section
Providing Ancestral and Temporal Navigation
- Temporal（时间性），按下返回键，应该回到上一界面
- Ancestral（父子性），ActionBar/ToolBar上的返回按钮，返回父界面（通常是上一界面，但并不全是，容纳WebView的Activity就是很好的例子），需要注意的是，一定要清除backstack
...

Creating Swipe Views with Tabs
- ViewPager，PagerTitleStrip，FragmentPagerAdapter，FragmentStatePagerAdapter
Creating a Navigation Drawer
- drawer layout里面可以显式一个菜单列表
- ActionBarDrawerToggle（appcompat-v7中）可以监听drawer的开启与关闭事件，也可以用代码控制drawer的开启与关闭
- 完整样例

Providing Up Navigation

首先在manifest里面为activity声明其parent activity，用于up navigation
然后在onOptionsItemSelected回调中处理up navigation：

 @Override
 public boolean onOptionsItemSelected(MenuItem item) {
     switch (item.getItemId()) {
     // Respond to the action bar's Up/Home button
     case android.R.id.home:
         Intent upIntent = NavUtils.getParentActivityIntent(this);
         if (NavUtils.shouldUpRecreateTask(this, upIntent)) {
             // This activity is NOT part of this app's task, so create a new task
             // when navigating up, with a synthesized back stack.
             TaskStackBuilder.create(this)
                     // Add all of this activity's parents to the back stack
                     .addNextIntentWithParentStack(upIntent)
                     // Navigate up to the closest parent
                     .startActivities();
         } else {
             // This activity is part of this app's task, so simply
             // navigate up to the logical parent activity.
             NavUtils.navigateUpTo(this, upIntent);
         }
         return true;
     }
     return super.onOptionsItemSelected(item);
 }

Providing Proper Back Navigation

安卓系统都有一个物理返回键，所以不应该在UI上额外添加一个返回键
安卓系统的back stack通常情况下都可以应对back navigation

但是以下情况需要特殊考虑

从通知栏消息、widget、navigation drawer直接进入一个深层次的activity

  // Intent for the activity to open when user selects the notification
  Intent detailsIntent = new Intent(this, DetailsActivity.class);

  // Use TaskStackBuilder to build the back stack and get the PendingIntent
  PendingIntent pendingIntent =
          TaskStackBuilder.create(this)
                          // add all of DetailsActivity's parents to the stack,
                          // followed by DetailsActivity itself
                          .addNextIntentWithParentStack(upIntent)
                          .getPendingIntent(0, PendingIntent.FLAG_UPDATE_CURRENT);

  NotificationCompat.Builder builder = new NotificationCompat.Builder(this);
  builder.setContentIntent(pendingIntent);

fragment之间的导航

  // Works with either the framework FragmentManager or the
  // support package FragmentManager (getSupportFragmentManager).
  getSupportFragmentManager().beginTransaction()
                          .add(detailFragment, "detail")
                          // Add this transaction to the back stack
                          .addToBackStack()
                          .commit();

需要注意的是，当fragment是在ViewPager中水平切换时，不应该把transaction 加入到 backstack中。

WebView

  @Override
  public void onBackPressed() {
      if (mWebView.canGoBack()) {
          mWebView.goBack();
          return;
      }

      // Otherwise defer to system default behavior.
      super.onBackPressed();
  }

Implementing Descendant Navigation
- 通常都是Intent加上startActivity(intent)，或者FragmentTransaction来完成向子界面的导航
- 需要注意的是，如果app将打开其他app的界面，为了防止用户中途离开，再次从launcher打开app时，却是其他app的界面，可以为intent设置FLAG_ACTIVITY_CLEAR_WHEN_TASK_RESET flag
```
 Intent externalActivityIntent = new Intent(Intent.ACTION_PICK);
 externalActivityIntent.setType("image/*");
 externalActivityIntent.addFlags(
         Intent.FLAG_ACTIVITY_CLEAR_WHEN_TASK_RESET);
 startActivity(externalActivityIntent);
```

Notifying the User

Building a Notification
- 使用NotificationCompat.Builder创建通知栏消息
- 响应用户对通知栏消息的点击，启动相应Activity，同时要考虑是否提供返回的导航设计
Preserving Navigation when Starting an Activity
- 点击通知栏消息，可能会启动两种类型的Activity：正常使用流程会启动的Activity；仅仅是把通知栏消息展开的Activity；
- 前者通常需要提供back导航支持，在manifest中声明Activity父子关系，同时构造PendingIntent时构造back stack，使用stackBuilder.getPendingIntent创建PendingIntent
- 后者通常不需要加入到back stack中，无需手动构造back stack，使用PendingIntent.getActivity创建PendingIntent，同时在manifest中设置以下选项：
```
<activity
   android:name=".ResultActivity"
...
   android:launchMode="singleTask"
   android:taskAffinity=""
   android:excludeFromRecents="true">
</activity>
```

完整示例：

Intent resultIntent = new Intent(this, ResultActivity.class);
TaskStackBuilder stackBuilder = TaskStackBuilder.create(this);
// Adds the back stack
stackBuilder.addParentStack(ResultActivity.class);
// Adds the Intent to the top of the stack
stackBuilder.addNextIntent(resultIntent);
// Gets a PendingIntent containing the entire back stack
PendingIntent resultPendingIntent =
      stackBuilder.getPendingIntent(0, PendingIntent.FLAG_UPDATE_CURRENT);

NotificationCompat.Builder mBuilder = new NotificationCompat.Builder(this)
  .setSmallIcon(R.drawable.notification_icon)
  .setContentTitle("My notification")
  .setContentText("Hello World!")
  .setContentIntent(resultPendingIntent);

// Sets an ID for the notification
int mNotificationId = 001;
// Gets an instance of the NotificationManager service
NotificationManager mNotifyMgr = 
      (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
// Builds the notification and issues it.
mNotifyMgr.notify(mNotificationId, mBuilder.build());

Updating Notifications
- 创建通知栏消息时，如果指定了id，以后可以通过id对已经显示的消息进行修改/更新、移除操作；
- 修改/更新只需以相同的id，新的Notification对象，调用mNotifyMgr.notify即可；
- 如果消息支持被移除，则用户可以手动移除（单个或者所有），setAutoCancel()会让消息在用户点击时自动消失；cancel(id)和cancelAll()可以代码移除通知栏消息；

Using Big View Styles

Android 4.1之后，通知栏消息引入了action的支持，方便用户快捷操作

// Sets up the Snooze and Dismiss action buttons that will appear in the
// big view of the notification.
Intent dismissIntent = new Intent(this, PingService.class);
dismissIntent.setAction(CommonConstants.ACTION_DISMISS);
PendingIntent piDismiss = PendingIntent.getService(this, 0, dismissIntent, 0);

Intent snoozeIntent = new Intent(this, PingService.class);
snoozeIntent.setAction(CommonConstants.ACTION_SNOOZE);
PendingIntent piSnooze = PendingIntent.getService(this, 0, snoozeIntent, 0);

// Constructs the Builder object.
NotificationCompat.Builder builder =
      new NotificationCompat.Builder(this)
      .setSmallIcon(R.drawable.ic_stat_notification)
      .setContentTitle(getString(R.string.notification))
      .setContentText(getString(R.string.ping))
      .setDefaults(Notification.DEFAULT_ALL) // requires VIBRATE permission
      /*
      * Sets the big view "big text" style and supplies the
      * text (the user's reminder message) that will be displayed
      * in the detail area of the expanded notification.
      * These calls are ignored by the support library for
      * pre-4.1 devices.
      */
      .setStyle(new NotificationCompat.BigTextStyle()
              .bigText(msg))
      .addAction (R.drawable.ic_stat_dismiss,
              getString(R.string.dismiss), piDismiss)
      .addAction (R.drawable.ic_stat_snooze,
              getString(R.string.snooze), piSnooze);

Displaying Progress in a Notification
- setProgress (int max, int progress, boolean indeterminate)可以为通知栏消息设置进度条，支持实时进度、持续模式

Supporting Swipe-to-Refresh
- 官方有SwipeRefreshLayout
- 民间有Ultra Pull To Refresh
- 滑到底部触发加载更多可以使用Mugen

Adding Search Functionality

在App Bar中添加SearchView，注意它有support版本

res/menu/options_menu.xml：

  <?xml version="1.0" encoding="utf-8"?>
  <menu xmlns:android="http://schemas.android.com/apk/res/android">
      <item android:id="@+id/search"
          android:title="@string/search_title"
          android:icon="@drawable/ic_search"
          android:showAsAction="collapseActionView|ifRoom"
          android:actionViewClass="android.widget.SearchView" />
  </menu>

  @Override
  public boolean onCreateOptionsMenu(Menu menu) {
      MenuInflater inflater = getMenuInflater();
      inflater.inflate(R.menu.options_menu, menu);

      return true;
  }

创建可搜索的配置

res/xml/searchable.xml，配置SearchView的label，hint

  <?xml version="1.0" encoding="utf-8"?>
  <searchable xmlns:android="http://schemas.android.com/apk/res/android"
          android:label="@string/app_name"
          android:hint="@string/search_hint" />

manifest

  <activity ... >
      ...
      <meta-data android:name="android.app.searchable"
              android:resource="@xml/searchable" />

  </activity>

  @Override
  public boolean onCreateOptionsMenu(Menu menu) {
      MenuInflater inflater = getMenuInflater();
      inflater.inflate(R.menu.options_menu, menu);

      // Associate searchable configuration with the SearchView
      SearchManager searchManager =
          (SearchManager) getSystemService(Context.SEARCH_SERVICE);
      SearchView searchView =
              (SearchView) menu.findItem(R.id.search).getActionView();
      searchView.setSearchableInfo(
              searchManager.getSearchableInfo(getComponentName()));

      return true;
  }

当用户提交一个query时，SearchView会发出一个ACTION_SEARCH intent，需要在manifest文件中声明响应此intent

Making Your App Content Searchable by Google
- Google对如何优化对app内的内容、网站的搜索，提供了相应的建议
- Deep Links，通过在manifest中声明感兴趣的Intent，可以在用户在其他app内触发此intent时启动自己的app，intent可以设置action, category, scheme来进行过滤
优化app的assistant内容
app link，让自己的app成为自己网站uri的默认打开方式

Best Practices for Interaction and Engagement

Best Practices for Interaction and Engagement

Designing Effective Navigation

Implementing Effective Navigation

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