Android pie slice开发小记

Android pie slice开发小记

slice创建和运行

1. 首先新建一个项目并选择使用的api为API 28:Android 9（pie）或者在已有的项目调整其编译、最低和目标版本为28（最低）。
2. 创建 slice provider：
   
   当生成slice provider后，编译器会报如下错误：

   Manifest merger failed : Attribute application@appComponentFactory value=(androidx.core.app.CoreComponentFactory) from [androidx.core:core:1.0.0] AndroidManifest.xml:22:18-86
   	is also present at [com.android.support:support-compat:28.0.0] AndroidManifest.xml:22:18-91 value=(android.support.v4.app.CoreComponentFactory).
   	Suggestion: add 'tools:replace="android:appComponentFactory"' to <application> element at AndroidManifest.xml:5:5-35:19 to override.

以上错误主要是android在api 28版本后，appconmpat、cardview和constraintlayout等都移到Androidx包名下，所以修正方式为：

      implementation fileTree(dir: 'libs', include: ['*.jar'])
//    implementation 'com.android.support:appcompat-v7:28.0.0'
//    implementation 'com.android.support.constraint:constraint-layout:1.1.3'
  implementation 'androidx.appcompat:appcompat:1.0.0'
  implementation 'androidx.constraintlayout:constraintlayout:1.1.3'

  implementation 'androidx.annotation:annotation:1.0.0'
  implementation 'androidx.slice:slice-builders:1.0.0'

  testImplementation 'junit:junit:4.12'
  androidTestImplementation 'androidx.test:runner:1.1.0-alpha3'
  androidTestImplementation 'androidx.test.espresso:espresso-core:3.1.0-alpha3'

参考地址：https://stackoverflow.com/questions/50782435/android-design-support-library-for-api-28-p-not-working

1. sliceProvider编码：

   public class PieSliceProvider extends SliceProvider {
       /**
        * Instantiate any required objects. Return true if the provider was successfully created,
        * false otherwise.
        */
       @Override
       public boolean onCreateSliceProvider() {
           return true;
       }
   
       /**
        * Converts URL to content URI (i.e. content://com.mugwort.demo...)
        */
       @Override
       @NonNull
       public Uri onMapIntentToUri(@Nullable Intent intent) {
           // Note: implementing this is only required if you plan on catching URL requests.
           // This is an example solution.
           Uri.Builder uriBuilder = new Uri.Builder().scheme(ContentResolver.SCHEME_CONTENT);
           if (intent == null) return uriBuilder.build();
           Uri data = intent.getData();
           if (data != null && data.getPath() != null) {
               String path = data.getPath().replace("/", "");
               uriBuilder = uriBuilder.path(path);
           }
           Context context = getContext();
           if (context != null) {
               uriBuilder = uriBuilder.authority(context.getPackageName());
           }
           return uriBuilder.build();
       }
   
       /**
        * Construct the Slice and bind data if available.
        */
       public Slice onBindSlice(Uri sliceUri) {
           Context context = getContext();
           SliceAction activityAction = createActivityAction();
           if (context == null || activityAction == null) {
               return null;
           }
           if ("/".equals(sliceUri.getPath())) {
               // Path recognized. Customize the Slice using the androidx.slice.builders API.
               // Note: ANRs and strict mode is enforced here so don't do any heavy operations.
               // Only bind data that is currently available in memory.
               return new ListBuilder(getContext(), sliceUri, ListBuilder.INFINITY)
                       .addRow(
                               new RowBuilder()
                                       .setTitle("URI found.hello i'am here")
                                       .setPrimaryAction(activityAction)
                       )
                       .build();
           } else {
               // Error: Path not found.
               return new ListBuilder(getContext(), sliceUri, ListBuilder.INFINITY)
                       .addRow(
                               new RowBuilder()
                                       .setTitle("URI not found.")
                                       .setPrimaryAction(activityAction)
                       )
                       .build();
           }
       }
   
       private SliceAction createActivityAction() {
           //return null;
           //Instead of returning null, you should create a SliceAction. Here is an example:
           return SliceAction.create(
               PendingIntent.getActivity(
                   getContext(), 0, new Intent(getContext(), MainActivity.class), 0
               ),
               IconCompat.createWithResource(getContext(), R.drawable.ic_launcher_foreground),
               ListBuilder.ICON_IMAGE,
               "Open App"
           );
       }
   
       /**
        * Slice has been pinned to external process. Subscribe to data source if necessary.
        */
       @Override
       public void onSlicePinned(Uri sliceUri) {
           // When data is received, call context.contentResolver.notifyChange(sliceUri, null) to
           // trigger PieSliceProvider#onBindSlice(Uri) again.
       }
   
       /**
        * Unsubscribe from data source if necessary.
        */
       @Override
       public void onSliceUnpinned(Uri sliceUri) {
           // Remove any observers if necessary to avoid memory leaks.
       }
   }

分析：

• 通过类我们发现SliceProvider继承于ContentProvider，其APP间数据的传递通过
  ContentProvider的方式，应用APP向搜索APP对外提供其对应Slice的Uri，封装成Slice对象通过Parcelable序列化的方式实现APP之间的数据传递。
• slice的绑定和展示：onBindSlice，

  public Slice onBindSlice(Uri sliceUri) {
      Context context = getContext();
      SliceAction activityAction = createActivityAction();
      if (context == null || activityAction == null) {
          return null;
      }
      //“/”是在manifest中定义的
      if ("/".equals(sliceUri.getPath())) {
          // Path recognized. Customize the Slice using the androidx.slice.builders API.
          // Note: ANRs and strict mode is enforced here so don't do any heavy operations.
          // Only bind data that is currently available in memory.
          return new ListBuilder(getContext(), sliceUri, ListBuilder.INFINITY)
                  .addRow(
                          new RowBuilder()
                                  .setTitle("URI found.hello i'am here")
                                  .setPrimaryAction(activityAction)
                  )
                  .build();
      } else {
          // Error: Path not found.
          return new ListBuilder(getContext(), sliceUri, ListBuilder.INFINITY)
                  .addRow(
                          new RowBuilder()
                                  .setTitle("URI not found.")
                                  .setPrimaryAction(activityAction)
                  )
                  .build();
      }
  }

Uri的scheme统一为content,如上述例子的Uri为:
content://x.x.x/

• SliceAction,这个类似notifications，可以使用PendingIntents 来处理用户的点击事件，比如点击Slice模块打开宿主APP：

  private SliceAction createActivityAction() {
      //return null;
      //Instead of returning null, you should create a SliceAction. Here is an example:
      return SliceAction.create(
          PendingIntent.getActivity(
              getContext(), 0, new Intent(getContext(), MainActivity.class), 0
          ),
          IconCompat.createWithResource(getContext(), R.drawable.ic_launcher_foreground),
          ListBuilder.ICON_IMAGE,
          "Open App"
      );
  }

• 通过安装
  SliceViewer，在搜索框输入uri即可添加slice并跳转:
  

Slice模板

• ListBuilder:Slices通过ListBuilder类来创建。在ListBuilder中，你可以添加不同类型的行模块在你的Slice中进行展示。

• SliceAction:对于每一个Slice来说，最基础的构造实现类是SliceAction，在SliceAction你可以添加PendingIntent来实现用户操作，比如Toggle选择操作：

  SliceAction toggleAction =SliceAction.createToggle(createToggleIntent(),"Toggle adaptive brightness",true);

SliceAction可以配置在搜索APP中显示的模块三种不同的显示方式：

  ICON_IMAGE:tiny size and tintable:

SMALL_IMAGE:small size and non-tintable:

  LARGE_IMAGE: largest size and non-tintable:

模块构造Builder

  对于每个Slice模块的创建构造，谷歌官方提供了HeaderBuilder、RowBuilder、GridBuilder、RangeBuilder模块四种构造器。其中，HeaderBuilder只支持一行头部的展示view；RowBuilder可以添加一行view进行展示，如此前没有添加header，则首行row默认为header；GridBuilder支持上述所说的三种模块展示方式；而RangeBuilder则支持进度条相关的view展示。

延时加载

  对于一些需要耗时加载数据的操作，比如网络请求图片等，可以采取与ListView加载图片类似的方法，先本地加载一个默认的占位数据，等耗时操作完成回调回来真实数据的时候调用getContentResolver().notifyChange(sliceUri) 方法，通知搜索APP调用Slice Uri，完成真实数据的显示。

结语

  Slice的功能模板非常的强大，通过不同的builder组合可以在搜索模块中搭配出丰富多彩的Slice，快速直达用户想要的功能。但是Slice只提供了三种模板，自带模板中对安卓原生控件的支持有所欠缺，比如ScollView等，可能需要用户自定义自己的模板才能实现更强大的功能。

参考：
[0].https://www.androidauthority.com/android-slices-872250/
[1].https://www.jianshu.com/p/a90563606e1f
[2].http://digi.aili.com/1642/2811309.html