Material Design UI Widgets

jopen 9年前

Android L 开发者预览支持库提供两个新的Widgets,RecyclerView和CardView。使用这两个Widgets可以显示复杂的Listview和卡片布局,这两个Widgets默认使用Material design。


RecyclerView

    RecyclerView是一个更高级柔性版本的Listview,RecyclerView是一个能包含很多视图的容器,它能完美的处理循环和滚动。在item动态变化的Listview使用RecyclerView。


RecyclerView使用很简单,因为它提供了:

1、定位item的布局管理器

2、常见的item操作默认动画


你能够灵活的为RecyclerView自定义布局管理器和动画。

使用RecyclerView,必须使用指定一个adapter、定义一个布局管理器。创建adapter必须继承自RecyclerView.Adapter。实施的细节需要看数据类型和需要的视图。


   RecyclerView widget



    RecyclerView 提供了 LayoutManager,RecylerView 不负责子 View 的布局,我们可以自定义 LayoutManager 来实现不同的布局效果,目前只提供了LinearLayoutManager。 LinearLayoutManager 可以指定方向,默认是垂直, 可以指定水平, 这样就轻松实现了水平的 ListView。


RecyclerView Demo:

1、布局文件

    <!-- A RecyclerView with some commonly used attributes -->        <android.support.v7.widget.RecyclerView            android:id="@+id/my_recycler_view"            android:scrollbars="vertical"            android:layout_width="match_parent"            android:layout_height="match_parent"/>  

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2、Activity文件

    public class MyActivity extends Activity {            private RecyclerView mRecyclerView;            private RecyclerView.Adapter mAdapter;            private RecyclerView.LayoutManager mLayoutManager;                    @Override            protected void onCreate(Bundle savedInstanceState) {                super.onCreate(savedInstanceState);                setContentView(R.layout.my_activity);                mRecyclerView = (RecyclerView) findViewById(R.id.my_recycler_view);                        // improve performance if you know that changes in content                // do not change the size of the RecyclerView                mRecyclerView.setHasFixedSize(true);                        // use a linear layout manager                mLayoutManager = new LinearLayoutManager(this);                mRecyclerView.setLayoutManager(mLayoutManager);                        // specify an adapter (see also next example)                mAdapter = new MyAdapter(myDataset);                mRecyclerView.setAdapter(mAdapter);            }            ...        }        To create a simple adapter:                public class MyAdapter extends RecyclerView.Adapter<MyAdapter.ViewHolder> {            private String[] mDataset;                    // Provide a reference to the type of views that you are using            // (custom viewholder)            public static class ViewHolder extends RecyclerView.ViewHolder {                public TextView mTextView;                public ViewHolder(TextView v) {                    super(v);                    mTextView = v;                }            }                    // Provide a suitable constructor (depends on the kind of dataset)            public MyAdapter(String[] myDataset) {                mDataset = myDataset;            }                    // Create new views (invoked by the layout manager)            @Override            public MyAdapter.ViewHolder onCreateViewHolder(ViewGroup parent,                                                           int viewType) {                // create a new view                View v = LayoutInflater.from(parent.getContext())                                       .inflate(R.layout.my_text_view, null);                // set the view's size, margins, paddings and layout parameters                ...                ViewHolder vh = new ViewHolder(v);                return vh;            }                    // Replace the contents of a view (invoked by the layout manager)            @Override            public void onBindViewHolder(ViewHolder holder, int position) {                // - get element from your dataset at this position                // - replace the contents of the view with that element                holder.mTextView.setText(mDataset[position]);                    }                    // Return the size of your dataset (invoked by the layout manager)            @Override            public int getItemCount() {                return mDataset.length;            }        }  


3、Recycler adapter

    public class MyAdapter extends RecyclerView.Adapter<MyAdapter.ViewHolder> {            private String[] mDataset;                    // Provide a reference to the type of views that you are using            // (custom viewholder)            public static class ViewHolder extends RecyclerView.ViewHolder {                public TextView mTextView;                public ViewHolder(TextView v) {                    super(v);                    mTextView = v;                }            }                    // Provide a suitable constructor (depends on the kind of dataset)            public MyAdapter(String[] myDataset) {                mDataset = myDataset;            }                    // Create new views (invoked by the layout manager)            @Override            public MyAdapter.ViewHolder onCreateViewHolder(ViewGroup parent,                                                           int viewType) {                // create a new view                View v = LayoutInflater.from(parent.getContext())                                       .inflate(R.layout.my_text_view, null);                // set the view's size, margins, paddings and layout parameters                ...                ViewHolder vh = new ViewHolder(v);                return vh;            }                    // Replace the contents of a view (invoked by the layout manager)            @Override            public void onBindViewHolder(ViewHolder holder, int position) {                // - get element from your dataset at this position                // - replace the contents of the view with that element                holder.mTextView.setText(mDataset[position]);                    }                    // Return the size of your dataset (invoked by the layout manager)            @Override            public int getItemCount() {                return mDataset.length;            }        }  


RecyclerView 的标准化了 ViewHolder, 编写 Adapter 面向的是 ViewHoder 而不在是View 了, 复用的逻辑被封装了, 写起来更加简单。

CardView


CardView继承自FrameLayout类,可以在一个卡片布局中一致性的显示内容,卡片可以包含圆角和阴影。


可以使用android:elevation属性,创建一个阴影的卡片。


怎样指定CardView的属性:

1、使用android:cardCornerRadius属性指定圆角半径

2、使用CardView.setRadius 设置圆角半径。

3、使用 android:cardBackgroundColor属性设置卡片颜色


在创建布局文件中创建CardView:

    <!-- A CardView that contains a TextView -->        <android.support.v7.widget.CardView            xmlns:card_view="http://schemas.android.com/apk/res-auto"            android:id="@+id/card_view"            android:layout_gravity="center"            android:layout_width="200dp"            android:layout_height="200dp"            card_view:cardCornerRadius="4dp">                    <TextView                android:id="@+id/info_text"                android:layout_width="match_parent"                android:layout_height="match_parent" />        </android.support.v7.widget.CardView>