Android 使用SwipeActionAdapter开源库实现简单列表的左右滑动操作

  我们做listview左右滑动操作时，一般中情况下，都是像QQ那样，左滑弹出操作菜单（删除、编辑），然后选择菜单操作； 这样的效果不可谓不好，算是非常经典。 另外，有少数的APP，尤其是任务管理类的APP，更加注重listview的操作交互，例如ToDoList及滴答清单，这两个APP对任务的操作是直接通过滑动列表进行操作的；效果图如下：

  gtihub上有一个开源项目，已经很好的实现了对该效果：https://github.com/wdullaer/SwipeActionAdapter ； 此处，就简单下介绍该开源项目。

1.  使用Android Studio新建项目导入该开源库：

  导入该库，可以在build.gradle中添加：

dependencies {
    compile 'com.wdullaer:swipeactionadapter:2.0.0'
}

  当然，我更建议直接把该项目的library直接导入到项目中，这样会更加方便对代码进行修改。

2.   首先，设置ListView显示：

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    // Create an Adapter for your content
    String[] content = new String[20];
    for (int i=0;i<20;i++) content[i] = "Row "+(i+1);
    ArrayAdapter<String> stringAdapter = new ArrayAdapter<String>(
            this,
            R.layout.row_bg,
            R.id.text,
            new ArrayList<String>(Arrays.asList(content))
    );

    // Wrap your content in a SwipeActionAdapter
    mAdapter = new SwipeActionAdapter(stringAdapter);

    // Pass a reference of your ListView to the SwipeActionAdapter
    mAdapter.setListView(getListView());

    // Set the SwipeActionAdapter as the Adapter for your ListView
    setListAdapter(mAdapter);
}

  上面的代码很简单，只是比正常使用ListView多了一步：SwipeActionAdapter mAdapter = new SwipeActionAdapter(stringAdapter); 就是在普通Adapter的基础上包裹上一层SwipeActionAdapter。

3. 为ListView的Item添加滑动时的背景色

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    // Create an Adapter for your content
    String[] content = new String[20];
    for (int i=0;i<20;i++) content[i] = "Row "+(i+1);
    ArrayAdapter<String> stringAdapter = new ArrayAdapter<String>(
            this,
            R.layout.row_bg,
            R.id.text,
            new ArrayList<String>(Arrays.asList(content))
    );

    // Wrap your content in a SwipeActionAdapter
    mAdapter = new SwipeActionAdapter(stringAdapter);

    // Pass a reference of your ListView to the SwipeActionAdapter
    mAdapter.setListView(getListView());

    // Set the SwipeActionAdapter as the Adapter for your ListView
    setListAdapter(mAdapter);

    // Set backgrounds for the swipe directions
    mAdapter.addBackground(SwipeDirection.DIRECTION_FAR_LEFT,R.layout.row_bg_left_far)
            .addBackground(SwipeDirection.DIRECTION_NORMAL_LEFT,R.layout.row_bg_left)
            .addBackground(SwipeDirection.DIRECTION_FAR_RIGHT,R.layout.row_bg_right_far)
            .addBackground(SwipeDirection.DIRECTION_NORMAL_RIGHT,R.layout.row_bg_right);
}

  上述代码最后，既是添加背景的代码，代码很明了，在为不同的滑动过程，添加不同的背景，该背景其实就是一个布局，例如row_bg_left_far.xml文件：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="?android:listPreferredItemHeight"
    android:background="@android:color/holo_blue_bright">
</LinearLayout>

  此处，可以查看下SwipeDirection.java类源码:

public enum SwipeDirection {
    // Constants
    DIRECTION_NORMAL_LEFT,
    DIRECTION_FAR_LEFT,
    DIRECTION_NORMAL_RIGHT,
    DIRECTION_FAR_RIGHT,
    DIRECTION_NEUTRAL;

    @NonNull
    public static List<SwipeDirection> getAllDirections(){
        return Arrays.asList(
                DIRECTION_FAR_LEFT,
                DIRECTION_FAR_RIGHT,
                DIRECTION_NEUTRAL,
                DIRECTION_NORMAL_LEFT,
                DIRECTION_NORMAL_RIGHT
        );
    }

    public boolean isLeft() {
        return this.equals(DIRECTION_NORMAL_LEFT) || this.equals(DIRECTION_FAR_LEFT);
    }

    public boolean isRight() {
        return this.equals(DIRECTION_NORMAL_RIGHT) || this.equals(DIRECTION_FAR_RIGHT);
    }
}

  我们可以看出，主要的操作有四个： DIRECTION_NORMAL_LEFT（左滑一小段距离）,DIRECTION_FAR_LEFT（左滑较长距离）, DIRECTION_NORMAL_RIGHT（右滑一小段距离）,DIRECTION_FAR_RIGHT（右滑较长距离）。 

4.  添加ListView左右滑动监听：

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    // Create an Adapter for your content
    String[] content = new String[20];
    for (int i=0;i<20;i++) content[i] = "Row "+(i+1);
    ArrayAdapter<String> stringAdapter = new ArrayAdapter<String>(
            this,
            R.layout.row_bg,
            R.id.text,
            new ArrayList<String>(Arrays.asList(content))
    );

    // Wrap your content in a SwipeActionAdapter
    mAdapter = new SwipeActionAdapter(stringAdapter);

    // Pass a reference of your ListView to the SwipeActionAdapter
    mAdapter.setListView(getListView());

    // Set the SwipeActionAdapter as the Adapter for your ListView
    setListAdapter(mAdapter);

    // Set backgrounds for the swipe directions
    mAdapter.addBackground(SwipeDirection.DIRECTION_FAR_LEFT,R.layout.row_bg_left_far)
            .addBackground(SwipeDirection.DIRECTION_NORMAL_LEFT,R.layout.row_bg_left)
            .addBackground(SwipeDirection.DIRECTION_FAR_RIGHT,R.layout.row_bg_right_far)
            .addBackground(SwipeDirection.DIRECTION_NORMAL_RIGHT,R.layout.row_bg_right);

    // Listen to swipes
    mAdapter.setSwipeActionListener(new SwipeActionListener(){
        @Override
        public boolean hasActions(int position, SwipeDirection direction){
            if(direction.isLeft()) return true; // Change this to false to disable left swipes
            if(direction.isRight()) return true;
            return false;
        }

        @Override
        public boolean shouldDismiss(int position, SwipeDirection direction){
            // Only dismiss an item when swiping normal left
            return direction == SwipeDirection.DIRECTION_NORMAL_LEFT;
        }

        @Override
        public void onSwipe(int[] positionList, SwipeDirection[] directionList){
            for(int i=0;i<positionList.length;i++) {
                int direction = directionList[i];
                int position = positionList[i];
                String dir = "";

                switch (direction) {
                    case SwipeDirection.DIRECTION_FAR_LEFT:
                        dir = "Far left";
                        break;
                    case SwipeDirection.DIRECTION_NORMAL_LEFT:
                        dir = "Left";
                        break;
                    case SwipeDirection.DIRECTION_FAR_RIGHT:
                        dir = "Far right";
                        break;
                    case SwipeDirection.DIRECTION_NORMAL_RIGHT:
                        AlertDialog.Builder builder = new AlertDialog.Builder(this);
                        builder.setTitle("Test Dialog").setMessage("You swiped right").create().show();
                        dir = "Right";
                        break;
                }
                Toast.makeText(
                        this,
                        dir + " swipe Action triggered on " + mAdapter.getItem(position),
                        Toast.LENGTH_SHORT
                ).show();
                mAdapter.notifyDataSetChanged();
            }
        }
    });
}

·  public boolean hasActions(int position, SwipeDirection direction) ： 该方法主要判断滑动方向：左滑还是右滑。

·  public boolean shouldDismiss(int position, SwipeDirection direction)：该方法主要判断list item滑动后是否有消失的动画。

·  public void onSwipe(int[] positionList, SwipeDirection[] directionList)： 主要在该方法中处理滑动逻辑。

  以上，就是SwipeActionAdapter的基本使用方式，相信善用该库，一定会给APP增添几分色彩，提高用户体验！