Android 水平布局的回收视图
创始人
2024-08-15 18:00:07
0

在Android中实现水平布局的回收视图,可以通过使用RecyclerView和自定义LayoutManager来实现。下面是一个示例代码,演示如何实现水平布局的回收视图。

  1. 创建一个布局文件activity_main.xml,其中包含一个RecyclerView:

  1. 创建一个item的布局文件item_layout.xml,用于定义每个item的视图:

  1. 创建一个自定义的LayoutManager类,继承自LinearLayoutManager,并覆盖onLayoutChildren()方法:
public class CustomLayoutManager extends LinearLayoutManager {

    public CustomLayoutManager(Context context) {
        super(context);
    }

    public CustomLayoutManager(Context context, int orientation, boolean reverseLayout) {
        super(context, orientation, reverseLayout);
    }

    @Override
    public void onLayoutChildren(RecyclerView.Recycler recycler, RecyclerView.State state) {
        super.onLayoutChildren(recycler, state);
        scrollHorizontallyBy(0, recycler, state);
    }

    private int scrollHorizontallyBy(int dx, RecyclerView.Recycler recycler, RecyclerView.State state) {
        int scrolled = super.scrollHorizontallyBy(dx, recycler, state);
        fill(recycler);
        return scrolled;
    }

    private void fill(RecyclerView.Recycler recycler) {
        int leftEdge = getWidth() - getPaddingRight();
        int rightEdge = getWidth() - getPaddingRight() + getMaxChildWidth();
        int topEdge = getPaddingTop();
        int bottomEdge = getHeight() - getPaddingBottom();

        int itemCount = getItemCount();
        int childCount = getChildCount();
        int lastPosition = childCount > 0 ? getPosition(getChildAt(childCount - 1)) : -1;

        while (rightEdge > leftEdge && lastPosition < itemCount - 1) {
            lastPosition++;
            View view = recycler.getViewForPosition(lastPosition);
            addView(view);
            measureChildWithMargins(view, 0, 0);

            int width = getDecoratedMeasuredWidth(view);
            int height = getDecoratedMeasuredHeight(view);

            layoutDecoratedWithMargins(view, rightEdge - width, topEdge, rightEdge, topEdge + height);

            rightEdge -= width;
        }

        while (getChildCount() > 0 && getDecoratedRight(getChildAt(0)) < getPaddingLeft()) {
            removeAndRecycleView(getChildAt(0), recycler);
        }
    }

    private int getMaxChildWidth() {
        int maxChildWidth = 0;
        for (int i = 0; i < getChildCount(); i++) {
            View child = getChildAt(i);
            int width = getDecoratedMeasuredWidth(child);
            if (width > maxChildWidth) {
                maxChildWidth = width;
            }
        }
        return maxChildWidth;
    }
}
  1. 在MainActivity中设置RecyclerView的LayoutManager为自定义的CustomLayoutManager,并创建一个适配器Adapter:
public class MainActivity extends AppCompatActivity {

    private RecyclerView recyclerView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        recyclerView = findViewById(R.id.recyclerView);
        recyclerView.setLayoutManager(new CustomLayoutManager(this, LinearLayoutManager.HORIZONTAL, false));

        List dataList = new ArrayList<>();
        for (int i = 0; i < 10; i++) {
            dataList.add("Item " + (i + 1));
        }

        Adapter adapter = new Adapter(dataList);
        recyclerView.setAdapter(adapter);
    }
}
  1. 创建一个适配器Adapter,用于将数据绑定到item上:
public class Adapter extends RecyclerView.Adapter {

    private List dataList;

    public Adapter(List dataList) {
        this.dataList = dataList;
    }

    @NonNull
    @Override
    public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_layout, parent, false);
        return new ViewHolder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
        String data = dataList.get(position);
        holder.textView.setText(data);
    }

    @Override
    public int getItemCount() {
        return dataList.size();
    }

    public static class ViewHolder extends RecyclerView.ViewHolder {
        TextView textView;

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