android - 如何制作可扩展的卡片 View 列表？

Question

我进行了很多搜索以找到一个我认为很受欢迎的问题的直接和明确的解决方案，但不幸的是我找不到。

我们想要一个卡片 View 列表，以便每张卡片都绑定(bind)到特定数据，并且每张卡片内部都有一个列表，显示有关其父级的元数据或详细数据。

所以我们在卡片 View 中有一个嵌套列表。

通过简单的搜索，我们知道我们应该使用展开的 ListView ，父项是卡片 View ，我们必须为其子项设置另一个布局。

因此，当您单击卡片时，项目列表会出现在根目录下的卡片下方。但是我们想在卡片中显示子列表？

并且无法访问诸如子列表 ID 之类的内容或任何其他内容来引用过渡动画和布局更改。

所以明确的问题是如何在卡片 View 中添加 ListView ？

我通过使用表格布局和表格行来完成我的工作。并且不喜欢使用外部库来解决稳定性和版本问题。这就是我的意思。

描述我的问题的图片

Answer 1

如果您不想使用外部库，您可以像这样扩展您的 CardView:

可扩展 CardView 的布局文件

<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.CardView
xmlns:card_view="http://schemas.android.com/apk/res-auto"
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/cv"
android:layout_marginTop="5dp"
android:layout_marginLeft="5dp"
android:layout_marginRight="5dp"
card_view:cardCornerRadius="5dp">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="10dp"
        android:orientation="vertical">

        <RelativeLayout
            android:layout_width="match_parent"
            android:layout_height="48dp"
            >

            <TextView
                android:id="@+id/textView_name"
                android:layout_marginTop="10dp"
                android:layout_marginBottom="10dp"
                android:textSize="18sp"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:textStyle="bold" />

            <!--My dropdown Button -->
            <RelativeLayout
                android:id="@+id/button"
                android:layout_width="48dp"
                android:layout_height="48dp"
                android:layout_gravity="end"
                android:layout_alignParentRight="true"
                android:gravity="center"
                >

                <View
                    android:layout_width="12dp"
                    android:layout_height="12dp"
                    android:background="@drawable/triangle"
                    android:layout_alignParentRight="false"
                    android:layout_alignParentEnd="false" />
            </RelativeLayout>
        </RelativeLayout>
         <!--The layout below is my ExpandableLayout -->
        <LinearLayout
            android:id="@+id/expandableLayout"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="horizontal"
            >

            <android.support.v7.widget.AppCompatImageView
                android:id="@+id/imageView_Owner"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content" />

            <LinearLayout
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_margin="5dp"
                android:orientation="vertical">

                <TextView
                    android:id="@+id/textView_Owner"
                    android:textSize="16sp"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content" />
                <TextView
                    android:id="@+id/textView_OwnerUrl"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content" />


            </LinearLayout>

        </LinearLayout>

    </LinearLayout>

</android.support.v7.widget.CardView>

我的 ExpandableRecyclerAdapter 类

import android.animation.ObjectAnimator;
import android.content.Context;
import android.support.v7.widget.RecyclerView;
import android.util.SparseBooleanArray;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.animation.LinearInterpolator;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.RelativeLayout;
import android.widget.TextView;

import com.squareup.picasso.Picasso;
import java.util.List;


public class ExpandableRecyclerAdapter extends RecyclerView.Adapter<ExpandableRecyclerAdapter.ViewHolder> {

private List<Repo> repos;
private SparseBooleanArray expandState = new SparseBooleanArray();
private Context context;

public ExpandableRecyclerAdapter(List<Repo> repos) {
    this.repos = repos;
    //set initial expanded state to false
    for (int i = 0; i < repos.size(); i++) {
        expandState.append(i, false);
    }
}

@Override
public ExpandableRecyclerAdapter.ViewHolder onCreateViewHolder(ViewGroup viewGroup, int i) {
    this.context = viewGroup.getContext();
    View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.expandable_card_row, viewGroup, false);
    return new ViewHolder(view);
}

@Override
public void onBindViewHolder(final ExpandableRecyclerAdapter.ViewHolder viewHolder, final  int i) {

    viewHolder.setIsRecyclable(false);

    viewHolder.tvName.setText(repos.get(i).getName());

    viewHolder.tvOwnerLogin.setText("Owner: " +repos.get(i).getOwner().getLogin());
    viewHolder.tvOwnerUrl.setText(repos.get(i).getOwner().getUrl());

    Picasso.with(context)
            .load(repos.get(i).getOwner().getImageUrl())
            .resize(500, 500)
            .centerCrop()
            .into(viewHolder.ivOwner);

    //check if view is expanded
    final boolean isExpanded = expandState.get(i);
    viewHolder.expandableLayout.setVisibility(isExpanded?View.VISIBLE:View.GONE);

    viewHolder.buttonLayout.setRotation(expandState.get(i) ? 180f : 0f);
    viewHolder.buttonLayout.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(final View v) {
            onClickButton(viewHolder.expandableLayout, viewHolder.buttonLayout,  i);
        }
    });
}

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

public class ViewHolder extends RecyclerView.ViewHolder{

    private TextView tvName,tvOwnerLogin, tvOwnerUrl;
    private ImageView ivOwner;
    public RelativeLayout buttonLayout;
    public LinearLayout expandableLayout;

    public ViewHolder(View view) {
        super(view);

        tvName = (TextView)view.findViewById(R.id.textView_name);
        tvId = (TextView)view.findViewById(R.id.textView_id);
        tvUrl = (TextView)view.findViewById(R.id.textView_url);
        tvOwnerLogin = (TextView)view.findViewById(R.id.textView_Owner);
        tvOwnerUrl = (TextView)view.findViewById(R.id.textView_OwnerUrl);
        ivOwner = (ImageView) view.findViewById(R.id.imageView_Owner);

        buttonLayout = (RelativeLayout) view.findViewById(R.id.button);
        expandableLayout = (LinearLayout) view.findViewById(R.id.expandableLayout);
    }
}

private void onClickButton(final LinearLayout expandableLayout, final RelativeLayout buttonLayout, final  int i) {

    //Simply set View to Gone if not expanded
    //Not necessary but I put simple rotation on button layout
    if (expandableLayout.getVisibility() == View.VISIBLE){
        createRotateAnimator(buttonLayout, 180f, 0f).start();
        expandableLayout.setVisibility(View.GONE);
        expandState.put(i, false);
    }else{
        createRotateAnimator(buttonLayout, 0f, 180f).start();
        expandableLayout.setVisibility(View.VISIBLE);
        expandState.put(i, true);
    }
}

//Code to rotate button
private ObjectAnimator createRotateAnimator(final View target, final float from, final float to) {
    ObjectAnimator animator = ObjectAnimator.ofFloat(target, "rotation", from, to);
    animator.setDuration(300);
    animator.setInterpolator(new LinearInterpolator());
    return animator;
}
}

在您的 Activity/Fragment 中，像这样设置 RecyclerView

private RecyclerView recyclerView;
private List<Repo> data;

recyclerView = (RecyclerView)findViewById(R.id.card_recycler_view);
recyclerView.setHasFixedSize(true);
RecyclerView.LayoutManager layoutManager = new LinearLayoutManager(getApplicationContext());
recyclerView.setLayoutManager(layoutManager);
//fetch data and on ExpandableRecyclerAdapter
recyclerView.setAdapter(new ExpandableRecyclerAdapter(data));

因此，在没有外部库的情况下创建可扩展的 CardView 非常简单。代码几乎与使用带有 RecyclerView 的普通 CardView 完全相同，主要变化是在单击按钮时设置 View.GONE/View.VISIBLE。