MVP+购物车+自定义View

一、展示一下基本的包、类，购物车的实现在AFragment

二、布局的XML:

三、直接从购物车的实现开始

总的效果图：

**/1.布局：/**组控件与子控件的实现使用的是二级列表

--------布局：ExpandableListView
①主布局

<?xml version="1.0" encoding="utf-8"?>

RelativeLayout
xmlns:android=“http://schemas.android.com/apk/res/android”
android:layout_width=“match_parent”
android:layout_height=“match_parent”
android:orientation=“vertical”>

<LinearLayout
    android:layout_alignParentBottom="true"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal"
    android:background="#f5d5ab"
    android:id="@+id/line1">

    <CheckBox
        android:layout_width="0dp"
        android:layout_weight="1"
        android:layout_height="60dp"
        android:textSize="20dp"
        android:text="全选"
        android:id="@+id/selAll"/>
    <TextView
        android:layout_width="0dp"
        android:layout_weight="1"
        android:layout_height="wrap_content"
        android:textSize="20dp"
        android:text="总价："
        android:id="@+id/Allprice"/>
    <TextView
        android:layout_width="0dp"
        android:layout_weight="1"
        android:layout_height="wrap_content"
        android:textSize="20dp"
        android:text="去结算"
        android:id="@+id/jiesuan"/>

</LinearLayout>
<ExpandableListView
    android:layout_above="@+id/line1"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/ExpListView"
    ></ExpandableListView>

/RelativeLayout>
②组控件的布局就一个CheckBox和一个TextView

③子控件的布局（注：把加减的布局引过来）

引加减布局

④加减的布局：三个TextView实现

/2.具体的代码执行：/

①构建出MVP基本的框架

②用OkHttp封装工具类

ModelImpe类里代码执行:

public class ModelImppe implements Model {

private MyCallBack callBack;
private Handler handler=new Handler(){
    @Override
    public void handleMessage(Message msg) {
        if (msg.what==0){
            String str=(String) msg.obj;
            Gson gson=new Gson();
            MyData myData = gson.fromJson(str, MyData.class);
            callBack.setData(myData.getData());
        }
    }
};

@Override
public void getData(String url, MyCallBack callBack) {
    this.callBack=callBack;
    
    OkUtils.getInstance().getAsync(url, new Callback() {
        @Override
        public void onFailure(Call call, IOException e) {

        }

        @Override
        public void onResponse(Call call, Response response) throws IOException {
            String s = response.body().string();
            handler.sendMessage(handler.obtainMessage(0,s));
        }
    });

}

}
/3.适配器：/
创建一个适配器的类继承BaseExpandableListAdapter

（二级列表适配器的个人解析：
）
写①②时，看封装的基本类里有没有判断状态

public class ErAdapter extends BaseExpandableListAdapter {

private List<MyData.DataBean> mlist;
private Context context;

public ErAdapter(List<MyData.DataBean> mlist, Context context) {
    this.mlist = mlist;
    this.context = context;
}

@Override
public int getGroupCount() {
    return mlist.size();
}

@Override
public int getChildrenCount(int groupPosition) {
    return mlist.get(groupPosition).getSpus().size();
}

@Override
public Object getGroup(int groupPosition) {
    return null;
}

@Override
public Object getChild(int groupPosition, int childPosition) {
    return null;
}

@Override
public long getGroupId(int groupPosition) {
    return 0;
}

@Override
public long getChildId(int groupPosition, int childPosition) {
    return 0;
}

@Override
public boolean hasStableIds() {
    return false;
}

@Override
public View getGroupView(final int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) {
    GroupHolder groupHolder;
    if (convertView==null){
        convertView=View.inflate(context,R.layout.group_list,null);
        groupHolder=new GroupHolder();
        groupHolder.GroupCb=convertView.findViewById(R.id.groupCB);
        groupHolder.GroupTv=convertView.findViewById(R.id.groupTV);
        convertView.setTag(groupHolder);
    }else {
        groupHolder=(GroupHolder)convertView.getTag();
    }

    groupHolder.GroupTv.setText(mlist.get(groupPosition).getName());

    boolean childAllChecked = isChildAllChecked(groupPosition);
    groupHolder.GroupCb.setChecked(childAllChecked);
    groupHolder.GroupCb.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            if (adapterCallBack!=null){
                adapterCallBack.setGroupCheck(groupPosition);
            }
        }
    });
    return convertView;
}

@Override
public View getChildView(final int groupPosition, final int childPosition, boolean isLastChild, View convertView, ViewGroup parent) {
    ChildHolder childHolder;
    if (convertView==null){
        convertView=View.inflate(context,R.layout.child_list,null);
        childHolder=new ChildHolder();
        childHolder.ChildCb=convertView.findViewById(R.id.childCB);
        childHolder.ChildImg=convertView.findViewById(R.id.childImg);
        childHolder.ChildTv=convertView.findViewById(R.id.childTitle);
        childHolder.ChildSal=convertView.findViewById(R.id.childSale);
        childHolder.ChildPri=convertView.findViewById(R.id.childPrice);
        childHolder.jiajianView=convertView.findViewById(R.id.jiajianV);
        convertView.setTag(childHolder);
    }else {
        childHolder=(ChildHolder)convertView.getTag();
    }
    childHolder.ChildCb.setChecked(mlist.get(groupPosition).getSpus().get(childPosition).isChildChecked());
    
    MyData.DataBean.SpusBean sBean = mlist.get(groupPosition).getSpus().get(childPosition);

    Glide.with(context).load(sBean.getPic_url()).into(childHolder.ChildImg);
    childHolder.ChildTv.setText(sBean.getName()+"");
    childHolder.ChildSal.setText(sBean.getMonth_saled()+"");
    childHolder.ChildPri.setText(sBean.getSkus().get(0).getPrice()+"");
    childHolder.jiajianView.setNum(sBean.getPraise_num());
    childHolder.ChildCb.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            if (adapterCallBack!=null){
                adapterCallBack.setChildCheck(groupPosition,childPosition);
            }
        }
    });

    childHolder.jiajianView.setOnChange(new JiajianView.OnCountChange() {
        @Override
        public void setCount(int count) {
            if (adapterCallBack!=null){
                adapterCallBack.setNumber(groupPosition,childPosition,count);
            }
        }
    });

    return convertView;
}

@Override
public boolean isChildSelectable(int groupPosition, int childPosition) {
    return false;
}

class GroupHolder{
    CheckBox GroupCb;
    TextView GroupTv;
}
class ChildHolder{
    JiajianView jiajianView;
    CheckBox ChildCb;
    ImageView ChildImg;
    TextView ChildTv;
    TextView ChildSal;
    TextView ChildPri;
}
//1.点击group的checkBox让所有child的复选框选中
public void childAllCheck(int groupPosition, boolean isCheck){
    MyData.DataBean bean = mlist.get(groupPosition);
    List<MyData.DataBean.SpusBean> spus = bean.getSpus();
    for (int i = 0; i < spus.size(); i++) {
        MyData.DataBean.SpusBean spusBean = spus.get(i);
        spusBean.setChildChecked(isCheck);
    }
}
//1.判断小组是否被选中
public boolean isChildAllChecked(int groupPositon){
    MyData.DataBean bean = mlist.get(groupPositon);
    List<MyData.DataBean.SpusBean> spus = bean.getSpus();
    for (int i = 0; i < spus.size(); i++) {
        MyData.DataBean.SpusBean spusBean = spus.get(i);
        //只要有一个没有被点中 点这个checkbox就是全选的功能
        if (!spusBean.isChildChecked()){
            return false;
        }
    }
    return true;
}
//2.点击child给他进行赋值
public void setChildChecked(int groupPositon, int childPositon, boolean isCheckBox){
    MyData.DataBean.SpusBean spusBean = mlist.get(groupPositon).getSpus().get(childPositon);
    spusBean.setChildChecked(isCheckBox);
}
//2.查看当前这个商品有没有被选中
public boolean isChildChecked(int groupPosition,int childPosition){
    MyData.DataBean.SpusBean spusBean = mlist.get(groupPosition).getSpus().get(childPosition);
    if (spusBean.isChildChecked()){
        return true;
    }
    return false;
}

//给商品数量进行赋值

public void setShangPingNumber(int groupPosition, int childPosition, int number) {
    MyData.DataBean.SpusBean spusBean = mlist.get(groupPosition).getSpus().get(childPosition);
    spusBean.setPraise_num(number);
}

//3.①全选反选
public boolean isAllGoods(){
    for (int i = 0; i <mlist.size() ; i++) {
        MyData.DataBean bean = mlist.get(i);
        for (int j = 0; j <bean.getSpus().size() ; j++) {
            MyData.DataBean.SpusBean spusBean = bean.getSpus().get(j);
            if (!spusBean.isChildChecked()){
                return false;
            }
        }
    }
    return true;
}
//3.①全选反选功能
public void SelectAll(boolean isAllChecked){
    for (int i = 0; i < mlist.size(); i++) {
        MyData.DataBean bean = mlist.get(i);
        for (int j = 0; j <bean.getSpus().size() ; j++) {
            MyData.DataBean.SpusBean spusBean = bean.getSpus().get(j);
            spusBean.setChildChecked(isAllChecked);
        }
    }
}
//3.②计算所有商品的价格
public float getAllPrice(){
    float allPrice=0;
    for (int i = 0; i <mlist.size() ; i++) {
        MyData.DataBean bean = mlist.get(i);
        for (int j = 0; j < bean.getSpus().size(); j++) {
            MyData.DataBean.SpusBean spusBean = bean.getSpus().get(j);
            if (spusBean.isChildChecked()){
                allPrice=allPrice+spusBean.getPraise_num()*Float.parseFloat(spusBean.getSkus().get(0).getPrice());
            }
        }
    }
    return allPrice;
}
//3.②计算所有商品的数量
public int getAllNum(){
    int allNum=0;
    for (int i = 0; i <mlist.size() ; i++) {
        MyData.DataBean bean = mlist.get(i);
        for (int j = 0; j <bean.getSpus().size() ; j++) {
            MyData.DataBean.SpusBean spusBean = bean.getSpus().get(j);
            if (spusBean.isChildChecked()){
                allNum=allNum+spusBean.getPraise_num();
            }
        }
    }
    return allNum;
}


//写一个接口
//点击Group和Child第CheckBox在主页面都需要刷新值所以做成接口回调
public interface AdapterCallBack{
    void setGroupCheck(int groupPosition);
    void setChildCheck(int groupPosition,int childPosition);
    //点击加减按钮刷新
    void setNumber(int groupPosition, int childPosition, int number);

}
//定义一个成员变量
private AdapterCallBack adapterCallBack;
//提供一个方法
public void setCallback(AdapterCallBack adapterCallBack){
    this.adapterCallBack=adapterCallBack;
}

}
注解：

1.适配器和Fragment里标 1 的展现的是点击组的CheckBox与否实现子控件的CheckBox的全选与全不选

2.适配器和Fragment里标 2 的展现的子的CheckBox是与组的CheckBox的联动
-----①当子的所有CheckBox选中时组的CheckBox也自动选中
-----②当子的所有CheckBox有一个没有选中时组的CheckBox也自动取消

3.适配器和Fragment里标 3 的展现的底部所有功能

/3.AFragment：/
public class AFragment extends Fragment implements IView,View.OnClickListener {

private String mUrl = "http://www.wanandroid.com/tools/mockapi/6523/restaurant-list";
private ExpandableListView expListView;
private List<MyData.DataBean> mlist = new ArrayList<>();
private ErAdapter erAdapter;
private CheckBox selAll;
private TextView Allprice;
private TextView jiesuan;


@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.fragment_a, null);
    initView(view);
    initPageLogic();
    erAdapter = new ErAdapter(mlist, getContext());
    expListView.setAdapter(erAdapter);

    erAdapter.setCallback(new ErAdapter.AdapterCallBack() {
        @Override
        public void setGroupCheck(int groupPosition) {
            //1.是否被全选中
            boolean childAllChecked = erAdapter.isChildAllChecked(groupPosition);
            erAdapter.childAllCheck(groupPosition, !childAllChecked);
            erAdapter.notifyDataSetChanged();
            fleshBtnLayout();
        }

        @Override
        public void setChildCheck(int groupPosition, int childPosition) {
            //2.得到要点击的商品child是否时选中状态
            boolean childChecked = erAdapter.isChildChecked(groupPosition, childPosition);
            erAdapter.setChildChecked(groupPosition, childPosition, !childChecked);
            erAdapter.notifyDataSetChanged();
            fleshBtnLayout();
        }

        @Override
        public void setNumber(int groupPosition, int childPosition, int number) {
            erAdapter.setShangPingNumber(groupPosition, childPosition, number);
            erAdapter.notifyDataSetChanged();
            fleshBtnLayout();
        }
    });

    return view;
}

private void initPageLogic() {
    PresenterImpe presenterImpe = new PresenterImpe(this);
    presenterImpe.getData(mUrl);
}
//查找控件
private void initView(View view) {
    expListView = view.findViewById(R.id.ExpListView);
    //去掉自带的小箭头
    expListView.setGroupIndicator(null);
    selAll = (CheckBox) view.findViewById(R.id.selAll);
    selAll.setOnClickListener(this);
    Allprice = (TextView) view.findViewById(R.id.Allprice);
    jiesuan = (TextView) view.findViewById(R.id.jiesuan);
}

@Override
public void success(Object data) {
    mlist.addAll((Collection<? extends MyData.DataBean>) data);
    erAdapter.notifyDataSetChanged();
    //首次加载全部展开
    for (int i = 0; i <mlist.size() ; i++) {
        expListView.expandGroup(i);
    }
    //不能点击伸缩
    expListView.setOnGroupClickListener(new ExpandableListView.OnGroupClickListener() {
        @Override
        public boolean onGroupClick(ExpandableListView parent, View v, int groupPosition, long id) {
            return true;
        }
    });


}

@Override
public void error(String error) {

}
//来回切换时数据不重新添加一遍
@Override
public void onStop() {
    super.onStop();
    mlist.clear();
}

//3.刷新底部数据
public void fleshBtnLayout() {
    boolean allGoods = erAdapter.isAllGoods();
    selAll.setChecked(allGoods);
    //总价
    float allPrice = erAdapter.getAllPrice();
    Allprice.setText("价格："+allPrice);
    //数量
    int allNum = erAdapter.getAllNum();
    jiesuan.setText("去结算："+allNum);
}

//3.全选按钮的监听
@Override
public void onClick(View v) {
    switch (v.getId()){
        case R.id.selAll:
            boolean allGoods = erAdapter.isAllGoods();
            erAdapter.SelectAll(!allGoods);
            erAdapter.notifyDataSetChanged();
            fleshBtnLayout();
            break;
    }

}

}