App实战节选-购物车

概述：开发的项目中有一个模块是购物车的，我就索性单独将它单独整理出来，供需要的小伙伴们交流使用，同时也提升一下自己。需要的可以到我github上下载，

链接是https://github.com/Oaman/shoppingcart

先看一张效果图

废话不多说，直接上代码。

1 首先需要一个显示的界面MainActivity;xml文件如下,其中ShoppingCartBottomView是简单自定义的一个底部控件，下面会讲到

<?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:background="#ffffff"              android:orientation="vertical">    <com.oman.shoppingcart.customview.ShoppingCartBottomView        android:id="@+id/shoppingcart_bottom"        android:layout_width="match_parent"        android:layout_height="60dp"        android:layout_alignParentBottom="true"/>    <ListView        android:id="@+id/listview"        android:layout_width="match_parent"        android:layout_height="match_parent"        android:layout_above="@id/shoppingcart_bottom"        android:layout_marginTop="10dp"        android:dividerHeight="10dp"/></RelativeLayout>

然后MainActivity.ava的代码如下，不要着急有些类没有讲到，后面会详细讲解，淡定。。。

public class MainActivity extends BaseActivity {    protected ShoppingCartBottomView mBottomView;    protected ListView mListView;    protected ShoppingCartListAdapter mAdapter;    protected ArrayList<CartCommodityModel> mData = new ArrayList<>();    @Override    protected int getLayoutId() {        return R.layout.activity_main;    }    @Override    protected void initView() {        CartCommodityModel model = new CartCommodityModel();        model.setId(1);        model.setName("测试商品1");        model.setPrice("100");        model.setOriginalPrice("120");        model.setVipPrice("80");        model.setBuyNum("2");        mData.add(model);        CartCommodityModel model2 = new CartCommodityModel();        model2.setId(1);        model2.setName("测试商品2");        model2.setPrice("200");        model2.setOriginalPrice("220");        model2.setVipPrice("160");        model2.setBuyNum("3");        mData.add(model2);        CartCommodityModel model3 = new CartCommodityModel();        model3.setId(1);        model3.setName("测试商品3");        model3.setPrice("300");        model3.setOriginalPrice("340");        model3.setVipPrice("280");        model3.setBuyNum("4");        mData.add(model3);        mBottomView = (ShoppingCartBottomView) findViewById(R.id.shoppingcart_bottom);        mAdapter = new ShoppingCartListAdapter(this, mData, mBottomView);        mBottomView.setData(mData);        mBottomView.setBinderAdapter(mAdapter);        mListView= (ListView) findViewById(R.id.listview);        mListView.setAdapter(mAdapter);        mBottomView.setOnConfirmListener(new View.OnClickListener() {            @Override            public void onClick(View view) {                startActivity(new Intent(MainActivity.this,PaymentActivity.class));            }        });    }}

2 这里面用到了几个类 ShoppingCartBottomView（底部的一些操作按钮）  ShoppingCartListAdapter（填充商品的适配器）  CartCommodityModel（商品的model）

   ShoppingCartViewHolder（这个就不用说了吧。。。你懂的）

   在hoppingCartViewHolder中我写了一个接口，用来监听商品的数量变化的接口，当点击加减号的时候就会回调；

  

addView.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View view) {                if (listener != null) {                    listener.onAmountAddClick(getAdapterPosition());                }            }        });        minusView.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View view) {                if (listener != null) {                    listener.onAmountMinusClick(getAdapterPosition());                }            }        });    }    public interface OnViewClickListener {        void onAmountAddClick(int position);        void onAmountMinusClick(int position);    }

 3  当然了，在ShoppingCartListAdapter中需要实现这个接口，那么就要实现他的方法，点击加号或者减号的时候要将商品的数量相应的加减1（当商品的数量是大于等于1的时候  才能减），当点击小计前面的CheckBox按钮时候需要监听中实现该model是否选中该商品，然后更新一下适配器（不过这里我自己重写了一下notifyDataSetChanged()方法，见 下面代码）；我还封装了两个抽象类，一个是适配器继承的类TemplateListAdapter，还有一个是Activity继承的类BaseActivity，在项目中挺实用的；

public class ShoppingCartListAdapter extends TemplateListAdapter<CartCommodityModel, ShoppingCartViewHolder>        implements ShoppingCartViewHolder.OnViewClickListener {    private DecimalFormat mDecimalFormat = new DecimalFormat("##0.00");    private ShoppingCartBottomView mBottomView;    public ShoppingCartListAdapter(Context context, List<CartCommodityModel> data, ShoppingCartBottomView mBottomView) {        super(context, data);        this.mBottomView = mBottomView;    }    @Override    public void notifyDataSetChanged() {        super.notifyDataSetChanged();        mBottomView.notifyDataSetChanged();    }    @Override    public int getLayoutId() {        return R.layout.item_shopping_cart;    }    @Override    public ShoppingCartViewHolder getViewHolder(View convertView) {        return new ShoppingCartViewHolder(convertView, this);    }    @Override    public void bindData(int position, ShoppingCartViewHolder holder) {        final CartCommodityModel model = getItem(position);        holder.sumPriceView.setText(getSumPrice(model));        holder.checkBox.setChecked(model.isSelected());        holder.amountView.setText(model.getBuyNum());        Picasso.with(mContext).load(R.mipmap.ic_launcher).into(holder.imageView);        holder.nameView.setText(model.getName());        holder.priceView.setText(model.getPrice());        holder.originPriceView.setText(model.getOriginalPrice());        holder.vipPriceView.setText(model.getVipPrice());        holder.rootView.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View view) {                Toast.makeText(mContext, "点击了" + model.getName(), Toast.LENGTH_SHORT).show();            }        });        holder.checkBox.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View view) {                model.setSelected(!model.isSelected());                mBottomView.notifyDataSetChanged();            }        });    }    private String getSumPrice(CartCommodityModel model) {        if (Integer.valueOf(model.getBuyNum()) != 0) {            return "小计:" + (Integer.valueOf(model.getBuyNum())) * (Integer.valueOf(model.getPrice()));        } else {            return "小计：¥0.00";        }    }    @Override    public void onAmountAddClick(int position) {        CartCommodityModel model = getItem(position);        model.setBuyNum(String.valueOf(Integer.valueOf(model.getBuyNum()) + 1));        notifyDataSetChanged();    }    @Override    public void onAmountMinusClick(int position) {        CartCommodityModel model = getItem(position);        if (Integer.valueOf(model.getBuyNum()) > 1) {            model.setBuyNum(String.valueOf(Integer.valueOf(model.getBuyNum()) - 1));            notifyDataSetChanged();        }    }}

 4 我认为这里面最主要的就属于ShoppingCartBottomView这个类了，下面详细讲解一下

   当点击全选按钮时候，需要将每一个model的选中状态和全选按钮一致，然后更新一下各个控件的显示（需要写几个方法用来在notifyDataSetChanged()中调用即可）

   当点击去结算按钮时候就会跳转到付款页面

   有没有被我的详细讲解惊艳到，哈哈，是不是很简单

  

public class ShoppingCartBottomView extends LinearLayout {    protected AppCompatCheckBox mCheckBox;    protected TextView mSelectedNumberView;    protected TextView mSumPriceView;    protected TextView mDiscountPriceView;    protected List<CartCommodityModel> mData;    protected ShoppingCartListAdapter mBinderAdapter;    protected OnClickListener mListener;    private DecimalFormat mDecimalFormat = new DecimalFormat("##0.00");    public ShoppingCartBottomView(Context context) {        super(context);        initView();    }    public ShoppingCartBottomView(Context context, AttributeSet attrs) {        super(context, attrs);        initView();    }    public ShoppingCartBottomView(Context context, AttributeSet attrs, int defStyleAttr) {        super(context, attrs, defStyleAttr);        initView();    }    public void setData(List<CartCommodityModel> data) {        mData = data;    }    public void setBinderAdapter(ShoppingCartListAdapter adapter) {        mBinderAdapter = adapter;    }    protected void initView() {        View view = View.inflate(getContext(), R.layout.view_shoppingcart_bottom, null);        mCheckBox = (AppCompatCheckBox) view.findViewById(R.id.shoppingcart_bottom_checkbox);        mSelectedNumberView = (TextView) view.findViewById(R.id.shoppingcart_bottom_selected_number);        mSumPriceView = (TextView) view.findViewById(R.id.shoppingcart_bottom_sum_price);        mDiscountPriceView = (TextView) view.findViewById(R.id.shoppingcart_bottom_discount_price);        mCheckBox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {            @Override            public void onCheckedChanged(CompoundButton compoundButton, boolean isChecked) {                for (CartCommodityModel model : mData) {                    model.setSelected(isChecked);                }                if (mBinderAdapter != null) {                    mBinderAdapter.notifyDataSetChanged();                }            }        });        view.findViewById(R.id.shoppingcart_bottom_confirm).setOnClickListener(new OnClickListener() {            @Override            public void onClick(View v) {                if (mListener != null) {                    mListener.onClick(v);                }            }        });        RelativeLayout.LayoutParams layoutParams = new RelativeLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT);        view.setLayoutParams(layoutParams);        addView(view);    }    @Override    protected void onAttachedToWindow() {        super.onAttachedToWindow();    }    @Override    protected void onDetachedFromWindow() {        super.onDetachedFromWindow();    }    private void updateNumberView(int number) {        mSelectedNumberView.setText("(" + number + ")");    }    private void updateSumPriceView(float sumPrice) {        mSumPriceView.setText("合计: " + mDecimalFormat.format(sumPrice) + "元");    }    private void updateDiscountView(float discount) {        mDiscountPriceView.setText("已优惠: " + mDecimalFormat.format(discount) + "元");    }    public void setOnConfirmListener(OnClickListener listener) {        mListener = listener;    }    public void notifyDataSetChanged() {        if (mData != null) {            float sumPrice = 0;            float originalPrice = 0;            int sumCount = 0;            for (CartCommodityModel model : mData) {                if (model.isSelected()) {                    sumPrice += Float.valueOf(model.getPrice()) * Integer.valueOf(model.getBuyNum());                    originalPrice += Float.valueOf(model.getOriginalPrice()) * Integer.valueOf(model.getBuyNum());                    sumCount += Integer.valueOf(model.getBuyNum());                }            }            updateNumberView(sumCount);            updateSumPriceView(sumPrice);            updateDiscountView(originalPrice - sumPrice);        }    }}

  这样的话这个完整的小购物车项目基本上就结束了，上面的代码我是整个类都粘贴上了，不过有的简单的我就没有粘贴了，需要下载的小伙伴到我的github上下载交流吧。