年底忙碌起来便挤不出时间更新笔记文章了，趁今天周末抽空把之前的功能笔记补齐O(∩_∩)O哈哈~
记录到这个功能我首先要感谢一下我目前的老大对我的帮助，一位英俊潇洒风流倜傥阳光幽默精通各大代码域的帅小伙guthub:https://github.com/KnifeStone

一.概述 ：

EventBus是针对Android优化的发布/订阅事件总线。主要是替代Intent/Handler/BroadCast在Fragment/Activity/Service线程之间传递消息。开销小，代码更优雅，将发送者和接收者解耦。

二.推荐：

针EventBus的简单用法推荐（作者写得通俗易懂）
http://blog.csdn.net/harvic880925/article/details/40660137
更深入了解EventBus推荐
//www.greatytc.com/p/31e3528ca7e5

(1). EventBus官网地址
(2). EventBus github地址
(3). EventBus 3.0的用法详解

三.实现步骤：

按照以往的惯例先上效果图：

GIF.gif

看完效果图可以知道实现添加购物车分为几部分：
首先先简单写一个产品列表，数据是存储在七牛云上面的临时数据，先拿来用。

github下载地址，欢迎star：https://github.com/LXLYHM/EventBusAddShoppingCart/blob/master/README.md

代码注释比较详细，感兴趣的小伙伴可以下载看看，下面直接上干货，就不多解释废话了

1.网络框架：是自封装的一个非常简单的Retrofit2网络框架
2.重点主要在加入购物车的时候使用EventBus全局通知事件上

首先是在总工程的build.gradle接入开源库资源：

allprojects {
    repositories {
        jcenter()
        mavenCentral()
        maven { url 'https://jitpack.io' }
    }
}

然后在app的build.gradle引用开源库：

compile 'org.greenrobot:eventbus:3.0.0'

在基类AddCartActivity.java里面注册关闭好EventBus和实现加入购物车动画给MainActivity.java继承：

public abstract class AddCartActivity extends AppCompatActivity {

    protected QBadgeView qBadgeView = null;//购物车数量红点
    protected ObjectAnimator animator = null;//动画view

    @Override
    protected void onStart() {
        super.onStart();
        //onStart的时候注册EventBus
        if (!EventBus.getDefault().isRegistered(this)) {
            EventBus.getDefault().register(this);
        }
    }

    @Override
    protected void onStop() {
        super.onStop();
        //onStop的时候释放EventBus
        EventBus.getDefault().unregister(this);
    }

    //发送消息线程
    @Subscribe(threadMode = ThreadMode.MAIN)
    public void onMessageEvent(ProductAnimEvent event) {
        if (qBadgeView == null) {
            return;
        }
        View view = event.view;
        //获取商品坐标
        int[] goodsPoint = new int[2];
        view.getLocationInWindow(goodsPoint);
        //获取购物车坐标
        int[] shoppingCartPoint = new int[2];
        qBadgeView.getLocationInWindow(shoppingCartPoint);
        //生成商品View 并播放商品加入购物车动画
        ProductAnimView animView = new ProductAnimView(this);
        ImageLoader.getInstance().loadRound(event.imgPath, animView);
        animView.setCircleStartPoint(goodsPoint[0] + view.getWidth() / 2 - ConvertUtils.dp2px(24f), goodsPoint[1] + view.getHeight() / 2 - ConvertUtils.dp2px(24f));
        animView.setCircleEndPoint(shoppingCartPoint[0], shoppingCartPoint[1] - ConvertUtils.dp2px(24f));
        ViewGroup decorView = (ViewGroup) getWindow().getDecorView();
        decorView.addView(animView, ConvertUtils.dp2px(48f), ConvertUtils.dp2px(48f));
        animView.startAnimation();
        //判断是否播放小红点跳跃动画
        if (animator == null && qBadgeView != null) {
            animator = ObjectAnimator.ofFloat(qBadgeView, "translationY", 0f, -ConvertUtils.dp2px(6f), 0f);
            animator.setDuration(300);
        }
        new Handler().postDelayed(new Runnable() {
            @Override
            public void run() {
                if (animator.isRunning()) {
                    return;
                }
                animator.start();
            }
        }, 500);
    }
}

封装AppCart.java作为辅助类：

public class AppCart {
    //购物车
    private static List<ProductListBean> mList;

    public static List<ProductListBean> getCartList() {
        if (mList == null) {
            mList = new ArrayList<>();
        }
        if (mList.isEmpty()) {
            mList = (List<ProductListBean>) CacheUtils.getInstance().getSerializable("cacheCart");
            if (mList == null) {
                mList = new ArrayList<>();
            }
        }
        return mList;
    }

    /**
     * 单个商品数量变化 先改变后传入
     */
    public static void onChangeOne(ProductListBean bean) {
        if (bean == null) {
            return;
        }
        if (mList == null) {
            getCartList();
        }
        int index;
        if (mList.contains(bean)) {
            index = mList.indexOf(bean);
            mList.get(index).buy_num = bean.buy_num;
            if (mList.get(index).buy_num <= 0) {
                mList.remove(bean);
            }
        } else {
            mList.add(0, bean);
        }
        putCartList(mList);
    }

    /**
     * 获得购物车数量
     */
    public static int getCartNumber() {
        if (getCartList()==null || getCartList().isEmpty()) {
            return 0;
        }
        int number = 0;
        for (ProductListBean productBean : mList) {
            number += productBean.buy_num;
        }
        return number;
    }

    /**
     * 写入缓存
     */
    public static void putCartList(List<ProductListBean> cartList) {
        mList = cartList;
        //发送广播
        EventBus.getDefault().post(new CartEvent());
    }

    /**
     * 移除一样商品
     */
    public static void onRemove(ProductListBean bean) {
        if (bean == null) {
            return;
        }
        bean.buy_num = 0;
        mList.remove(bean);
        putCartList(mList);
    }

    /**
     * 清除补货清单
     */
    public static void clear() {
        if (getCartList()==null || getCartList().isEmpty()) {
            return;
        }
        CacheUtils.getInstance().remove("cacheCart");
        mList.clear();
    }

    /**
     * 比对数据
     * @param list
     * @return true有比对 false无比对
     */
    public static boolean comparison(List<ProductListBean> list) {
        List<ProductListBean> listCart = getCartList();
        if (list == null || list.size() == 0) {
            return false;
        }
        if (listCart == null || listCart.size() == 0) {
            for (ProductListBean productBean : list) {
                productBean.buy_num = 0;
            }
            return true;
        }
        int index;
        for (ProductListBean productBean : list) {
            if (listCart.contains(productBean)) {
                index = listCart.indexOf(productBean);
                productBean.buy_num = listCart.get(index).buy_num;
            } else {
                productBean.buy_num = 0;
            }
        }
        return true;
    }
}

接下来就是最重要的MainActivity.java了：

/**
 * Created by LXL on 2017/12/8.
 * http://my.csdn.net/lxlyhm
 * https://github.com/LXLYHM
 * //www.greatytc.com/u/8fd63a0d4c4c
 * 购物车
 */
public class MainActivity extends AddCartActivity {

    private RecyclerView mRecyclerView;
    private List<ProductListBean> mList = new ArrayList();
    private ProductAdapter mAdapter;

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

        //状态栏全局默认统一成白底黑字
        ImmersionBar.with(this).statusBarColor(R.color.colorPrimary).fitsSystemWindows(true).init();
        mRecyclerView = (RecyclerView) findViewById(R.id.recyclerView);
        mRecyclerView.setLayoutManager(new LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false));
        mAdapter = new ProductAdapter();
        mRecyclerView.setAdapter(mAdapter);
        mAdapter.setNewData(mList);

        initData();
    }

    /**
     * 加载数据
     */
    private void initData() {
        new AppData().getData(new CallBackAdapter<String>() {
            @Override
            public void onSuccess(String object) {
                List<ProductListBean> list = new Gson().fromJson(object, new TypeToken<List<ProductListBean>>() {}.getType());
                AppCart.comparison(list);
                mList = list;
                mAdapter.setNewData(mList);
            }

            @Override
            public void onFailure(int code, String message) {
            }

            @Override
            public void onCompleted() {
            }
        });
    }

    /**
     * 显示状态
     */
    public void checkState() {
        if (AppCart.getCartNumber() <= 0) {
            if (qBadgeView != null) {
                qBadgeView.hide(true);
            }
        } else {
            //动画
            if (qBadgeView == null) {
                View view = findViewById(R.id.containerBageView);
                qBadgeView = new QBadgeView(this);
                qBadgeView.setGravityOffset(0f, ConvertUtils.dp2px(6f), false).bindTarget(view);
            }
            qBadgeView.setBadgeNumber(AppCart.getCartNumber());
        }
    }

    @Subscribe(threadMode = ThreadMode.MAIN)
    public void onMessageEvent(CartEvent event) {
        checkState();
    }

    @Override
    protected void onStart() {
        super.onStart();
        checkState();
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        AppCart.clear();//清除
        ImmersionBar.with(this).destroy();
    }
}

ProductAdapter.java：

public class ProductAdapter extends BaseQuickAdapter<ProductListBean, BaseViewHolder> {

    public ProductAdapter(){
        super(R.layout.item_product);
    }

    @Override
    protected void convert(final BaseViewHolder helper, final ProductListBean item) {
        helper.setText(R.id.productsName, item.name);
        ImageLoader.getInstance().load(item.cover_image_url, (ImageView) helper.getView(R.id.imgProducts));

        final MyEditText etNumber = helper.getView(R.id.et_number);//数量
        etNumber.clearFocus();//清除焦点
        etNumber.setOnTouchListener(new View.OnTouchListener() {
            @Override
            public boolean onTouch(View v, MotionEvent event) {
                if (MotionEvent.ACTION_DOWN == event.getAction()) {
                    etNumber.setCursorVisible(true);// 再次点击显示光标
                }
                return false;
            }
        });

        etNumber.addTextChangedListener(new TextWatcher() {
            @Override
            public void beforeTextChanged(CharSequence s, int start, int count, int after) {
            }

            @Override
            public void onTextChanged(CharSequence s, int start, int before, int count) {
                if (!"".equals(s.toString())) {
                    int buy_num = parseInt(s.toString());
                    item.buy_num = buy_num;
                    if (buy_num > 0) {
                        AppCart.onChangeOne(item);//发送购物车变化
                    }
                    if (buy_num == 0){
                        AppCart.onRemove(item);
                    }
                }
            }

            @Override
            public void afterTextChanged(Editable s) {
            }
        });
        etNumber.setText(item.buy_num + "");
        // 加
        helper.getView(R.id.bt_add).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                item.buy_num++;
                if (item.buy_num > 0){
                    EventBus.getDefault().post(new ProductAnimEvent(helper.getView(R.id.imgProducts), item.cover_image_url));
                }
                etNumber.setText(item.buy_num + "");
            }
        });
        // 减
        helper.getView(R.id.bt_float).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (item.buy_num == 0) {
                    return;
                }
                item.buy_num--;
                etNumber.setText(item.buy_num + "");
            }
        });
    }
}

如果有需要kotlin语言项目的小伙伴们可以留言私信我