android 实现购物车加减功能

public class adderView extends LinearLayout implements View.OnClickListener, TextWatcher {

    private int amount = 0; //购买数量
    private int goods_storage = Integer.MAX_VALUE; //商品库存

    private OnAmountChangeListener mListener;

    private EditText etAmount;
    private Button btnDecrease;
    private Button btnIncrease;

    public adderView(Context context) {
        this(context, null);
    }

    public adderView(Context context, AttributeSet attrs) {
        super(context, attrs);

        LayoutInflater.from(context).inflate(R.layout.number_adder, this);
        etAmount = (EditText) findViewById(R.id.etAmount);
        btnDecrease = (Button) findViewById(R.id.btnDecrease);
        btnIncrease = (Button) findViewById(R.id.btnIncrease);
        btnDecrease.setOnClickListener(this);
        btnIncrease.setOnClickListener(this);
        etAmount.addTextChangedListener(this);

        TypedArray obtainStyledAttributes = getContext().obtainStyledAttributes(attrs, R.styleable.AmountView);
        int btnWidth = obtainStyledAttributes.getDimensionPixelSize(R.styleable.AmountView_btnWidth, 100);
        int tvWidth = obtainStyledAttributes.getDimensionPixelSize(R.styleable.AmountView_tvWidth, 200);
        int tvTextSize = obtainStyledAttributes.getDimensionPixelSize(R.styleable.AmountView_tvTextSize, 0);
        int btnTextSize = obtainStyledAttributes.getDimensionPixelSize(R.styleable.AmountView_btnTextSize, 0);
        obtainStyledAttributes.recycle();

        LayoutParams btnParams = new LayoutParams(btnWidth, LayoutParams.MATCH_PARENT);
        btnDecrease.setLayoutParams(btnParams);
        btnIncrease.setLayoutParams(btnParams);
        if (btnTextSize != 0) {
            btnDecrease.setTextSize(TypedValue.COMPLEX_UNIT_PX, btnTextSize);
            btnIncrease.setTextSize(TypedValue.COMPLEX_UNIT_PX, btnTextSize);
        }

        LayoutParams textParams = new LayoutParams(tvWidth, LayoutParams.MATCH_PARENT);
        etAmount.setLayoutParams(textParams);
        if (tvTextSize != 0) {
            etAmount.setTextSize(tvTextSize);
        }
    }

    public void setOnAmountChangeListener(OnAmountChangeListener onAmountChangeListener) {
        this.mListener = onAmountChangeListener;
    }

    public void setGoods_storage(int goods_storage) {
        this.goods_storage = goods_storage;
    }

    public void setTextCount(int count){
        this.amount = count;
        this.etAmount.setText(amount+"");
    }

    @Override
    public void onClick(View v) {
        int i = v.getId();
        if (i == R.id.btnDecrease) {
            if (amount > 0) {
                amount--;
                etAmount.setText(amount + "");
            }
        } else if (i == R.id.btnIncrease) {
            if (amount < goods_storage) {
                amount++;
                etAmount.setText(amount + "");

            }
        }

        etAmount.clearFocus();

        if (mListener != null) {
            mListener.onAmountChange(this, amount);
        }
    }

    @Override
    public void beforeTextChanged(CharSequence s, int start, int count, int after) {

    }

    @Override
    public void onTextChanged(CharSequence s, int start, int before, int count) {

    }

    @Override
    public void afterTextChanged(Editable s) {
        if (s.toString().isEmpty())
            return;
        amount = Integer.valueOf(s.toString());
        if (amount > goods_storage) {
            etAmount.setText(goods_storage + "");
            return;
        }
        if (amount == 0){
//            btnDecrease.setBackgroundResource(R.drawable.jian);
        }
        if (amount > 0){
//            btnDecrease.setBackgroundResource(R.drawable.lvjian);
        }

        if (mListener != null) {
            mListener.onAmountChange(this, amount);
        }
    }


    public interface OnAmountChangeListener {
        void onAmountChange(View view, int amount);
    }

<?xml version="1.0" encoding="utf-8"?>
<com.zhy.autolayout.AutoLinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="90px"
    android:focusable="true"
    android:divider="@drawable/divder"
    android:background="@drawable/bg_amout_layout"
    android:showDividers="middle"
    android:orientation="horizontal">


    <Button
        android:id="@+id/btnDecrease"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:gravity="center"
        android:background="@drawable/jian"/>

    <EditText
        android:id="@+id/etAmount"
        android:layout_width="200px"
        android:layout_height="match_parent"
        android:minWidth="150px"
        android:layout_weight="2"
        android:background="@null"
        android:inputType="number"
        android:textSize="13sp"
        android:text="0"
        android:gravity="center"/>

    <Button
        android:id="@+id/btnIncrease"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:gravity="center"
        android:background="@drawable/jia"/>
</com.zhy.autolayout.AutoLinearLayout>