Android自定义控件之购物车数量加减器

一、前言

刚开始在网上搜寻了一番，没找到特别合适，所以就自己简单的写了一个，其实也没什么复杂，就是一个组合控件，记录一下，方便自己以后的使用，同时也希望可以帮助有需要的朋友。

二、效果展示

三、实现思路

整个控件其实是由两个Button和一个EditText组成，直接上代码进行分析。

初始化控件，设置了自定义属性（这几个自定义属性的作用大概通过名字也能够知道了）和设置监听器

        LayoutInflater.from(context).inflate(R.layout.view_amount, 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, LayoutParams.WRAP_CONTENT);
        int tvWidth = obtainStyledAttributes.getDimensionPixelSize(R.styleable.AmountView_tvWidth, 80);
        int tvTextSize = obtainStyledAttributes.getDimensionPixelSize(R.styleable.AmountView_tvTextSize, 0);
        int btnTextSize = obtainStyledAttributes.getDimensionPixelSize(R.styleable.AmountView_btnTextSize, 0);
        obtainStyledAttributes.recycle();

定义一个数量变化的回调接口OnAmountChangeListener ，方便在其他地方调用

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

加减按钮的点击事件，当数值改变时，调用OnAmountChangeListener回调接口

public void onClick(View v) {
        int i = v.getId();
        if (i == R.id.btnDecrease) {
            if (amount > 1) {
                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);
        }
    }

同样的设置EditText的数量改变监听，只要实现afterTextChanged（）就可以了，也是需要调用OnAmountChangeListener回调接口，ok，就是这么简单，o(∩_∩)o 哈哈

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

四、完整代码

/**
 * 自定义组件：购买数量，带减少增加按钮
 * Created by hiwhitley on 2016/7/4.
 */
public class AmountView extends LinearLayout implements View.OnClickListener, TextWatcher {

    private static final String TAG = "AmountView";
    private int amount = 1; //购买数量
    private int goods_storage = 1; //商品库存

    private OnAmountChangeListener mListener;

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

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

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

        LayoutInflater.from(context).inflate(R.layout.view_amount, 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, LayoutParams.WRAP_CONTENT);
        int tvWidth = obtainStyledAttributes.getDimensionPixelSize(R.styleable.AmountView_tvWidth, 80);
        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;
    }

    @Override
    public void onClick(View v) {
        int i = v.getId();
        if (i == R.id.btnDecrease) {
            if (amount > 1) {
                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 (mListener != null) {
            mListener.onAmountChange(this, amount);
        }
    }


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

}

详细使用可以下载Demo

五、源码下载

Github下载

源码下载

欢迎Star和交流。o(∩_∩)o