自定义功能EditText 尾部添加按钮

android 在编辑文本时经常会用到一些功能按钮,例如输入密码时后面显示一个眼睛图标或者显示一键清理图标, 如果采用多ViewGroup嵌套,很容易就能解决问题,但是这样真的好吗,其实不然, 咱们也可以直接继承EditText对它背景进行绘制，思路很简单, 将Drawable 绘制到Canves再转成BitmapDrawable 设置成背景, 不然每次在onDraw方法中绘制挺耗性能的，贴上主要代码

package com.dy.mydemo;


import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Rect;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.support.v4.content.ContextCompat;
import android.text.Editable;
import android.text.TextUtils;
import android.text.TextWatcher;
import android.util.AttributeSet;
import android.util.TypedValue;
import android.view.MotionEvent;


/**
 * @author DaiYao
 */
public class EditTextExtend extends android.support.v7.widget.AppCompatEditText implements TextWatcher {

    private int drawableSize;
    private Drawable drawableRight;

    private Rect drawableClickRect;
    private Rect drawableBounds;

    private boolean isDisplayIcon;
    private Bitmap bgBitmap;

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


    public EditTextExtend(Context context, AttributeSet attrs) {
        this(context, attrs, android.support.v7.appcompat.R.attr.editTextStyle);
    }

    public EditTextExtend(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        initView(attrs);
    }

    private void initView(AttributeSet attrs) {
        TypedArray typedArray = getContext().obtainStyledAttributes(attrs, R.styleable.EditTextExtend);

        int drawableRightRes = typedArray.getResourceId(R.styleable.EditTextExtend_drawableRight,
                R.mipmap.icon_close);
        drawableSize = typedArray.getDimensionPixelSize(R.styleable.EditTextExtend_drawableSize,
                dp2px(getContext(), 17));

        typedArray.recycle();

        drawableRight = ContextCompat.getDrawable(getContext(), drawableRightRes);

        addTextChangedListener(this);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);

        if (bgBitmap == null) {

            bgBitmap = Bitmap.createBitmap(getWidth(),
                    getHeight(),
                    Bitmap.Config.ARGB_8888);
            Canvas bgCanvas = new Canvas(bgBitmap);

            if (drawableBounds == null) {
                drawableBounds = new Rect(0, 0, drawableSize, drawableSize);
                drawableRight.setBounds(drawableBounds);
            }

            bgCanvas.save();
            //垂直居中 右对齐  找到偏移Y
            int offsetPadding = (getHeight() - drawableBounds.height()) / 2;
            int offsetX = getWidth() - drawableBounds.width() - drawableBounds.width() / 2;
            bgCanvas.translate(offsetX, offsetPadding);

            drawableRight.draw(bgCanvas);

            if (drawableClickRect == null) {
                drawableClickRect = new Rect(offsetX - offsetPadding,
                        0,
                        offsetX + drawableBounds.width() + offsetPadding,
                        getHeight());
            }
            setBackgroundDrawable(new BitmapDrawable(getResources(), bgBitmap));
          int drawableWidth = drawableBounds.width() + offsetPadding;
            int minRightPadding = drawableWidth < getPaddingRight() ?
                    getPaddingRight() :
                    drawableWidth;
            setPadding(getPaddingLeft(), getPaddingTop(), minRightPadding,       getPaddingBottom());
            bgCanvas.restore();

            afterTextChanged(getEditableText());
        }
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                if (isDisplayIcon) {
                    boolean contains = drawableClickRect.contains(
                            (int) event.getX(),
                            (int) event.getY());

                    if (contains) {
                        setText(null);
                        return true;
                    }
                }
                break;
            default:
                break;
        }
        return super.onTouchEvent(event);
    }

    @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 == null || TextUtils.isEmpty(s.toString())) {
            isDisplayIcon = false;
        } else {
            isDisplayIcon = true;
        }

        setBackgroundDrawable(
                isDisplayIcon ?
                        new BitmapDrawable(getResources(), bgBitmap) :
                        null);
    }

    /**
     * DP转PX
     */
    public static int dp2px(Context context, float dpVal) {
        return (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP,
                dpVal,
                context.getResources()
                        .getDisplayMetrics());
    }
}

这样就能显示一键清理文本的效果了,代码提供思路, 如果要封装的更加完美就需要你自己来动手了