项目中正好要用到这个功能。

• 先看效果

方形格子密码输入

说一下，6个格子这个有2种画法，一种就是直接画6个小格子，第二种就是先画外面的大矩形，里面在画5条竖线。我采取后者。一定要在xml设置 android:maxLength属性

/**
 * 方格子密码控件
 * Created by Admin on 2016/6/3.
 */
public class SquarePasswordView extends EditText {
    /**
     * 密码长度。通过在xml中的 android:maxLength 设置
     */
    private int max;
    private final Paint paint;
    private int borderColor = Color.LTGRAY;

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

        paint = new Paint();
        //获得android:maxLength设置的值
        max = UIUtils.getMaxLen(this);
        if (max <1){
            throw  new IllegalArgumentException("android:maxLength < 1");
        }
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        int widthMode = MeasureSpec.getMode(widthMeasureSpec);
        int widthSize = MeasureSpec.getSize(widthMeasureSpec);
        int heightMode = MeasureSpec.getMode(heightMeasureSpec);
        int heightSize = MeasureSpec.getSize(heightMeasureSpec);

        if (MeasureSpec.AT_MOST == widthMode) {
            widthMeasureSpec = MeasureSpec.makeMeasureSpec(200, MeasureSpec.EXACTLY);
        }


        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    }

    //屏蔽长按时出现那个粘贴功能
    @Override
    public boolean onTouchEvent(MotionEvent event) {
        return false;
    }

    @Override
    protected void onDraw(Canvas canvas) {
        //单个密码格子的宽度
        int itemW = getMeasuredWidth() / max;
        int itemH = getMeasuredHeight() / 2;
        paint.setColor(borderColor);
        paint.setStyle(Paint.Style.STROKE);
        //先画外面的大矩形
        canvas.drawRect(0, 0, getMeasuredWidth() - 1, getMeasuredHeight() - 1, paint);
        //在画内部的几条竖线。
        for (int i = 0; i < max - 1; i++) {
            int x = itemW * (i + 1);
            canvas.drawLine(x, 0, x, getMeasuredHeight()-1, paint);
        }
    
      //下面画圆形密码。每输入一个就画一个
        paint.setColor(Color.BLACK);
        paint.setStyle(Paint.Style.FILL);
        int y = itemH;
        int x = 0;
        int radius = itemW / 6;
        //根据输入的文本长度来画圆
        for (int i = 0; i < getText().length(); i++) {
            x = (itemW / 2) + i * itemW;
            canvas.drawCircle(x, y, radius, paint);
        }
    }
}