Android 自定义软键盘实现数字九宫格，2021年Android常见面试题目

实现效果GIF

实现代码

自定义View 一个NineNumericKeyboardView

/**

Author by Lyu
Date on 2021/5/26-19:55
Description:九宫格数字软键盘
/
public class NineNumericKeyboardView extends View {
/*
列
/
private static final int TOTAL_COL = 3;
/*
行
*/
private static final int TOTAL_ROW = 4;

private Paint HuiseBgPaint, linePaint;
private Paint mTextPaint;
private int mViewWidth; // 键盘宽度
private int mViewHight; // 键盘高度
private float mCellWidth, mCellHight; // 单元格宽度、高度
private Row rows[] = new Row[TOTAL_ROW];
private Bitmap bitmap; // 删除按钮图片
private Paint mCutTextPaint;

//回调方法
public interface CallBack {
void clickNum(String num)
;// 回调点击的数字

void deleteNum();// 回调删除
}

private CallBack mCallBack;// 回调

public void setOnCallBack(CallBack callBack) {
mCallBack = callBack;
}

public NineNumericKeyboardView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init(context);

}

public NineNumericKeyboardView(Context context, AttributeSet attrs) {
super(context, attrs);
init(context);

}

public NineNumericKeyboardView(Context context) {
super(context);
init(context);
}

@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
drawLine(canvas);
for (int i = 0; i < TOTAL_ROW; i++) {
if (rows[i] != null)
rows[i].drawCells(canvas);
}
}

/**

画6条直线
@param canvas
*/
private void drawLine(Canvas canvas) {
canvas.drawLine(0, 0, mViewWidth, 0, linePaint);
canvas.drawLine(0, mCellHight, mViewWidth, mCellHight, linePaint);
canvas.drawLine(0, mCellHight * 2, mViewWidth, mCellHight * 2, linePaint);
canvas.drawLine(0, mCellHight * 3, mViewWidth, mCellHight * 3, linePaint);
canvas.drawLine(mCellWidth, 0, mCellWidth, mViewHight, linePaint);
canvas.drawLine(mCellWidth * 2, 0, mCellWidth * 2, mViewHight, linePaint);

}

/**

初始化画笔
@param context
*/
private void init(Context context) {
mTextPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
mCutTextPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
linePaint = new Paint(Paint.ANTI_ALIAS_FLAG);
linePaint.setTextSize(1.0f);
linePaint.setColor(0x90000000);

HuiseBgPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
HuiseBgPaint.setStyle(Paint.Style.FILL);
HuiseBgPaint.setColor(Color.parseColor("#e9e9e9"));

initDate();
}

private void initDate() {
fillDate();
}

@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
mViewWidth = w;
mViewHight = h;
mCellWidth = mViewWidth / TOTAL_COL;
mCellHight = mViewHight / TOTAL_ROW;
mTextPaint.setTextSize(mCellHight / 3);

}

private Cell mClickCell = null;
private float mDownX;
private float mDownY;

/*
*

触摸事件为了确定点击位置的数字
*/
@Override
public boolean onTouchEvent(MotionEvent event) {
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
mDownX = event.getX();
mDownY = event.getY();
int col = (int) (mDownX / mCellWidth);
int row = (int) (mDownY / mCellHight);
measureClickCell(col, row);
break;
case MotionEvent.ACTION_UP:
if (mClickCell != null) {
// 在抬起后把状态置为默认
rows[mClickCell.i].cells[mClickCell.j].state = State.DEFAULT_NUM;
mClickCell = null;
invalidate();
}
break;
}
return true;
}

/**

测量点击单元格
@param col 列
@param row 行
*/
private void measureClickCell(int col, int row) {
if (col >= TOTAL_COL || row >= TOTAL_ROW)
return;
if (rows[row] != null) {
mClickCell = new Cell(rows[row].cells[col].num, rows[row].cells[col].state, rows[row].cells[col].i,
rows[row].cells[col].j);
rows[row].cells[col].state = State.CLICK_NUM;
if ("-5".equals(rows[row].cells[col].num)) {
mCallBack.deleteNum();
} else {
mCallBack.clickNum(rows[row].cells[col].num);
}
invalidate();
}
}

/**

组以一行为一组
*/
private class Row {
public int j;

Row(int j) {
this.j = j;
}

// 一行3个单元格
public Cell[] cells = new Cell[TOTAL_COL];

public void drawCells(Canvas canvas) {
for (int i = 0; i < cells.length; i++) {
if (cells[i] != null)
cells[i].drawSelf(canvas);
}

}
}

// 单元格
private class Cell {
public String num;
public State state;
/**

i = 行 j = 列
*/
public int i;
nt i = 0; i < cells.length; i++) {
if (cells[i] != null)
cells[i].drawSelf(canvas);
}

}
}

// 单元格
private class Cell {
public String num;
public State state;
/**

i = 行 j = 列
*/
public int i;