Android自定义View实现数字雨效果的全过程

    // 文字的颜色值
    final int DEFAULT_TEXT_COLOR = Color.argb(255, 0, 255, 70);
    // 文字大小
    final int TEXT_SIZE = 24;
    // 普通画笔
    Paint mPaint;
    // 高亮画笔
    Paint mPaintLight;
    // 改变文字的间隔时间
    int switchInternal = interval[random.nextInt(interval.length)];
    // 数字落下的速度
    int speed;

// 构建0和1的字符串
if (contentArray == null) {
    contentArray = new String[2];
    contentArray[0] = "0";
    contentArray[1] = "1";
} 

private String getChar() {
            return contentArray[random.nextInt(2)];
        }

public NumberView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init();
    }

private void init() {
        mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        mPaint.setARGB(255, 0, 255, 70);
        mPaint.setTextSize(TEXT_SIZE);
        a = textColor >> 24 & 0xff;
        r = textColor >> 16 & 0xff;
        g = textColor >> 8 & 0xff;
        b = textColor & 0xff;
        mPaint.setARGB(a, r, g, b);

        mPaintLight = new Paint(Paint.ANTI_ALIAS_FLAG);
        mPaintLight.setARGB(255, 140, 255, 170);
        mPaintLight.setTextSize(TEXT_SIZE);
    }

@Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        int widthSize = MeasureSpec.getSize(widthMeasureSpec);
        int widthMode = MeasureSpec.getMode(widthMeasureSpec);
        int heightSize = MeasureSpec.getSize(heightMeasureSpec);
        int heightMode = MeasureSpec.getMode(heightMeasureSpec);
        if (widthMode == MeasureSpec.EXACTLY) {
            mWidth = widthSize;
        }
        if (heightMode == MeasureSpec.EXACTLY) {
            mHeight = heightSize;
        }
        setMeasuredDimension((int) mWidth, (int) mHeight);
  }

@Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        render(canvas);
        rain();
    }
    
private void rain() {
    for (int j = 0; j < streams.length; j++) {
        Symbol[] symbols = (Symbol[]) streams[j];
        for (int i = 0; i < symbols.length; i++) {
            Symbol symbol = symbols[i];
            symbol.y = symbol.y >= mHeight ? 0 : symbol.y + symbol.speed;
        }
    }
}