一、效果

二、代码

public class PZHelp_ProgressBar extends ProgressBar { Paint paint; Rect rect; String string = "请稍等，正在加载......"; int viewwidth, viewheight; public PZHelp_ProgressBar(Context context) { super(context); initView(); } public PZHelp_ProgressBar(Context context, AttributeSet attrs) { super(context, attrs); initView(); } public PZHelp_ProgressBar(Context context, AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); initView(); } void setText(String string){ this.string = string; } void initView() { paint = new Paint(); rect = new Rect(); //因为绘制时需要缩放二分之一，所以这里放大一倍使用32 paint.setTextSize(32); paint.setColor(Color.BLACK); paint.setAntiAlias(true); paint.getTextBounds(string, 0, string.length(), rect); } @Override protected synchronized void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); //计算出最适合的尺寸 viewwidth = getMeasuredWidth() + rect.width(); viewheight = Math.max(getMeasuredHeight(), rect.height()); //保存 setMeasuredDimension(viewwidth, viewheight); } @Override protected synchronized void onDraw(Canvas canvas) { //添加背景色 canvas.drawColor(Color.WHITE); //缩放一半，为了在周围留出白边 canvas.scale(0.5f, 0.5f); //让显示的内容居中，注意，这里是先执行了translate后执行了scale canvas.translate(getHeight() >> 1, getHeight() >> 1); //绘制原本的ProgressBar super.onDraw(canvas); //绘制文字 canvas.drawText(string, (getWidth() + getHeight()) >> 1, (getMeasuredHeight() + rect.height()) >> 1, paint); } }

三、总结

最初是因为官方推荐使用 ProgressBar 来代替 ProgressDialog，而 ProgressBar 并没有添加文字的功能，所以才自定义的。ProgressDialog是继承dialog，使用的是window，能够做到隔绝页面的用户操作，而ProgressBar 没有，但如果我也继续写一个window，那为何不直接用ProgressDialog呢？似乎有点鸡肋。就当练习自定义View了，我还是接着用我 的dialog吧，下面是顺带的ViewGroup代码

四、附

<com.example.myview_tets.MyViewGroup android:id="@+id/myViewGroup" android:layout_width="wrap_content" android:layout_height="wrap_content" app:layout_constraintBottom_toBottomOf="parent" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toTopOf="parent"> <ProgressBar android:layout_width="wrap_content" android:layout_height="wrap_content" /> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="请稍等，正在加载......" /> </com.example.myview_tets.MyViewGroup> public class MyViewGroup extends ViewGroup { int viewWidth, viewHeight; public MyViewGroup(Context context) { super(context); } public MyViewGroup(Context context, AttributeSet attrs) { super(context, attrs); } public MyViewGroup(Context context, AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); //让所有子View计算自己的尺寸 measureChildren(widthMeasureSpec, heightMeasureSpec); //获取子View的尺寸 viewWidth = 0;viewHeight = 0; for (int i = 0; i < getChildCount(); i++) { View child = getChildAt(i); viewWidth = Math.max(viewWidth, child.getMeasuredWidth()); viewHeight = viewHeight + child.getMeasuredHeight(); } setMeasuredDimension(viewWidth, viewHeight); } @Override protected void onLayout(boolean changed, int l, int t, int r, int b) { int childtop = 0; //计算子View的布局 for (int i = 0; i < getChildCount(); i++) { View child = getChildAt(i); //获取子View的尺寸 int childwidth = child.getMeasuredWidth(); int childheight = child.getMeasuredHeight(); //为了view水平居中而计算的左边距 int childleft = (viewWidth - childwidth) / 2; child.layout(childleft, childtop, childleft + childwidth, childtop + childheight); childtop += childheight; } } }