效果图：

代码优化/简化、教科书级别注释、复制粘贴即可用

代码：

package com.zistone.factorytest0718.view;import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.graphics.RectF;
import android.util.AttributeSet;
import android.util.Log;
import android.view.View;import com.zistone.factorytest0718.BaseActivity;/*** 圆形进度条控件** @author LiWei* @date 2021/2/19 16:17* @email 652276536@qq.com*/
public class MyCircleProgress extends View {private static final String TAG = "MyCircleProgress";private Paint _paint;private RectF _rectF;private Rect _rect;private int _current = 1, _max = 100;//圆弧（也可以说是圆环）的宽度private float _arcWidth = 30;//控件的宽度private float _width;public MyCircleProgress(Context context) {this(context, null);}public MyCircleProgress(Context context, AttributeSet attrs) {this(context, attrs, 0);}public MyCircleProgress(Context context, AttributeSet attrs, int defStyleAttr) {super(context, attrs, defStyleAttr);_paint = new Paint();_paint.setAntiAlias(true);_rectF = new RectF();_rect = new Rect();}public void SetCurrent(int _current) {Log.i(TAG, "当前值：" + _current + "，最大值：" + _max);this._current = _current;invalidate();}public void SetMax(int _max) {this._max = _max;}@Overrideprotected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {super.onMeasure(widthMeasureSpec, heightMeasureSpec);//getMeasuredWidth获取的是view的原始大小，也就是xml中配置或者代码中设置的大小//getWidth获取的是view最终显示的大小，这个大小不一定等于原始大小_width = getMeasuredWidth();}@Overrideprotected void onDraw(Canvas canvas) {super.onDraw(canvas);//绘制圆形//设置为空心圆，如果不理解绘制弧线是什么意思就把这里的属性改为“填充”，跑一下瞬间就明白了_paint.setStyle(Paint.Style.STROKE);//设置圆弧的宽度（圆环的宽度）_paint.setStrokeWidth(_arcWidth);_paint.setColor(Color.GRAY);//大圆的半径float bigCircleRadius = _width / 2;//小圆的半径float smallCircleRadius = bigCircleRadius - _arcWidth;//绘制小圆canvas.drawCircle(bigCircleRadius, bigCircleRadius, smallCircleRadius, _paint);_paint.setColor(BaseActivity.SPRING_GREEN);_rectF.set(_arcWidth, _arcWidth, _width - _arcWidth, _width - _arcWidth);//绘制圆弧canvas.drawArc(_rectF, 90, _current * 360 / _max, false, _paint);//计算百分比String txt = _current * 100 / _max + "%";_paint.setStrokeWidth(0);_paint.setTextSize(40);_paint.getTextBounds(txt, 0, txt.length(), _rect);_paint.setColor(BaseActivity.SPRING_GREEN);//绘制百分比canvas.drawText(txt, bigCircleRadius - _rect.width() / 2, bigCircleRadius + _rect.height() / 2, _paint);}}

调用：

package com.zistone.factorytest0718;import android.os.Bundle;import com.zistone.factorytest0718.view.MyCircleProgress;/*** 用来测试一些东西的，没有任何实际功能...** @author LiWei* @date 2020/7/18 9:33* @email 652276536@qq.com*/
public class Test1Activity extends BaseActivity {private static final String TAG = "Test1Activity";private boolean _threadFlag = false;@Overrideprotected void onDestroy() {_threadFlag = true;super.onDestroy();}@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_test1);MyCircleProgress myCircleProgress = findViewById(R.id.控件名);Thread thread = new Thread(() -> {int j = 0;while (!_threadFlag && j < 100) {try {Thread.sleep(100);} catch (InterruptedException e) {e.printStackTrace();}j++;int finalJ = j;runOnUiThread(() -> myCircleProgress.SetCurrent(finalJ));}});thread.start();}}