超简单的Android圆形进度条

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;
    }

    @Override
    protected 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();
    }

    @Override
    protected 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;

    @Override
    protected void onDestroy() {
        _threadFlag = true;
        super.onDestroy();
    }

    @Override
    protected 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();
    }

}