第一次在简书上写东西，还不太熟悉，希望能一直坚持写。
刚刚模仿了一个启动页倒数读秒按钮。效果如下：

CircleProgressView.class

package com.test.circleprogressviewtest;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.RectF;
import android.util.AttributeSet;
import android.view.View;

/**
 * 启动页-倒数读秒跳转按钮
 */
public class CircleProgressView extends View {
    private Paint pProgress;
    private Paint pText;
    private Paint pBorder;
    private Paint pCircle;

    private int progressColor;
    private int borderColor;
    private int circleColor;

    private float circleRadius;
    private float borderWidth;
    private float circleAndBorderRadius;

    private String text = "";
    private float textSize = 20.0F;
    private int textColor;

    private int halfWidth;
    private int halfHeight;
    private float topOffset = 60.0F;

    private int borderAlpha = 100;
    private int currentAlpha = 100;

    private ITimeout iTimeout;

    public CircleProgressView(Context paramContext, AttributeSet paramAttributeSet) {
        super(paramContext, paramAttributeSet);
        TypedArray typedArray = paramContext.getTheme().obtainStyledAttributes(paramAttributeSet, R.styleable.CircleProgressView, 0, 0);
        circleRadius = typedArray.getDimension(R.styleable.CircleProgressView_circleRadius, 80.0F);

        circleColor = typedArray.getColor(R.styleable.CircleProgressView_circleColor, 0);
        borderColor = typedArray.getColor(R.styleable.CircleProgressView_circleBorderColor, -1);
        progressColor = typedArray.getColor(R.styleable.CircleProgressView_circleProgressColor, -1);

        borderWidth = typedArray.getDimension(R.styleable.CircleProgressView_circleBorderWidth, 10.0F);
        borderAlpha = typedArray.getInteger(R.styleable.CircleProgressView_circleBorderAlpha, 100);

        text = typedArray.getString(R.styleable.CircleProgressView_circleText);
        textSize = typedArray.getDimension(R.styleable.CircleProgressView_circleTextSize, 0.0F);
        textColor = typedArray.getColor(R.styleable.CircleProgressView_circleTextColor, -1);

        circleAndBorderRadius = (circleRadius + borderWidth / 2.0F);

        pProgress = new Paint();
        pProgress.setAntiAlias(true);
        pProgress.setColor(progressColor);
        pProgress.setStyle(Paint.Style.FILL);

        pBorder = new Paint();
        pBorder.setAntiAlias(true);
        pBorder.setColor(borderColor);
        pBorder.setStyle(Paint.Style.STROKE);
        pBorder.setStrokeWidth(borderWidth);

        pCircle = new Paint();
        pCircle.setAntiAlias(true);
        pCircle.setColor(circleColor);
        pCircle.setStyle(Paint.Style.STROKE);
        pCircle.setStrokeWidth(borderWidth);

        pText = new Paint();
        pText.setAntiAlias(true);
        pText.setStyle(Paint.Style.FILL);
        pText.setColor(textColor);
        pText.setTextSize(textSize);
    }

    public int getCurrentAlpha() {
        return currentAlpha;
    }

    public void invalidate(int alpha) {
        currentAlpha = alpha;
        postInvalidate();
    }

    public void startProgress(long totalTime, ITimeout iTimeout) {
        this.iTimeout = iTimeout;

        new Thread(new CountDownRunnable(this, totalTime)).start();
    }

    protected void onDraw(Canvas paramCanvas) {
        halfWidth = (getWidth() / 2);
        halfHeight = (getHeight() / 2);
        paramCanvas.drawCircle(halfWidth, halfHeight, circleRadius, pProgress);

        if (currentAlpha >= 0) {
            RectF localRectF = new RectF();
            localRectF.left = (halfWidth - circleAndBorderRadius);
            localRectF.top = (halfHeight - circleAndBorderRadius);
            localRectF.right = (circleAndBorderRadius * 2.0F + (halfWidth - circleAndBorderRadius));
            localRectF.bottom = (circleAndBorderRadius * 2.0F + (halfHeight - circleAndBorderRadius));
            paramCanvas.drawArc(localRectF, -90.0F, -360.0F, false, pCircle);
            paramCanvas.drawArc(localRectF, -90.0F, 360.0F * (100 - currentAlpha) / borderAlpha, false, pBorder);
            float textWidth = pText.measureText(text, 0, text.length());
            paramCanvas.drawText(text, halfWidth - textWidth / 2.0F, halfHeight + topOffset / 4.0F, pText);

            if (currentAlpha == 0 && iTimeout != null) {
                iTimeout.timeout();
            }
        }
    }

    public interface ITimeout {
        void timeout();
    }
}

CountDownRunnable.class

package com.test.circleprogressviewtest;

final class CountDownRunnable implements Runnable {
    private CircleProgressView circleProgressView;
    private long totalTime = 2000L;

    public CountDownRunnable(CircleProgressView circleProgressView, long paramLong) {
        this.circleProgressView = circleProgressView;
        this.totalTime = paramLong;
    }

    public final void run() {
        long sleepTime = this.totalTime / circleProgressView.getCurrentAlpha();

        circleProgressView.invalidate(100);
        while (circleProgressView.getCurrentAlpha() > 0) {
            circleProgressView.invalidate(circleProgressView.getCurrentAlpha() - 1);
            try {
                Thread.sleep(1L * sleepTime);
            } catch (Exception localException) {
                localException.printStackTrace();
            }
        }
    }
}

attrs.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <declare-styleable name="CircleProgressView">
        <attr name="circleRadius" format="dimension" />
        <attr name="circleColor" format="color" />
        <attr name="circleText" format="string" />
        <attr name="circleTextSize" format="dimension" />
        <attr name="circleTextColor" format="color" />
        <attr name="circleBorderWidth" format="dimension" />
        <attr name="circleBorderColor" format="color" />
        <attr name="circleBorderAlpha" format="integer" />
        <attr name="circleProgressColor" format="color" />
    </declare-styleable>
</resources>

activity_splash.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:progress="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.test.circleprogressviewtest.SplashActivity">

    <com.test.circleprogressviewtest.CircleProgressView
        android:id="@+id/jump_btn"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="28dp"
        android:layout_marginRight="28dp"
        android:layout_alignParentTop="true"
        android:layout_alignParentRight="true"
        progress:circleRadius="20.0dp"
        progress:circleColor="#66000000"
        progress:circleText="跳转"
        progress:circleTextSize="14sp"
        progress:circleTextColor="#e6ffffff"
        progress:circleBorderWidth="2dp"
        progress:circleBorderColor="#ffe2e2e2"
        progress:circleBorderAlpha="100"
        progress:circleProgressColor="#fff39c11" />
</android.support.constraint.ConstraintLayout>

SplashActivity.class

package com.test.circleprogressviewtest;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Toast;

public class SplashActivity extends AppCompatActivity implements 
          View.OnClickListener, CircleProgressView.ITimeout {
    CircleProgressView circleProgressView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_splash);

        circleProgressView = (CircleProgressView) findViewById(R.id.jump_btn);

        circleProgressView.startProgress(2000, this);

        circleProgressView.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        Toast.makeText(SplashActivity.this, "点击了跳转", Toast.LENGTH_SHORT).show();
    }

    @Override
    public void timeout() {
        Toast.makeText(SplashActivity.this, "跳转", Toast.LENGTH_SHORT).show();
    }
}