效果圖如下：　

　實現程式碼：

import android.content.Context;

import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.LinearGradient;
import android.graphics.Paint;
import android.graphics.RectF;
import android.graphics.Shader;
import android.util.AttributeSet;
import android.view.View;
 
/**
 * Created by dawn on 2017/12/7.
 *
 * 自定義漸變進度條
 */
public class ProgressView extends View{

    public ProgressView(Context context) {
        super(context);
}

    /**漸變顏色*/
private static final int[] SECTION_COLORS = {0xff123b9d,0xff4e9bce,0xff85f4fb};
/**進度條最大值*/
private float maxCount;
/**進度條當前值*/
private float 
 
currentCount;
/**畫筆*/
private Paint mPaint;
    private int mWidth,mHeight;//設定寬度和高度
public ProgressView(Context context, AttributeSet attrs,
                              int defStyleAttr) {
        super(context, attrs, defStyleAttr);
}
    public ProgressView(Context context, AttributeSet attrs) {
        super
 
(context, attrs);
}

    @Override
protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
mPaint = new Paint();
mPaint.setAntiAlias(true);
        int round = mHeight/2;
//藍色邊框
        //繪製陰影效果
int beginP=dipToPx(0);
mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
mPaint.setColor(0xff00a3d5);
mPaint.setStyle(Paint.Style.FILL);
mPaint.setShadowLayer(100, 0, 0,Color.WHITE);
RectF rectBg = new RectF(beginP, beginP, mWidth, mHeight);
canvas.drawRoundRect(rectBg, round, round, mPaint);
//深藍色邊框
mPaint.setColor(Color.rgb(7, 38, 85));
RectF rectBg1 = new RectF(beginP+2, beginP+2, mWidth-2, mHeight-2);
canvas.drawRoundRect(rectBg1, round, round, mPaint);
mPaint.setColor(0xff072655);
RectF rectBlackBg = new RectF(beginP+4, beginP+4, mWidth-4, mHeight-4);
canvas.drawRoundRect(rectBlackBg, round, round, mPaint);
        float section = currentCount/maxCount;
RectF rectProgressBg = new RectF(beginP+3, beginP+3, (mWidth-3)*section, mHeight-3);
        if(section <= 1.0f/3.0f){
            if(section != 0.0f){
                mPaint.setColor(SECTION_COLORS[0]);
}else{
                mPaint.setColor(Color.TRANSPARENT);
}
        }else{
            int count = (section <= 1.0f/3.0f*2 ) ? 2 : 3;
            int[] colors = new int[count];
System.arraycopy(SECTION_COLORS, 0, colors, 0, count);
            float[] positions = new float[count];
            if(count == 2){
                positions[0] = 0.0f;
positions[1] = 1.0f-positions[0];
}else{
                positions[0] = 0.0f;
positions[1] = (maxCount/3)/currentCount;
positions[2] = 1.0f-positions[0]*2;
}
            positions[positions.length-1] = 1.0f;
//線性渲染
LinearGradient shader = new LinearGradient(3, 3, (mWidth-3)*section, mHeight-3, colors,null, Shader.TileMode.MIRROR);
mPaint.setShader(shader);
}
        canvas.drawRoundRect(rectProgressBg, round, round, mPaint);
}

    /**
     * dp轉換成畫素
     * @param dip
* @return
*/
private int dipToPx(int dip) {
        float scale = getContext().getResources().getDisplayMetrics().density;
        return (int) (dip * scale + 0.5f * (dip >= 0 ? 1 : -1));
}

    /***
     * 設定最大的進度值
     * @param maxCount
*/
public void setMaxCount(float maxCount) {
        this.maxCount = maxCount;
}

    /***
     * 設定當前的進度值
     * @param currentCount
*/
public void setCurrentCount(float currentCount) {
        this.currentCount = currentCount > maxCount ? maxCount : currentCount;
invalidate();
}

    /**
     * UNSPECIFIED 父容器沒有對當前View有任何限制，當前View可以任意取尺寸
     * EXACTLY 當前的尺寸就是當前View應該取的尺寸
     * AT_MOST 當前尺寸是當前View能取的最大尺寸
     * @param widthMeasureSpec
* @param heightMeasureSpec
*/
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        int widthSpecMode = MeasureSpec.getMode(widthMeasureSpec);
        int widthSpecSize = MeasureSpec.getSize(widthMeasureSpec);
        int heightSpecMode = MeasureSpec.getMode(heightMeasureSpec);
        int heightSpecSize = MeasureSpec.getSize(heightMeasureSpec);
        if (widthSpecMode == MeasureSpec.EXACTLY || widthSpecMode == MeasureSpec.AT_MOST) {
            mWidth = widthSpecSize;
} else {
            mWidth = 0;
}
        if (heightSpecMode == MeasureSpec.AT_MOST || heightSpecMode == MeasureSpec.UNSPECIFIED) {
            mHeight = dipToPx(25);
} else {
            mHeight = heightSpecSize;
}
        setMeasuredDimension(mWidth, mHeight);
}

}

　　效果圖還有一層陰影，我怎麼改都實現不了。若有人知道，勞煩告訴我一聲，謝謝。