获取自定义属性

TimeRingView.java

TypedArray a = context.getTheme().obtainStyledAttributes(attrs,R.styleable.RoundRateView,0);
        int n = a.getIndexCount(); //自定义属性的个数
        for (int i = 0; i < n; i++) {
            int attr = a.getIndex(i); //获取逐条属性
            switch (attr) {
                case R.styleable.RoundRateView_RateColor1:
                    RateColor1 = a.getColor(attr,Color.parseColor("#fac62d"));
                    break;
                case R.styleable.RoundRateView_RateColor3:
                    RateColor2 = a.getColor(attr,Color.parseColor("#65cff6"));
                    break;
                case R.styleable.RoundRateView_RateColor2:
                    RateColor3 = a.getColor(attr,Color.parseColor("#fe9a9c"));
                    break;
                case R.styleable.RoundRateView_RateColor4:
                    RateColor4 = a.getColor(attr,Color.parseColor("#a286da"));
                    break;
                case R.styleable.RoundRateView_circleWidth:
                    mCircleWidth = a.getDimensionPixelSize(attr,dp2px(context,20));
                    break;
                case R.styleable.RoundRateView_radius:
                    mRadius = a.getDimensionPixelSize(attr,20));
                    break;
        }
    }
    a.recycle();</code></pre>
这一步主要是使得可以在java文件中使用xml文件中定义的属性。
RateColor1/RateColor2等变量都是需要在类中先申明的，这里就省去了。
重写onMeasure方法 设置控件在布局中的大小
TimeRingView.java
@Override
    protected void onMeasure(int widthMeasureSpec,int heightMeasureSpec) {
        // 设置宽度
        int specMode = MeasureSpec.getMode(widthMeasureSpec); //获取控件中layout_width设定大小模式（有wrap_content,match_parent和具体数值）
        int specSize = MeasureSpec.getSize(widthMeasureSpec); //获取系统设定的控件宽度
    int mHeight = 0;
    int mWidth = 0;

    if (specMode == MeasureSpec.EXACTLY)//当控件大小设定为match_parent或者是具体值时
    {
        mWidth = specSize;
    } else{

        if (specMode == MeasureSpec.AT_MOST)//控件layout_width设定为wrap_content，将控件宽度设置为圆环半径的两倍
        {
            mWidth = (int) (mRadius*2);
        }
    }

    // 设置高度
    specMode = MeasureSpec.getMode(heightMeasureSpec);
    specSize = MeasureSpec.getSize(heightMeasureSpec);
    if (specMode == MeasureSpec.EXACTLY)// match_parent,accurate
    {
        mHeight = specSize;
    } else{
        if (specMode == MeasureSpec.AT_MOST)//控件layou_hight设定为wrap_content，将控件高度设置为圆环半径的两倍
        {
            mHeight = (int) (mRadius*2);
        }
    }
    setMeasuredDimension(mWidth+10,mHeight+10);//最后应用到项目的时候发现圆饼有些超出控件定义的大小，所以将控件总大小稍微加大一点
}</code></pre>
初始化画笔
TimeRingView.java
    void initPaint(){
        mPaint = new Paint();
        mPaint.setAntiAlias(true); //抗锯齿
        mPaint.setStyle(Paint.Style.STROKE); //描边style
    }
重写onDraw方法 绘制自定义控件
TimeRingView.java
protected void onDraw(Canvas canvas) {
        mPaint.setStrokeWidth(mCircleWidth); //画笔宽
    //arc 1
    mRectF = new RectF(mCircleWidth/2,mCircleWidth/2,mRadius*2 - mCircleWidth/2,mRadius*2-mCircleWidth/2); //(left,top,right,bottom)
    float startAngle = -90; //12点方向
    float Sweep1 = 150; //弧度
    mPaint.setColor((int) RateColor1); //画笔颜色
    canvas.drawArc(mRectF,startAngle,Sweep1,false,mPaint);

    //arc 2
    startAngle += Sweep1;
    float Sweep2 = 50;
    mPaint.setColor((int) RateColor3);
    canvas.drawArc(mRectF,Sweep2,mPaint);

    //arc 3
    startAngle += Sweep2;
    float Sweep3 = 95;
    mPaint.setColor((int) RateColor2);
    canvas.drawArc(mRectF,Sweep3,mPaint);

    //arc 4
    startAngle += Sweep3;
    float Sweep4 = 65;
    mPaint.setColor((int) RateColor4);
    canvas.drawArc(mRectF,Sweep4,mPaint);

添加到布局文件
time_ring_layout.xml




其中xmlns:***(app)="http://schemas.android.com/apk/res-auto"为自定义命名空间
以上就完成了一个数据写死了的环状饼图。想要更改数据只需要增加一个相应方法即可。
P.S.
Utils.java
public static int dp2px(Context context,float dpValue) {
        final float scale = context.getResources().getDisplayMetrics().density;
        return (int) (dpValue * scale + 0.5f);
    }