自定义View(进度条)

继承View重写带两个参数的构造方法,一个参数的不行不会加载视图,构造方法中初始化画笔这样不用没次刷新都要初始化浪费内存,在ondraw方法中绘图,invalidate方法会掉用ondraw方法重新绘制.在attrs中声明你将要设置的属性,名字要和自定义类名一样,在布局文件中引用属性,随便输入属性名然后alt+enter自动生成命名空间,就可以引用自定义属性了.最后在主activity中调用接口,使用传来的参数current

public class MainActivity extends AppCompatActivity {

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        final CircleProgressView myView = findViewById(R.id.circle);
        ValueAnimator animator = ValueAnimator.ofFloat(0, 100);
        animator.setDuration(4000);
        animator.setInterpolator(new LinearInterpolator());
        animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
            @Override
            public void onAnimationUpdate(ValueAnimator animation) {
                float current = (float) animation.getAnimatedValue();
                myView.setmCurrent((int) current);
            }
        });
        animator.start();
myView.setOnLoadingCompleteListener(new CircleProgressView.OnLoadingCompleteListener() {
    @Override
    public void complete(int current) {
        System.out.println(current);
        if (current == 100) {
            myView.setVisibility(View.GONE);
            Toast.makeText(MainActivity.this, "加载完成", Toast.LENGTH_SHORT).show();
        }

    }
});

    }
}

主activity

public class CircleProgressView extends View {
    private int mCurrent;//当前进度
    private Paint mPaintOut;
    private Paint mPaintCurrent;
    private Paint mPaintText;
    private float mPaintWidth;//画笔宽度
    private int mPaintColor = Color.RED;//画笔颜色
    private int mTextColor = Color.BLACK;//字体颜色
    private float mTextSize;//字体大小
    private int location;//从哪个位置开始
    private float startAngle;//开始角度

    public CircleProgressView(Context context, AttributeSet attrs) {
        super(context, attrs);
        TypedArray array = context.obtainStyledAttributes(attrs, R.styleable.CircleProgressView);
        location = array.getInt(R.styleable.CircleProgressView_location, 1);
        mPaintWidth = array.getDimension(R.styleable.CircleProgressView_progress_paint_width, dip2px(context,4));//默认4dp
        mPaintColor = array.getColor(R.styleable.CircleProgressView_progress_paint_color, mPaintColor);
        mTextSize = array.getDimension(R.styleable.CircleProgressView_progress_text_size, dip2px(context,18));//默认18sp
        mTextColor = array.getColor(R.styleable.CircleProgressView_progress_text_color, mTextColor);
        array.recycle();

        //画笔->背景圆弧
        mPaintOut = new Paint();
        mPaintOut.setAntiAlias(true);
        mPaintOut.setStrokeWidth(mPaintWidth);
        mPaintOut.setStyle(Paint.Style.STROKE);
        mPaintOut.setColor(Color.GRAY);
        mPaintOut.setStrokeCap(Paint.Cap.ROUND);
        //画笔->进度圆弧
        mPaintCurrent = new Paint();
        mPaintCurrent.setAntiAlias(true);
        mPaintCurrent.setStrokeWidth(mPaintWidth);
        mPaintCurrent.setStyle(Paint.Style.STROKE);
        mPaintCurrent.setColor(mPaintColor);
        mPaintCurrent.setStrokeCap(Paint.Cap.ROUND);
        //画笔->绘制字体
        mPaintText = new Paint();
        mPaintText.setAntiAlias(true);
        mPaintText.setStyle(Paint.Style.FILL);
        mPaintText.setColor(mTextColor);
        mPaintText.setTextSize(mTextSize);

        if (location == 1) {//默认从左侧开始
            startAngle = -180;
        } else if (location == 2) {
            startAngle = -90;
        } else if (location == 3) {
            startAngle = 0;
        } else if (location == 4) {
            startAngle = 90;
        }
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        RectF rectF = new RectF(mPaintWidth / 2, mPaintWidth / 2, getWidth() - mPaintWidth / 2, getHeight() - mPaintWidth / 2);
        canvas.drawArc(rectF, 0, 360, false, mPaintOut);
        //绘制当前进度
        float sweepAngle = 360 * mCurrent / 100;
        canvas.drawArc(rectF, startAngle, sweepAngle, false, mPaintCurrent);

        //绘制进度数字
        String text = mCurrent + "%";
        //获取文字宽度
        float textWidth = mPaintText.measureText(text, 0, text.length());
        float dx = getWidth() / 2 - textWidth / 2;
        Paint.FontMetricsInt fontMetricsInt = mPaintText.getFontMetricsInt();
        float dy = (fontMetricsInt.bottom - fontMetricsInt.top) / 2 - fontMetricsInt.bottom;
        float baseLine = getHeight() / 2 + dy;
        canvas.drawText(text, dx, baseLine, mPaintText);

      if (mLoadingCompleteListener != null ) {
          mLoadingCompleteListener.complete(mCurrent);

      }
    }
    public void setmCurrent(int mCurrent) {
        this.mCurrent = mCurrent;
        invalidate();
    }
    public interface OnLoadingCompleteListener {
        void complete(int current);
    }
    //暴露回调方法
    public void setOnLoadingCompleteListener(OnLoadingCompleteListener loadingCompleteListener) {
        this.mLoadingCompleteListener = loadingCompleteListener;
    }
//监听
    /**
     * 根据手机的分辨率从 dp 的单位 转成为 px(像素)
     */
    public static int dip2px(Context context, float dpValue) {
        final float scale = context.getResources().getDisplayMetrics().density;
        return (int) (dpValue * scale + 0.5f);
    }

    private OnLoadingCompleteListener mLoadingCompleteListener;
}

自定义view

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    xmlns:myview="http://schemas.android.com/apk/res-auto"
    android:id="@+id/line1"
    android:orientation="vertical"
    android:layout_height="match_parent"
    tools:context=".MainActivity">
<com.january.summer.CircleProgressView
    android:id="@+id/circle"
    android:layout_width="50dp"
  myview:location="left"
    android:layout_gravity="center"
    android:layout_height="50dp" />

</LinearLayout>

布局文件

<resources>

    <declare-styleable name="CircleProgressView">//要跟类名一样
        <!--画笔宽度-->
        <attr name="progress_paint_width" format="dimension" />
        <!--画笔颜色-->
        <attr name="progress_paint_color" format="color" />
        <!--字体颜色-->
        <attr name="progress_text_color" format="color" />
        <!--字体尺寸-->
        <attr name="progress_text_size" format="dimension" />
        <!--加载进度的开始位置-->
        <attr name="location" format="enum">
            <enum name="left" value="1" />
            <enum name="top" value="2" />
            <enum name="right" value="3" />
            <enum name="bottom" value="4" />
        </attr>
    </declare-styleable>

</resources>

attrs文件,注意,demension属性使用时自动把dp转为px