简单的进度条

先一个自定义view

public class JinDuTiao extends View {
    private Context context;
    private Paint paint;

    public JinDuTiao(Context context) {
        super(context);
        this.context=context;
        init();
    }

    public JinDuTiao(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
        this.context=context;
        init();
    }

    public JinDuTiao(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        this.context=context;
        init();
    }

    private void init() {
        paint = new Paint();
        paint.setColor(Color.parseColor("#cccfff"));
        paint.setStyle(Paint.Style.STROKE);
        paint.setStrokeWidth(2);
    }

    private  int index = 1;
    public void diaoyong(int i){
        index = i;
        invalidate();
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        paint.setColor(Color.parseColor("#ff6699"));
        canvas.drawCircle(50,50,50,paint);
        RectF rectF=new RectF();
        rectF.top=0;
        rectF.bottom=100;
        rectF.left=0;
        rectF.right=100;
        paint.setColor(Color.parseColor("#cccfff"));
        canvas.drawArc(rectF,0,(float)(7.2 *index),false,paint);
    }}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="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=".MainActivity">
<shopping.example.sd.dome.JinDuTiao
    android:id="@+id/jindutiao"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#00000000"/>
<TextView
    android:id="@+id/text"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintTop_toTopOf="parent"
    android:layout_marginLeft="50dp"
    android:layout_marginTop="50dp"
    />
</android.support.constraint.ConstraintLayout>

MainActivity

public class MainActivity extends AppCompatActivity {
    private int i=1;
    @SuppressLint("HandlerLeak")
    private Handler handler=new Handler(){
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);

            textView.setText(i*2+"");
            jindutiao.diaoyong(i);
            if (i==50){
                //可以执行跳转
                return ;
            }
            sendEmptyMessageDelayed(0,100);
            i++;
        }
    };
    private JinDuTiao jindutiao;
    private TextView textView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        jindutiao = findViewById(R.id.jindutiao);
        handler.sendEmptyMessage(0);
        textView = findViewById(R.id.text);
    }}