自定义控件—入门随机数

package com.example.administrator.randomnumber_view_demo;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;

import java.util.HashSet;
import java.util.Random;
import java.util.Set;

/**
 * Created by Administrator on 2017/4/9.
 */
public class Ranom_view extends View {
    public Ranom_view(Context context) {
        super(context);
    }

    public Ranom_view(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public Ranom_view(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }
    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        //对于画笔
        Paint paint = new Paint();
        //设置抗锯齿
        paint.setAntiAlias(true);
        //设置画笔颜色
        paint.setColor(Color.BLUE);
        //样式
        paint.setStyle(Paint.Style.STROKE);
        paint.setStrokeWidth(5);
        canvas.drawCircle(300,400,100,paint);
        //设置文字大小
        paint.setTextSize(40);
        String s = randomText();
        //指定坐标，最好指定文字大小
        canvas.drawText(s, 300, 400,paint);
    }
    /**
     * 获取四位随机数验证码
     *
     * @return
     */
    private String randomText() {
        Random random = new Random();
        Set<Integer> set = new HashSet<Integer>();
        while (set.size() < 4) {
            int randomInt = random.nextInt(10);
            set.add(randomInt);
        }
        StringBuffer sb = new StringBuffer();
        for (Integer i : set) {
            sb.append("" + i);
        }

        return sb.toString();
    }
    @Override
    protected boolean dispatchHoverEvent(MotionEvent event) {
        return super.dispatchHoverEvent(event);
    }
    @Override
    public boolean onTouchEvent(MotionEvent event) {
        invalidate();
        return true;
    }
}