下面是一个小例子，跟随手指的小球

创建一个继承自View的类，用来绘制圆形

package WangLi.CustomView.Space;

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

public class DrawView extends View {
    public float currentX = 40;
    public float currentY = 50;
	public DrawView(Context context) {
		super(context);
		// TODO Auto-generated constructor stub
	}

	@Override
	public void onDraw(Canvas canvas)
	{
		super.onDraw(canvas);
		//创建画笔
		Paint p = new Paint();
		//设置画笔颜色
		p.setColor(Color.RED);
		//绘制一个小圆(作为小球)
		canvas.drawCircle(currentX, currentY, 15, p);
	}

下面是该应用的Activity类

package WangLi.CustomView.Space;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnTouchListener;
import android.widget.LinearLayout;
import android.view.MotionEvent;

public class CustomView extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        //获取LinearLayout布局容器
        LinearLayout root = (LinearLayout)findViewById(R.id.root);
        //创建DrewView组件
        final DrawView draw = new DrawView(this);
        //设置自定义组件的最大宽度,高度
        draw.setMinimumWidth(300);
        draw.setMinimumHeight(500);
        //为draw组件绑定Touch事件
        draw.setOnTouchListener(new OnTouchListener(){
        	public boolean onTouch(View view, MotionEvent event) 
        	{
        		//修改draw组件的currentX,currentY两个属性
        		draw.currentX = event.getX();
        		draw.currentY = event.getY();
        		//通知draw组件重绘
        		draw.invalidate();
        		//返回true表明处理方法已经处理该事件
        		return true;
        	}
        });
        root.addView(draw);
    }
}

运行效果如下

这个红色的球，在手机模拟器中，鼠标按下(模拟Touch事件)就会跟着光标移动