Android应用小实例--跟随手指的小球

实现效果图：

实现方式：

继承View类自己重绘一个圆，然后将这个自定义的继承于View类的加入到当前的Activity并且为这个自定义的View控件添加一个onTouchLitener事件

自定义组件继承于View类：

package com.jiahui.draw;    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;      //必须重写一个构造方法   public DrawView(Context context) {    super(context);    // TODO Auto-generated constructor stub   }   //重写onDraw方法通过Canvas绘画   @Override   protected void onDraw(Canvas canvas) {      super.onDraw(canvas);    //创建画笔    Paint paint=new Paint();    paint.setColor(Color.RED);    //绘制一个小圆    canvas.drawCircle(currentX, currentY, 25, paint);     }     }

package com.jiahui.draw;    import android.app.Activity;  import android.os.Bundle;  import android.view.MotionEvent;  import android.view.View;  import android.widget.LinearLayout;    public class CustomeViewActivity extends Activity {      public void onCreate(Bundle savedInstanceState) {          super.onCreate(savedInstanceState);          setContentView(R.layout.main);                    LinearLayout root=(LinearLayout) findViewById(R.id.root);                    //创建一个自己继承于View的对象          final DrawView drawView=new DrawView(this);          //设置自定义组件的最大宽度和高度          drawView.setMinimumWidth(300);          drawView.setMinimumHeight(500);              drawView.setOnTouchListener(new View.OnTouchListener() {      public boolean onTouch(View v, MotionEvent event) {      drawView.currentX=event.getX();      drawView.currentY=event.getY();       //重绘      drawView.invalidate();      //返回true表明算是方法已经处理该事件      return true;     }    });          root.addView(drawView);      }  }

<?xml version="1.0" encoding="utf-8"?>  <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"      android:layout_width="fill_parent"      android:layout_height="fill_parent"      android:orientation="vertical"       android:background="#99FFCC"      android:id="@+id/root">  </LinearLayout>

 源代码下载：http://download.csdn.net/detail/jiahui524/3786788