Android应用开发提高篇（3）-----传感器（Sensor）编程

一、概述

     Android支持的传感器种类越来越多了，这确实是一件可喜的事情，两年前在单片机上玩过加速度传感器模块，当时做的是一个摔倒检测的项目，利用相关的算法对三轴数据进行采集、处理、判断来实现检测，既然是摔倒检测，那肯定是一个便携式设备吧，没错，当时做出来的设备是小到可以放进口袋里的。庆幸的是，今天这些东西完全可以在手机上完成了，而且不用涉及到硬件设计的问题，不过今天不是讲如何去移植那个项目，而是讲讲Android上的传感器编程。Android，再一次让我看到你的强大！再一次坚定了我学习你的信心！

二、要求

     了解、熟悉传感器的编程方法。

三、实现

     新建工程MySensor，修改/res/layout/main.xml文件，在里面添加一个SurfaceView，完整的main.xml文件如下：

 1 <?xml version="1.0" encoding="utf-8"?>
 2 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 3     android:layout_width="fill_parent"
 4     android:layout_height="fill_parent"
 5     android:orientation="vertical" >
 6 
 7     <SurfaceView 
 8         android:id="@+id/surfaceview"
 9         android:layout_width="fill_parent"
10         android:layout_height="180dip"
11         />
12 
13     
14 </LinearLayout>

接着，修改MySensorActivity.java文件，代码中有详细注释，完整的MySensorActivity.java文件如下：

 

  1 package com.nan.sensor;
  2 
  3 import android.app.Activity;
  4 import android.graphics.Canvas;
  5 import android.graphics.Color;
  6 import android.graphics.Paint;
  7 import android.graphics.Rect;
  8 import android.hardware.Sensor;
  9 import android.hardware.SensorEvent;
 10 import android.hardware.SensorEventListener;
 11 import android.hardware.SensorManager;
 12 import android.os.Bundle;
 13 import android.view.SurfaceHolder;
 14 import android.view.SurfaceView;
 15 
 16 public class MySensorActivity extends Activity 
 17 {
 18     private float acceValusX = 0f;
 19     private float acceValusY = 0f;
 20     private float acceValusZ = 0f;
 21     private int x = 0;
 22     
 23     private SurfaceView mSurfaceView = null;
 24     private SurfaceHolder mSurfaceHolder = null;
 25     private Paint mPaint = null;
 26     
 27     private SensorManager mSensorManager;
 28     private Sensor mAccelerometer;
 29     private OnSensorEventListener mOnSensorEventListener = new OnSensorEventListener();
 30     
 31     /** Called when the activity is first created. */
 32     @Override
 33     public void onCreate(Bundle savedInstanceState) 
 34     
 35     {
 36         super.onCreate(savedInstanceState);
 37         setContentView(R.layout.main);
 38         
 39         mSurfaceView = (SurfaceView)findViewById(R.id.surfaceview);
 40         mSurfaceHolder = mSurfaceView.getHolder();
 41         mSurfaceHolder.addCallback(new MyHolder());
 42         
 43         mPaint = new Paint();    
 44         //画笔的粗细
 45         mPaint.setStrokeWidth(1.0f);
 46         //从系统服务中获得传感器管服务
 47         mSensorManager = (SensorManager) getSystemService(SENSOR_SERVICE);
 48         mAccelerometer = mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
 49         //注册传感器监听
 50         mSensorManager.registerListener(mOnSensorEventListener, mAccelerometer, SensorManager.SENSOR_DELAY_GAME);
 51     }
 52     
 53     
 54     private class OnSensorEventListener implements SensorEventListener
 55     {
 56 
 57         @Override
 58         public void onAccuracyChanged(Sensor sensor, int accuracy) 
 59         {
 60             // TODO Auto-generated method stub
 61             
 62         }
 63 
 64         @Override
 65         public void onSensorChanged(SensorEvent event) 
 66         {
 67             // TODO Auto-generated method stub
 68             
 69             //获得x轴的值
 70             acceValusX = event.values[0];
 71             //获得y轴的值
 72             acceValusY = event.values[1];
 73             //获得z轴的值
 74             acceValusZ = event.values[2];
 75                 
 76             //锁定整个SurfaceView
 77             Canvas mCanvas = mSurfaceHolder.lockCanvas();
 78             try
 79             {
 80                 if(mCanvas!=null)
 81                 {
 82                     //画笔的颜色(红)
 83                     mPaint.setColor(Color.RED);
 84                     //画X轴的点
 85                     mCanvas.drawPoint(x, (int)(30 + acceValusX), mPaint);
 86                     //画笔的颜色(绿)
 87                     mPaint.setColor(Color.GREEN);
 88                     //画Y轴的点
 89                     mCanvas.drawPoint(x, (int)(60 + acceValusY), mPaint);
 90                     //画笔的颜色(蓝)
 91                     mPaint.setColor(Color.BLUE);
 92                     //画Z轴的点
 93                     mCanvas.drawPoint(x, (int)(90 + acceValusZ), mPaint);
 94                     //横坐标+1
 95                     x++;
 96                     //如果已经画到了屏幕的最右边
 97                     if(x > getWindowManager().getDefaultDisplay().getWidth())
 98                     {
 99                         x = 0;
100                         //清屏
101                         mCanvas.drawColor(Color.BLACK);
102                     }
103                     //绘制完成，提交修改
104                     mSurfaceHolder.unlockCanvasAndPost(mCanvas);
105                 }
106             }
107             catch(Exception e)
108             {
109                 e.printStackTrace();
110             }
111             finally
112             {
113                 if(mCanvas!=null)
114                 {
115                     //重新锁一次
116                     mSurfaceHolder.lockCanvas(new Rect(0, 0, 0, 0));
117                     mSurfaceHolder.unlockCanvasAndPost(mCanvas);
118                 }
119             }
120             
121         }
122         
123     }
124     
125     
126       //定义一个类，实现Callback接口
127       public class MyHolder implements SurfaceHolder.Callback
128       {
129 
130           public void surfaceChanged(SurfaceHolder holder, int format, int width,
131                   int height) 
132           {
133               // TODO Auto-generated method stub
134               //add your code
135           }
136 
137           public void surfaceCreated(SurfaceHolder holder) 
138           {
139               // TODO Auto-generated method stub
140               //add your code
141           }
142 
143           public void surfaceDestroyed(SurfaceHolder holder) 
144           {
145               // TODO Auto-generated method stub
146               //add your code
147           }
148           
149       }
150     
151     @Override
152     public void onDestroy()
153     {
154         super.onDestroy();
155         //注销传感器监听
156         mSensorManager.unregisterListener(mOnSensorEventListener, mAccelerometer);
157     }
158     
159 }

好了，在真机上运行它，效果如下：

 

晃动手机几下，效果如下：

 

完成。