Android开发中的重力传感器用法实例详解

本文实例讲述了android开发中的重力传感器用法。分享给大家供大家参考，具体如下：

重力传感器与方向传感器的开发步骤类似，只要理清了期中的x,y,z的值之后就可以根据他们的变化来进行编程了，首先来看一副图

假设当地的重力加速度值为g
当手机正面朝上的时候,z的值为q，反面朝上的时候，z的值为-g
当手机右侧面朝上的时候，x的值为g,右侧面朝上的时候,x的值为-g
当手机上侧面朝上的时候，y的值为g,右侧面朝上的时候,y的值为-g

了解了重力传感器中x,y，z的含义之后下面我们就开始学习如何使用

首先我们创建一个传感器管理器和一个传感器监听器，管理器用来管理传感器以及创建各种各样的传感器，监听器用来监视传感器的变化并且进行相应的操作

private sensormanager sensormanager;
private mysensoreventlistener mysensoreventlistener;
mysensoreventlistener= new mysensoreventlistener();//这个监听器当然是我们自己定义的，在重力感应器感应到手机位置有变化的时候，我们可以采取相应的操作，这里紧紧是将x,y,z的值打印出来
private final class mysensoreventlistener implements sensoreventlistener{
@override
//可以得到传感器实时测量出来的变化值
public void onsensorchanged(sensorevent event) {
//重力传感器
if(event.sensor.gettype()==sensor.type_accelerometer){
float x = event.values[sensormanager.data_x];
float y = event.values[sensormanager.data_y];
float z = event.values[sensormanager.data_z];
//tv_accelerometer是界面上的一个textview标签，不再赘述
tv_orientation.settext("orientation:"+x+","+y+","+z);
}
}

我们在onresume()方法中创建重力传感器，并向系统注册监听器

protected void onresume() {
 sensor sensor_accelerometer=sensormanager.getdefaultsensor(sensor.type_accelerometer);
 sensormanager.registerlistener(mysensoreventlistener,sensor_accelerometer, sensormanager.sensor_delay_ui);
super.onresume();
}

最后我们在onpause()中注销所有传感器的监听，释放重力感应器资源!

protected void onpause() {
//注销所有传感器的监听
sensormanager.unregisterlistener(mysensoreventlistener);
super.onpause();
}

到此，有关重力传感器的介绍完毕!

接下来看一个android用重力传感器做横竖屏切换的例子

在播放视频的时候，可能要做横竖屏的切换，但是，用户可以设置自己的手机关掉屏幕旋转，这个时候就需要想其他的办法了，比如：重力传感器。

public class screenswitchutils {
 private static final string tag = screenswitchutils.class.getsimplename();
 private volatile static screenswitchutils minstance;
 private activity mactivity;
 // 是否是竖屏
 private boolean isportrait = true;
 private sensormanager sm;
 private orientationsensorlistener listener;
 private sensor sensor;
 private sensormanager sm1;
 private sensor sensor1;
 private orientationsensorlistener1 listener1;
 private handler mhandler = new handler() {
  public void handlemessage(message msg) {
   switch (msg.what) {
   case 888:
    int orientation = msg.arg1;
    if (orientation > 45 && orientation < 135) {
    } else if (orientation > 135 && orientation < 225) {
    } else if (orientation > 225 && orientation < 315) {
     if (isportrait) {
      log.e(test, 切换成横屏);
      mactivity.setrequestedorientation(0);
      isportrait = false;
     }
    } else if ((orientation > 315 && orientation < 360) || (orientation > 0 && orientation < 45)) {
     if (!isportrait) {
      log.e(test,切换成竖屏);
      mactivity.setrequestedorientation(1);
      isportrait = true;
     }
    }
    break;
   default:
    break;
   }
  };
 };
 /** 返回screenswitchutils单例 **/
 public static screenswitchutils init(context context) {
  if (minstance == null) {
   synchronized (screenswitchutils.class) {
    if (minstance == null) {
     minstance = new screenswitchutils(context);
    }
   }
  }
  return minstance;
 }
 private screenswitchutils(context context) {
  log.d(tag, init orientation listener.);
  // 注册重力感应器,监听屏幕旋转
  sm = (sensormanager) context.getsystemservice(context.sensor_service);
  sensor = sm.getdefaultsensor(sensor.type_accelerometer);
  listener = new orientationsensorlistener(mhandler);
  // 根据 旋转之后/点击全屏之后 两者方向一致,激活sm.
  sm1 = (sensormanager) context.getsystemservice(context.sensor_service);
  sensor1 = sm1.getdefaultsensor(sensor.type_accelerometer);
  listener1 = new orientationsensorlistener1();
 }
 /** 开始监听 */
 public void start(activity activity) {
  log.d(tag, start orientation listener.);
  mactivity = activity;
  sm.registerlistener(listener, sensor, sensormanager.sensor_delay_ui);
 }
 /** 停止监听 */
 public void stop() {
  log.d(tag, stop orientation listener.);
  sm.unregisterlistener(listener);
  sm1.unregisterlistener(listener1);
 }
 /**
  * 手动横竖屏切换方向
  */
 public void togglescreen() {
  sm.unregisterlistener(listener);
  sm1.registerlistener(listener1, sensor1,sensormanager.sensor_delay_ui);
  if (isportrait) {
   isportrait = false;
   // 切换成横屏
   mactivity.setrequestedorientation(activityinfo.screen_orientation_landscape);
  } else {
   isportrait = true;
   // 切换成竖屏
   mactivity.setrequestedorientation(activityinfo.screen_orientation_portrait);
  }
 }
 public boolean isportrait(){
  return this.isportrait;
 }
 /**
  * 重力感应监听者
  */
 public class orientationsensorlistener implements sensoreventlistener {
  private static final int _data_x = 0;
  private static final int _data_y = 1;
  private static final int _data_z = 2;
  public static final int orientation_unknown = -1;
  private handler rotatehandler;
  public orientationsensorlistener(handler handler) {
   rotatehandler = handler;
  }
  public void onaccuracychanged(sensor arg0, int arg1) {
  }
  public void onsensorchanged(sensorevent event) {
   float[] values = event.values;
   int orientation = orientation_unknown;
   float x = -values[_data_x];
   float y = -values[_data_y];
   float z = -values[_data_z];
   float magnitude = x * x + y * y;
   // don't trust the angle if the magnitude is small compared to the y
   // value
   if (magnitude * 4 >= z * z) {
    // 屏幕旋转时
    float oneeightyoverpi = 57.29577957855f;
    float angle = (float) math.atan2(-y, x) * oneeightyoverpi;
    orientation = 90 - (int) math.round(angle);
    // normalize to 0 - 359 range
    while (orientation >= 360) {
     orientation -= 360;
    }
    while (orientation < 0) {
     orientation += 360;
    }
   }
   if (rotatehandler != null) {
    rotatehandler.obtainmessage(888, orientation, 0).sendtotarget();
   }
  }
 }
 public class orientationsensorlistener1 implements sensoreventlistener {
  private static final int _data_x = 0;
  private static final int _data_y = 1;
  private static final int _data_z = 2;
  public static final int orientation_unknown = -1;
  public orientationsensorlistener1() {
  }
  public void onaccuracychanged(sensor arg0, int arg1) {
  }
  public void onsensorchanged(sensorevent event) {
   float[] values = event.values;
   int orientation = orientation_unknown;
   float x = -values[_data_x];
   float y = -values[_data_y];
   float z = -values[_data_z];
   float magnitude = x * x + y * y;
   // don't trust the angle if the magnitude is small compared to the y
   // value
   if (magnitude * 4 >= z * z) {
    // 屏幕旋转时
    float oneeightyoverpi = 57.29577957855f;
    float angle = (float) math.atan2(-y, x) * oneeightyoverpi;
    orientation = 90 - (int) math.round(angle);
    // normalize to 0 - 359 range
    while (orientation >= 360) {
     orientation -= 360;
    }
    while (orientation < 0) {
     orientation += 360;
    }
   }
   if (orientation > 225 && orientation < 315) {// 检测到当前实际是横屏
    if (!isportrait) {
     sm.registerlistener(listener, sensor,sensormanager.sensor_delay_ui);
     sm1.unregisterlistener(listener1);
    }
   } else if ((orientation > 315 && orientation < 360) || (orientation > 0 && orientation < 45)) {// 检测到当前实际是竖屏
    if (isportrait) {
     sm.registerlistener(listener, sensor,sensormanager.sensor_delay_ui);
     sm1.unregisterlistener(listener1);
    }
   }
  }
 }
}

使用的时候：

public class mainactivity extends activity implements onclicklistener {
 private screenswitchutils instance;
 @override
 protected void oncreate(bundle savedinstancestate) {
  super.oncreate(savedinstancestate);
  instance = screenswitchutils.init(this.getapplicationcontext());
 }
 @override
 protected void onstart() {
  super.onstart();
  instance.start(this);
 }
 @override
 protected void onstop() {
  super.onstop();
  instance.stop();
 }
 @suppresslint(newapi)
 @override
 public void onconfigurationchanged(configuration newconfig) {
  super.onconfigurationchanged(newconfig);
  log.e(test, onconfigurationchanged);
  if (instance.isportrait()) {
   // 切换成竖屏
   layoutparams params1 = new relativelayout.layoutparams(screenwidth, densityutil.dip2px(this, 160));
   videoview.setlayoutparams(params1);
   toast.maketext(getapplicationcontext(), 竖屏, 0).show();
   log.e(test, 竖屏);
  } else {
   // 切换成横屏
   layoutparams params1 = new relativelayout.layoutparams(screenheight, screenwidth);
   videoview.setlayoutparams(params1);
   toast.maketext(getapplicationcontext(), 横屏, 0).show();
   log.e(test, 横屏);
  }
 }
 @override
 public void onclick(view arg0) {
  switch (arg0.getid()) {
  case r.id.iv_stretch:
   instance.togglescreen();
   break;
  }
 }
}

调用了activity.setrequestedorientation()以后，会触发activity.onconfigurationchanged();可以在这里面重新设置播放界面的大小。

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希望本文所述对大家android程序设计有所帮助。