【移動(dòng)應(yīng)用開發(fā)技術(shù)】AndrdoidSensorsOverview(探測(cè)器概述)二

IntroductiontoSensors介紹傳感器TheAndroidsensorframeworkletsyouaccessmanytypesofsensors.Someofthesesensorsare

hardware-basedandsomearesoftware-based.Hardware-basedsensorsarephysicalcomponentsbuilt

intoahandsetortabletdevice.Theyderivetheirdatabydirectlymeasuringspecificenvironmental

properties,suchasacceleration,geomagneticfieldstrength,orangularchange.Software-based

sensorsarenotphysicaldevices,althoughtheymimichardware-basedsensors.Software-basedsensors

derivetheirdatafromoneormoreofthehardware-basedsensorsandaresometimescalledvirtual

sensorsorsyntheticsensors.Thelinearaccelerationsensorandthegravitysensorareexamplesof

software-basedsensors.Androidsensorframework讓你使用多種傳感器。有基于硬件和基于軟件的。基于硬件的傳感器是內(nèi)置于設(shè)備中的物理組件。它們直接測(cè)量具體的環(huán)境屬性來得出數(shù)據(jù)，例如加速度，地磁場(chǎng)強(qiáng)度，或者角的變化。基于軟件的傳感器你不是物理設(shè)備，盡管它們模擬硬件傳感器。軟件探測(cè)器通過一個(gè)或者多個(gè)硬件傳感器來得出數(shù)據(jù)，有時(shí)稱為虛擬傳感器或者合成傳感器。線性加速度傳感器和重力傳感器是軟件傳感器的例子。Table1summarizesthesensorsthataresupportedbytheAndroid

platform.表1總結(jié)了android平臺(tái)支持的傳感器。FewAndroid-powereddeviceshaveeverytypeofsensor.Forexample,mosthandsetdevicesand

tabletshaveanaccelerometerandamagnetometer,butfewerdeviceshave

barometersorthermometers.Also,adevicecanhavemorethanonesensorofagiventype.For

example,adevicecanhavetwogravitysensors,eachonehavingadifferentrange.少有android設(shè)備每種傳感器都有。例如，大部分手機(jī)設(shè)備和平板有一個(gè)加速計(jì)和一個(gè)磁力計(jì)，但是較少設(shè)備有氣壓計(jì)或溫度計(jì)。一個(gè)設(shè)備也可以有一個(gè)以上的同類傳感器，如果可以用兩個(gè)不同范圍的重力傳感器。Table1.SensortypessupportedbytheAndroidplatform.表1。Android平臺(tái)支持的傳感器種類。Measurestheaccelerationforceinm/s2thatisappliedtoadeviceon

allthreephysicalaxes(x,y,andz),includingtheforceofgravity.測(cè)量在設(shè)備的三個(gè)軸的加速度，單位m/s2，包括重力加速度Motiondetection(shake,tilt,etc.).運(yùn)動(dòng)檢測(cè)MeasurestheambientroomtemperatureindegreesCelsius(°C).Seenotebelow.測(cè)量室溫，單位攝氏度(°C)Monitoringairtemperatures.監(jiān)視空氣溫度Measurestheforceofgravityinm/s2thatisappliedtoadeviceonallthreephysicalaxes(x,y,z).測(cè)量在設(shè)備三個(gè)軸的重力加速度，單位m/s2。Measuresadevice'srateofrotationinrad/saroundeachofthethree

physicalaxes(x,y,andz).測(cè)量在設(shè)備三個(gè)軸上的角速度。單位rad/sRotationdetection(spin,turn,etc.).旋轉(zhuǎn)檢測(cè)Measurestheambientlightlevel(illumination)inlx.測(cè)試環(huán)境亮度級(jí)，單位lxControllingscreenbrightness.控制屏幕亮度Measurestheaccelerationforceinm/s2thatis

appliedtoadeviceonallthreephysicalaxes(x,y,andz),excludingtheforceofgravity.測(cè)量在設(shè)備三軸上的加速度，排除了重力。Monitoringaccelerationalongasingleaxis.檢測(cè)一個(gè)軸上的加速度Measurestheambientgeomagneticfieldforallthreephysicalaxes(x,y,z)in

μT.測(cè)量三軸的地磁場(chǎng)，單位μTCreatingacompass.創(chuàng)建一個(gè)羅盤Measuresdegreesofrotationthatadevicemakesaroundallthreephysicalaxes(x,y,z).AsofAPIlevel3youcanobtaintheinclinationmatrixandrotation