HarmonyOS 鸿蒙Next--定位服务获取经纬度，逆地理编码为地址，并计算两个经纬度之间的距离

0、使用定位服务获取经纬度，再通过逆地理编码获取地址，并计算两个经纬度之间的距离

1、获取定位权限

Button(“获取定位权限”)
.onClick(async () => {
const permissions: Array<Permissions> =
[‘ohos.permission.APPROXIMATELY_LOCATION’, ‘ohos.permission.LOCATION’];
const context: common.UIAbilityContext = getContext(this) as common.UIAbilityContext;
await checkPermissions(permissions, context).then((isGrant: boolean) => {
if (isGrant) {
this.appPathStack.pushPathByName(NavigationKey.ATTENDANCE_CLOCK_IN_PAGE, null)
}
})
}) 

2、获取定位信息

  initLocation() {
let requestInfo: geoLocationManager.LocationRequest = {
‘priority’: geoLocationManager.LocationRequestPriority.FIRST_FIX, // 快速定位优先策略
‘timeInterval’: 0,
‘distanceInterval’: 0,
‘maxAccuracy’: 0
};
let locationChange = (location: geoLocationManager.Location): void => {
console.log('locationChanger: data: ’ + JSON.stringify(location));
this.getAddresses(location)  // 逆地理编码
};
// 启动定位
try {
geoLocationManager.on(‘locationChange’, requestInfo, locationChange);
} catch (err) {
setTimeout(() => {
toast(“请打开定位功能”)
}, 1000)
console.error(“errCode:” + (err as BusinessError.BusinessError).code + “,errMessage:” +
(err as BusinessError.BusinessError).message);
}
} 

3、逆地理编码获取地理信息

getAddresses(location: geoLocationManager.Location) {
let reverseGeocodeRequest: geoLocationManager.ReverseGeoCodeRequest = {
“latitude”: location.latitude,
“longitude”: location.longitude,
“maxItems”: 1
};
let isAvailable = false
// 查询geoCoder服务是否可用
try {
isAvailable = geoLocationManager.isGeocoderAvailable();
} catch (err) {
console.error(“errCode:” + (err as BusinessError.BusinessError).code + “,errMessage:” +
(err as BusinessError.BusinessError).message);
}
if (isAvailable) {
try {
geoLocationManager.getAddressesFromLocation(reverseGeocodeRequest, (err, data) => {
if (err) {
// 定位失败
console.log('getAddressesFromLocation err: ’ + JSON.stringify(err));
} else {
// 定位成功，处理位置信息
console.log('getAddressesFromLocation data: ’ + JSON.stringify(data[0]));
}
});
} catch (err) {
console.error(“errCode:” + (err as BusinessError.BusinessError).code + “,errMessage:” +
(err as BusinessError.BusinessError).message);
}
}
} 

4、结束定位

  aboutToDisappear(): void {
// 结束定位
geoLocationManager.off(‘locationChange’, this.locationChange);
} 

5、计算两个经纬度之间的距离

function getRad(d: number) {
const PI = Math.PI
return d * PI / 180.0
}

export function getDistance(lat1: number, lng1: number, lat2: number, lng2: number) {
const EARTH_RADIUS = 6378137.0
let f = getRad((lat1 + lat2) / 2)
let g = getRad((lat1 - lat2) / 2)
let l = getRad((lng1 - lng2) / 2)
let sg = Math.sin(g)
let sl = Math.sin(l)
let sf = Math.sin(f)
let s: number, c: number, w: number, r: number, d: number, h1: number, h2: number
let a = EARTH_RADIUS
let fl = 1 / 298.257
sg = sg * sg
sl = sl * sl
sf = sf * sf
s = sg * (1 - sl) + (1 - sf) * sl
c = (1 - sg) * (1 - sl) + sf * sl
w = Math.atan(Math.sqrt(s / c))
r = Math.sqrt(s * c) / w
d = 2 * w * a
h1 = (3 * r - 1) / 2 / c
h2 = (3 * r + 1) / 2 / s
return d * (1 + fl * (h1 * sf * (1 - sg) - h2 * (1 - sf) * sg))
}