Android GPS 定位流程

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已于 2023-06-15 09:55:11 修改 · 1.2k 阅读

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于 2023-04-15 23:00:18 首次发布

Android P 代码：http://androidxref.com/9.0.0_r3/

上一篇幅我们梳理了位置开关打开的一个流程，这里我们梳理下请求Gps定位的一个流程

这里我们假设一个app发起Gps定位，首先调用 LocationManager 接口，通过AIDL最终调用到 LocationManagerService 里面的 requestLocationUpdates 方法：

http://androidxref.com/9.0.0_r3/xref/frameworks/base/location/java/android/location/LocationManager.java#requestLocationUpdates

553    @RequiresPermission(anyOf = {
 
 ACCESS_COARSE_LOCATION, ACCESS_FINE_LOCATION})
554    public void requestLocationUpdates(String provider, long minTime, float minDistance,
555            LocationListener listener) {
556        checkProvider(provider);
557        checkListener(listener);
558
559        LocationRequest request = LocationRequest.createFromDeprecatedProvider(  ---> 封装成LocationRequest，作为参数传下去
560                provider, minTime, minDistance, false);
561        requestLocationUpdates(request, listener, null, null);
562    }

http://androidxref.com/9.0.0_r3/xref/frameworks/base/services/core/java/com/android/server/LocationManagerService.java#requestLocationUpdates

2061    public void requestLocationUpdates(LocationRequest request, ILocationListener listener,
2062            PendingIntent intent, String packageName) {
2063        if (request == null) request = DEFAULT_LOCATION_REQUEST;
2064        checkPackageName(packageName);
2065        int allowedResolutionLevel = getCallerAllowedResolutionLevel();   ---> 这里指的就是 fine、coarse、no location data 三种
2066        checkResolutionLevelIsSufficientForProviderUse(allowedResolutionLevel,
2067                request.getProvider());
2068        WorkSource workSource = request.getWorkSource();
2069        if (workSource != null && !workSource.isEmpty()) {
2070            checkDeviceStatsAllowed();
2071        }
2072        boolean hideFromAppOps = request.getHideFromAppOps();
2073        if (hideFromAppOps) {
2074            checkUpdateAppOpsAllowed();
2075        }
2076        boolean callerHasLocationHardwarePermission =
2077                mContext.checkCallingPermission(android.Manifest.permission.LOCATION_HARDWARE)
2078                        == PERMISSION_GRANTED;
2079        LocationRequest sanitizedRequest = createSanitizedRequest(request, allowedResolutionLevel,
2080                callerHasLocationHardwarePermission);
2081
2082        final int pid = Binder.getCallingPid();
2083        final int uid = Binder.getCallingUid();
2084        // providers may use public location API's, need to clear identity
2085        long identity = Binder.clearCallingIdentity();
2086        try {
2087            // We don't check for MODE_IGNORED here; we will do that when we go to deliver
2088            // a location.
2089            checkLocationAccess(pid, uid, packageName, allowedResolutionLevel);
2090
2091            synchronized (mLock) {
2092                Receiver recevier = checkListenerOrIntentLocked(listener, intent, pid, uid,
2093                        packageName, workSource, hideFromAppOps);
2094                requestLocationUpdatesLocked(sanitizedRequest, recevier, pid, uid, packageName);  ---> 继续看下这个
2095            }
2096        } finally {
2097            Binder.restoreCallingIdentity(identity);
2098        }
2099    }

2101    private void requestLocationUpdatesLocked(LocationRequest request, Receiver receiver,
2102            int pid, int uid, String packageName) {
2103        // Figure out the provider. Either its explicitly request (legacy use cases), or
2104        // use the fused provider
2105        if (request == null) request = DEFAULT_LOCATION_REQUEST;
2106        String name = request.getProvider();   ---> 获取此时的provide，下面就是根据这个provide决定走GPS还是走network，所以不能为空
2107        if (name == null) {
2108            throw new IllegalArgumentException("provider name must not be null");
2109        }