android中uid用于标识一个应用程序，uid在应用安装时被分配，并且在应用存在于手机上期间，都不会改变，范围是从10000开始，到19999结束,而且，UID由用户ID(UserId)和应用ID(AppId)共同决定
frameworks/base/services/core/java/com/android/server/pm/PackageManagerService.java
10170 private void commitScanResultsLocked(@NonNull ScanRequest request, @NonNull ScanResult result) 10171 throws PackageManagerException { .... 10184 10185 if (newPkgSettingCreated) { 10186 if (originalPkgSetting != null) { 10187 mSettings.addRenamedPackageLPw(pkg.packageName, originalPkgSetting.name); 10188 } 10189 // THROWS: when we can't allocate a user id. add call to check if there's 10190 // enough space to ensure we won't throw; otherwise, don't modify state 10191 mSettings.addUserToSettingLPw(pkgSetting); 10192 10193 if (originalPkgSetting != null && (scanFlags & SCAN_CHECK_ONLY) == 0) { 10194 mTransferedPackages.add(originalPkgSetting.name); 10195 } 10196 }frameworks/base/services/core/java/com/android/server/pm/Settings.java
882 void addUserToSettingLPw(PackageSetting p) throws PackageManagerException { 883 if (p.appId == 0) { 884 // Assign new user ID 885 p.appId = newUserIdLPw(p); 886 } else { 887 // Add new setting to list of user IDs 888 addUserIdLPw(p.appId, p, p.name); 889 } 890 if (p.appId < 0) { 891 PackageManagerService.reportSettingsProblem(Log.WARN, 892 "Package " + p.name + " could not be assigned a valid UID"); 893 throw new PackageManagerException(INSTALL_FAILED_INSUFFICIENT_STORAGE, 894 "Package " + p.name + " could not be assigned a valid UID"); 895 } 896 } 4213 private int newUserIdLPw(Object obj) { 4214 // Let's be stupidly inefficient for now... 4215 final int N = mUserIds.size(); 4216 for (int i = mFirstAvailableUid; i < N; i++) { 4217 if (mUserIds.get(i) == null) { 4218 mUserIds.set(i, obj); 4219 return Process.FIRST_APPLICATION_UID + i; 4220 } 4221 } 4222 4223 // None left? 4224 if (N > (Process.LAST_APPLICATION_UID-Process.FIRST_APPLICATION_UID)) { 4225 return -1; 4226 } 4227 4228 mUserIds.add(obj); 4229 return Process.FIRST_APPLICATION_UID + N; 4230 }frameworks/base/core/java/android/os/UserHandle.java
32 /** 33 * @hide Range of uids allocated for a user. 34 */ 35 public static final int PER_USER_RANGE = 100000; 207 /** 208 * Returns the uid that is composed from the userId and the appId. 209 * @hide 210 */ 211 public static int getUid(@UserIdInt int userId, @AppIdInt int appId) { 212 if (MU_ENABLED) { 213 return userId * PER_USER_RANGE + (appId % PER_USER_RANGE); 214 } else { 215 return appId; 216方式1：abd shell cat data/system/packages.xml，里面包含所有应用的uid和一些有关其的信息（需要root） 方式2：adb shell dumpsys package 应用包名 | adb shell grep userId= 方式3：adb shell cat /proc/<pid>/status | adb shell grep Uid 1、adb shell ps -A | adb shell grep -r “com.example.testpor”（-A:高android版本的adb shell需要带-A参数）,其中，第二列30209就是pid
octopus-n106:/ # ps | grep -r "com.example.testpor" (standard input):u0_a65 30209 1662 1006360 48836 ep_poll aae7b2d8 S com.example.testpor2、adb shell cat /proc/30209 /status | grep Uid
Uid: 10065 10065 10065 10065系统中会有多个用户 (User，即手机里的主机、访客等多用户), 每个用户也有一个唯一的 ID 值, 称为"UserId"
在初始化或安装的时候就决定了
Pid就是各进程的身份标识,程序一运行系统就会自动分配给进程一个独一无二的PID。进程中止后PID被系统回收，可能会被继续分配给新运行的程序，但是在android系统中一般不会把已经kill掉的进程ID重新分配给新的进程，新产生进程的进程号，一般比产生之前所有的进程号都要大。
