Android系统应用信息中存储和缓存的计算方法-优快云博客

本文详细解析了Android应用存储空间的计算方式，包括内部存储和SD卡存储的占用情况，并深入探讨了Android 4.2源代码中相关函数的具体实现。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

进行例如以下操作：

设置->应用->选择一个应用->应用信息

会到达例如以下界面：

能够看到这个应用占用的磁盘空间。

先说结果，这几项会计算哪些文件（夹）。

1.应用，由三项相加组成

/data/data/com.myapp/lib，即so库文件夹大小
/data/app/com.myapp-1.apk，原始apk文件的复制
/data/dalvik-cache/data@app@com.myapp-1.apk@classes.dex，dalvik虚拟机对dex文件的缓存

2.USB存储（应用）。把程序装到（或移到）sd卡后的大小。/sdcard/Android/...，參考“应用”项。

3.数据 = /data/data/com.myapp/文件夹大小 - cache子文件夹大小 - lib子文件夹大小

4.SD 卡 = /sdcard/Android/data/com.myapp/文件夹大小 - /sdcard/Android/data/com.myapp/cache文件夹大小

（总计是以上4个之和）

5.缓存 = /data/data/com.myapp/cache文件夹大小 + /sdcard/Android/data/com.myapp/cache文件夹大小

以下是分析Android4.2源代码怎么做的。比較具体说分析过程，会累赘些，授之以渔吧。

依据应用信息的界面Settings这个名字，推測到源代码

android4.2/packages/apps/Settings/src/com/android/settings/applications/InstalledAppDetails.java

负责，相应的xml是

android4.2/packages/apps/Settings/res/layout/installed_app_details.xml

刷新磁盘占用大小的函数是

InstalledAppDetaileds.refreshSizeInfo()

依据代码线索反查

mDataSize.setText(getSizeStr(dataSize));

long dataSize = mAppEntry.dataSize;

mAppEntry = mState.getEntry(packageName);

mState.requestSize(mAppEntry.info.packageName);

ApplicationsState mState

android4.2/packages/apps/Settings/src/com/android/settings/applications/ApplicationState.java

mPm.getPackageSizeInfo(packageName, mBackgroundHandler.mStatsObserver);

final PackageManager mPm

android4.2/frameworks/base/core/java/android/app/ApplicationPackageManager.java

public void getPackageSizeInfo(String packageName, int userHandle,
IPackageStatsObserver observer) {

mPM.getPackageSizeInfo(packageName, userHandle, observer);

private final IPackageManager mPM;

IPackageManager是个接口。用查找文件内容的方式搜索它的实现，依据java语法，可用keyword“extends IPackageManager”

用shell命令行可得到这种结果：

liuhx@uc ~/Desktop/android4.2 $ grep -rnsw "extends IPackageManager" *
frameworks/base/services/java/com/android/server/pm/PackageManagerService.java:172:public class PackageManagerService extends IPackageManager.Stub {

android4.2/frameworks/base/services/java/com/android/server/pm/PackageManagerService.java

public void getPackageSizeInfo(

Message msg = mHandler.obtainMessage(INIT_COPY);
msg.obj = new MeasureParams(stats, observer);
mHandler.sendMessage(msg);

内部类class MeasureParams

void handleStartCopy() throws RemoteException {

mSuccess = getPackageSizeInfoLI(mStats.packageName, mStats.userHandle, mStats);

getPackageSizeInfoLI函数

int res = mInstaller.getSizeInfo(packageName, userHandle, p.mPath, publicSrcDir,
asecPath, pStats);

final Installer mInstaller

frameworks/base/services/java/com/android/server/pm/Installer.java

public int getSizeInfo(

String s = transaction(builder.toString());

private synchronized String transaction(String cmd) {

if (!writeCommand(cmd)) {

private boolean writeCommand(String _cmd)

mOut.write(buf, 0, 2);
mOut.write(cmd, 0, len);

OutputStream mOut;

LocalSocketAddress address = new LocalSocketAddress("installd",
LocalSocketAddress.Namespace.RESERVED);
mSocket.connect(address);
mOut = mSocket.getOutputStream();

到此非常无语。用socket的方式来通信。

查找文件内容。keyword为 "installd"。注意包括双引號

得到结果：

liuhx@uc ~/Desktop/android4.2 $ grep -rnsw "\"installd\"" *
cts/tools/device-setup/TestDeviceSetup/src/android/tests/getinfo/RootProcessScanner.java:33: "installd",
frameworks/base/services/java/com/android/server/pm/Installer.java:51: LocalSocketAddress address = new LocalSocketAddress("installd",
frameworks/base/cmds/installd/installd.h:18:#define LOG_TAG "installd"
frameworks/base/cmds/installd/installd.h:49:#define SOCKET_PATH "installd"
sdk/files/ant/build.xml:1355: <condition property="tested.project.install.target" value="installi" else="installd">
sdk/files/ant/build.xml:1392: <target name="installd" depends="-set-debug-files, install"

frameworks/base/cmds/installd/installd.h

int get_size(const char *pkgname, int persona, const char *apkpath, const char *fwdlock_apkpath,
const char *asecpath, int64_t *codesize, int64_t *datasize, int64_t *cachesize,
int64_t *asecsize);

或

frameworks/base/cmds/installd/installd.c

static int do_get_size(char **arg, char reply[REPLY_MAX])

res = get_size(arg[0], atoi(arg[1]), arg[2], arg[3], arg[4],
&codesize, &datasize, &cachesize, &asecsize);

看到在installd.c没有实现get_size函数。

能够依据函数声明搜索文件内容，只是既然是c语言。那可能是把函数分离实现。

所以在installd.c的文件夹下，看到还有一个代码文件中实现了。

转载请注明出处：http://blog.youkuaiyun.com/hursing

frameworks/base/cmds/installd/commands.c

这里就是计算的源代码了。

int get_size(const char *pkgname, int persona, const char *apkpath,
             const char *fwdlock_apkpath, const char *asecpath,
             int64_t *_codesize, int64_t *_datasize, int64_t *_cachesize,
             int64_t* _asecsize)
{
    DIR *d;
    int dfd;
    struct dirent *de;
    struct stat s;
    char path[PKG_PATH_MAX];

    int64_t codesize = 0;
    int64_t datasize = 0;
    int64_t cachesize = 0;
    int64_t asecsize = 0;

        /* count the source apk as code -- but only if it's not
         * on the /system partition and its not on the sdcard.
         */
    if (validate_system_app_path(apkpath) &&
            strncmp(apkpath, android_asec_dir.path, android_asec_dir.len) != 0) {
        if (stat(apkpath, &s) == 0) {
            codesize += stat_size(&s);
        }
    }
        /* count the forward locked apk as code if it is given
         */
    if (fwdlock_apkpath != NULL && fwdlock_apkpath[0] != '!') {
        if (stat(fwdlock_apkpath, &s) == 0) {
            codesize += stat_size(&s);
        }
    }
        /* count the cached dexfile as code */
    if (!create_cache_path(path, apkpath)) {
        if (stat(path, &s) == 0) {
            codesize += stat_size(&s);
        }
    }

        /* add in size of any libraries */
    if (!create_pkg_path_in_dir(path, &android_app_lib_dir, pkgname, PKG_DIR_POSTFIX)) {
        d = opendir(path);
        if (d != NULL) {
            dfd = dirfd(d);
            codesize += calculate_dir_size(dfd);
            closedir(d);
        }
    }

        /* compute asec size if it is given
         */
    if (asecpath != NULL && asecpath[0] != '!') {
        if (stat(asecpath, &s) == 0) {
            asecsize += stat_size(&s);
        }
    }

    if (create_pkg_path(path, pkgname, PKG_DIR_POSTFIX, persona)) {
        goto done;
    }

    d = opendir(path);
    if (d == NULL) {
        goto done;
    }
    dfd = dirfd(d);

    /* most stuff in the pkgdir is data, except for the "cache"
     * directory and below, which is cache, and the "lib" directory
     * and below, which is code...
     */
    while ((de = readdir(d))) {
        const char *name = de->d_name;

        if (de->d_type == DT_DIR) {
            int subfd;
            int64_t statsize = 0;
            int64_t dirsize = 0;
                /* always skip "." and ".." */
            if (name[0] == '.') {
                if (name[1] == 0) continue;
                if ((name[1] == '.') && (name[2] == 0)) continue;
            }
            if (fstatat(dfd, name, &s, AT_SYMLINK_NOFOLLOW) == 0) {
                statsize = stat_size(&s);
            }
            subfd = openat(dfd, name, O_RDONLY | O_DIRECTORY);
            if (subfd >= 0) {
                dirsize = calculate_dir_size(subfd);
            }
            if(!strcmp(name,"lib")) {
                codesize += dirsize + statsize;
            } else if(!strcmp(name,"cache")) {
                cachesize += dirsize + statsize;
            } else {
                datasize += dirsize + statsize;
            }
        } else if (de->d_type == DT_LNK && !strcmp(name,"lib")) {
            // This is the symbolic link to the application's library
            // code.  We'll count this as code instead of data, since
            // it is not something that the app creates.
            if (fstatat(dfd, name, &s, AT_SYMLINK_NOFOLLOW) == 0) {
                codesize += stat_size(&s);
            }
        } else {
            if (fstatat(dfd, name, &s, AT_SYMLINK_NOFOLLOW) == 0) {
                datasize += stat_size(&s);
            }
        }
    }
    closedir(d);
done:
    *_codesize = codesize;
    *_datasize = datasize;
    *_cachesize = cachesize;
    *_asecsize = asecsize;
    return 0;
}

以上是计算了内部磁盘的占用。还不齐，还有线索：

PackageManagerService.java的内部类MeasureParams.handleStartCopy()函数：

void handleStartCopy() throws RemoteException {
            synchronized (mInstallLock) {
                mSuccess = getPackageSizeInfoLI(mStats.packageName, mStats.userHandle, mStats);
            }

            final boolean mounted;
            if (Environment.isExternalStorageEmulated()) {
                mounted = true;
            } else {
                final String status = Environment.getExternalStorageState();
                mounted = (Environment.MEDIA_MOUNTED.equals(status)
                        || Environment.MEDIA_MOUNTED_READ_ONLY.equals(status));
            }

            if (mounted) {
                final UserEnvironment userEnv = new UserEnvironment(mStats.userHandle);

                final File externalCacheDir = userEnv
                        .getExternalStorageAppCacheDirectory(mStats.packageName);
                final long externalCacheSize = mContainerService
                        .calculateDirectorySize(externalCacheDir.getPath());
                mStats.externalCacheSize = externalCacheSize;

                final File externalDataDir = userEnv
                        .getExternalStorageAppDataDirectory(mStats.packageName);
                long externalDataSize = mContainerService.calculateDirectorySize(externalDataDir
                        .getPath());

                if (externalCacheDir.getParentFile().equals(externalDataDir)) {
                    externalDataSize -= externalCacheSize;
                }
                mStats.externalDataSize = externalDataSize;

                final File externalMediaDir = userEnv
                        .getExternalStorageAppMediaDirectory(mStats.packageName);
                mStats.externalMediaSize = mContainerService
                        .calculateDirectorySize(externalMediaDir.getPath());

                final File externalObbDir = userEnv
                        .getExternalStorageAppObbDirectory(mStats.packageName);
                mStats.externalObbSize = mContainerService.calculateDirectorySize(externalObbDir
                        .getPath());
            }
        }

这里计算了sd卡上的磁盘占用。

内部磁盘的计算，是用linux的stat函数。

一些文件夹和文件的常量，定义在installd.h

认真看代码，则会得到文章开头的结果。

代码计算的结果得到的是占用磁盘的大小。但因为存储器有"4K对齐”的概念，所以占用磁盘大小不等于文件大小。

比如一个实际为2.98K的文件。会在应用信息里显示为4K。

搜索源代码的还有一个方法是在线搜索。http://androidxref.com/

转载请注明出处：http://blog.youkuaiyun.com/hursing