Android6.0 MountService和vold详解（三） vold SD卡、otg
16lz
2021-01-26
既上面两篇博客，继续分析vold、对外置SD卡和OTG的分析：
一、process_config函数
上一篇我们再main函数中分析了VolumeManager的start函数，这次我们接下来分析process_config函数
static int process_config(VolumeManager *vm) { std::string path(android::vold::DefaultFstabPath()); fstab = fs_mgr_read_fstab(path.c_str()); if (!fstab) { PLOG(ERROR) << "Failed to open default fstab " << path; return -1; } /* Loop through entries looking for ones that vold manages */ bool has_adoptable = false; for (int i = 0; i < fstab->num_entries; i++) { if (fs_mgr_is_voldmanaged(&fstab->recs[i])) { if (fs_mgr_is_nonremovable(&fstab->recs[i])) { LOG(WARNING) << "nonremovable no longer supported; ignoring volume"; continue; } std::string sysPattern(fstab->recs[i].blk_device); std::string nickname(fstab->recs[i].label); int flags = 0; if (fs_mgr_is_encryptable(&fstab->recs[i])) { flags |= android::vold::Disk::Flags::kAdoptable; has_adoptable = true; } if (fs_mgr_is_noemulatedsd(&fstab->recs[i]) || property_get_bool("vold.debug.default_primary", false)) { flags |= android::vold::Disk::Flags::kDefaultPrimary; } PLOG(ERROR) << "process_config:" <<" sysPattern:" << sysPattern <<" nickname:" << nickname<<" end"; vm->addDiskSource(std::shared_ptr( new VolumeManager::DiskSource(sysPattern, nickname, flags))); } } property_set("vold.has_adoptable", has_adoptable ? "1" : "0"); return 0;} process_config函数就是遍历fstab文件，下面就是fstab文件
# Android fstab file.# # The filesystem that contains the filesystem checker binary (typically /system) cannot# specify MF_CHECK, and must come before any filesystems that do specify MF_CHECK/dev/block/platform/comip-mmc.1/by-name/system /system ext4 ro,barrier=1 wait/dev/block/platform/comip-mmc.1/by-name/cache /cache ext4 noatime,nosuid,nodev,barrier=1,data=ordered wait,check/dev/block/platform/comip-mmc.1/by-name/userdata /data ext4 noatime,nosuid,nodev,barrier=1,data=ordered,noauto_da_alloc wait,check,encryptable=footer#/dev/block/platform/comip-mmc.1/by-name/amt /amt ext4 rw wait/devices/platform/comip-mmc.0/mmc_host/mmc1/* auto vfat defaults voldmanaged=sdcard1:auto,encryptable=false/devices/a0400000.usb_hcd/usb1/* auto vfat defaults voldmanaged=usbotg:auto,noemulatedsd/dev/block/mmcblk1p1 /sdcard vfat defaults recoveryonly/dev/block/platform/comip-mmc.1/by-name/kernel /kernel emmc defaults defaults/dev/block/platform/comip-mmc.1/by-name/ramdisk /boot emmc defaults defaults/dev/block/platform/comip-mmc.1/by-name/ramdisk_recovery /recovery emmc defaults defaults/dev/block/platform/comip-mmc.1/by-name/ramdisk_amt1 /ramdisk_amt1 emmc defaults defaults/dev/block/platform/comip-mmc.1/by-name/ramdisk_amt3 /ramdisk_amt3 emmc defaults defaults/dev/block/platform/comip-mmc.1/by-name/kernel_recovery /kernel_recovery emmc defaults defaults/dev/block/platform/comip-mmc.1/by-name/logo /logo emmc defaults defaults/dev/block/platform/comip-mmc.1/by-name/misc /misc emmc defaults defaults/dev/block/platform/comip-mmc.1/by-name/fota /fota emmc defaults defaults/dev/block/platform/comip-mmc.1/by-name/modemarm /modemarm emmc defaults defaults/dev/block/platform/comip-mmc.1/by-name/modemdsp /modemdsp emmc defaults defaults/dev/block/mmcblk0boot0 /uboot emmc defaults defaults/dev/block/platform/comip-mmc.1/by-name/lcboot /lcboot emmc defaults defaults/dev/block/zram0 none swap defaults zramsize=268435456 简单说上面的函数就是遍历fstab文件中有voldmanaged的那项，然后新建一个DiskSource对象，加入volumeManager。
我们再来看看上面加的log的打印
01-01 09:00:25.347 164 164 E vold :process_config: sysPattern:/devices/platform/comip-mmc.0/mmc_host/mmc1/* nickname:sdcard1 end: Success01-01 09:00:25.347 164 164 E vold :process_config: sysPattern:/devices/a0400000.usb_hcd/usb1/* nickname:usbotg end: Success一个nickname是sdcard1，另一个是usbotg。
二、Disk的创建
下面我们来看下kernel对sdcard的检测到之后，通知vold后，vold如何操作。
kernel收到插入sd或者otg的event后，先到NetlinkHandler的onEvent函数，这个在之前分析android5.1的时候分析过了，不再详述。
void NetlinkHandler::onEvent(NetlinkEvent *evt) { VolumeManager *vm = VolumeManager::Instance(); const char *subsys = evt->getSubsystem(); if (!subsys) { SLOGW("No subsystem found in netlink event"); return; } if (!strcmp(subsys, "block")) { vm->handleBlockEvent(evt); }}然后就到VolumeManager的handleBlockEvent函数，我们先看add的处理
void VolumeManager::handleBlockEvent(NetlinkEvent *evt) { std::lock_guard lock(mLock); if (mDebug) { LOG(VERBOSE) << "----------------"; LOG(VERBOSE) << "handleBlockEvent with action " << (int) evt->getAction(); evt->dump(); } std::string eventPath(evt->findParam("DEVPATH")); std::string devType(evt->findParam("DEVTYPE")); if (devType != "disk") return; int major = atoi(evt->findParam("MAJOR")); int minor = atoi(evt->findParam("MINOR")); dev_t device = makedev(major, minor); switch (evt->getAction()) { case NetlinkEvent::Action::kAdd: { for (auto source : mDiskSources) {//把之前在process_config中加入的disksources的资源遍历，看是否有匹配的 if (source->matches(eventPath)) { // For now, assume that MMC devices are SD, and that // everything else is USB int flags = source->getFlags(); if (major == kMajorBlockMmc) { flags |= android::vold::Disk::Flags::kSd; } else { flags |= android::vold::Disk::Flags::kUsb; } auto disk = new android::vold::Disk(eventPath, device, source->getNickname(), flags); disk->create(); mDisks.push_back(std::shared_ptr(disk)); break; } } break; } 遍历之前在process_config函数中放入VolumeManager的DiskSource，看看是否有匹配的。匹配的新建一个Disk对象，放入VolumeManager的mDisks中。并且调用disk的create函数：
status_t Disk::create() { CHECK(!mCreated); mCreated = true; notifyEvent(ResponseCode::DiskCreated, StringPrintf("%d", mFlags)); readMetadata(); readPartitions(); return OK;}在create函数中，先给MountService发送了DiskCreated的消息，我们看看MountService是如何处理的？
在MountService中在onEventLocked中对DiskCreated处理，也是放在mDisks变量中
private boolean onEventLocked(int code, String raw, String[] cooked) { switch (code) { case VoldResponseCode.DISK_CREATED: { if (cooked.length != 3) break; final String id = cooked[1]; int flags = Integer.parseInt(cooked[2]); if (SystemProperties.getBoolean(StorageManager.PROP_FORCE_ADOPTABLE, false) || mForceAdoptable) { flags |= DiskInfo.FLAG_ADOPTABLE; } mDisks.put(id, new DiskInfo(id, flags)); break; }下面继续分析disk的create函数,看Disk::readMetadata函数
status_t Disk::readMetadata() { mSize = -1; mLabel.clear(); int fd = open(mDevPath.c_str(), O_RDONLY | O_CLOEXEC); if (fd != -1) { if (ioctl(fd, BLKGETSIZE64, &mSize)) { mSize = -1; } close(fd); } switch (major(mDevice)) { case kMajorBlockScsiA: case kMajorBlockScsiB: case kMajorBlockScsiC: case kMajorBlockScsiD: case kMajorBlockScsiE: case kMajorBlockScsiF: case kMajorBlockScsiG: case kMajorBlockScsiH: case kMajorBlockScsiI: case kMajorBlockScsiJ: case kMajorBlockScsiK: case kMajorBlockScsiL: case kMajorBlockScsiM: case kMajorBlockScsiN: case kMajorBlockScsiO: case kMajorBlockScsiP: { std::string path(mSysPath + "/device/vendor"); std::string tmp; if (!ReadFileToString(path, &tmp)) { PLOG(WARNING) << "Failed to read vendor from " << path; return -errno; } mLabel = tmp; break; } case kMajorBlockMmc: { std::string path(mSysPath + "/device/manfid"); std::string tmp; if (!ReadFileToString(path, &tmp)) { PLOG(WARNING) << "Failed to read manufacturer from " << path; return -errno; } uint64_t manfid = strtoll(tmp.c_str(), nullptr, 16); // Our goal here is to give the user a meaningful label, ideally // matching whatever is silk-screened on the card. To reduce // user confusion, this list doesn't contain white-label manfid. switch (manfid) { case 0x000003: mLabel = "SanDisk"; break; case 0x00001b: mLabel = "Samsung"; break; case 0x000028: mLabel = "Lexar"; break; case 0x000074: mLabel = "Transcend"; break; } break; } default: { LOG(WARNING) << "Unsupported block major type" << major(mDevice); return -ENOTSUP; } } notifyEvent(ResponseCode::DiskSizeChanged, StringPrintf("%" PRId64, mSize)); notifyEvent(ResponseCode::DiskLabelChanged, mLabel); notifyEvent(ResponseCode::DiskSysPathChanged, mSysPath); return OK;}这个函数主要获取一些参数，然后发送给MountService,而MountService的处理如下，主要是把disk的参数修改下
case VoldResponseCode.DISK_SIZE_CHANGED: { if (cooked.length != 3) break; final DiskInfo disk = mDisks.get(cooked[1]); if (disk != null) { disk.size = Long.parseLong(cooked[2]); } break; } case VoldResponseCode.DISK_LABEL_CHANGED: { final DiskInfo disk = mDisks.get(cooked[1]); if (disk != null) { final StringBuilder builder = new StringBuilder(); for (int i = 2; i < cooked.length; i++) { builder.append(cooked[i]).append(' '); } disk.label = builder.toString().trim(); } break; } case VoldResponseCode.DISK_SCANNED: { if (cooked.length != 2) break; final DiskInfo disk = mDisks.get(cooked[1]); if (disk != null) { onDiskScannedLocked(disk); } break; } case VoldResponseCode.DISK_SYS_PATH_CHANGED: { if (cooked.length != 3) break; final DiskInfo disk = mDisks.get(cooked[1]); if (disk != null) { disk.sysPath = cooked[2]; } br下面我们继续看Disk的readParttitions函数
status_t Disk::readPartitions() { int8_t maxMinors = getMaxMinors(); if (maxMinors < 0) { return -ENOTSUP; } destroyAllVolumes(); // Parse partition table std::vector cmd; cmd.push_back(kSgdiskPath); cmd.push_back("--android-dump"); cmd.push_back(mDevPath); std::vector output; status_t res = ForkExecvp(cmd, output); if (res != OK) { LOG(WARNING) << "sgdisk failed to scan " << mDevPath; notifyEvent(ResponseCode::DiskScanned); mJustPartitioned = false; return res; } Table table = Table::kUnknown; bool foundParts = false; for (auto line : output) { char* cline = (char*) line.c_str(); char* token = strtok(cline, kSgdiskToken); if (token == nullptr) continue; if (!strcmp(token, "DISK")) { const char* type = strtok(nullptr, kSgdiskToken); if (!strcmp(type, "mbr")) { table = Table::kMbr; } else if (!strcmp(type, "gpt")) { table = Table::kGpt; } } else if (!strcmp(token, "PART")) { foundParts = true; int i = strtol(strtok(nullptr, kSgdiskToken), nullptr, 10); if (i <= 0 || i > maxMinors) { LOG(WARNING) << mId << " is ignoring partition " << i << " beyond max supported devices"; continue; } dev_t partDevice = makedev(major(mDevice), minor(mDevice) + i); if (table == Table::kMbr) { const char* type = strtok(nullptr, kSgdiskToken); switch (strtol(type, nullptr, 16)) { case 0x06: // FAT16 case 0x0b: // W95 FAT32 (LBA) case 0x0c: // W95 FAT32 (LBA) case 0x0e: // W95 FAT16 (LBA) createPublicVolume(partDevice); break; } } else if (table == Table::kGpt) { const char* typeGuid = strtok(nullptr, kSgdiskToken); const char* partGuid = strtok(nullptr, kSgdiskToken); if (!strcasecmp(typeGuid, kGptBasicData)) { createPublicVolume(partDevice); } else if (!strcasecmp(typeGuid, kGptAndroidExpand)) { createPrivateVolume(partDevice, partGuid); } } } } // Ugly last ditch effort, treat entire disk as partition if (table == Table::kUnknown || !foundParts) { LOG(WARNING) << mId << " has unknown partition table; trying entire device"; std::string fsType; std::string unused; if (ReadMetadataUntrusted(mDevPath, fsType, unused, unused) == OK) { createPublicVolume(mDevice); } else { LOG(WARNING) << mId << " failed to identify, giving up"; } } notifyEvent(ResponseCode::DiskScanned); mJustPartitioned = false; return OK;} 这个函数就主要会createPublicVolume或者createPrivateVolume，然后会通知MountService DiskScanned消息。先看上层对这个消息的处理。
case VoldResponseCode.DISK_SCANNED: { if (cooked.length != 2) break; final DiskInfo disk = mDisks.get(cooked[1]); if (disk != null) { onDiskScannedLocked(disk); } break; }找到DiskInfo后，调用了onDiskScannedLocked函数
private void onDiskScannedLocked(DiskInfo disk) { int volumeCount = 0; for (int i = 0; i < mVolumes.size(); i++) { final VolumeInfo vol = mVolumes.valueAt(i); if (Objects.equals(disk.id, vol.getDiskId())) { volumeCount++; } } final Intent intent = new Intent(DiskInfo.ACTION_DISK_SCANNED); intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY_BEFORE_BOOT); intent.putExtra(DiskInfo.EXTRA_DISK_ID, disk.id); intent.putExtra(DiskInfo.EXTRA_VOLUME_COUNT, volumeCount); mHandler.obtainMessage(H_INTERNAL_BROADCAST, intent).sendToTarget(); final CountDownLatch latch = mDiskScanLatches.remove(disk.id); if (latch != null) { latch.countDown(); } disk.volumeCount = volumeCount; mCallbacks.notifyDiskScanned(disk, volumeCount); }这个函数中发送了广播，然后通知了回调。
三、CreatePublicVolume
接下来我们主要分析下createPublicVolume和createPrivateVolume两个函数。
先看createPublicVolume函数：
void Disk::createPublicVolume(dev_t device) { auto vol = std::shared_ptr(new PublicVolume(device)); if (mJustPartitioned) { LOG(DEBUG) << "Device just partitioned; silently formatting"; vol->setSilent(true); vol->create(); vol->format("auto"); vol->destroy(); vol->setSilent(false); } mVolumes.push_back(vol); vol->setDiskId(getId()); vol->create();} 这个函数中，先新建了一个PublicVolume，然后让如了Disk的mVolumes中，最后调用了volume的create函数
status_t VolumeBase::create() { CHECK(!mCreated); mCreated = true; status_t res = doCreate(); notifyEvent(ResponseCode::VolumeCreated, StringPrintf("%d \"%s\" \"%s\"", mType, mDiskId.c_str(), mPartGuid.c_str())); setState(State::kUnmounted); return res;}create函数又回调之前分析过得，给上层发送VolumeCreated消息
只是这个create的doCreate函数在PublicVolume中有实现：
status_t PublicVolume::doCreate() { return CreateDeviceNode(mDevPath, mDevice);}然后往MountService发送VolumeCreated后，MountService会往vold发送mount。
status_t VolumeBase::mount() { if ((mState != State::kUnmounted) && (mState != State::kUnmountable)) { LOG(WARNING) << getId() << " mount requires state unmounted or unmountable"; return -EBUSY; } setState(State::kChecking); status_t res = doMount(); if (res == OK) { setState(State::kMounted); } else { setState(State::kUnmountable); } return res;}在Volumebase执行mount函数的时候，到doMount是一个虚函数会到PublicVolume的doMount函数
status_t PublicVolume::doMount() { // TODO: expand to support mounting other filesystems readMetadata(); if (mFsType != "vfat") { LOG(ERROR) << getId() << " unsupported filesystem " << mFsType; return -EIO; } if (vfat::Check(mDevPath)) { LOG(ERROR) << getId() << " failed filesystem check"; return -EIO; } // Use UUID as stable name, if available std::string stableName = getId(); if (!mFsUuid.empty()) { stableName = mFsUuid; } mRawPath = StringPrintf("/mnt/media_rw/%s", stableName.c_str());//挂载地址，stableName为uuid mFuseDefault = StringPrintf("/mnt/runtime/default/%s", stableName.c_str()); mFuseRead = StringPrintf("/mnt/runtime/read/%s", stableName.c_str()); mFuseWrite = StringPrintf("/mnt/runtime/write/%s", stableName.c_str()); setInternalPath(mRawPath); if (getMountFlags() & MountFlags::kVisible) { setPath(StringPrintf("/storage/%s", stableName.c_str())); } else { setPath(mRawPath); } if (fs_prepare_dir(mRawPath.c_str(), 0700, AID_ROOT, AID_ROOT) || fs_prepare_dir(mFuseDefault.c_str(), 0700, AID_ROOT, AID_ROOT) || fs_prepare_dir(mFuseRead.c_str(), 0700, AID_ROOT, AID_ROOT) || fs_prepare_dir(mFuseWrite.c_str(), 0700, AID_ROOT, AID_ROOT)) { PLOG(ERROR) << getId() << " failed to create mount points"; return -errno; } if (vfat::Mount(mDevPath, mRawPath, false, false, false,//挂载sd卡 AID_MEDIA_RW, AID_MEDIA_RW, 0007, true)) { PLOG(ERROR) << getId() << " failed to mount " << mDevPath; return -EIO; } if (getMountFlags() & MountFlags::kPrimary) { initAsecStage(); } if (!(getMountFlags() & MountFlags::kVisible)) { // Not visible to apps, so no need to spin up FUSE return OK; } dev_t before = GetDevice(mFuseWrite); if (!(mFusePid = fork())) { if (getMountFlags() & MountFlags::kPrimary) {//开启fuse文件系统，让storage下面的sd卡读取直接到mnt下挂载的地址 if (execl(kFusePath, kFusePath, "-u", "1023", // AID_MEDIA_RW "-g", "1023", // AID_MEDIA_RW "-U", std::to_string(getMountUserId()).c_str(), "-w", mRawPath.c_str(), stableName.c_str(), NULL)) { PLOG(ERROR) << "Failed to exec"; } } else { if (execl(kFusePath, kFusePath, "-u", "1023", // AID_MEDIA_RW "-g", "1023", // AID_MEDIA_RW "-U", std::to_string(getMountUserId()).c_str(), mRawPath.c_str(), stableName.c_str(), NULL)) { PLOG(ERROR) << "Failed to exec"; } } LOG(ERROR) << "FUSE exiting"; _exit(1); } if (mFusePid == -1) { PLOG(ERROR) << getId() << " failed to fork"; return -errno; } while (before == GetDevice(mFuseWrite)) { LOG(VERBOSE) << "Waiting for FUSE to spin up..."; usleep(50000); // 50ms } return OK;}这个函数我们先看readMetadata函数，会读取各个参数，然后发送到MountService中，在上层会把这些参数保存在DiskInfo中
status_t PublicVolume::readMetadata() { status_t res = ReadMetadataUntrusted(mDevPath, mFsType, mFsUuid, mFsLabel); notifyEvent(ResponseCode::VolumeFsTypeChanged, mFsType); notifyEvent(ResponseCode::VolumeFsUuidChanged, mFsUuid); notifyEvent(ResponseCode::VolumeFsLabelChanged, mFsLabel); return res;}再看下面这段代码，当uuid不为空，statbleName为uuid
if (!mFsUuid.empty()) { stableName = mFsUuid; }doMount就是把sd卡设备挂载到mnt/media_rw下面创建一个uuid的目录。然后在Storage下面也有一个uuid的目录，用fuse文件系统连接起来。大家可以看上面代码的注释。
四、createPrivateVolume
下面我们再来看Disk的createPrivateVolume方法
void Disk::createPrivateVolume(dev_t device, const std::string& partGuid) { std::string normalizedGuid; if (NormalizeHex(partGuid, normalizedGuid)) { LOG(WARNING) << "Invalid GUID " << partGuid; return; } std::string keyRaw; if (!ReadFileToString(BuildKeyPath(normalizedGuid), &keyRaw)) { PLOG(ERROR) << "Failed to load key for GUID " << normalizedGuid; return; } LOG(DEBUG) << "Found key for GUID " << normalizedGuid; auto vol = std::shared_ptr(new PrivateVolume(device, keyRaw)); if (mJustPartitioned) { LOG(DEBUG) << "Device just partitioned; silently formatting"; vol->setSilent(true); vol->create(); vol->format("auto"); vol->destroy(); vol->setSilent(false); } mVolumes.push_back(vol); vol->setDiskId(getId()); vol->setPartGuid(partGuid); vol->create();} 和PublicVolume类似我们就直接看privateVolume的doMount函数
tatus_t PrivateVolume::doMount() { if (readMetadata()) { LOG(ERROR) << getId() << " failed to read metadata"; return -EIO; } mPath = StringPrintf("/mnt/expand/%s", mFsUuid.c_str());//mount地址 setPath(mPath); if (PrepareDir(mPath, 0700, AID_ROOT, AID_ROOT)) { PLOG(ERROR) << getId() << " failed to create mount point " << mPath; return -EIO; } if (mFsType == "ext4") {//fs类型 int res = ext4::Check(mDmDevPath, mPath); if (res == 0 || res == 1) { LOG(DEBUG) << getId() << " passed filesystem check"; } else { PLOG(ERROR) << getId() << " failed filesystem check"; return -EIO; } if (ext4::Mount(mDmDevPath, mPath, false, false, true)) { PLOG(ERROR) << getId() << " failed to mount"; return -EIO; } } else if (mFsType == "f2fs") { int res = f2fs::Check(mDmDevPath); if (res == 0) { LOG(DEBUG) << getId() << " passed filesystem check"; } else { PLOG(ERROR) << getId() << " failed filesystem check"; return -EIO; } if (f2fs::Mount(mDmDevPath, mPath)) { PLOG(ERROR) << getId() << " failed to mount"; return -EIO; } } else { LOG(ERROR) << getId() << " unsupported filesystem " << mFsType; return -EIO; } LOG(VERBOSE) << "Starting restorecon of " << mPath; // TODO: find a cleaner way of waiting for restorecon to finish property_set("selinux.restorecon_recursive", ""); property_set("selinux.restorecon_recursive", mPath.c_str()); char value[PROPERTY_VALUE_MAX]; while (true) { property_get("selinux.restorecon_recursive", value, ""); if (strcmp(mPath.c_str(), value) == 0) { break; } sleep(1); LOG(VERBOSE) << "Waiting for restorecon..."; } LOG(VERBOSE) << "Finished restorecon of " << mPath; // Verify that common directories are ready to roll if (PrepareDir(mPath + "/app", 0771, AID_SYSTEM, AID_SYSTEM) ||//创建了各个目录 PrepareDir(mPath + "/user", 0711, AID_SYSTEM, AID_SYSTEM) || PrepareDir(mPath + "/media", 0770, AID_MEDIA_RW, AID_MEDIA_RW) || PrepareDir(mPath + "/media/0", 0770, AID_MEDIA_RW, AID_MEDIA_RW) || PrepareDir(mPath + "/local", 0751, AID_ROOT, AID_ROOT) || PrepareDir(mPath + "/local/tmp", 0771, AID_SHELL, AID_SHELL)) { PLOG(ERROR) << getId() << " failed to prepare"; return -EIO; } // Create a new emulated volume stacked above us, it will automatically // be destroyed during unmount std::string mediaPath(mPath + "/media");//只把media传过去，fuse给storage auto vol = std::shared_ptr( new EmulatedVolume(mediaPath, mRawDevice, mFsUuid)); addVolume(vol); vol->create(); return OK;} 当然最后完成后setState（kMounted）会通知MountService，上层只会调用onVolumeStateChangedLocked会发送广播并且通知回调。
这样整个vold主要的流程分析完了，当然这边没有分析fuse的相关内容，等以后再分析吧！
更多相关文章
- Android(安卓)display架构分析(5-8)
- android 多线程 UI 入门
- Android中Framgment的构造函数
- Android7.0启动SystemServer进程
- Surface与SurfaceHolder.Callback
- Android(安卓)图片加载框架Glide缓存原理源码分析
- Android(安卓)-- 网络管理分析
- Android事件分发中的ViewGroup
- HAL层开发基础 ＆＆ Android(安卓)HAL module执行过程分析