修改Android系统的软件版本号等

在Android系统中有几个版本号经常遇到，有时还要做特殊处理。下面整理一下，这些都保留在文件系统的/system/build.prop文件里，build.prop相当于Windows下的注册表，这个文件内定义了系统初始（或永久）的一些参数属性、功能的开放等。

下面的代码均是基于Android8.1分析。

系统设置--关于手机--版本号

1、在系统设置代码中搜索“版本号”，AndroidStudio中全局搜索快捷键“Ctrl+Shift+f”。

"版本号"

全局搜索“build_number”，找到com.android.settings.deviceinfo.BuildNumberPreferenceController类。

private static final String KEY_BUILD_NUMBER = "build_number";

    public void displayPreference(PreferenceScreen screen) {
        super.displayPreference(screen);
        final Preference preference = screen.findPreference(KEY_BUILD_NUMBER);
        if (preference != null) {
            try {
                preference.setSummary(BidiFormatter.getInstance().unicodeWrap(Build.DISPLAY));
                preference.setEnabled(true);
            } catch (Exception e) {
                preference.setSummary(R.string.device_info_default);
            }
        }
    }

此时关键就是找到Build.DISPLAY。

这里是定义在android.os.Build类中，该类位于frameworks/base/core/java目录下，如下：

    /** A build ID string meant for displaying to the user */
    public static final String DISPLAY = getString("ro.build.display.id");

    private static String getString(String property) {
        return SystemProperties.get(property, UNKNOWN);
    }

我们看到了DISPLAY是Build类中的静态变量，表示“ro.build.display.id”的属性值。

2、此时我们就需要知道“ro.build.display.id”属性值是在哪里定义的。

这里我们在Android源码环境下全局搜索“ro.build.display.id”，命令：grep -r "ro.build.display.id" ./

其实只在build目录下搜索即可，build存放系统编译规则。

在build/make/tools/buildinfo.sh文件中搜索出：

echo "ro.build.display.id=$BUILD_DISPLAY_ID"

我们继续在build目录下，搜索“BUILD_DISPLAY_ID”，命令：grep -r "BUILD_DISPLAY_ID"。在文件build/make/core/MakeFile中搜索出：

# Display parameters shown under Settings -> About Phone
ifeq ($(TARGET_BUILD_VARIANT),user)
  # User builds should show:
  # release build number or branch.buld_number non-release builds

  # Dev. branches should have DISPLAY_BUILD_NUMBER set
  ifeq (true,$(DISPLAY_BUILD_NUMBER))
    BUILD_DISPLAY_ID := $(BUILD_ID).$(BUILD_NUMBER_FROM_FILE) $(BUILD_KEYS)
  else
    BUILD_DISPLAY_ID := $(BUILD_ID) $(BUILD_KEYS)
  endif
else
  # Non-user builds should show detailed build information
  BUILD_DISPLAY_ID := $(build_desc)
endif

BUILD_ID定义在build/make/core/build_id.mk中，如下：

# BUILD_ID is usually used to specify the branch name
# (like "MAIN") or a branch name and a release candidate
# (like "CRB01").  It must be a single word, and is
# capitalized by convention.

export BUILD_ID=OPM1.171019.011

BUILD_NUMBER_FROM_FILE定义在build/make/core/main.mk中，如下：

BUILD_NUMBER_FROM_FILE := $$(cat $(OUT_DIR)/build_number.txt)

这里OUT_DIR就是out目录，build_number.txt就是在out目录下生成的一个文件，内容如下：

eng.sgf.20180421.152052

这里是eng版本。

BUILD_KEYS定义在build/make/core/MakeFile中，表示系统签名，test-keys只适用于开发阶段。如下：

# The "test-keys" tag marks builds signed with the old test keys,
# which are available in the SDK.  "dev-keys" marks builds signed with
# non-default dev keys (usually private keys from a vendor directory).
# Both of these tags will be removed and replaced with "release-keys"
# when the target-files is signed in a post-build step.
ifeq ($(DEFAULT_SYSTEM_DEV_CERTIFICATE),build/target/product/security/testkey)
BUILD_KEYS := test-keys
else
BUILD_KEYS := dev-keys
endif

如果不是user版本，BUILD_DISPLAY_ID的取值就是$(build_desc)

# A human-readable string that descibes this build in detail.
build_desc := $(TARGET_PRODUCT)-$(TARGET_BUILD_VARIANT) $(PLATFORM_VERSION) $(BUILD_ID) $(BUILD_NUMBER_FROM_FILE) $(BUILD_VERSION_TAGS)

BUILD_NUMBER定义在build/make/core/version_default.mk文件中，如下：

ifndef BUILD_NUMBER
  # BUILD_NUMBER should be set to the source control value that
  # represents the current state of the source code.  E.g., a
  # perforce changelist number or a git hash.  Can be an arbitrary string
  # (to allow for source control that uses something other than numbers),
  # but must be a single word and a valid file name.
  #
  # If no BUILD_NUMBER is set, create a useful "I am an engineering build
  # from this date/time" value.  Make it start with a non-digit so that
  # anyone trying to parse it as an integer will probably get "0".
  BUILD_NUMBER := eng.$(shell echo $${USER:0:6}).$(shell $(DATE) +%Y%m%d.%H%M%S)
endif

总结：想要修改版本号，可以通过两个部分修改。

1、修改Java文件，直接写死；

2、修改编译系统，在device中修改。

https://blog.csdn.net/codingnotes/article/details/62222656

系统设置--蓝牙--手机名称

1、手机名称的修改，定位到LocalDeviceNameDialogFragment中，如下：

    @Override
    protected String getDeviceName() {
        if (mLocalAdapter != null && mLocalAdapter.isEnabled()) {
            return mLocalAdapter.getName();
        }
        return null;
    }

    @Override
    protected void setDeviceName(String deviceName) {
        mLocalAdapter.setName(deviceName);
    }

    private LocalBluetoothAdapter mLocalAdapter;

frameworks/base/packages/SettingsLib/src/com/android/settingslib/bluetooth/LocalBluetoothAdapter.java

    public String getName() {
        return mAdapter.getName();
    }

    /** This class does not allow direct access to the BluetoothAdapter. */
    private final BluetoothAdapter mAdapter;

frameworks/base/core/java/android/bluetooth/BluetoothAdapter.java

    public String getName() {
        try {
            return mManagerService.getName();
        } catch (RemoteException e) {Log.e(TAG, "", e);}
        return null;
    }

BluetoothManagerService.java

    public String getName() {
        mContext.enforceCallingOrSelfPermission(BLUETOOTH_PERM,
                                                "Need BLUETOOTH permission");

        if ((Binder.getCallingUid() != Process.SYSTEM_UID) &&
            (!checkIfCallerIsForegroundUser())) {
            Slog.w(TAG,"getName(): not allowed for non-active and non system user");
            return null;
        }

        try {
            mBluetoothLock.readLock().lock();
            if (mBluetooth != null) return mBluetooth.getName();
        } catch (RemoteException e) {
            Slog.e(TAG, "getName(): Unable to retrieve name remotely. Returning cached name", e);
        } finally {
            mBluetoothLock.readLock().unlock();
        }

        // mName is accessed from outside.
        // It alright without a lock. Here, bluetooth is off, no other thread is
        // changing mName
        return mName;
    }

mName = Settings.Secure.getString(mContentResolver, SECURE_SETTINGS_BLUETOOTH_NAME);

这里的bluetooth_name保存在/data/system/users/0/settings_secure.xml文件中。

在 Android6.0版本时，SettingsProvider被重构，Android 从性能、安全等方面考虑，把SettingsProvider 中原本保存在settings.db中的数据，目前全部保存在 XML 文件中。

具体修改地方：

device/qcom/common/bdroid_buildcfg.h

#define BTM_DEF_LOCAL_NAME   "Acuteag-P6"

MTK平台，修改device目录下custom.conf文件中的bluetooth.HostName的值。

热点--设置WLAN热点--修改名称

在Settings的WifiTetherSSIDPreferenceController类中，获取WiFiConfiguration的SSID。

    @Override
    public void displayPreference(PreferenceScreen screen) {
        super.displayPreference(screen);
        final WifiConfiguration config = mWifiManager.getWifiApConfiguration();
        if (config != null) {
            mSSID = config.SSID;
        } else {
            mSSID = DEFAULT_SSID;
        }
        ((ValidatedEditTextPreference) mPreference).setValidator(this);
        updateSsidDisplay((EditTextPreference) mPreference);
    }

在WiFiManager类中的getWifiApConfiguration()方法如下：

    public WifiConfiguration getWifiApConfiguration() {
        try {
            return mService.getWifiApConfiguration();
        } catch (RemoteException e) {
            throw e.rethrowFromSystemServer();
        }
    }

    IWifiManager mService;

如果不知道是哪个类继承IWiFiManager.Stub，可以搜索该字符串。

frameworks/opt/net/wifi/service/java/com/android/server/wifi/WifiServiceImpl.java

    @Override
    public WifiConfiguration getWifiApConfiguration() {
        enforceAccessPermission();
        int uid = Binder.getCallingUid();
        // only allow Settings UI to get the saved SoftApConfig
        if (!mWifiPermissionsUtil.checkConfigOverridePermission(uid)) {
            // random apps should not be allowed to read the user specified config
            throw new SecurityException("App not allowed to read or update stored WiFi Ap config "
                    + "(uid = " + uid + ")");
        }
        mLog.info("getWifiApConfiguration uid=%").c(uid).flush();
        return mWifiStateMachine.syncGetWifiApConfiguration();
    }

frameworks/opt/net/wifi/service/java/com/android/server/wifi/WifiStateMachine.java

    public WifiConfiguration syncGetWifiApConfiguration() {
        return mWifiApConfigStore.getApConfiguration();
    }

frameworks/opt/net/wifi/service/java/com/android/server/wifi/WifiApConfigStore.java

    private WifiConfiguration getDefaultApConfiguration() {
        WifiConfiguration config = new WifiConfiguration();
        config.SSID = mContext.getResources().getString(
                R.string.wifi_tether_configure_ssid_default) + "_" + getRandomIntForDefaultSsid();
        config.allowedKeyManagement.set(KeyMgmt.WPA2_PSK);
        String randomUUID = UUID.randomUUID().toString();
        //first 12 chars from xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx
        config.preSharedKey = randomUUID.substring(0, 8) + randomUUID.substring(9, 13);
        return config;
    }

最后全局搜索字符串wifi_tether_configure_ssid_default，定位到frameworks/base/core/res/res/values/strings.xml，如下：

    
    AndroidAP

正好匹配起来，修改上面strings.xml文件中的字符串值即可。

最后，上一篇好文章：

Android系统默认参数的修改