MMKV
MMKV
MMKV 使用
简单使用
SP 迁移 MMKV 步骤
所有要迁移的 sp filename，可以用个数组列举出要迁移的 sp filename
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// 需要迁移MMKV的sp filename
private val xmlIds = arrayOf(
"buyers_guide",
"SP_AROUTER_CACHE",
)
不能迁移到 mmkv 的 sp，如使用到 mmkv 未实现的 getAll 方法，可以弄个 blacklist
- WebViewProfilePrefsDefault
- WebViewChromiumPrefs
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// 不能使用mmkv的SharedPreferences
private val blackList = arrayOf(
"WebViewProfilePrefsDefault", // 使用到mmkv未实现的getAll方法。
"WebViewChromiumPrefs",
"BraintreeApi", // BraintreeSharedPreferences 用到 androidx.security.crypto.EncryptedSharedPreferences
// 华为相关sp
"move_to_de_records",
"aaid",
"push_notify_flag",
"grs_move2DE_records",
"share_pre_grs_conf_",
"share_pre_grs_services_",
"hms_"
)
只需要迁移一次，需要保存迁移的标记
重写 Application 和 Activity 的 getSharedPreferences，用 mmkv
- Application
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open class BaseApplication : Application() {
override fun attachBaseContext(base: Context) {
super.attachBaseContext(base)
MMKVUtils.init(base);
}
override fun getSharedPreferences(name: String, mode: Int): SharedPreferences? {
return MMKVUtils.replaceSharedPreferences(
applicationContext,
super.getSharedPreferences(name, mode),
name
)
}
}
- Activity
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class Activity {
@Override
public SharedPreferences getSharedPreferences(String name, int mode) {
return MMKVUtils.replaceSharedPreferences(getApplicationContext(), super.getSharedPreferences(name, mode), name);
}
}
迁移失败后返回 NoMainThreadWriteSharedPreferences
NoMainThreadWriteSharedPreferences
NoMainThreadWriteSharedPreferences 是用来避免 ANR 的 SharedPreferences，子线程更新数据
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/**
*
* https://gist.github.com/tprochazka/d91d89ec54bd6c3c1cb46f62faf3c12c
*
* ANR free implementation of SharedPreferences.
*
* Fast fix for ANR caused by writing all non written changes on main thread during activity/service start/stop.
*
* Disadvantage of current implementation:
* - OnSharedPreferenceChangeListener is called after all changes are written to disk.
* - If somebody will call edit() apply() several times after each other it will also several times write whole prefs file.
*
* Usage:
*
* Override this method in your Application class.
*
* public SharedPreferences getSharedPreferences(String name, int mode) {
* return NoMainThreadWriteSharedPreferences.getInstance(super.getSharedPreferences(name, mode), name);
* }
*
* You need to override also parent activity, because if somebody will use activity context instead
* of the application one, he will get a different implementation, you can do something like
*
* public SharedPreferences getSharedPreferences(String name, int mode) {
* return getApplicationContext().getSharedPreferences(name, mode);
* }
*
* @author Tomáš Procházka (prochazka)
*/
@RequiresApi(11)
class NoMainThreadWriteSharedPreferences private constructor(
private val sysPrefs: SharedPreferences,
val name: String
) :
SharedPreferences {
private val preferencesCache: MutableMap<String, Any?> = HashMap()
companion object {
private val executor: ExecutorService = Executors.newSingleThreadExecutor()
private val INSTANCES: MutableMap<String, NoMainThreadWriteSharedPreferences> = HashMap()
@JvmStatic
fun getInstance(sharedPreferences: SharedPreferences, name: String): SharedPreferences {
return INSTANCES.getOrPut(
name,
{ NoMainThreadWriteSharedPreferences(sharedPreferences, name) })
}
/**
* Remove all instances for testing purpose.
*/
@VisibleForTesting
@JvmStatic
fun reset() {
INSTANCES.clear()
}
}
init {
/**
* I will think about it if there is no synchronization issue. But generally, I think that it will bring no difference. Because system shared preference itself loading whole properties file to memory anyway. So preferencesCache.putAll(sysPrefs.all) is just an in-memory operation that will be much faster than loading and parsing files from the storage.
*/
preferencesCache.putAll(sysPrefs.all)
}
override fun contains(key: String?) = preferencesCache[key] != null
override fun getAll() = HashMap(preferencesCache)
override fun getBoolean(key: String, defValue: Boolean): Boolean {
return preferencesCache[key] as Boolean? ?: defValue
}
override fun getInt(key: String, defValue: Int): Int {
return preferencesCache[key] as Int? ?: defValue
}
override fun getLong(key: String, defValue: Long): Long {
return preferencesCache[key] as Long? ?: defValue
}
override fun getFloat(key: String, defValue: Float): Float {
return preferencesCache[key] as Float? ?: defValue
}
override fun getStringSet(key: String, defValues: MutableSet<String>?): MutableSet<String>? {
@Suppress("UNCHECKED_CAST")
return preferencesCache[key] as MutableSet<String>? ?: defValues
}
override fun getString(key: String, defValue: String?): String? {
return preferencesCache[key] as String? ?: defValue
}
override fun edit(): SharedPreferences.Editor {
return Editor(sysPrefs.edit())
}
override fun registerOnSharedPreferenceChangeListener(listener: SharedPreferences.OnSharedPreferenceChangeListener) {
sysPrefs.registerOnSharedPreferenceChangeListener(listener)
}
override fun unregisterOnSharedPreferenceChangeListener(listener: SharedPreferences.OnSharedPreferenceChangeListener) {
sysPrefs.unregisterOnSharedPreferenceChangeListener(listener)
}
inner class Editor(private val sysEdit: SharedPreferences.Editor) : SharedPreferences.Editor {
private val modifiedData: MutableMap<String, Any?> = HashMap()
private var keysToRemove: MutableSet<String> = HashSet()
private var clear = false
override fun commit(): Boolean {
submit()
return true
}
override fun apply() {
submit()
}
private fun submit() {
synchronized(preferencesCache) {
storeMemCache()
queuePersistentStore()
}
}
private fun storeMemCache() {
if (clear) {
preferencesCache.clear()
clear = false
} else {
preferencesCache.keys.removeAll(keysToRemove)
}
keysToRemove.clear()
preferencesCache.putAll(modifiedData)
modifiedData.clear()
}
private fun queuePersistentStore() {
try {
executor.submit {
sysEdit.commit()
}
} catch (ex: Exception) {
Log.e(
"NoMainThreadWritePrefs",
"NoMainThreadWriteSharedPreferences.queuePersistentStore(), submit failed for $name"
)
}
}
override fun remove(key: String): SharedPreferences.Editor {
keysToRemove.add(key)
modifiedData.remove(key)
sysEdit.remove(key)
return this
}
override fun clear(): SharedPreferences.Editor {
clear = true
sysEdit.clear()
return this
}
override fun putLong(key: String, value: Long): SharedPreferences.Editor {
modifiedData[key] = value
sysEdit.putLong(key, value)
return this
}
override fun putInt(key: String, value: Int): SharedPreferences.Editor {
modifiedData[key] = value
sysEdit.putInt(key, value)
return this
}
override fun putBoolean(key: String, value: Boolean): SharedPreferences.Editor {
modifiedData[key] = value
sysEdit.putBoolean(key, value)
return this
}
override fun putStringSet(
key: String,
values: MutableSet<String>?
): SharedPreferences.Editor {
modifiedData[key] = values
sysEdit.putStringSet(key, values)
return this
}
override fun putFloat(key: String, value: Float): SharedPreferences.Editor {
modifiedData[key] = value
sysEdit.putFloat(key, value)
return this
}
override fun putString(key: String, value: String?): SharedPreferences.Editor {
modifiedData[key] = value
sysEdit.putString(key, value)
return this
}
}
}
注意：替换掉系统的 SP，注意 null 的问题；我们有个项目用自己的 SP，用 ConcurrentHashMap 替换掉 HashMap，由于 ConcurrentHashMap 的 key 和 value 不能为 null，容易导致很隐蔽的一些 NPE 问题
sp 迁移到 mmkv 时，mmkv 存储时类型是擦除的，所以最好是带上类型存储，否则 getAll 出来的数据不知道是什么类型
在初次使用 mmvk 时就做好包装，带类型存储，所以避免了后期无法迁移。
具体见 MMKV存在的问题→MMKV不支持getAll
完整工具类
- MMKVUtils
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object MMKVUtils {
const val TAG = "mmkv"
private const val KEY_IMPORT = "has_old_sp_data_import"
private const val delOldSpData = false // 是否删除旧的SharedPreferences数据
private var hasImport = false
// 需要迁移MMKV的sp filename
private val xmlIds = arrayOf(
"buyers_guide",
"SP_AROUTER_CACHE",
)
// 不能使用mmkv的SharedPreferences
private val blackList = arrayOf(
"WebViewProfilePrefsDefault", // 使用到mmkv未实现的getAll方法。
"WebViewChromiumPrefs",
"BraintreeApi", // BraintreeSharedPreferences 用到 androidx.security.crypto.EncryptedSharedPreferences
// 华为相关sp
"move_to_de_records",
"aaid",
"push_notify_flag",
"grs_move2DE_records",
"share_pre_grs_conf_",
"share_pre_grs_services_",
"hms_"
)
/**
* 是否已经纳入mmkv管理
* @param name
* @return
*/
fun contains(context: Context, name: String): Boolean {
if (name == getDefaultId(context)) return true
for (item in xmlIds) {
if (item == name) {
return true
}
}
return false
}
fun isAvailable(name: String): Boolean {
for (item in blackList) {
if (name.contains(item)) {
return false
}
}
return true
}
/**
* 尽量提前初始化，最好是放到Application.attachBaseContext中，否则其他用了sp的地方会报错，因为在Activity和Application会替换掉系统的SharedPreferences导致出错
*/
@JvmStatic
fun init(context: Context) {
val logLevel =
if (BuildConfig.DEBUG) MMKVLogLevel.LevelDebug else MMKVLogLevel.LevelNone // 日志开关
val path: String = MMKV.initialize(
context,
{ libName -> ReLinker.loadLibrary(context, libName) },
logLevel
)
Log.d(TAG, "MMKV存放路径: $path")
// 迁移数据
Log.d(TAG, ">>>>>>MMKV开始迁移<<<<<<")
val start = System.currentTimeMillis()
hasImport = getBoolean(getDefaultId(context), KEY_IMPORT, false)
if (!hasImport) {
importDefaultSharedPreferences(context, getDefaultId(context))
importSharedPreferences(context)
putBoolean(getDefaultId(context), KEY_IMPORT, true)
}
val cost = System.currentTimeMillis() - start
Log.d(TAG, ">>>>>>MMKV迁移结束<<<<<< 总耗时：" + cost + "ms")
}
/**
* 遍历数组：迁移数据到mmkv
* @param context
*/
private fun importSharedPreferences(context: Context) {
try {
for (id in xmlIds) {
val prefs = context.getSharedPreferences(id, Context.MODE_PRIVATE)
if (prefs.all.isNotEmpty()) {
val mmkv = MMKV.mmkvWithID(id, MMKV.MULTI_PROCESS_MODE)
if (mmkv != null) {
mmkv.importFromSharedPreferences(prefs) // 迁移旧数据
if (delOldSpData) {
prefs.edit().clear().apply() // 清空旧数据
}
}
}
}
} catch (e: Throwable) {
Log.d(TAG, "数据迁移失败：" + e.message)
}
}
/**
* 迁移DefaultSharedPreferences数据，特殊处理
*
* @param context
* @param id
*/
private fun importDefaultSharedPreferences(context: Context, id: String) {
try {
val prefs = context.getSharedPreferences(id, Context.MODE_PRIVATE)
val prefsKeySize = prefs.all.size
if (prefsKeySize > 0) {
val originMmkv = MMKV.mmkvWithID(id, MMKV.MULTI_PROCESS_MODE)
val mmkv = MMKVWrapper(originMmkv)
if (mmkv != null) {
// 判断是否已经迁移
if (mmkv.allKeys() != null) {
val mmkvKeySize = mmkv.allKeys()!!.size
if (mmkvKeySize > prefsKeySize && prefsKeySize < 10) {
return
}
}
// 迁移旧数据
mmkv.importFromSharedPreferences(prefs)
if (delOldSpData) {
// 清除旧数据
val editor = prefs.edit()
for (mutableEntry in prefs.all) {
val key = mutableEntry.key
val value = mutableEntry.value
if (key.startsWith("com.facebook.appevents.SessionInfo")
|| key.startsWith("IABUSPrivacy_String")
|| key.startsWith("variations_seed_native_stored")
) {
Log.d(
TAG,
"保留的三方key-value：key = $key,value = $value"
)
} else {
editor.remove(key)
}
}
editor.apply()
}
}
}
} catch (e: Throwable) {
Log.d(TAG, "数据迁移失败：" + e.message)
}
}
/**
* 设置字符串
*
* @param id
* @param key
* @param value
*/
@JvmStatic
fun putString(id: String, key: String, value: String?) {
val mmkv = MMKV.mmkvWithID(id, MMKV.MULTI_PROCESS_MODE)
mmkv?.encode(key, value)
}
/**
* 获取字符串
*
* @param id
* @param key
* @param defValue
* @return
*/
@JvmStatic
fun getString(id: String, key: String, defValue: String?): String? {
val mmkv = MMKV.mmkvWithID(id, MMKV.MULTI_PROCESS_MODE)
return if (mmkv != null) mmkv.decodeString(key, defValue) else defValue
}
/**
* 保存Parcelable对象
*
* @param id
* @param key
* @param value
*/
fun putParcelable(id: String, key: String, value: Parcelable?) {
val mmkv = MMKV.mmkvWithID(id, MMKV.MULTI_PROCESS_MODE)
mmkv?.encode(key, value)
}
/**
* 获取Parcelable对象
*
* @param id
* @param key
* @return
*/
fun <T : Parcelable?> getParcelable(id: String, key: String, tClass: Class<T>): T? {
val mmkv = MMKV.mmkvWithID(id, MMKV.MULTI_PROCESS_MODE)
return mmkv?.decodeParcelable(key, tClass)
}
/**
* 设置整型数值
*
* @param id
* @param key
* @param value
*/
fun putInt(id: String, key: String, value: Int) {
val mmkv = MMKV.mmkvWithID(id, MMKV.MULTI_PROCESS_MODE)
mmkv?.encode(key, value)
}
/**
* 获取整型数值
*
* @param id
* @param key
* @param defValue
* @return
*/
fun getInt(id: String, key: String, defValue: Int): Int {
val mmkv = MMKV.mmkvWithID(id, MMKV.MULTI_PROCESS_MODE)
return mmkv?.decodeInt(key, defValue) ?: defValue
}
/**
* 设置bool值
*
* @param id
* @param key
* @param value
*/
@JvmStatic
fun putBoolean(id: String, key: String, value: Boolean) {
val mmkv = MMKV.mmkvWithID(id, MMKV.MULTI_PROCESS_MODE)
mmkv?.encode(key, value)
}
/**
* 获取bool值
*
* @param id
* @param key
* @param defValue
* @return
*/
@JvmStatic
fun getBoolean(id: String, key: String, defValue: Boolean): Boolean {
val mmkv = MMKV.mmkvWithID(id, MMKV.MULTI_PROCESS_MODE)
return mmkv?.decodeBool(key, defValue) ?: defValue
}
/**
* 设置long值
*
* @param id
* @param key
* @param value
*/
fun putLong(id: String, key: String, value: Long) {
val mmkv = MMKV.mmkvWithID(id, MMKV.MULTI_PROCESS_MODE)
mmkv?.encode(key, value)
}
/**
* 获取long值
*
* @param id
* @param key
* @param defValue
* @return
*/
fun getLong(id: String, key: String, defValue: Long): Long {
val mmkv = MMKV.mmkvWithID(id, MMKV.MULTI_PROCESS_MODE)
return mmkv?.decodeLong(key, defValue) ?: defValue
}
/**
* 设置float值
*
* @param id
* @param key
* @param value
*/
fun putFloat(id: String, key: String, value: Float) {
val mmkv = MMKV.mmkvWithID(id, MMKV.MULTI_PROCESS_MODE)
mmkv?.encode(key, value)
}
/**
* 获取float值
*
* @param id
* @param key
* @param defValue
* @return
*/
fun getFloat(id: String, key: String, defValue: Float): Float {
val mmkv = MMKV.mmkvWithID(id, MMKV.MULTI_PROCESS_MODE)
return mmkv?.decodeFloat(key, defValue) ?: defValue
}
/**
* 设置double值
*
* @param id
* @param key
* @param value
*/
fun putDouble(id: String, key: String, value: Double) {
val mmkv = MMKV.mmkvWithID(id, MMKV.MULTI_PROCESS_MODE)
mmkv?.encode(key, value)
}
/**
* 获取double值
*
* @param id
* @param key
* @param defValue
* @return
*/
fun getDouble(id: String, key: String, defValue: Double): Double {
val mmkv = MMKV.mmkvWithID(id, MMKV.MULTI_PROCESS_MODE)
return mmkv?.decodeDouble(key, defValue) ?: defValue
}
/**
* 设置字符串集合
*
* @param id
* @param key
* @param values
*/
fun putStringSet(id: String, key: String, values: Set<String?>?) {
val mmkv = MMKV.mmkvWithID(id, MMKV.MULTI_PROCESS_MODE)
mmkv?.putStringSet(key, values)
}
/**
* 获取字符串集合
*
* @param id
* @param key
* @param defValues
*/
fun getStringSet(id: String, key: String, defValues: Set<String?>?): Set<String?>? {
val mmkv = MMKV.mmkvWithID(id, MMKV.MULTI_PROCESS_MODE)
return if (mmkv != null) mmkv.getStringSet(key, defValues) else defValues
}
/**
* 根据Key移除value
*
* @param id
* @param key
*/
fun remove(id: String, key: String) {
val mmkv = MMKV.mmkvWithID(id, MMKV.MULTI_PROCESS_MODE)
mmkv?.removeValueForKey(key)
}
/**
* 根据多个Key移除value
*
* @param id
* @param arrKeys
*/
fun removeKeys(id: String, arrKeys: Array<String?>) {
val mmkv = MMKV.mmkvWithID(id, MMKV.MULTI_PROCESS_MODE)
mmkv?.removeValuesForKeys(arrKeys)
}
/**
* 根据ID清除所有数据
*
* @param id
*/
fun clearAll(id: String) {
val mmkv = MMKV.mmkvWithID(id, MMKV.MULTI_PROCESS_MODE)
mmkv?.clearAll()
}
/**
* 判断key是否存在
*
* @param id
* @param key
* @return
*/
fun contains(id: String, key: String): Boolean {
val mmkv = MMKV.mmkvWithID(id, MMKV.MULTI_PROCESS_MODE)
return mmkv != null && mmkv.contains(key)
}
private var defaultId: String = ""
/**
* 获取默认SharedPreferences_xml名称
*
* @return sp id
*/
@JvmStatic
fun getDefaultId(context: Context): String {
if (defaultId.isBlank()) {
defaultId = context.packageName + "_preferences"
}
return defaultId
}
/**
* 替换掉系统的SharedPreferences
*/
@JvmStatic
fun replaceSharedPreferences(
context: Context,
oldSP: SharedPreferences,
name: String
): SharedPreferences? {
// return NoMainThreadWriteSharedPreferences.getInstance(super.getSharedPreferences(name, mode), name);
return if (!hasImport && contains(context, name)
|| !isAvailable(name)
/** 迁移数据时需要返回默认的SP */
) {
NoMainThreadWriteSharedPreferences.getInstance(oldSP, name)
} else {
if (!getBoolean(getDefaultId(context), name, false)) {
try {
Log.d(TAG, ">>>>>>MMKV开始迁移<<<<<< : $name")
val start = System.currentTimeMillis()
if (oldSP.all.isNotEmpty()) {
val mmkv = MMKV.mmkvWithID(name, MMKV.MULTI_PROCESS_MODE)
if (mmkv != null) {
mmkv.importFromSharedPreferences(oldSP) // 迁移旧数据
if (delOldSpData) {
oldSP.edit().clear().apply() // 清空旧数据
}
}
}
val cost = System.currentTimeMillis() - start
Log.d(TAG, name + "： >>>>>>MMKV迁移结束<<<<<< 总耗时：" + cost + "ms")
putBoolean(getDefaultId(context), name, true)
MMKVWrapper(MMKV.mmkvWithID(name, MMKV.MULTI_PROCESS_MODE))
} catch (e: Exception) {
e.printStackTrace()
Log.d(
TAG,
"MMKV数据迁移失败，退回NoMainThreadWriteSharedPreferences：" + e.message
)
NoMainThreadWriteSharedPreferences.getInstance(oldSP, name)
}
} else {
Log.d(TAG, ">>>>>> MMKV已经迁移了，直接用MMKV <<<<<< : $name")
MMKVWrapper(MMKV.mmkvWithID(name, MMKV.MULTI_PROCESS_MODE))
}
}
}
}
- NoMainThreadWriteSharedPreferences
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/**
*
* https://gist.github.com/tprochazka/d91d89ec54bd6c3c1cb46f62faf3c12c
*
* ANR free implementation of SharedPreferences.
*
* Fast fix for ANR caused by writing all non written changes on main thread during activity/service start/stop.
*
* Disadvantage of current implementation:
* - OnSharedPreferenceChangeListener is called after all changes are written to disk.
* - If somebody will call edit() apply() several times after each other it will also several times write whole prefs file.
*
* Usage:
*
* Override this method in your Application class.
*
* public SharedPreferences getSharedPreferences(String name, int mode) {
* return NoMainThreadWriteSharedPreferences.getInstance(super.getSharedPreferences(name, mode), name);
* }
*
* You need to override also parent activity, because if somebody will use activity context instead
* of the application one, he will get a different implementation, you can do something like
*
* public SharedPreferences getSharedPreferences(String name, int mode) {
* return getApplicationContext().getSharedPreferences(name, mode);
* }
*
* @author Tomáš Procházka (prochazka)
*/
@RequiresApi(11)
class NoMainThreadWriteSharedPreferences private constructor(
private val sysPrefs: SharedPreferences,
val name: String
) :
SharedPreferences {
private val preferencesCache: MutableMap<String, Any?> = HashMap()
companion object {
private val executor: ExecutorService = Executors.newSingleThreadExecutor()
private val INSTANCES: MutableMap<String, NoMainThreadWriteSharedPreferences> = HashMap()
@JvmStatic
fun getInstance(sharedPreferences: SharedPreferences, name: String): SharedPreferences {
return INSTANCES.getOrPut(
name,
{ NoMainThreadWriteSharedPreferences(sharedPreferences, name) })
}
/**
* Remove all instances for testing purpose.
*/
@VisibleForTesting
@JvmStatic
fun reset() {
INSTANCES.clear()
}
}
init {
/**
* I will think about it if there is no synchronization issue. But generally, I think that it will bring no difference. Because system shared preference itself loading whole properties file to memory anyway. So preferencesCache.putAll(sysPrefs.all) is just an in-memory operation that will be much faster than loading and parsing files from the storage.
*/
preferencesCache.putAll(sysPrefs.all)
}
override fun contains(key: String?) = preferencesCache[key] != null
override fun getAll() = HashMap(preferencesCache)
override fun getBoolean(key: String, defValue: Boolean): Boolean {
return preferencesCache[key] as Boolean? ?: defValue
}
override fun getInt(key: String, defValue: Int): Int {
return preferencesCache[key] as Int? ?: defValue
}
override fun getLong(key: String, defValue: Long): Long {
return preferencesCache[key] as Long? ?: defValue
}
override fun getFloat(key: String, defValue: Float): Float {
return preferencesCache[key] as Float? ?: defValue
}
override fun getStringSet(key: String, defValues: MutableSet<String>?): MutableSet<String>? {
@Suppress("UNCHECKED_CAST")
return preferencesCache[key] as MutableSet<String>? ?: defValues
}
override fun getString(key: String, defValue: String?): String? {
return preferencesCache[key] as String? ?: defValue
}
override fun edit(): SharedPreferences.Editor {
return Editor(sysPrefs.edit())
}
override fun registerOnSharedPreferenceChangeListener(listener: SharedPreferences.OnSharedPreferenceChangeListener) {
sysPrefs.registerOnSharedPreferenceChangeListener(listener)
}
override fun unregisterOnSharedPreferenceChangeListener(listener: SharedPreferences.OnSharedPreferenceChangeListener) {
sysPrefs.unregisterOnSharedPreferenceChangeListener(listener)
}
inner class Editor(private val sysEdit: SharedPreferences.Editor) : SharedPreferences.Editor {
private val modifiedData: MutableMap<String, Any?> = HashMap()
private var keysToRemove: MutableSet<String> = HashSet()
private var clear = false
override fun commit(): Boolean {
submit()
return true
}
override fun apply() {
submit()
}
private fun submit() {
synchronized(preferencesCache) {
storeMemCache()
queuePersistentStore()
}
}
private fun storeMemCache() {
if (clear) {
preferencesCache.clear()
clear = false
} else {
preferencesCache.keys.removeAll(keysToRemove)
}
keysToRemove.clear()
preferencesCache.putAll(modifiedData)
modifiedData.clear()
}
private fun queuePersistentStore() {
try {
executor.submit {
sysEdit.commit()
}
} catch (ex: Exception) {
Log.e(
"NoMainThreadWritePrefs",
"NoMainThreadWriteSharedPreferences.queuePersistentStore(), submit failed for $name"
)
}
}
override fun remove(key: String): SharedPreferences.Editor {
keysToRemove.add(key)
modifiedData.remove(key)
sysEdit.remove(key)
return this
}
override fun clear(): SharedPreferences.Editor {
clear = true
sysEdit.clear()
return this
}
override fun putLong(key: String, value: Long): SharedPreferences.Editor {
modifiedData[key] = value
sysEdit.putLong(key, value)
return this
}
override fun putInt(key: String, value: Int): SharedPreferences.Editor {
modifiedData[key] = value
sysEdit.putInt(key, value)
return this
}
override fun putBoolean(key: String, value: Boolean): SharedPreferences.Editor {
modifiedData[key] = value
sysEdit.putBoolean(key, value)
return this
}
override fun putStringSet(
key: String,
values: MutableSet<String>?
): SharedPreferences.Editor {
modifiedData[key] = values
sysEdit.putStringSet(key, values)
return this
}
override fun putFloat(key: String, value: Float): SharedPreferences.Editor {
modifiedData[key] = value
sysEdit.putFloat(key, value)
return this
}
override fun putString(key: String, value: String?): SharedPreferences.Editor {
modifiedData[key] = value
sysEdit.putString(key, value)
return this
}
}
}
MMKV 存在的问题
替换系统 SP
- 注意 NPE 的问题
MMKV 不支持的 API
registerOnSharedPreferenceChangeListener/unregisterOnSharedPreferenceChangeListener 不支持
这 2 个 API 在 mmkv 中，会抛出异常？
mmkv 未设计数据变化监听，推荐开发者用 eventbus 这样的框架来实现；如果这样设计很糟糕
MMKV 不支持 getAll
mmkv 存储的时候，类型是擦除的
解决 1：用 allKeys() 替代 getAll()
- use allKeys() instead, getAll() not implement because type-erasure inside mmkv
- what to do with Compatibility of getAll() on Android? #168
存在的问题：mmkv 存储的时候进行的类型擦除，取出来的值不知道是什么类型
解决 2：寻找规律，自己判断类型
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private fun getObjectValue2(mmkv: MMKV, key: String): Any? {
// 因为其他基础类型value会读成空字符串,所以不是空字符串即为string or string-set类型
val str = mmkv.decodeString(key)
if (!TextUtils.isEmpty(str)) {
// 判断 string or string-set
return if (str!![0].code == 5) { // mmkv v1.2.15 ENQ 对应ANSI控制字符，表示询问字符，用于数据通信中询问对方是否准备好，或者用于空操作
val strings = mmkv.decodeStringSet(key)
Log.d(
TAG,
"MMKVFlipperPlugin -> getObjectValue2 判定为Set<String>, key=$key, value=$strings"
)
strings
} else {
Log.d(
TAG,
"MMKVFlipperPlugin -> getObjectValue2 判定为String, key=$key, value=$str"
)
str
}
}
// float double类型可通过string-set配合判断：
// 通过数据分析可以看到类型为float或double时string类型为空字符串且string-set类型读出为null，此时float和double有值
// float有值时，decodeDouble为0.0；其他情况为double
val set = mmkv.decodeStringSet(key)
if (str == null && set == null) {
// float和double有值时，如果是float，decodeDouble会为0
val valueFloat = mmkv.decodeFloat(key)
val valueDouble = mmkv.decodeDouble(key)
return if (valueDouble == 0.0) { // 是float
Log.d(
TAG,
"MMKVFlipperPlugin -> getObjectValue2 判断为Float, key=$key, valueFloat=$valueDouble"
)
valueFloat
} else {
Log.d(
TAG,
"MMKVFlipperPlugin -> getObjectValue2 判断为Double, key=$key, valueDouble=$valueDouble"
)
valueDouble
}
}
// int long bool 类型的处理放在一起, int类型1和0等价于bool类型true和false
// 判断long或int类型时, 如果数据长度超出int的最大长度, 则long与int读出的数据不等, 可确定为long类型
val valueInt = mmkv.decodeInt(key)
val valueLong = mmkv.decodeLong(key)
// 如果int/long/bool都为0，说明没有值，全部0.0F存储，可能造成String类型在Flipper中编辑不了
if (valueInt == 0 && valueLong == 0L) {
Log.d(
TAG,
"MMKVFlipperPlugin -> getObjectValue2 判断为Float, 如果int/long/bool都为0，说明没有值，全部以0.0存储 key=$key, value=$valueInt"
)
return 0.0F
}
Log.v(
TAG,
"MMKVFlipperPlugin -> getObjectValue2 key=$key, valueInt=$valueInt, valueLong=$valueLong"
)
return if (valueInt.toLong() != valueLong) {
Log.d(
TAG,
"MMKVFlipperPlugin -> getObjectValue2 判断为long, key=$key, valueLong=$valueLong"
)
valueLong
} else {
Log.d(
TAG,
"MMKVFlipperPlugin -> getObjectValue2 判断为int, key=$key, valueInt=$valueInt"
)
valueInt
}
}
- 微信开源库MMKV遍历读取存储的所有key以及对应的value方法（旧版本的，新版本不适用）
解决 3：sp 升级到 mmkv 时，在 key 上带类型存储
具体的实现可参考这个：在初次使用mmvk时就做好包装，所以避免了后期无法迁移。
解决 4：带类型存储，flipper 支持 getAll，自动更新
- 存储时，key 带类型存储 (
key@类型)；需要封装 mmkv - 封装支持自动更新
完善：https://github.com/hacket/mmkv-flipper
参考：https://github.com/porum/KVCompat
MMKV v1.2.15 类型擦除，不同类型直接 decode 测试
String
- test_string=”” 空串
- test_string = “hacket”
Set<String>
- test_string_set = setOf()
test_string_set = setOf<String>("hello","world")
bool
- test_bool = true
int
- test_init = 0
- test_init = 110
long
- test_long = 0L
- test_long = 111110000L
float
- test_float = 0.0F
- test_float = 110.110f
double
- test_double = 0.0
- test_double = 1111100000.111000
旧版本解决：
测试的版本 1.2.15，如果是 bool，decodeDouble/decodeFloat 返回 0.0 了，不再是一个 1.4E-45 或 1.4E-45
Ref
本文由作者按照 CC BY 4.0 进行授权