數(shù)據(jù)持久化有文件存儲力麸、SharedPreferences可款、數(shù)據(jù)庫存儲、ContentProvider克蚂、網(wǎng)絡(luò)存儲幾種方式闺鲸。

1.文件存儲（不包括緩存目錄下存儲）、網(wǎng)絡(luò)存儲跟平時使用一樣

2.SharedPreferences使用
在“宿主”中存放

val sharedPreferences = applicationContext.getSharedPreferences("testReplugin", Context.MODE_PRIVATE)
sharedPreferences.edit().putString("first","測試").apply()

在“插件”中取出

val sharedPreferences = RePlugin.getHostContext().applicationContext.getSharedPreferences("testReplugin", Context.MODE_PRIVATE)
val s = sharedPreferences.getString("first", "默認")
//彈出提示
Toast.makeText(this, s.toString(), Toast.LENGTH_SHORT).show()

取出的地方彈出的Toast應(yīng)為“測試”埃叭，如果去掉RePlugin.getHostContext()摸恍，彈出的就會是“默認”了。

緩存目錄下存儲與sp文件類似游盲，插件中需要通過RePlugin.getHostContext()獲取目錄误墓。

3.數(shù)據(jù)庫存儲
宿主項目中新建DatabaseOpenHelper.kt

class DatabaseOpenHelper(context: Context) : SQLiteOpenHelper(context, DB_NAME, null, DB_VERSION) {

    companion object {

        private val DB_NAME = "person_list.db"
        val TABLE_NAME = "person"
        private val DB_VERSION = 1
    }

    override fun onCreate(db: SQLiteDatabase) {
        val SQL_CREATE_TABLE = "create table if not exists $TABLE_NAME(_id integer primary key, name varchar(64), description TEXT)"
        db.execSQL(SQL_CREATE_TABLE)
    }

    override fun onUpgrade(db: SQLiteDatabase, oldVersion: Int, newVersion: Int) {

    }
}

用PersonDao.kt作測試

class PersonDao(private val context: Context) {
    private var helper: SQLiteOpenHelper? = null

    fun insert(person: Person) {

        helper = DatabaseOpenHelper(context)

        val db = helper!!.writableDatabase

        db.execSQL("insert into person(name, description) values(?,?)", arrayOf<Any>(person.name!!, person.description!!))

        db.close()

        Log.e("dbDao", person.name + ":" + person.description)
    }
}

新建數(shù)據(jù)庫存儲對象類,Person.kt

class Person {
    var name: String? = null
    var description: String? = null
}

插件項目中插入數(shù)據(jù)

    //獲取宿主類加載器
    val hostClassLoader = RePlugin.getHostClassLoader()
    //獲取Person類
    val person = hostClassLoader.loadClass("com.test.qby.myapplication.pojo.Person")
    //獲取Person對象
    val personInstance = person.newInstance()
    //獲取set方法
    val nameMethod = person.getDeclaredMethod("setName", String::class.java)
    val descriptionMethod = person.getDeclaredMethod("setDescription", String::class.java)
    //調(diào)用set方法，傳參
    nameMethod.invoke(personInstance,"數(shù)據(jù)哈哈")
    descriptionMethod.invoke(personInstance,"試試數(shù)據(jù)庫呵呵")
    //獲取PersonDao類
    val personDao = hostClassLoader.loadClass("com.test.qby.myapplication.dao.PersonDao")
    //獲取有參構(gòu)造
    val constructor = personDao.getConstructor(Context::class.java)
    //獲取PersonDao對象
    val daoInstance = constructor.newInstance(RePlugin.getHostContext())
    //獲取插入方法
    val insertMethod = personDao.getDeclaredMethod("insert", person)
    //調(diào)用插入方法
    insertMethod.invoke(daoInstance,personInstance)

通過反射來完成數(shù)據(jù)庫操作益缎。

4.ContentProvider使用
宿主項目中DatabaseOpenHelper.kt同上，然后創(chuàng)建PersonProvider.kt繼承ContentProvider

class PersonProvider : ContentProvider() {
    private val TAG = this.javaClass.simpleName

    private var mDatabase: SQLiteDatabase? = null
    private var mContext: Context? = null
    private var mTable: String? = null


    override fun onCreate(): Boolean {
        initProvider()
        return false
    }

    /**
     * 初始化時清除舊數(shù)據(jù)然想，插入一條數(shù)據(jù)
     */
    private fun initProvider() {
        mTable = DatabaseOpenHelper.TABLE_NAME
        mContext = context
        mDatabase = DatabaseOpenHelper(mContext!!).writableDatabase

        Thread(Runnable { mDatabase!!.execSQL("delete from " + mTable!!) }).start()
    }

    override fun query(uri: Uri, projection: Array<String>?, selection: String?,
                       selectionArgs: Array<String>?, sortOrder: String?): Cursor? {
        val tableName = getTableName(uri)
        showLog(tableName + " 查詢數(shù)據(jù)")
        when (mUriMatcher.match(uri)) {
            TABLE_CODE_PERSON //查詢所有記錄
            -> return mDatabase!!.query(tableName, projection, selection, selectionArgs, null, null, null)
            TABLE_CODE_PERSON_SINGLE//查詢特定記錄
            -> {
                val where = expendSelection(uri, selection)
                return mDatabase!!.query(tableName, projection, where, selectionArgs, null, null, null)
            }
            else -> throw IllegalArgumentException("wrong uri")
        }
    }

    override fun insert(uri: Uri, values: ContentValues?): Uri? {
        val tableName = getTableName(uri)
        showLog(tableName + " 插入數(shù)據(jù)")
        val insert = mDatabase!!.insert(tableName, null, values)
        mContext!!.contentResolver.notifyChange(uri, null)
        return Uri.parse(PERSON_CONTENT_URI.toString() + "/" + insert)
    }

    override fun delete(uri: Uri, selection: String?, selectionArgs: Array<String>?): Int {
        val tableName = getTableName(uri)
        showLog(tableName + " 刪除數(shù)據(jù)")

        when (mUriMatcher.match(uri)) {
            TABLE_CODE_PERSON -> {
                val deleteCount = mDatabase!!.delete(tableName, selection, selectionArgs)
                if (deleteCount > 0) {
                    mContext!!.contentResolver.notifyChange(uri, null)
                }
                return deleteCount
            }
            TABLE_CODE_PERSON_SINGLE //刪除特定id記錄
            -> {
                val where = expendSelection(uri, selection)
                val deleteCount2 = mDatabase!!.delete(tableName, where, selectionArgs)
                if (deleteCount2 > 0) {
                    mContext!!.contentResolver.notifyChange(uri, null)
                }
                return deleteCount2
            }
            else -> throw IllegalArgumentException("wrong uri")
        }
    }


    override fun update(uri: Uri, values: ContentValues?, selection: String?, selectionArgs: Array<String>?): Int {
        val tableName = getTableName(uri)
        showLog(tableName + " 更新數(shù)據(jù)")
        when (mUriMatcher.match(uri)) {
            TABLE_CODE_PERSON -> return mDatabase!!.update(tableName, values, selection, selectionArgs)
            TABLE_CODE_PERSON_SINGLE //更新特定id記錄
            -> {
                val where = expendSelection(uri, selection)
                val updateCount = mDatabase!!.update(tableName, values, where, selectionArgs)
                if (updateCount > 0) {
                    mContext!!.contentResolver.notifyChange(uri, null)
                }
                return updateCount
            }
            else -> throw IllegalArgumentException("wrong uri")
        }

    }

    /**
     * CRUD 的參數(shù)是 Uri莺奔，根據(jù) Uri 獲取對應(yīng)的表名
     *
     * @param uri URI
     * @return 表名
     */
    private fun getTableName(uri: Uri): String {
        var tableName = ""
        val match = mUriMatcher.match(uri)
        when (match) {
            TABLE_CODE_PERSON_SINGLE, TABLE_CODE_PERSON -> tableName = DatabaseOpenHelper.TABLE_NAME
        }
        showLog("UriMatcher " + uri.toString() + ", result: " + match)
        return tableName
    }

    override fun getType(uri: Uri): String? {
        when (mUriMatcher.match(uri)) {
            TABLE_CODE_PERSON_SINGLE -> return "vnd.android.cursor.item/person"
            TABLE_CODE_PERSON -> return "vnd.android.cursor.dir/person"
        }
        return null
    }


    /**
     * 根據(jù)URI和查詢條件獲取查詢子句
     *
     * @param uri       URI
     * @param selection 查詢條件
     * @return 查詢子句
     */
    private fun expendSelection(uri: Uri, selection: String?): String {
        val split = uri.toString().split("/".toRegex()).dropLastWhile { it.isEmpty() }.toTypedArray()
        val id = java.lang.Long.getLong(split[split.size - 1])!!
        var where = "id=" + id
        if (!TextUtils.isEmpty(selection)) {
            where += " and " + selection!!
        }
        return where
    }

    private fun showLog(s: String) {
        Log.d(TAG, s + " : " + Thread.currentThread().name)
    }

    companion object {
        private val mUriMatcher = UriMatcher(UriMatcher.NO_MATCH)
        val AUTHORITY = "com.test.qby.myapplication.provider.PersonProvider"  //授權(quán)
        val PERSON_CONTENT_URI = Uri.parse("content://$AUTHORITY/person")

        private val TABLE_CODE_PERSON_SINGLE = 1
        private val TABLE_CODE_PERSON = 2

        init {
            //關(guān)聯(lián)不同的 URI 和 code，便于后續(xù) getType
            mUriMatcher.addURI(AUTHORITY, "person", TABLE_CODE_PERSON)
            //匹配：content://com.test.qby.myapplication.provider.PersonProvider/person/數(shù)字,返回值為1
            mUriMatcher.addURI(AUTHORITY, "person/#", TABLE_CODE_PERSON_SINGLE)
        }
    }
}

在清單文件中注冊

<provider
            android:name=".provider.PersonProvider"
            android:authorities="com.test.qby.myapplication.provider.PersonProvider"/>

插件中操作Provider

        //ContentProvider
        //內(nèi)容提供者URI
        val uri = Uri.parse("content://com.test.qby.myapplication.provider.PersonProvider/person")
        //數(shù)據(jù)
        val values = ContentValues()
        values.put("name", "yyy")
        values.put("description", "你猜我猜不猜你是誰")
        //插入操作
        val insert = PluginProviderClient.insert(RePlugin.getHostContext(),uri, values)
        Log.e(TAG, insert.toString())
        //查詢操作变泄，獲得游標(biāo)
        val cursor = PluginProviderClient.query(RePlugin.getHostContext(),uri, arrayOf("name","description"), null, null, "DESC")
        Log.e(TAG, "查詢條目數(shù)".plus(cursor.count))
        //根據(jù)查詢結(jié)果令哟，循環(huán)打印結(jié)果
        if(cursor.moveToNext()){
            val name = cursor.getString(cursor.getColumnIndex("name"))
            val description = cursor.getString(cursor.getColumnIndex("description"))
            Log.e(TAG, "name = $name，description = $description")
        }
        //關(guān)閉游標(biāo)
        cursor.close()

用到反射的地方寫起來代碼比較多妨蛹，真正用的時候還是要抽取放到工具類里屏富，優(yōu)化一下代碼蛙卤。

以上僅個人學(xué)習(xí)記錄狠半，如有疏漏或謬誤，歡迎留言交流神年！