Question

我是android开发的新手。目前，我想对一个名为Shared Preference的自定义进行加密并与PreferenceScreen集成，但未能这样做。我正在使用依赖项：

androidx.security:security-crypto:1.0.0-alpha02 [EncryptedSharedPreference]
androidx.preference：preference：1.1.0 [PreferenceScreen]

我曾尝试研究有关这两个功能集成的相关信息，但未找到相关信息。

根据我的测试，我有一个现有的加密共享首选项，并测试了以下API：

@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);

    try {
        for (Fragment fragment : getSupportFragmentManager().getFragments()) {
            fragment.onActivityResult(requestCode, resultCode, data);
            Log.d("Activity", "ON RESULT CALLED");
        }
    } catch (Exception e) {
        Log.d("ERROR", e.toString());
    }
}

但是最终将首选项保存为纯值。

我的问题：

在当前阶段是否可以将这两个功能集成在一起？
我不知道PreferenceScreen是否提供加密功能？
如果我坚持使用EncryptedSharedPreference，那么创建一个类似于首选项屏幕的自定义活动会更好吗？

Answer 1

使用getPreferenceManager().setPreferenceDataStore(PreferenceDataStore)。 PreferenceDataStore可以更改加载/保存首选项的方式。

PreferenceDataStore的简单实现：

public class SharedPreferenceDataStore extends PreferenceDataStore {

    private final SharedPreferences mSharedPreferences;

    public SharedPreferenceDataStore(@NonNull SharedPreferences sharedPreferences) {
        mSharedPreferences = sharedPreferences;
    }

    @NonNull
    public SharedPreferences getSharedPreferences() {
        return mSharedPreferences;
    }

    @Override
    public void putString(String key, @Nullable String value) {
        mSharedPreferences.edit().putString(key, value).apply();
    }

    @Override
    public void putStringSet(String key, @Nullable Set<String> values) {
        mSharedPreferences.edit().putStringSet(key, values).apply();
    }

    @Override
    public void putInt(String key, int value) {
        mSharedPreferences.edit().putInt(key, value).apply();
    }

    @Override
    public void putLong(String key, long value) {
        mSharedPreferences.edit().putLong(key, value).apply();
    }

    @Override
    public void putFloat(String key, float value) {
        mSharedPreferences.edit().putFloat(key, value).apply();
    }

    @Override
    public void putBoolean(String key, boolean value) {
        mSharedPreferences.edit().putBoolean(key, value).apply();
    }

    @Nullable
    @Override
    public String getString(String key, @Nullable String defValue) {
        return mSharedPreferences.getString(key, defValue);
    }

    @Nullable
    @Override
    public Set<String> getStringSet(String key, @Nullable Set<String> defValues) {
        return mSharedPreferences.getStringSet(key, defValues);
    }

    @Override
    public int getInt(String key, int defValue) {
        return mSharedPreferences.getInt(key, defValue);
    }

    @Override
    public long getLong(String key, long defValue) {
        return mSharedPreferences.getLong(key, defValue);
    }

    @Override
    public float getFloat(String key, float defValue) {
        return mSharedPreferences.getFloat(key, defValue);
    }

    @Override
    public boolean getBoolean(String key, boolean defValue) {
        return mSharedPreferences.getBoolean(key, defValue);
    }
}

getPreferenceManager().setPreferenceDataStore(new SharedPreferenceDataStore(EncryptedSharedPreferences.create()));

Answer 2

将EncryptedSharePreferences与AndroidX首选项GUI集成时遇到一些问题。

PreferenceManager无法全局设置默认首选项数据存储，因为只能检索默认的共享首选项（未加密的变量，并绑定到应用程序包名称），而不能将默认的共享首选项设置为加密的变量。 PreferenceManager.getDefaultSharedPreferences(context);没有相应的set方法。
PreferenceManager只能由具有相同库组的软件包创建。

我创建的解决方案是不依赖于SharedPreferences，而是利用PreferenceFragmentCompat写入EncryptedPreferenceDataStore。但是，这仍然带来一个问题，直到用户进入“首选项”屏幕，默认值才被初始化。

依赖项

dependencies {
    implementation 'androidx.preference:preference:1.1.1'
    implementation 'androidx.security:security-crypto:1.0.0-rc01'
}

首选项片段

import android.app.Activity;
import android.app.ActivityManager;
import android.os.Bundle;

import androidx.preference.Preference;
import androidx.preference.PreferenceFragmentCompat;
import androidx.preference.PreferenceManager;

public class PreferencesFragment extends PreferenceFragmentCompat {

    @Override
    public void onCreatePreferences(Bundle savedInstanceState, String rootKey) {
        PreferenceManager preferenceManager = getPreferenceManager();
        preferenceManager.setPreferenceDataStore(EncryptedPreferenceDataStore.getInstance(getContext()));

        // Load the preferences from an XML resource
        setPreferencesFromResource(R.xml.preferences, rootKey);
    }

EncryptedPreferenceDataStore

import android.content.Context;
import android.content.SharedPreferences;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.preference.PreferenceDataStore;
import androidx.security.crypto.EncryptedSharedPreferences;

import java.util.Set;

public class EncryptedPreferenceDataStore extends PreferenceDataStore {

    private static final String CONFIG_FILE_NAME = "FileName";
    private static final String CONFIG_MASTER_KEY_ALIAS = "KeyAlias";
    private static EncryptedPreferenceDataStore mInstance;
    private SharedPreferences mSharedPreferences;
    private Context mContext;

    private EncryptedPreferenceDataStore(Context context) {
        try {
            mContext = context;
            mSharedPreferences = EncryptedSharedPreferences.create(
                    CONFIG_FILE_NAME,
                    CONFIG_MASTER_KEY_ALIAS,
                    context,
                    EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV, //for encrypting Keys
                    EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM ////for encrypting Values
            );
        } catch (Exception e) {
            // Fallback
            mSharedPreferences = context.getSharedPreferences(CONFIG_FILE_NAME, Context.MODE_PRIVATE);
        }
    }

    @Override
    public void putString(String key, @Nullable String value) {
        mSharedPreferences.edit().putString(key, value).apply();
    }

    @Override
    public void putStringSet(String key, @Nullable Set<String> values) {
        mSharedPreferences.edit().putStringSet(key, values).apply();
    }

    @Override
    public void putInt(String key, int value) {
        mSharedPreferences.edit().putInt(key, value).apply();
    }

    @Override
    public void putLong(String key, long value) {
        mSharedPreferences.edit().putLong(key, value).apply();
    }

    @Override
    public void putFloat(String key, float value) {
        mSharedPreferences.edit().putFloat(key, value).apply();
    }

    @Override
    public void putBoolean(String key, boolean value) {
        mSharedPreferences.edit().putBoolean(key, value).apply();
    }

    @Nullable
    @Override
    public String getString(String key, @Nullable String defValue) {
        return mSharedPreferences.getString(key, defValue);
    }

    @Nullable
    @Override
    public Set<String> getStringSet(String key, @Nullable Set<String> defValues) {
        return mSharedPreferences.getStringSet(key, defValues);
    }

    @Override
    public int getInt(String key, int defValue) {
        return mSharedPreferences.getInt(key, defValue);
    }

    @Override
    public long getLong(String key, long defValue) {
        return mSharedPreferences.getLong(key, defValue);
    }

    @Override
    public float getFloat(String key, float defValue) {
        return mSharedPreferences.getFloat(key, defValue);
    }

    @Override
    public boolean getBoolean(String key, boolean defValue) {
        return mSharedPreferences.getBoolean(key, defValue);
    }
}

用法

    EncryptedPreferenceDataStore prefs = EncryptedPreferenceDataStore.getInstance(getContext());
    boolean bIsXXX = prefs.getBoolean(getString(R.string.pref_access_xxx), true);

Answer 3

这个问题可能是Java特有的，但是Kotlin在一段时间内是首选的一等公民。对于Kotlin来说，诀窍仍然是设置preferencesDataSource，它是这样的：

class SettingsFragment : PreferenceFragmentCompat() {
    override fun onCreatePreferences(savedInstanceState: Bundle?, rootKey: String?) {
        preferenceManager.preferenceDataStore =
            EncryptedPreferenceDataStore.getInstance(requireContext())

        // Load the preferences from an XML resource
        setPreferencesFromResource(R.xml.preferences, rootKey)
    }

EncryptedPreferenceDataStore的Kotlin版本：我为单例使用also关键字，类似于Singleton with parameter in Kotlin

中与Google源代码相关的Room示例。

class EncryptedPreferenceDataStore private constructor(context: Context) : PreferenceDataStore() {
    companion object {
        private const val SHARED_PREFERENCES_NAME = "secret_shared_preferences"

        @Volatile private var INSTANCE: EncryptedPreferenceDataStore? = null

        fun getInstance(context: Context): EncryptedPreferenceDataStore =
            INSTANCE ?: synchronized(this) {
                INSTANCE ?: EncryptedPreferenceDataStore(context).also { INSTANCE = it }
            }
    }

    private var mSharedPreferences: SharedPreferences
    private lateinit var mContext: Context

    init {
        try {
            mContext = context
            val masterKey = MasterKey.Builder(context, MasterKey.DEFAULT_MASTER_KEY_ALIAS)
                .setKeyScheme(MasterKey.KeyScheme.AES256_GCM)
                .build()

            mSharedPreferences = EncryptedSharedPreferences.create(
                context,
                SHARED_PREFERENCES_NAME,
                masterKey,
                EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV,
                EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM
            )
        } catch (e: Exception) {
            // Fallback, default mode is Context.MODE_PRIVATE!
            mSharedPreferences = PreferenceManager.getDefaultSharedPreferences(context)
        }
    }

    override fun putString(key: String, value: String?) {
        mSharedPreferences.edit().putString(key, value).apply()
    }

    override fun putStringSet(key: String, values: Set<String>?) {
        mSharedPreferences.edit().putStringSet(key, values).apply()
    }

    override fun putInt(key: String, value: Int) {
        mSharedPreferences.edit().putInt(key, value).apply()
    }

    override fun putLong(key: String, value: Long) {
        mSharedPreferences.edit().putLong(key, value).apply()
    }

    override fun putFloat(key: String, value: Float) {
        mSharedPreferences.edit().putFloat(key, value).apply()
    }

    override fun putBoolean(key: String, value: Boolean) {
        mSharedPreferences.edit().putBoolean(key, value).apply()
    }

    override fun getString(key: String, defValue: String?): String? {
        return mSharedPreferences.getString(key, defValue)
    }

    override fun getStringSet(key: String, defValues: Set<String>?): Set<String>? {
        return mSharedPreferences.getStringSet(key, defValues)
    }

    override fun getInt(key: String, defValue: Int): Int {
        return mSharedPreferences.getInt(key, defValue)
    }

    override fun getLong(key: String, defValue: Long): Long {
        return mSharedPreferences.getLong(key, defValue)
    }

    override fun getFloat(key: String, defValue: Float): Float {
        return mSharedPreferences.getFloat(key, defValue)
    }

    override fun getBoolean(key: String, defValue: Boolean): Boolean {
        return mSharedPreferences.getBoolean(key, defValue)
    }
}

也许通过双重同步检查可以使线程更安全？

有没有一种方法可以将EncryptedSharedPreference与PreferenceScreen集成在一起？

3 个答案: