如何将 2 个 SharedPreferences 合并为一个？

Question

假设我有 2 个 sharedPreferences 文件，一个是通过“PreferenceManager.getDefaultSharedPreferences(...);”创建的，一个是通过 getSharedPreferences(someString, Context.MODE_PRIVATE) 创建的"，而且我知道两者的键都是唯一的。

如何将所有键和值从一个文件移动到另一个文件？

有没有简单的方法来移动它们？

我正在考虑使用类似于this answer 的代码，但我不需要考虑那里每个值的类型吗？

编辑：

这是一种方法，但有点不安全，因为将来可能会将新类型添加到 SharedPreferences 中，这意味着它将不受支持：

        final Editor edit = targetSharedPreferences.edit();
        final Map<String, ?> srcSharedPreferenceAll = srcSharedPreference.getAll();
        for (final Entry<String, ?> entry : srcSharedPreferenceAll.entrySet()) {
            if (entry.getValue() instanceof Integer)
                edit.putInt(entry.getKey(), (Integer) entry.getValue());
            else if (entry.getValue() instanceof Boolean)
                edit.putBoolean(entry.getKey(), (Boolean) entry.getValue());
            else if (entry.getValue() instanceof Long)
                edit.putLong(entry.getKey(), (Long) entry.getValue());
            else if (entry.getValue() instanceof String)
                edit.putString(entry.getKey(), (String) entry.getValue());
            else if (entry.getValue() instanceof Float)
                edit.putFloat(entry.getKey(), (Float) entry.getValue());
            else if (entry.getValue() instanceof Set<?>)
                edit.putStringSet(entry.getKey(), (Set<String>) entry.getValue());
        }
        edit.apply();
        srcSharedPreference.edit().clear().apply();

我已经成功地将 xml 标记从一个 SharedPreference 文件复制到另一个文件，但由于某种原因，它只会在下一个会话中被 SharedPreference 对象注意到，而不是当前会话（可能它已被缓存）。代码如下：

    private static final String DST_XML_FILE = "dst";

    // creating the data, for reading&writing later:
    final SharedPreferences srcSharedPreference = getSharedPreferences(String , Context.MODE_PRIVATE);
    srcSharedPreference.edit().clear().putInt("someInt", 12).putString("someString", "hi").putBoolean("someBoolean", true).apply();
    final SharedPreferences targetSharedPreferences = PreferenceManager.getDefaultSharedPreferences(this);
    targetSharedPreferences.edit().clear().putInt("someInt2", 23).putString("someString2", "hi there").putBoolean("someBoolean2", false).apply(); 

    //checking content before
    Log.d("AppLog", "before");
    final Map<String, ?> src = srcSharedPreference.getAll();
    Log.d("AppLog", "src:" + src.size());
    final Map<String, ?> targetSharedPreferencesAll = targetSharedPreferences.getAll();
    Log.d("AppLog", "target:" + targetSharedPreferencesAll.size());

    // the moving of the XML tags:
    final PackageInfo packageInfo = getPackageManager().getPackageInfo(getPackageName(), 0);
    File dstFile = new File(packageInfo.applicationInfo.dataDir, "shared_prefs/" + (VERSION.SDK_INT >= VERSION_CODES.N ? PreferenceManager.getDefaultSharedPreferencesName(this) : getPackageName() + "_preferences") + ".xml");
    File srcFile = new File(packageInfo.applicationInfo.dataDir, "shared_prefs/" + SRC_XML_FILE + ".xml");

    DocumentBuilderFactory docFactory = DocumentBuilderFactory.newInstance();
    Node srcNode = docFactory.newDocumentBuilder().parse(srcFile).getFirstChild();
    Node dstNode = docFactory.newDocumentBuilder().parse(dstFile).getFirstChild();
    final NodeList childNodes = srcNode.getChildNodes();
    for (int i = 0; i < childNodes.getLength(); ++i) {
        final Node item = childNodes.item(i);
        Node importedNode = dstNode.getOwnerDocument().importNode(item, true);
        srcNode.removeChild(item);
        dstNode.appendChild(importedNode);
    }
    TransformerFactory transformerFactory = TransformerFactory.newInstance();
    Transformer transformer = transformerFactory.newTransformer();
    DOMSource source = new DOMSource(dstNode);
    StreamResult result = new StreamResult(dstFile);
    transformer.transform(source, result);

    //checking content after
    Log.d("AppLog", "after");
    final Map<String, ?> src = srcSharedPreference.getAll();
    Log.d("AppLog", "src:" + src.size());
    final Map<String, ?> targetSharedPreferencesAll = targetSharedPreferences.getAll();
    Log.d("AppLog", "target:" + targetSharedPreferencesAll.size());

Answer 1

Map<String,?> keys = prefs.getAll();
for(Map.Entry<String,?> entry : keys.entrySet()){
        Object o = keys.get(entry);
        if (o instanceof Boolean)
        {
            pref2.putBoolean(o);
        }
        if (o instanceof String)
        {
            pref2.putString(o);
        }
        ...
    }
}