Question

假设我有2个sharedPreferences文件，其中一个是通过＆＃34; PreferenceManager.getDefaultSharedPreferences（...）; ＆＃34;和一个通过 getSharedPreferences（someString，Context.MODE_PRIVATE）＆＃34;，我知道这两个键都是唯一的。

将所有键和值从一个文件移动到另一个文件需要什么？

有一种简单的方法可以移动它们吗？

我在考虑使用与this answer类似的代码，但我不想考虑那里每个值的类型吗？

编辑：

这是一种方法，但它有点不安全，因为将来可能会向SharedPreferences添加新类型，这意味着它不会得到支持：

        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();

我成功地将xml标签从一个SharedPreference文件复制到另一个，但由于某种原因，它只会被下一个会话中的SharedPreference对象注意到，而不是当前的那个（可能是它＆＃39; s缓存）。这是代码：

    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);
        }
        ...
    }
}

如何将2个SharedPreferences合并为一个？

1 个答案: