Android：複製/複製SharedPreferences

Question

有沒有辦法複製或複製SharedPreference？或者我需要從一個變量中獲取每個變量，然後將它們放入另一個變量中？

Answer 1

嘗試這樣：

//sp1 is the shared pref to copy to 
SharedPreferences.Editor ed = sp1.edit(); 
SharedPreferences sp = Sp2; //The shared preferences to copy from 
ed.clear(); // This clears the one we are copying to, but you don't necessarily need to do that. 
//Cycle through all the entries in the sp 
for(Entry<String,?> entry : sp.getAll().entrySet()){ 
Object v = entry.getValue(); 
String key = entry.getKey(); 
//Now we just figure out what type it is, so we can copy it. 
// Note that i am using Boolean and Integer instead of boolean and int. 
// That's because the Entry class can only hold objects and int and boolean are primatives. 
if(v instanceof Boolean) 
// Also note that i have to cast the object to a Boolean 
// and then use .booleanValue to get the boolean 
    ed.putBoolean(key, ((Boolean)v).booleanValue()); 
else if(v instanceof Float) 
    ed.putFloat(key, ((Float)v).floatValue()); 
else if(v instanceof Integer) 
    ed.putInt(key, ((Integer)v).intValue()); 
else if(v instanceof Long) 
    ed.putLong(key, ((Long)v).longValue()); 
else if(v instanceof String) 
    ed.putString(key, ((String)v));   
} 
ed.commit(); //save it. 

希望這有助於。

Answer 2

這裏的一個版本也支持字符串集。

public static void copySharedPreferences(SharedPreferences fromPreferences, SharedPreferences toPreferences) { 
    copySharedPreferences(fromPreferences, toPreferences, true); 
} 

public static void copySharedPreferences(SharedPreferences fromPreferences, SharedPreferences toPreferences, boolean clear) { 

    SharedPreferences.Editor editor = toPreferences.edit(); 
    if (clear) { 
     editor.clear(); 
    } 
    copySharedPreferences(fromPreferences, editor); 
    editor.commit(); 
} 

@TargetApi(Build.VERSION_CODES.HONEYCOMB) 
@SuppressWarnings({"unchecked", "ConstantConditions"}) 
public static void copySharedPreferences(SharedPreferences fromPreferences, SharedPreferences.Editor toEditor) { 

    for (Map.Entry<String, ?> entry : fromPreferences.getAll().entrySet()) { 
     Object value = entry.getValue(); 
     String key = entry.getKey(); 
     if (value instanceof String) { 
      toEditor.putString(key, ((String) value)); 
     } else if (value instanceof Set) { 
      toEditor.putStringSet(key, (Set<String>) value); // EditorImpl.putStringSet already creates a copy of the set 
     } else if (value instanceof Integer) { 
      toEditor.putInt(key, (Integer) value); 
     } else if (value instanceof Long) { 
      toEditor.putLong(key, (Long) value); 
     } else if (value instanceof Float) { 
      toEditor.putFloat(key, (Float) value); 
     } else if (value instanceof Boolean) { 
      toEditor.putBoolean(key, (Boolean) value); 
     } 
    } 
}