原文地址：https://developer.android.com/training/basics/data-storage/shared-preferences.html

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If you have a relatively small collection of key-values that you'd like to save, you should use theSharedPreferences APIs. ASharedPreferences object points to a file containing key-value pairs and provides simple methods to read and write them. EachSharedPreferences file is managed by the framework and can be private or shared.

如果你有一個相對較小的鍵-值對集合想要存儲，你應該使用SharedPreferences?APIs。一個SharedPreferences對象指向一個包含鍵值對的文件，并且提供了一些簡單的方法來進行讀取和寫入它們。每個SharedPreferences文件可以是私有的或是共享的，靠framework來管理它們。

This class shows you how to use the SharedPreferences APIs to store and retrieve simple values.

這節課演示如何使用SharedPreferences?APIs來存儲和檢索簡單的值。

Note: The SharedPreferences APIs are only for reading and writing key-value pairs and you should not confuse them with thePreference APIs, which help you build a user interface for your app settings (although they useSharedPreferences as their implementation to save the app settings). For information about using thePreference APIs, see theSettings guide.

注意：SharedPreferences?APIs不僅僅可以讀取和寫入鍵值對，而且你不應該把它們和Preference APIs相混淆，后者幫助你為你的app設置建立一個用戶接口（盡管在存儲app設置時它們使用SharedPreferences實現）。

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Get a Handle to a SharedPreferences ——得到一個SharedPreferences的句柄

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You can create a new shared preference file or access an existing one by calling one of two methods:

• getSharedPreferences() — Use this if you need multiple shared preference files identified by name, which you specify with the first parameter. You can call this from anyContext in your app.
• getPreferences() — Use this from anActivity if you need to use only one shared preference file for the activity. Because this retrieves a default shared preference file that belongs to the activity, you don't need to supply a name.

你可以通過調用下面兩個方法之一創建一個新的共享引用文件或進入一個已經存在的文件：

• getSharedPreferences()——如果你需要多個 依靠名字（第一個參數）定義的共享引用文件，你可以使用這個函數。你可以從你的app中的任意Context里調用它。
• getPreferences()——如果你在這個activity中僅僅需要使用一個共享應用文件，就使用這個方法。因為它檢索一個屬于這個activity的默認共享應用文件，你不需要提供一個名稱。

For example, the following code is executed inside a Fragment. It accesses the shared preferences file that's identified by the resource stringR.string.preference_file_key and opens it using the private mode so the file is accessible by only your app.

例如，下面的代碼在一個Fragment中執行。它依靠資源字符R.string.preference_file_key定義來訪問一個共享應用文件，然后使用私有模式打開它，以使文件僅僅對你的app是可訪問的。

Context context = getActivity(); SharedPreferences sharedPref = context.getSharedPreferences(getString(R.string.preference_file_key), Context.MODE_PRIVATE);

When naming your shared preference files, you should use a name that's uniquely identifiable to your app, such as"com.example.myapp.PREFERENCE_FILE_KEY"

Alternatively, if you need just one shared preference file for your activity, you can use thegetPreferences() method:

當給你的共享引用文件命名時，你應該使用一個唯一的、可確認的名字，例如“com.example.myapp.PREFERENCE_FILE_KEY”。或者，如果你僅僅需要一個共享引用文件，你可以使用getPreferences()方法。

SharedPreferences sharedPref = getActivity().getPreferences(Context.MODE_PRIVATE);

Caution: If you create a shared preferences file withMODE_WORLD_READABLE orMODE_WORLD_WRITEABLE, then any other apps that know the file identifier can access your data.

警告：如果你使用MODE_WORLD_READABLE 或者MODE_WORLD_WRITEABLE ，那么其他任何apps都知道這個文件標識符可以訪問你的數據。

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Write to Shared Preferences —— 向共享引用寫入數據

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To write to a shared preferences file, create a SharedPreferences.Editor by callingedit() on yourSharedPreferences.

為了向一個共享的應用文件寫入，通過在你的SharedPreferences調用edit() 來創建一個SharedPreferences.Editor。

Pass the keys and values you want to write with methods such as putInt() andputString(). Then callcommit() to save the changes. For example:

利用putInt()?和putString()這樣的方法傳遞你想要寫入的鍵和值。然后調用commit()來存儲變化。例如：

SharedPreferences sharedPref = getActivity().getPreferences(Context.MODE_PRIVATE); SharedPreferences.Editor editor = sharedPref.edit(); editor.putInt(getString(R.string.saved_high_score), newHighScore); editor.commit();

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Read from Shared Preferences —— 從共享引用中讀取數據

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To retrieve values from a shared preferences file, call methods such as getInt() andgetString(), providing the key for the value you want, and optionally a default value to return if the key isn't present. For example:

為了從一個共享引用文件中檢索數值，調用getInt() andgetString()等方法，提供一個你想到得到的鍵，和一個供選擇的默認返回值（如果這個鍵不存在的話）。例如：

SharedPreferences sharedPref = getActivity().getPreferences(Context.MODE_PRIVATE); int defaultValue = getResources().getInteger(R.string.saved_high_score_default); long highScore = sharedPref.getInt(getString(R.string.saved_high_score), defaultValue);

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轉載于:https://www.cnblogs.com/xiaowangba/archive/2013/02/04/6314740.html

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