Preferences Android数据存储_preferences保存的位置

除了SQLite数据库外，SharedPreferences也是一种轻型的数据存储方式，它的本

质是基于XML文件存储key- value键值 对数据，通常用来存储一些简单的配置信

息。其存储位置在/data/data/<包名>/shared_prefs目录下。SharedPreferences

对象本身只能获取数据而不支持存储和修改，存储修改是通过Editor对象实现。实

现SharedPreferences存储的步骤如下：

 

　　一、根据Context获取SharedPreferences对象

 

　　二、利用edit()方法获取Editor对象。

 

　　三、通过Editor对象存储key-value键值对数据。

 

　　四、通过commit()方法提交数据。

 

下述对Preferences做了一个简单的封装，方便使用

 

public class PreferencesUtils {

 

 

public static String PREFERENCE_NAME ="xml_db";

 

/**

* put string preferences

*

* @param context

* @param key The name of the preferenceto modify

* @param value The new value for thepreference

* @return True if the new values weresuccessfully written to persistent storage.

*/

public static boolean putString(Contextcontext, String key, String value) { SharedPreferences settings =context.getSharedPreferences(PREFERENCE_NAME, Context.MODE_PRIVATE);SharedPreferences.Editor editor = settings.edit(); editor.putString(key, value);return editor.commit(); }

 

/**

* get string preferences

*

* @param context

* @param key The name of the preferenceto retrieve

* @return The preference value if itexists, or null. Throws ClassCastException if there is a preference with this

* name that is not a string

* @see #getString(Context, String,String) */ public static String getString(Context context, String key) { returngetString(context, key, null); }

 

/**

* get string preferences

*

* @param context

* @param key The name of the preferenceto retrieve

* @param defaultValue Value to return ifthis preference does not exist

* @return The preference value if itexists, or defValue. Throws ClassCastException if there is a preference with

* this name that is not a string

*/

public static String getString(Contextcontext, String key, String

defaultValue) {

SharedPreferences settings =

context.getSharedPreferences(PREFERENCE_NAME,Context.MODE_PRIVATE); return settings.getString(key, defaultValue); }

 

/**

* put int preferences

*

* @param context

* @param key The name of the preferenceto modify

* @param value The new value for thepreference

* @return True if the new values weresuccessfully written to persistent storage.

*/

public static boolean putInt(Contextcontext, String key, int value) { SharedPreferences settings =context.getSharedPreferences(PREFERENCE_NAME, Context.MODE_PRIVATE);SharedPreferences.Editor editor = settings.edit(); editor.putInt(key, value);return editor.commit(); }

 

/**

* get int preferences

*

* @param context

* @param key The name of the preferenceto retrieve

* @return The preference value if itexists, or -1. Throws ClassCastException if there is a preference with this

* name that is not a int

* @see #getInt(Context, String, int)

*/

public static int getInt(Context context,String key) { return getInt(context, key, -1); }

 

/**

* get int preferences

*

* @param context

* @param key The name of the preferenceto retrieve

* @param defaultValue Value to return ifthis preference does not exist

* @return The preference value if itexists, or defValue. Throws ClassCastException if there is a preference with

* this name that is not a int

*/

public static int getInt(Contextcontext, String key, int defaultValue) { SharedPreferences settings =context.getSharedPreferences(PREFERENCE_NAME, Context.MODE_PRIVATE); returnsettings.getInt(key, defaultValue); }

 

/**

* put long preferences

*

* @param context

* @param key The name of the preferenceto modify

* @param value The new value for thepreference

* @return True if the new values weresuccessfully written to persistent storage.

*/

public static boolean putLong(Contextcontext, String key, long value) { SharedPreferences settings =context.getSharedPreferences(PREFERENCE_NAME, Context.MODE_PRIVATE); SharedPreferences.Editoreditor = settings.edit(); editor.putLong(key, value); return editor.commit(); }

 

/**

* get long preferences

*

* @param context

* @param key The name of the preferenceto retrieve

* @return The preference value if itexists, or -1. Throws ClassCastException if there is a preference with this

* name that is not a long

* @see #getLong(Context, String, long)

*/

public static long getLong(Contextcontext, String key) { return getLong(context, key, -1); }

 

/**

* get long preferences

*

* @param context

* @param key The name of the preferenceto retrieve

* @param defaultValue Value to return ifthis preference does not exist

* @return The preference value if itexists, or defValue. Throws ClassCastException if there is a preference with

* this name that is not a long

*/

public static long getLong(Contextcontext, String key, long defaultValue) { SharedPreferences settings =context.getSharedPreferences(PREFERENCE_NAME, Context.MODE_PRIVATE); returnsettings.getLong(key, defaultValue); }

 

/**

* put float preferences

*

* @param context

* @param key The name of the preferenceto modify

* @param value The new value for thepreference

* @return True if the new values weresuccessfully written to persistent storage.

*/

public static boolean putFloat(Contextcontext, String key, float value) { SharedPreferences settings =context.getSharedPreferences(PREFERENCE_NAME, Context.MODE_PRIVATE);SharedPreferences.Editor editor = settings.edit(); editor.putFloat(key, value);return editor.commit(); }

 

/**

* get float preferences

*

* @param context

* @param key The name of the preferenceto retrieve

* @return The preference value if itexists, or -1. Throws ClassCastException if there is a preference with this

* name that is not a float

* @see #getFloat(Context, String, float)*/ public static float getFloat(Context context, String key) { returngetFloat(context, key, -1); }

 

/**

* get float preferences

*

* @param context

* @param key The name of the preferenceto retrieve

* @param defaultValue Value to return ifthis preference does not exist

* @return The preference value if itexists, or defValue. Throws ClassCastException if there is a preference with

* this name that is not a float

*/

public static float getFloat(Contextcontext, String key, float

defaultValue) {

SharedPreferences settings =

context.getSharedPreferences(PREFERENCE_NAME,Context.MODE_PRIVATE); return settings.getFloat(key, defaultValue); }

 

/**

* put boolean preferences

*

* @param context

* @param key The name of the preferenceto modify

* @param value The new value for thepreference

* @return True if the new values weresuccessfully written to persistent storage.

*/

public static boolean putBoolean(Contextcontext, String key, boolean

value) {

SharedPreferences settings =

context.getSharedPreferences(PREFERENCE_NAME,Context.MODE_PRIVATE); SharedPreferences.Editor editor = settings.edit();editor.putBoolean(key, value); return editor.commit(); }

 

/**

* get boolean preferences, default isfalse

*

* @param context

* @param key The name of the preferenceto retrieve

* @return The preference value if itexists, or false. Throws ClassCastException if there is a preference with this

* name that is not a boolean

* @see #getBoolean(Context, String,boolean) */ public static boolean getBoolean(Context context, String key) {return getBoolean(context, key, false); }

 

/**

* get boolean preferences

*

* @param context

* @param key The name of the preferenceto retrieve

* @param defaultValue Value to return ifthis preference does not exist

* @return The preference value if itexists, or defValue. Throws ClassCastException if there is a preference with

* this name that is not a boolean

*/

public static boolean getBoolean(Contextcontext, String key, boolean

defaultValue) {

SharedPreferences settings =

context.getSharedPreferences(PREFERENCE_NAME,Context.MODE_PRIVATE); return settings.getBoolean(key, defaultValue); } }