Android 数据存储之SharedPreferences存储小记

前言

Android的数据存储机制中还提供了SharedPreferences，SharedPreferences是这其中最容易理解的数据存储技术，采用键值对的方式进行存储，而且支持存储多中数据类型。

获取SharedPreferences对象

SharedPreferences文件存放在/data/data/<package name>/shared_prefs/中，在Android的中，主要提供了三种方式进行SharedPreferences对象的获取。

1.Context中的getSharedPreferences()方法

@Override
public SharedPreferences getSharedPreferences(String name, int mode) {return mBase.getSharedPreferences(name, mode);
}

2.Activity中的getPreferences()

/*** Retrieve a {@link SharedPreferences} object for accessing preferences* that are private to this activity.  This simply calls the underlying* {@link #getSharedPreferences(String, int)} method by passing in this activity's* class name as the preferences name.* * @param mode Operating mode.  Use {@link #MODE_PRIVATE} for the default *             operation, {@link #MODE_WORLD_READABLE} and *             {@link #MODE_WORLD_WRITEABLE} to control permissions.** @return Returns the single SharedPreferences instance that can be used*         to retrieve and modify the preference values.*/
public SharedPreferences getPreferences(int mode) {return getSharedPreferences(getLocalClassName(), mode);
}

3.PreferenceManager中的getDefaultSharedPreferences()

/*** Gets a SharedPreferences instance that points to the default file that is* used by the preference framework in the given context.* * @param context The context of the preferences whose values are wanted.* @return A SharedPreferences instance that can be used to retrieve and*         listen to values of the preferences.*/
public static SharedPreferences getDefaultSharedPreferences(Context context) {return context.getSharedPreferences(getDefaultSharedPreferencesName(context),getDefaultSharedPreferencesMode());
}

SharedPreferences进行存储

获取了SharedPreferences对象，进行存储操作就简单了，实例如下：

public void onClick(View v) {SharedPreferences.Editor editor = getSharedPreferences("data", MODE_PRIVATE).edit();editor.putString("name", "Xiaoming");editor.putInt("age", 18);editor.commit();Toast.makeText(getApplicationContext(), "SP写入成功", Toast.LENGTH_SHORT).show();
}

这是存储后生成的文件：

<?xml version='1.0' encoding='utf-8' standalone='yes' ?>
<map><boolean name="married" value="false" /><string name="name">Xiaoming</string><int name="age" value="18" />
</map>

SharedPreferences进行读取

读取同样简单，代码如下：

public void onClick(View v) {SharedPreferences pref = getSharedPreferences("data", MODE_PRIVATE);String str = pref.getString("name", "") + "\n"+ pref.getInt("age", 0);Toast.makeText(getApplicationContext(), str, Toast.LENGTH_SHORT).show();
}