一、getSharedPreferences(String name, int mode)

abstract SharedPreferences

getSharedPreferences( String name, int mode)

Retrieve and hold the contents of the preferences file 'name', returning a SharedPreferences through which you can retrieve and modify its values. Only one instance of the SharedPreferences object is returned to any callers for the same name, meaning they will see each other's edits as soon as they are made.

得到名为‘name’的偏好文件。同时你可以更改和返回他的值。任何调用者在调用同样名字的偏好文件时只有一个实例返回，这就意味着这些调用者都可以看到其他调用者做出的更改。

这个函数的参数如下：

Parameters

name：

	Desired preferences file. If a preferences file by this name does not exist, it will be created when you retrieve an editor (SharedPreferences.edit()) and then commit changes (Editor.commit()). mode：
	Operating mode. Use 0 or `MODE_PRIVATE` for the default operation, `MODE_WORLD_READABLE` and`MODE_WORLD_WRITEABLE` to control permissions. The bit `MODE_MULTI_PROCESS` can also be used if multiple processes are mutating the same SharedPreferences file. `MODE_MULTI_PROCESS` is always on in apps targetting Gingerbread (Android 2.3) and below, and off by default in later versions.

Desired preferences file. If a preferences file by this name does not exist, it will be created when you retrieve an editor (SharedPreferences.edit()) and then commit changes (Editor.commit()).

mode：

Operating mode. Use 0 or MODE_PRIVATE for the default operation, MODE_WORLD_READABLE andMODE_WORLD_WRITEABLE to control permissions. The bit MODE_MULTI_PROCESS can also be used if multiple processes are mutating the same SharedPreferences file. MODE_MULTI_PROCESS is always on in apps targetting Gingerbread (Android 2.3) and below, and off by default in later versions.

name为本组件的配置文件名( 自己定义，也就是一个文件名)，当这个文件不存在时，直接创建，如果已经存在，则直接使用，

mode为操作模式，默认的模式为0或MODE_PRIVATE，还可以使用MODE_WORLD_READABLE和MODE_WORLD_WRITEABLE
mode指定为MODE_PRIVATE，则该配置文件只能被自己的应用程序访问。
mode指定为MODE_WORLD_READABLE，则该配置文件除了自己访问外还可以被其它应该程序读取。
mode指定为MODE_WORLD_WRITEABLE，则该配置文件除了自己访问外还可以被其它应该程序读取和写入

二、PreferenceManager的方法getSharedPreferences()

这个方法我们可以通过查看其源码：

/**

* Gets a SharedPreferences instance that preferences managed by this will
* use.
*
* @return A SharedPreferences instance pointing to the file that contains
* the values of preferences that are managed by this.
*/
public SharedPreferences getSharedPreferences() {
if (mSharedPreferences == null) {
mSharedPreferences = mContext.getSharedPreferences(mSharedPreferencesName,
mSharedPreferencesMode);
}
return mSharedPreferences;
}

 /**
* Gets a SharedPreferences instance that preferences managed by this will
* use.
*
* @return A SharedPreferences instance pointing to the file that contains
*         the values of preferences that are managed by this.
*/
public SharedPreferences getSharedPreferences() {
if (mSharedPreferences == null) {
mSharedPreferences = mContext.getSharedPreferences(mSharedPreferencesName,
mSharedPreferencesMode);
}
return mSharedPreferences;
}

这个方法是一个普通的方法，必须有PreferenceManager的实例调用才行，因此我们再按图索骥找找其构造方法。