android 使用sharedPreferences保存用户设置的参数

官方文档介绍：

Using Shared Preferences

The SharedPreferences class provides a general framework that allows you to save and retrieve persistent key-value pairs of primitive data types. You can use SharedPreferences to save any primitive data: booleans, floats, ints, longs, and strings. This data will persist across user sessions (even if your application is killed).

User Preferences

Shared preferences are not strictly for saving "user preferences," such as what ringtone a user has chosen. If you're interested in creating user preferences for your application, seePreferenceActivity, which provides an Activity framework for you to create user preferences, which will be automatically persisted (using shared preferences).

To get a SharedPreferences object for your application, use one of two methods:

• getSharedPreferences() - Use this if you need multiple preferences files identified by name, which you specify with the first parameter.
• getPreferences() - Use this if you need only one preferences file for your Activity. Because this will be the only preferences file for your Activity, you don't supply a name.

To write values:

1. Call edit() to get a SharedPreferences.Editor.
2. Add values with methods such as putBoolean() and putString().
3. Commit the new values with commit()

To read values, use SharedPreferences methods such as getBoolean() and getString().

a.示例程序：保存用户设置的数据

/**
	 * 保存各项参数
	 * @param name 姓名
	 * @param age 年龄
	 */
	public void save(String name, int age) {
		SharedPreferences preferences = context.getSharedPreferences("preferences", Context.MODE_PRIVATE);
		Editor edit = preferences.edit();
		edit.putString("name", name);
		edit.putInt("age", age);
		edit.commit();
	}

在保存之后，sharedPreferences将会把数据保存在 /data/data/<应用程序包名>/shared_pres/目录下，且使用xml方式保存数据

示例程序保存的数据是：

<?xml version='1.0' encoding='utf-8' standalone='yes' ?>
<map>
<int name="age" value="23" />
<string name="name">g形成</string>
</map>

b.示例程序：从sharedPreferences中读取数据

/**
	 * @return 返回参数设置数据
	 */
	public Map<String, String > getPreferences(){
		Map<String, String> params = new HashMap<String, String>();
		SharedPreferences sp = context.getSharedPreferences("preferences", Context.MODE_PRIVATE);
		params.put("name", sp.getString("name", ""));
		params.put("age", String.valueOf(sp.getInt("age", 0)));
		return params;
	}