SharedPreferences简介：
SharedPreferences是Android平台上一个轻量级的存储类，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，比如窗口状态，一些小型自定义数据等。其存储位置在/data/data/<包名>/shared_prefs目录下，可以通过DDMS--FileExplorer下查看（选中文件点击DDMS右上角的导出文件）。
数据的存储：
1.构造函数：
如示例，一般常用的构造函数为2个参数
第一个为sp的名称，第二个一般为权限比如Activity.MODE_PRIVATE, MODE_APPEND, MODE_WORLD_READABLE, MODE_WORLD_WRITEABLE
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public
class
Calc extends Activity {
public
static
final String PREFS_NAME =
"MyPrefsFile"
;
@Override
protected
void
onCreate(Bundle state){
super.onCreate(state);
. . .
// Restore preferences
SharedPreferences settings = getSharedPreferences(PREFS_NAME, 0);
boolean silent = settings.getBoolean(
"silentMode"
,
false
);
setSilent(silent);
}
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2.数据的存储以及修改：
使用SharedPreferences.Editor类来构造一个编辑器进行存储数据
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add.setOnClickListener(
new
OnClickListener(){
@Override
public
void
onClick(View v) {
// TODO Auto-generated method stub
String str_name = (String) name.getText();
String str_path = (String) text.getText();
SharedPreferences Addresses = getSharedPreferences(PREFS_NAME,Activity.M );
SharedPreferences.Editor editor = Addresses.edit();
//通过SharedPreferences.edit()来对Editor进行初始化
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editor.putString(str_name,str_path);
//添加数据 <br> editor.commit(); //数据添加后必须提交才会修改xml文件 <br> Toast.makeText(getApplicationContext(), "Successed", Toast.LENGTH_LONG).show(); <br> } <br> });
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删除数据
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public
boolean onItemLongClick(AdapterView<?> parent, View view,
int
position,
long
id) {
SharedPreferences Addresses = getSharedPreferences(PREFS_NAME,
Activity.MODE_PRIVATE);
SharedPreferences.Editor editor = Addresses.edit();
//通过SharedPreferences.edit()来对Editor进行初始化
editor.
remove
((String) listview.getSelectedItem());
//删除相应的数据
editor.commit();
//同样需要提交
}
});
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3.一些常用的方法：
| void apply()
Commit your preferences changes back from this Editor to the
SharedPreferences object it is editing.
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| SharedPreferences.Editor clear()
Mark in the editor to remove all values from the preferences.
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| boolean commit()
Commit your preferences changes back from this Editor to the
SharedPreferences object it is editing.
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| SharedPreferences.Editorput Boolean(String key, boolean value)
Set a boolean value in the preferences editor, to be written back once
commit() or
apply() are called.
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| SharedPreferences.Editor putInt(String key, int value)
Set an int value in the preferences editor, to be written back once
commit() or
apply() are called.
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| SharedPreferences.Editor putString(String key, String value)
Set a String value in the preferences editor, to be written back once
commit() or
apply() are called.
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| SharedPreferences.Editor putStringSet(String key, Set<String> values)
Set a set of String values in the preferences editor, to be written back once
commit() is called.
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| SharedPreferences.Editor remove(String key)
Mark in the editor that a preference value should be removed, which will be done in the actual preferences once
commit() is called.
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数据的读取：
| SharedPreferences.Editor edit()
Create a new Editor for these preferences, through which you can make modifications to the data in the preferences and atomically commit those changes back to the SharedPreferences object.
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| Map<String, ?> getAll()
Retrieve all values from the preferences.
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| boolean getBoolean(String key, boolean defValue)
Retrieve a boolean value from the preferences.
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| String getString(String key, String defValue)
Retrieve a String value from the preferences.
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| Set<String> getStringSet(String key, Set<String> defValues)
Retrieve a set of String values from the preferences.
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| void registerOnSharedPreferenceChangeListener(SharedPreferences.OnSharedPreferenceChangeListener listener)
Registers a callback to be invoked when a change happens to a preference.
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| void unregisterOnSharedPreferenceChangeListener(SharedPreferences.OnSharedPreferenceChangeListener listener)
Unregisters a previous callback.
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使用getAll()读取所有数据存储在一个HashMap中：
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listview = (ListView) findViewById(R.id.lv);
SharedPreferences Addresses = getSharedPreferences(PREFS_NAME, 0);
listItems = (HashMap<String, Object>) Addresses.getAll();
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还是挺好用的哈～～