我想存储一个时间值,需要检索和编辑它。我如何使用SharedPreferences来做到这一点?
当前回答
使用这个简单的库,下面是如何调用SharedPreferences..
TinyDB tinydb = new TinyDB(context);
tinydb.putInt("clickCount", 2);
tinydb.putString("userName", "john");
tinydb.putBoolean("isUserMale", true);
tinydb.putList("MyUsers", mUsersArray);
tinydb.putImagePNG("DropBox/WorkImages", "MeAtlunch.png", lunchBitmap);
//These plus the corresponding get methods are all Included
其他回答
使用这个例子简单明了
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.sairamkrishna.myapplication" >
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name=".MainActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
public class MainActivity extends AppCompatActivity {
EditText ed1,ed2,ed3;
Button b1;
public static final String MyPREFERENCES = "MyPrefs" ;
public static final String Name = "nameKey";
public static final String Phone = "phoneKey";
public static final String Email = "emailKey";
SharedPreferences sharedpreferences;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ed1=(EditText)findViewById(R.id.editText);
ed2=(EditText)findViewById(R.id.editText2);
ed3=(EditText)findViewById(R.id.editText3);
b1=(Button)findViewById(R.id.button);
sharedpreferences = getSharedPreferences(MyPREFERENCES, Context.MODE_PRIVATE);
b1.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String n = ed1.getText().toString();
String ph = ed2.getText().toString();
String e = ed3.getText().toString();
SharedPreferences.Editor editor = sharedpreferences.edit();
editor.putString(Name, n);
editor.putString(Phone, ph);
editor.putString(Email, e);
editor.commit();
Toast.makeText(MainActivity.this,"Thanks",Toast.LENGTH_LONG).show();
}
});
}
}
如果你正在与团队中的其他开发人员一起开发一个大型应用程序,并打算让所有内容都很好地组织起来,而不是分散的代码或不同的SharedPreferences实例,你可以这样做:
//SharedPreferences manager class
public class SharedPrefs {
//SharedPreferences file name
private static String SHARED_PREFS_FILE_NAME = "my_app_shared_prefs";
//here you can centralize all your shared prefs keys
public static String KEY_MY_SHARED_BOOLEAN = "my_shared_boolean";
public static String KEY_MY_SHARED_FOO = "my_shared_foo";
//get the SharedPreferences object instance
//create SharedPreferences file if not present
private static SharedPreferences getPrefs(Context context) {
return context.getSharedPreferences(SHARED_PREFS_FILE_NAME, Context.MODE_PRIVATE);
}
//Save Booleans
public static void savePref(Context context, String key, boolean value) {
getPrefs(context).edit().putBoolean(key, value).commit();
}
//Get Booleans
public static boolean getBoolean(Context context, String key) {
return getPrefs(context).getBoolean(key, false);
}
//Get Booleans if not found return a predefined default value
public static boolean getBoolean(Context context, String key, boolean defaultValue) {
return getPrefs(context).getBoolean(key, defaultValue);
}
//Strings
public static void save(Context context, String key, String value) {
getPrefs(context).edit().putString(key, value).commit();
}
public static String getString(Context context, String key) {
return getPrefs(context).getString(key, "");
}
public static String getString(Context context, String key, String defaultValue) {
return getPrefs(context).getString(key, defaultValue);
}
//Integers
public static void save(Context context, String key, int value) {
getPrefs(context).edit().putInt(key, value).commit();
}
public static int getInt(Context context, String key) {
return getPrefs(context).getInt(key, 0);
}
public static int getInt(Context context, String key, int defaultValue) {
return getPrefs(context).getInt(key, defaultValue);
}
//Floats
public static void save(Context context, String key, float value) {
getPrefs(context).edit().putFloat(key, value).commit();
}
public static float getFloat(Context context, String key) {
return getPrefs(context).getFloat(key, 0);
}
public static float getFloat(Context context, String key, float defaultValue) {
return getPrefs(context).getFloat(key, defaultValue);
}
//Longs
public static void save(Context context, String key, long value) {
getPrefs(context).edit().putLong(key, value).commit();
}
public static long getLong(Context context, String key) {
return getPrefs(context).getLong(key, 0);
}
public static long getLong(Context context, String key, long defaultValue) {
return getPrefs(context).getLong(key, defaultValue);
}
//StringSets
public static void save(Context context, String key, Set<String> value) {
getPrefs(context).edit().putStringSet(key, value).commit();
}
public static Set<String> getStringSet(Context context, String key) {
return getPrefs(context).getStringSet(key, null);
}
public static Set<String> getStringSet(Context context, String key, Set<String> defaultValue) {
return getPrefs(context).getStringSet(key, defaultValue);
}
}
在您的活动中,您可以这样保存SharedPreferences
//saving a boolean into prefs
SharedPrefs.savePref(this, SharedPrefs.KEY_MY_SHARED_BOOLEAN, booleanVar);
你可以这样检索你的SharedPreferences
//getting a boolean from prefs
booleanVar = SharedPrefs.getBoolean(this, SharedPrefs.KEY_MY_SHARED_BOOLEAN);
单例共享首选项类。这可能对将来的其他人有所帮助。
import android.app.Activity;
import android.content.Context;
import android.content.SharedPreferences;
public class SharedPref
{
private static SharedPreferences mSharedPref;
public static final String NAME = "NAME";
public static final String AGE = "AGE";
public static final String IS_SELECT = "IS_SELECT";
private SharedPref()
{
}
public static void init(Context context)
{
if(mSharedPref == null)
mSharedPref = context.getSharedPreferences(context.getPackageName(), Activity.MODE_PRIVATE);
}
public static String read(String key, String defValue) {
return mSharedPref.getString(key, defValue);
}
public static void write(String key, String value) {
SharedPreferences.Editor prefsEditor = mSharedPref.edit();
prefsEditor.putString(key, value);
prefsEditor.commit();
}
public static boolean read(String key, boolean defValue) {
return mSharedPref.getBoolean(key, defValue);
}
public static void write(String key, boolean value) {
SharedPreferences.Editor prefsEditor = mSharedPref.edit();
prefsEditor.putBoolean(key, value);
prefsEditor.commit();
}
public static Integer read(String key, int defValue) {
return mSharedPref.getInt(key, defValue);
}
public static void write(String key, Integer value) {
SharedPreferences.Editor prefsEditor = mSharedPref.edit();
prefsEditor.putInt(key, value).commit();
}
}
只需在MainActivity上调用一次SharedPref.init()
SharedPref.init(getApplicationContext());
写入数据
SharedPref.write(SharedPref.NAME, "XXXX");//save string in shared preference.
SharedPref.write(SharedPref.AGE, 25);//save int in shared preference.
SharedPref.write(SharedPref.IS_SELECT, true);//save boolean in shared preference.
读取数据
String name = SharedPref.read(SharedPref.NAME, null);//read string in shared preference.
int age = SharedPref.read(SharedPref.AGE, 0);//read int in shared preference.
boolean isSelect = SharedPref.read(SharedPref.IS_SELECT, false);//read boolean in shared preference.
编辑sharedpreference中的数据
SharedPreferences.Editor editor = getPreferences(MODE_PRIVATE).edit();
editor.putString("text", mSaved.getText().toString());
editor.putInt("selection-start", mSaved.getSelectionStart());
editor.putInt("selection-end", mSaved.getSelectionEnd());
editor.apply();
从sharedpreference中检索数据
SharedPreferences prefs = getPreferences(MODE_PRIVATE);
String restoredText = prefs.getString("text", null);
if (restoredText != null)
{
//mSaved.setText(restoredText, TextView.BufferType.EDITABLE);
int selectionStart = prefs.getInt("selection-start", -1);
int selectionEnd = prefs.getInt("selection-end", -1);
/*if (selectionStart != -1 && selectionEnd != -1)
{
mSaved.setSelection(selectionStart, selectionEnd);
}*/
}
Edit
我从API Demo样本中截取了这个片段。它有一个编辑文本框。在这种情况下,它不是必需的。我也有同样的看法。
要获得共享首选项,请使用以下方法 在活动中:
SharedPreferences prefs = this.getSharedPreferences(
"com.example.app", Context.MODE_PRIVATE);
读取首选项:
String dateTimeKey = "com.example.app.datetime";
// use a default value using new Date()
long l = prefs.getLong(dateTimeKey, new Date().getTime());
编辑和保存首选项
Date dt = getSomeDate();
prefs.edit().putLong(dateTimeKey, dt.getTime()).apply();
android sdk的示例目录包含一个检索和存储共享首选项的示例。它位于:
<android-sdk-home>/samples/android-<platformversion>/ApiDemos directory
编辑= = >
我注意到,在这里写commit()和apply()之间的区别也很重要。
如果保存成功,Commit()返回true,否则返回false。它同步保存值到SharedPreferences。
Apply()是在2.3中添加的,无论成功还是失败都不返回任何值。它会立即将值保存到SharedPreferences,但会启动异步提交。 更多细节在这里。
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