我需要在许多地方获得用户对象,其中包含许多字段。登录后,我想保存/存储这些用户对象。我们如何实现这种场景?
我不能这样存储它:
SharedPreferences.Editor prefsEditor = myPrefs.edit();
prefsEditor.putString("BusinessUnit", strBusinessUnit);
我需要在许多地方获得用户对象,其中包含许多字段。登录后,我想保存/存储这些用户对象。我们如何实现这种场景?
我不能这样存储它:
SharedPreferences.Editor prefsEditor = myPrefs.edit();
prefsEditor.putString("BusinessUnit", strBusinessUnit);
当前回答
关于这个问题有很多很好的答案,穆罕穆德·阿米尔·阿里和穆哈默德·埃尔-班纳在Kotlin使用通用方法实现了答案。
为了节省
fun storeObjectInSharedPref(dataObject: Any, prefName: String): Boolean{
val dataObjectInJson = Gson().toJson(dataObject)
prefsEditor.putString(prefName, dataObjectInJson)
return prefsEditor.commit()
}
检索
fun <T> retrieveStoredObject(prefName: String, baseClass: Class<T>): T?{
val dataObject: String? = preferences.getString(prefName, "")
return Gson().fromJson(dataObject, baseClass)
}
要了解Kotlin中的泛型,请访问这里
其他回答
您可以使用以下代码存储类对象,并从共享首选项检索任何对象。
将以下依赖项添加到应用gradle中
dependencies {
implementation 'com.google.code.gson:gson:2.8.6'
//Other dependencies of our project
}
在共享pref文件中添加以下代码。
/**
* Saves object into the Preferences.
*
* @param `object` Object of model class (of type [T]) to save
* @param key Key with which Shared preferences to
**/
fun <T> put(`object`: T, key: String) {
//Convert object to JSON String.
val jsonString = GsonBuilder().create().toJson(`object`)
//Save that String in SharedPreferences
preferences.edit().putString(key, jsonString).apply()
}
/**
* Used to retrieve object from the Preferences.
*
* @param key Shared Preference key with which object was saved.
**/
inline fun <reified T> get(key: String): T? {
//We read JSON String which was saved.
val value = preferences.getString(key, null)
//JSON String was found which means object can be read.
//We convert this JSON String to model object. Parameter "c" (of
//type Class < T >" is used to cast.
return GsonBuilder().create().fromJson(value, T::class.java)
}
}
有两个文件解决了共享首选项的所有问题
1)AppPersistence.java
public class AppPersistence {
public enum keys {
USER_NAME, USER_ID, USER_NUMBER, USER_EMAIL, USER_ADDRESS, CITY, USER_IMAGE,
DOB, MRG_Anniversary, COMPANY, USER_TYPE, support_phone
}
private static AppPersistence mAppPersistance;
private SharedPreferences sharedPreferences;
public static AppPersistence start(Context context) {
if (mAppPersistance == null) {
mAppPersistance = new AppPersistence(context);
}
return mAppPersistance;
}
private AppPersistence(Context context) {
sharedPreferences = context.getSharedPreferences(context.getString(R.string.prefrence_file_name),
Context.MODE_PRIVATE);
}
public Object get(Enum key) {
Map<String, ?> all = sharedPreferences.getAll();
return all.get(key.toString());
}
void save(Enum key, Object val) {
SharedPreferences.Editor editor = sharedPreferences.edit();
if (val instanceof Integer) {
editor.putInt(key.toString(), (Integer) val);
} else if (val instanceof String) {
editor.putString(key.toString(), String.valueOf(val));
} else if (val instanceof Float) {
editor.putFloat(key.toString(), (Float) val);
} else if (val instanceof Long) {
editor.putLong(key.toString(), (Long) val);
} else if (val instanceof Boolean) {
editor.putBoolean(key.toString(), (Boolean) val);
}
editor.apply();
}
void remove(Enum key) {
SharedPreferences.Editor editor = sharedPreferences.edit();
editor.remove(key.toString());
editor.apply();
}
public void removeAll() {
SharedPreferences.Editor editor = sharedPreferences.edit();
editor.clear();
editor.apply();
}
}
2)AppPreference.java
public static void setPreference(Context context, Enum Name, String Value) {
AppPersistence.start(context).save(Name, Value);
}
public static String getPreference(Context context, Enum Name) {
return (String) AppPersistence.start(context).get(Name);
}
public static void removePreference(Context context, Enum Name) {
AppPersistence.start(context).remove(Name);
}
}
现在你可以保存,删除或者获取,
保存
AppPreference.setPreference(context, AppPersistence.keys.USER_ID, userID);
删除
AppPreference.removePreference(context, AppPersistence.keys.USER_ID);
-get
AppPreference.getPreference(context, AppPersistence.keys.USER_ID);
我的utils类保存列表到SharedPreferences
public class SharedPrefApi {
private SharedPreferences sharedPreferences;
private Gson gson;
public SharedPrefApi(Context context, Gson gson) {
this.sharedPreferences = context.getSharedPreferences(PREFS_NAME, Context.MODE_PRIVATE);
this.gson = gson;
}
...
public <T> void putObject(String key, T value) {
SharedPreferences.Editor editor = sharedPreferences.edit();
editor.putString(key, gson.toJson(value));
editor.apply();
}
public <T> T getObject(String key, Class<T> clazz) {
return gson.fromJson(getString(key, null), clazz);
}
}
使用
// for save
sharedPrefApi.putList(SharedPrefApi.Key.USER_LIST, userList);
// for retrieve
List<User> userList = sharedPrefApi.getList(SharedPrefApi.Key.USER_LIST, User.class);
. 我的utils的完整代码//检查使用实例的活动代码
更好的方法是创建一个全局Constants类来保存键或变量以获取或保存数据。
要保存数据,请调用此方法保存来自任何地方的数据。
public static void saveData(Context con, String variable, String data)
{
SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(con);
prefs.edit().putString(variable, data).commit();
}
用它来获取数据。
public static String getData(Context con, String variable, String defaultValue)
{
SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(con);
String data = prefs.getString(variable, defaultValue);
return data;
}
像这样的方法就可以了
public static User getUserInfo(Context con)
{
String id = getData(con, Constants.USER_ID, null);
String name = getData(con, Constants.USER_NAME, null);
if(id != null && name != null)
{
User user = new User(); //Hope you will have a user Object.
user.setId(id);
user.setName(name);
//Here set other credentials.
return user;
}
else
return null;
}
步骤1:在java文件中复制粘贴这两个函数。
public void setDefaults(String key, String value, Context context) {
SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(context);
SharedPreferences.Editor editor = preferences.edit();
editor.putString(key, value);
editor.commit();
}
public static String getDefaults(String key, Context context) {
SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(context);
return preferences.getString(key, null);
}
步骤2: 为了节省使用:
setDefaults("key","value",this);
检索使用:
String retrieve= getDefaults("key",this);
你可以通过使用不同的键名来设置不同的共享首选项,比如:
setDefaults("key1","xyz",this);
setDefaults("key2","abc",this);
setDefaults("key3","pqr",this);