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

使用delegate Kotlin,我们可以轻松地从共享首选项中放置和获取数据。

    inline fun <reified T> Context.sharedPrefs(key: String) = object : ReadWriteProperty<Any?, T> {

        val sharedPrefs by lazy { this@sharedPrefs.getSharedPreferences("APP_DATA", Context.MODE_PRIVATE) }
        val gson by lazy { Gson() }
        var newData: T = (T::class.java).newInstance()

        override fun getValue(thisRef: Any?, property: KProperty<*>): T {
            return getPrefs()
        }

        override fun setValue(thisRef: Any?, property: KProperty<*>, value: T) {
            this.newData = value
            putPrefs(newData)
        }

        fun putPrefs(value: T?) {
            sharedPrefs.edit {
                when (value) {
                    is Int -> putInt(key, value)
                    is Boolean -> putBoolean(key, value)
                    is String -> putString(key, value)
                    is Long -> putLong(key, value)
                    is Float -> putFloat(key, value)
                    is Parcelable -> putString(key, gson.toJson(value))
                    else          -> throw Throwable("no such type exist to put data")
                }
            }
        }

        fun getPrefs(): T {
            return when (newData) {
                       is Int -> sharedPrefs.getInt(key, 0) as T
                       is Boolean -> sharedPrefs.getBoolean(key, false) as T
                       is String -> sharedPrefs.getString(key, "") as T ?: "" as T
                       is Long -> sharedPrefs.getLong(key, 0L) as T
                       is Float -> sharedPrefs.getFloat(key, 0.0f) as T
                       is Parcelable -> gson.fromJson(sharedPrefs.getString(key, "") ?: "", T::class.java)
                       else          -> throw Throwable("no such type exist to put data")
                   } ?: newData
        }

    }

    //use this delegation in activity and fragment in following way
        var ourData by sharedPrefs<String>("otherDatas")

其他回答

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);
// SharedPrefHelper is a class contains the get and save sharedPrefernce data
public class SharedPrefHelper {

    // save data in sharedPrefences
    public static void setSharedOBJECT(Context context, String key, 
                                           Object value) {

        SharedPreferences sharedPreferences =  context.getSharedPreferences(
                context.getPackageName(), Context.MODE_PRIVATE);

        SharedPreferences.Editor prefsEditor = sharedPreferences.edit();
        Gson gson = new Gson();
        String json = gson.toJson(value);
        prefsEditor.putString(key, json);
        prefsEditor.apply();
    }

    // get data from sharedPrefences 
    public static Object getSharedOBJECT(Context context, String key) {

         SharedPreferences sharedPreferences = context.getSharedPreferences(
                           context.getPackageName(), Context.MODE_PRIVATE);

        Gson gson = new Gson();
        String json = sharedPreferences.getString(key, "");
        Object obj = gson.fromJson(json, Object.class);
        User objData = new Gson().fromJson(obj.toString(), User.class);
        return objData;
    }
}
// save data in your activity

User user = new User("Hussein","h@h.com","3107310890983");        
SharedPrefHelper.setSharedOBJECT(this,"your_key",user);        
User data = (User) SharedPrefHelper.getSharedOBJECT(this,"your_key");

Toast.makeText(this,data.getName()+"\n"+data.getEmail()+"\n"+data.getPhone(),Toast.LENGTH_LONG).show();
// User is the class you want to save its objects

public class User {

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public String getPhone() {
        return phone;
    }

    public void setPhone(String phone) {
        this.phone = phone;
    }

    private String name,email,phone;
    public User(String name,String email,String phone){
          this.name=name;
          this.email=email;
          this.phone=phone;
    }
}
// put this in gradle

compile 'com.google.code.gson:gson:2.7'

希望这对你有所帮助:)

将数据存储在SharedPreference中

SharedPreferences mprefs = getSharedPreferences(AppConstant.PREFS_NAME, MODE_PRIVATE)
mprefs.edit().putString(AppConstant.USER_ID, resUserID).apply();

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

使用delegate Kotlin,我们可以轻松地从共享首选项中放置和获取数据。

    inline fun <reified T> Context.sharedPrefs(key: String) = object : ReadWriteProperty<Any?, T> {

        val sharedPrefs by lazy { this@sharedPrefs.getSharedPreferences("APP_DATA", Context.MODE_PRIVATE) }
        val gson by lazy { Gson() }
        var newData: T = (T::class.java).newInstance()

        override fun getValue(thisRef: Any?, property: KProperty<*>): T {
            return getPrefs()
        }

        override fun setValue(thisRef: Any?, property: KProperty<*>, value: T) {
            this.newData = value
            putPrefs(newData)
        }

        fun putPrefs(value: T?) {
            sharedPrefs.edit {
                when (value) {
                    is Int -> putInt(key, value)
                    is Boolean -> putBoolean(key, value)
                    is String -> putString(key, value)
                    is Long -> putLong(key, value)
                    is Float -> putFloat(key, value)
                    is Parcelable -> putString(key, gson.toJson(value))
                    else          -> throw Throwable("no such type exist to put data")
                }
            }
        }

        fun getPrefs(): T {
            return when (newData) {
                       is Int -> sharedPrefs.getInt(key, 0) as T
                       is Boolean -> sharedPrefs.getBoolean(key, false) as T
                       is String -> sharedPrefs.getString(key, "") as T ?: "" as T
                       is Long -> sharedPrefs.getLong(key, 0L) as T
                       is Float -> sharedPrefs.getFloat(key, 0.0f) as T
                       is Parcelable -> gson.fromJson(sharedPrefs.getString(key, "") ?: "", T::class.java)
                       else          -> throw Throwable("no such type exist to put data")
                   } ?: newData
        }

    }

    //use this delegation in activity and fragment in following way
        var ourData by sharedPrefs<String>("otherDatas")