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

看这里,这可以帮助你:

public static boolean setObject(Context context, Object o) {
        Field[] fields = o.getClass().getFields();
        SharedPreferences sp = context.getSharedPreferences(o.getClass()
                .getName(), Context.MODE_PRIVATE);
        Editor editor = sp.edit();
        for (int i = 0; i < fields.length; i++) {
            Class<?> type = fields[i].getType();
            if (isSingle(type)) {
                try {
                    final String name = fields[i].getName();
                    if (type == Character.TYPE || type.equals(String.class)) {
                        Object value = fields[i].get(o);
                        if (null != value)
                            editor.putString(name, value.toString());
                    } else if (type.equals(int.class)
                            || type.equals(Short.class))
                        editor.putInt(name, fields[i].getInt(o));
                    else if (type.equals(double.class))
                        editor.putFloat(name, (float) fields[i].getDouble(o));
                    else if (type.equals(float.class))
                        editor.putFloat(name, fields[i].getFloat(o));
                    else if (type.equals(long.class))
                        editor.putLong(name, fields[i].getLong(o));
                    else if (type.equals(Boolean.class))
                        editor.putBoolean(name, fields[i].getBoolean(o));

                } catch (IllegalAccessException e) {
                    LogUtils.e(TAG, e);
                } catch (IllegalArgumentException e) {
                    LogUtils.e(TAG, e);
                }
            } else {
                // FIXME 是对象则不写入
            }
        }

        return editor.commit();
    }

https://github.com/AltasT/PreferenceVObjectFile/blob/master/PreferenceVObjectFile/src/com/altas/lib/PreferenceUtils.java

其他回答

我知道这个帖子有点旧了。 但我还是要把这个贴出来,希望它能帮助到一些人。 通过将对象序列化为String,可以将任何Object的字段存储为共享首选项。 这里我使用GSON存储共享首选项的任何对象。

保存对象到首选项:

public static void saveObjectToSharedPreference(Context context, String preferenceFileName, String serializedObjectKey, Object object) {
    SharedPreferences sharedPreferences = context.getSharedPreferences(preferenceFileName, 0);
    SharedPreferences.Editor sharedPreferencesEditor = sharedPreferences.edit();
    final Gson gson = new Gson();
    String serializedObject = gson.toJson(object);
    sharedPreferencesEditor.putString(serializedObjectKey, serializedObject);
    sharedPreferencesEditor.apply();
}

从首选项检索对象:

public static <GenericClass> GenericClass getSavedObjectFromPreference(Context context, String preferenceFileName, String preferenceKey, Class<GenericClass> classType) {
    SharedPreferences sharedPreferences = context.getSharedPreferences(preferenceFileName, 0);
    if (sharedPreferences.contains(preferenceKey)) {
        final Gson gson = new Gson();
        return gson.fromJson(sharedPreferences.getString(preferenceKey, ""), classType);
    }
    return null;
}

注意:

记得在gradle的dependencies中添加compile 'com.google.code.gson:gson:2.6.2'。

例子:

//assume SampleClass exists
SampleClass mObject = new SampleObject();

//to store an object
saveObjectToSharedPreference(context, "mPreference", "mObjectKey", mObject);

//to retrive object stored in preference
mObject = getSavedObjectFromPreference(context, "mPreference", "mObjectKey", SampleClass.class);

更新:

正如@Sharp_Edge在评论中指出的那样,上述解决方案不适用于List。

稍微修改一下getSavedObjectFromPreference()的签名——从Class<GenericClass> classType到Type classType将使这个解决方案一般化。修改后的函数签名

public static <GenericClass> GenericClass getSavedObjectFromPreference(Context context, String preferenceFileName, String preferenceKey, Type classType)

用于调用,

getSavedObjectFromPreference(context, "mPreference", "mObjectKey", (Type) SampleClass.class)

编码快乐!

你还没有说明在这之后你对prefsEditor对象做了什么,但是为了持久化首选项数据,你还需要使用:

prefsEditor.commit();

您可以使用gson.jar将类对象存储到SharedPreferences中。 你可以从google-gson下载这个罐子

或者在Gradle文件中添加GSON依赖项:

implementation 'com.google.code.gson:gson:2.8.8'

你可以在这里找到最新的版本

创建共享首选项:

SharedPreferences  mPrefs = getPreferences(MODE_PRIVATE);

保存:

MyObject myObject = new MyObject;
//set variables of 'myObject', etc.

Editor prefsEditor = mPrefs.edit();
Gson gson = new Gson();
String json = gson.toJson(myObject);
prefsEditor.putString("MyObject", json);
prefsEditor.commit();

检索:

Gson gson = new Gson();
String json = mPrefs.getString("MyObject", "");
MyObject obj = gson.fromJson(json, MyObject.class);

要添加到@MuhammadAamirALi的答案,您可以使用Gson保存和检索对象列表

保存用户定义对象的列表到SharedPreferences

public static final String KEY_CONNECTIONS = "KEY_CONNECTIONS";
SharedPreferences.Editor editor = getPreferences(MODE_PRIVATE).edit();

User entity = new User();
// ... set entity fields

List<Connection> connections = entity.getConnections();
// convert java object to JSON format,
// and returned as JSON formatted string
String connectionsJSONString = new Gson().toJson(connections);
editor.putString(KEY_CONNECTIONS, connectionsJSONString);
editor.commit();

从SharedPreferences获取用户定义对象的列表

String connectionsJSONString = getPreferences(MODE_PRIVATE).getString(KEY_CONNECTIONS, null);
Type type = new TypeToken < List < Connection >> () {}.getType();
List < Connection > connections = new Gson().fromJson(connectionsJSONString, type);

另一种不使用Json格式保存和恢复android sharedpreferences对象的方法

private static ExampleObject getObject(Context c,String db_name){
            SharedPreferences sharedPreferences = c.getSharedPreferences(db_name, Context.MODE_PRIVATE);
            ExampleObject o = new ExampleObject();
            Field[] fields = o.getClass().getFields();
            try {
                for (Field field : fields) {
                    Class<?> type = field.getType();
                    try {
                        final String name = field.getName();
                        if (type == Character.TYPE || type.equals(String.class)) {
                            field.set(o,sharedPreferences.getString(name, ""));
                        } else if (type.equals(int.class) || type.equals(Short.class))
                            field.setInt(o,sharedPreferences.getInt(name, 0));
                        else if (type.equals(double.class))
                            field.setDouble(o,sharedPreferences.getFloat(name, 0));
                        else if (type.equals(float.class))
                            field.setFloat(o,sharedPreferences.getFloat(name, 0));
                        else if (type.equals(long.class))
                            field.setLong(o,sharedPreferences.getLong(name, 0));
                        else if (type.equals(Boolean.class))
                            field.setBoolean(o,sharedPreferences.getBoolean(name, false));
                        else if (type.equals(UUID.class))
                            field.set(
                                    o,
                                    UUID.fromString(
                                            sharedPreferences.getString(
                                                    name,
                                                    UUID.nameUUIDFromBytes("".getBytes()).toString()
                                            )
                                    )
                            );

                    } catch (IllegalAccessException e) {
                        Log.e(StaticConfig.app_name, "IllegalAccessException", e);
                    } catch (IllegalArgumentException e) {
                        Log.e(StaticConfig.app_name, "IllegalArgumentException", e);
                    }
                }
            } catch (Exception e) {
                System.out.println("Exception: " + e);
            }
            return o;
        }
        private static void setObject(Context context, Object o, String db_name) {
            Field[] fields = o.getClass().getFields();
            SharedPreferences sp = context.getSharedPreferences(db_name, Context.MODE_PRIVATE);
            SharedPreferences.Editor editor = sp.edit();
            for (Field field : fields) {
                Class<?> type = field.getType();
                try {
                    final String name = field.getName();
                    if (type == Character.TYPE || type.equals(String.class)) {
                        Object value = field.get(o);
                        if (value != null)
                            editor.putString(name, value.toString());
                    } else if (type.equals(int.class) || type.equals(Short.class))
                        editor.putInt(name, field.getInt(o));
                    else if (type.equals(double.class))
                        editor.putFloat(name, (float) field.getDouble(o));
                    else if (type.equals(float.class))
                        editor.putFloat(name, field.getFloat(o));
                    else if (type.equals(long.class))
                        editor.putLong(name, field.getLong(o));
                    else if (type.equals(Boolean.class))
                        editor.putBoolean(name, field.getBoolean(o));
                    else if (type.equals(UUID.class))
                        editor.putString(name, field.get(o).toString());

                } catch (IllegalAccessException e) {
                    Log.e(StaticConfig.app_name, "IllegalAccessException", e);
                } catch (IllegalArgumentException e) {
                    Log.e(StaticConfig.app_name, "IllegalArgumentException", e);
                }
            }

            editor.apply();
        }