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
我已经使用jackson来存储我的对象(jackson)。
添加杰克逊库到gradle:
api 'com.fasterxml.jackson.core:jackson-core:2.9.4'
api 'com.fasterxml.jackson.core:jackson-annotations:2.9.4'
api 'com.fasterxml.jackson.core:jackson-databind:2.9.4'
我的测试类:
public class Car {
private String color;
private String type;
// standard getters setters
}
Java对象转换为JSON:
ObjectMapper objectMapper = new ObjectMapper();
String carAsString = objectMapper.writeValueAsString(car);
存储在共享首选项中:
preferences.edit().car().put(carAsString).apply();
从共享首选项中恢复:
ObjectMapper objectMapper = new ObjectMapper();
Car car = objectMapper.readValue(preferences.car().get(), Car.class);
其他回答
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;
}
在SharedPreferences中存储Model的数组列表
Add this dependency implementation 'com.google.code.gson:gson:2.8.8' Then after you convert your Model Class into JSON using Gson. Gson gson = new Gson(); String json = gson.toJson(chModelArrayList); //here chModelArrayList is a ArrayList<Model> of Model Class Then after you can add this string to SharedPreferences SharedPreferences preferences; //Create Object of SharedPreferences SharedPreferences.Editor editor; //Create Object of SharedPreferences.Editor //initialize SharedPreferences preferences = activity.getPreferences(Context.MODE_PRIVATE); editor = preferences.edit(); //Add-In SharedPreferences editor.putString(key, json); editor.commit(); for your list from SharedPreferences String json = preferences.getString(key, defVal); Gson gson = new Gson(); //Pass Your Model ArrayList in TypeToken Type type = new TypeToken<ArrayList<ChModel>>() {}.getType(); //here you get your list ArrayList<ChModel> switchGroup1 = gson.fromJson(json, type);
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!
这么多好答案,她是我的2美分
我更喜欢使用内联函数和旧风格的put和get值
object PreferenceHelper {
private const val PREFERENCES_KEY = "MyLocalPreference"
private fun getPreference(context: Context): SharedPreferences {
return context.getSharedPreferences(
PREFERENCES_KEY,
Context.MODE_PRIVATE
)
}
fun setBoolean(appContext: Context, key: String?, value: Boolean?) =
getPreference(appContext).edit().putBoolean(key, value!!).apply()
fun setInteger(appContext: Context, key: String?, value: Int) =
getPreference(appContext).edit().putInt(key, value).apply()
fun setFloat(appContext: Context, key: String?, value: Float) =
getPreference(appContext).edit().putFloat(key, value).apply()
fun setString(appContext: Context, key: String?, value: String?) =
getPreference(appContext).edit().putString(key, value).apply()
// To retrieve values from shared preferences:
fun getBoolean(appContext: Context, key: String?, defaultValue: Boolean?): Boolean =
getPreference(appContext).getBoolean(key, defaultValue!!)
fun getInteger(appContext: Context, key: String?, defaultValue: Int): Int =
getPreference(appContext)
.getInt(key, defaultValue)
fun getString(appContext: Context, key: String?, defaultValue: String?): String? =
getPreference(appContext)
.getString(key, defaultValue)
}
使用
PreferenceHelper.setString(context,"CUSTOMER_NAME", "HITESH")
Toast.makeText(context, "Hello " + PreferenceHelper.getString(context,"CUSTOMER_NAME", "User"), Toast.LENGTH_LONG).show()
如果你的对象很复杂,我建议序列化/XML/JSON,并将这些内容保存到SD卡。你可以在这里找到关于如何保存到外部存储的其他信息: http://developer.android.com/guide/topics/data/data-storage.html#filesExternal