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
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
其他回答
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();
}
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;
}
我在使用已接受的答案访问跨活动的共享首选项数据时遇到了麻烦。在这些步骤中,您将为getSharedPreferences提供一个名称以访问它。
在构建中添加以下依赖项。Gradle脚本下的gradel (Module: app)文件:
implementation 'com.google.code.gson:gson:2.8.5'
保存:
MyObject myObject = new MyObject;
//set variables of 'myObject', etc.
SharedPreferences mPrefs = getSharedPreferences("Name", Context.MODE_PRIVATE);
Editor prefsEditor = mPrefs.edit();
Gson gson = new Gson();
String json = gson.toJson(myObject);
prefsEditor.putString("Key", json);
prefsEditor.commit();
在不同的活动中检索:
SharedPreferences mPrefs = getSharedPreferences("Name", Context.MODE_PRIVATE);
Gson gson = new Gson();
String json = mPrefs.getString("Key", "");
MyObject obj = gson.fromJson(json, MyObject.class);
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);
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()