次の形式のクラスのセールスマンがあります。
class salesman
{
public string name, address, email;
public int sales;
}
ユーザーが名前、住所、電子メール、売上を入力する別のクラスがあります。この入力はリストに追加されます
List<salesman> salesmanList = new List<salesman>();
ユーザーが好きなだけセールスマンをリストに入力した後、リストを選択したファイルに保存するオプションがあります (.xml または .txt (より適切な方) に制限できます)。このリストをファイルに追加するにはどうすればよいですか? また、ユーザーが後でレコードを表示したい場合は、このファイルをリストに再度読み込む必要があります。
オブジェクトのデータを Binary、XML、または Json に保存する方法についてのブログ記事を書きました。オブジェクトまたはオブジェクトのリストをファイルに書き込んでいます。さまざまな形式でそれを行う関数を次に示します。詳細については、私のブログ投稿を参照してください。
/// <summary>
/// Writes the given object instance to a binary file.
/// <para>Object type (and all child types) must be decorated with the [Serializable] attribute.</para>
/// <para>To prevent a variable from being serialized, decorate it with the [NonSerialized] attribute; cannot be applied to properties.</para>
/// </summary>
/// <typeparam name="T">The type of object being written to the XML file.</typeparam>
/// <param name="filePath">The file path to write the object instance to.</param>
/// <param name="objectToWrite">The object instance to write to the XML file.</param>
/// <param name="append">If false the file will be overwritten if it already exists. If true the contents will be appended to the file.</param>
public static void WriteToBinaryFile<T>(string filePath, T objectToWrite, bool append = false)
{
using (Stream stream = File.Open(filePath, append ? FileMode.Append : FileMode.Create))
{
var binaryFormatter = new System.Runtime.Serialization.Formatters.Binary.BinaryFormatter();
binaryFormatter.Serialize(stream, objectToWrite);
}
}
/// <summary>
/// Reads an object instance from a binary file.
/// </summary>
/// <typeparam name="T">The type of object to read from the XML.</typeparam>
/// <param name="filePath">The file path to read the object instance from.</param>
/// <returns>Returns a new instance of the object read from the binary file.</returns>
public static T ReadFromBinaryFile<T>(string filePath)
{
using (Stream stream = File.Open(filePath, FileMode.Open))
{
var binaryFormatter = new System.Runtime.Serialization.Formatters.Binary.BinaryFormatter();
return (T)binaryFormatter.Deserialize(stream);
}
}
System.Xml アセンブリをプロジェクトに含める必要があります。
/// <summary>
/// Writes the given object instance to an XML file.
/// <para>Only Public properties and variables will be written to the file. These can be any type though, even other classes.</para>
/// <para>If there are public properties/variables that you do not want written to the file, decorate them with the [XmlIgnore] attribute.</para>
/// <para>Object type must have a parameterless constructor.</para>
/// </summary>
/// <typeparam name="T">The type of object being written to the file.</typeparam>
/// <param name="filePath">The file path to write the object instance to.</param>
/// <param name="objectToWrite">The object instance to write to the file.</param>
/// <param name="append">If false the file will be overwritten if it already exists. If true the contents will be appended to the file.</param>
public static void WriteToXmlFile<T>(string filePath, T objectToWrite, bool append = false) where T : new()
{
TextWriter writer = null;
try
{
var serializer = new XmlSerializer(typeof(T));
writer = new StreamWriter(filePath, append);
serializer.Serialize(writer, objectToWrite);
}
finally
{
if (writer != null)
writer.Close();
}
}
/// <summary>
/// Reads an object instance from an XML file.
/// <para>Object type must have a parameterless constructor.</para>
/// </summary>
/// <typeparam name="T">The type of object to read from the file.</typeparam>
/// <param name="filePath">The file path to read the object instance from.</param>
/// <returns>Returns a new instance of the object read from the XML file.</returns>
public static T ReadFromXmlFile<T>(string filePath) where T : new()
{
TextReader reader = null;
try
{
var serializer = new XmlSerializer(typeof(T));
reader = new StreamReader(filePath);
return (T)serializer.Deserialize(reader);
}
finally
{
if (reader != null)
reader.Close();
}
}
Json.NET NuGet Packageから取得できる Newtonsoft.Json アセンブリへの参照を含める必要があります。
/// <summary>
/// Writes the given object instance to a Json file.
/// <para>Object type must have a parameterless constructor.</para>
/// <para>Only Public properties and variables will be written to the file. These can be any type though, even other classes.</para>
/// <para>If there are public properties/variables that you do not want written to the file, decorate them with the [JsonIgnore] attribute.</para>
/// </summary>
/// <typeparam name="T">The type of object being written to the file.</typeparam>
/// <param name="filePath">The file path to write the object instance to.</param>
/// <param name="objectToWrite">The object instance to write to the file.</param>
/// <param name="append">If false the file will be overwritten if it already exists. If true the contents will be appended to the file.</param>
public static void WriteToJsonFile<T>(string filePath, T objectToWrite, bool append = false) where T : new()
{
TextWriter writer = null;
try
{
var contentsToWriteToFile = JsonConvert.SerializeObject(objectToWrite);
writer = new StreamWriter(filePath, append);
writer.Write(contentsToWriteToFile);
}
finally
{
if (writer != null)
writer.Close();
}
}
/// <summary>
/// Reads an object instance from an Json file.
/// <para>Object type must have a parameterless constructor.</para>
/// </summary>
/// <typeparam name="T">The type of object to read from the file.</typeparam>
/// <param name="filePath">The file path to read the object instance from.</param>
/// <returns>Returns a new instance of the object read from the Json file.</returns>
public static T ReadFromJsonFile<T>(string filePath) where T : new()
{
TextReader reader = null;
try
{
reader = new StreamReader(filePath);
var fileContents = reader.ReadToEnd();
return JsonConvert.DeserializeObject<T>(fileContents);
}
finally
{
if (reader != null)
reader.Close();
}
}
// Write the list of salesman objects to file.
WriteToXmlFile<List<salesman>>("C:\salesmen.txt", salesmanList);
// Read the list of salesman objects from the file back into a variable.
List<salesman> salesmanList = ReadFromXmlFile<List<salesman>>("C:\salesmen.txt");
JSON を使用する場合は、通常、Json.NET を使用するのが最善の方法です。
何らかの理由で Json.NET を使用できない場合は、.NET に組み込まれている JSON サポートを使用できます。
次の using ステートメントを含め、 System.Web.Extentsへの参照を追加する必要があります。
using System.Web.Script.Serialization;
次に、これらを使用してオブジェクトをシリアライズおよびデシリアライズします。
//Deserialize JSON to your Object
YourObject obj = new JavaScriptSerializer().Deserialize<YourObject>("File Contents");
//Serialize your object to JSON
string sJSON = new JavaScriptSerializer().Serialize(YourObject);