#### Newtonsoft.Json程式包的引用 ####
c#中使用json功能，需要Newtonsoft.Json程式包，可以透過NuGet程式包管理器搜尋Newtonsoft.Json來安裝，也可以在NuGet程式包管理器控制檯下使用以下命令來安裝：
```csharp
install-package Newtonsoft.Json
```
然後引用NewTonSoft.Json名稱空間。之後就可以將建立的物件轉換為JSON字串了。
#### 將物件序列化為JSON字串 ####
如下建立一個類
```csharp
public class Student
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string Sex { get; set; }
    public string Description { get; set; }
}
```
生成物件並序列化為JSON字串
```csharp
List<student> students = new List<student>();
students.Add(new Student { Id = 1, Name = "張三", Sex = "男", Description = "班長" });
students.Add(new Student { Id = 2, Name = "李四", Sex = "女", Description = "小組長" });
students.Add(new Student { Id = 3, Name = "王五", Sex = "男", Description = "宣傳委員" });

string studentsJson = JsonConvert.SerializeObject(students);

Console.WriteLine(studentsJson);
```
輸出結果：
[{"Id":1,"Name":"張三","Sex":"男","Description":"班長"},{"Id":2,"Name":"李四","Sex":"女","Description":"小組長"},{"Id":3,"Name":"王五","Sex":"男","Description":"宣傳委員"}]
#### 使用[JsonIgnore]特性忽略欄位的序列化 ####
有時我們可能不希望某些欄位參與物件的JSON序列化，此時可以在該欄位上使用[JsonIgnore]特性，物件被序列化後不會包含被忽略的欄位
```csharp
public class Student
{
    public int Id { get; set; }
    public string Name { get; set; }
    [JsonIgnore]
    public string Sex { get; set; }
    public string Description { get; set; }
}
```
輸出結果：
[{"Id":1,"Name":"張三","Description":"班長"},{"Id":2,"Name":"李四","Description":"小組長"},{"Id":3,"Name":"王五","Description":"宣傳委員"}]
#### 使用[JsonProperty]特性標識欄位的序列化名稱 ####
有時我們可能想在物件序列化時更換欄位的輸出名稱，譬如簡化欄位名稱以縮短JSON字串的長度，此時可使用[JsonProperty]特性標識欄位
```csharp
public class Student
{
    public int Id { get; set; }
    public string Name { get; set; }
    [JsonIgnore]
    public string Sex { get; set; }
    [JsonProperty("Desc")]
    public string Description { get; set; }
}
```
輸出結果：
[{"Id":1,"Name":"張三","Desc":"班長"},{"Id":2,"Name":"李四","Desc":"小組長"},{"Id":3,"Name":"王五","Desc":"宣傳委員"}]
#### 格式化輸出JSON字串 ####
如果要將生成的JSON字串以友好的格式化形式輸出，可呼叫以下方法來轉換
```csharp
/// <summary>
/// 格式化JSON字串
/// </summary>
/// <param name="str">
/// <returns></returns>
private static string ConvertJsonString(string str)
{
    JsonSerializer serializer = new JsonSerializer();
    TextReader tr = new StringReader(str);
    JsonTextReader jtr = new JsonTextReader(tr);
    object obj = serializer.Deserialize(jtr);
    if (obj != null)
    {
        StringWriter textWriter = new StringWriter();
        JsonTextWriter jsonWriter = new JsonTextWriter(textWriter)
        {
            Formatting = Formatting.Indented,
            Indentation = 4,
            IndentChar = ' '
        };
        serializer.Serialize(jsonWriter, obj);
        return textWriter.ToString();
    }
    else
    {
        return str;
    }
}
```
於是上面的JSON字串可改用格式化的形式輸出
```csharp
List<student> students = new List<student>();
students.Add(new Student { Id = 1, Name = "張三", Sex = "男", Description = "班長" });
students.Add(new Student { Id = 2, Name = "李四", Sex = "女", Description = "小組長" });
students.Add(new Student { Id = 3, Name = "王五", Sex = "男", Description = "宣傳委員" });

//string studentsJson = JsonConvert.SerializeObject(students);
string studentsJson = ConvertJsonString(JsonConvert.SerializeObject(students));
Console.WriteLine(studentsJson);
```
輸出結果：
[
    {
        "Id": 1,
        "Name": "張三",
        "Desc": "班長"
    },
    {
        "Id": 2,
        "Name": "李四",
        "Desc": "小組長"
    },
    {
        "Id": 3,
        "Name": "王五",
        "Desc": "宣傳委員"
    }
]
#### JSON字串的反序列化 ####
以下例子將構建的JSON字串反序列化為物件，類的定義不要使用以上描述的兩個附加特性
```csharp
public class Student
{
    public int Id { get; set; }
    public string Name { get; set; }
    //[JsonIgnore]
    public string Sex { get; set; }
    //[JsonProperty("Desc")]
    public string Description { get; set; }
}
```
```csharp
string inputJsonString = @"[
{ Id: 1, Name: '張三', Sex: '男', Description: '班長' },
{ Id: 2, Name: '李四', Sex: '女', Description: '小組長' },
{ Id: 3, Name: '王五', Sex: '男', Description: '宣傳委員' }
]";

List<student> objects = JsonConvert.DeserializeObject<list>>(inputJsonString);

foreach (Student item in objects)
{
Console.WriteLine($"Id: {item.Id}, Name: {item.Name}, Sex: {item.Sex}, Description: {item.Description}");
}
```
輸出結果：
Id: 1, Name: 張三, Sex: 男, Description: 班長
Id: 2, Name: 李四, Sex: 女, Description: 小組長
Id: 3, Name: 王五, Sex: 男, Description: 宣傳委員
#### 一般物件的序列化和反序列化 ####
有時候我們可能需要序列化一個物件到字串，或者反序列化字串到物件，如對一個類進行封裝傳輸或者儲存。這首先需要使用特性[Serializable]將該物件型別標記為可序列化
```csharp
// 標記型別可序列化
[Serializable]
public class Student
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string Sex { get; set; }
    public string Description { get; set; }
}
```
一般物件的序列化和反序列化可以用以下兩個方法來實現
```csharp
/// <summary>
/// 序列化物件到字串
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="obj">
/// <returns></returns>
private static string Serialize<t>(T obj)
{
    try
    {
        IFormatter formatter = new BinaryFormatter();
        MemoryStream stream = new MemoryStream();
        formatter.Serialize(stream, obj);
        stream.Position = 0;
        byte[] buffer = new byte[stream.Length];
        stream.Read(buffer, 0, buffer.Length);
        stream.Flush();
        stream.Close();
        return Convert.ToBase64String(buffer);
    }
    catch (Exception ex)
    {
        throw new Exception(ex.Message);
    }
}
```
```csharp
/// <summary>
/// 反序列化字串到物件
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="obj">
/// <param name="str">
/// <returns></returns>
public static T Deserialize<t>(T obj, string str)
{
    try
    {
        obj = default(T);
        IFormatter formatter = new BinaryFormatter();
        byte[] buffer = Convert.FromBase64String(str);
        MemoryStream stream = new MemoryStream(buffer);
        obj = (T)formatter.Deserialize(stream);
        stream.Flush();
        stream.Close();
    }
    catch (Exception ex)
    {
        throw new Exception(ex.Message);
    }
    return obj;
}
```
以下例子使用上述兩個方法實現一般物件的序列化和反序列化
```csharp
List<student> students = new List<student>();
students.Add(new Student { Id = 1, Name = "張三", Sex = "男", Description = "班長" });
students.Add(new Student { Id = 2, Name = "李四", Sex = "女", Description = "小組長" });
students.Add(new Student { Id = 3, Name = "王五", Sex = "男", Description = "宣傳委員" });

string studentsString = Serialize(students);

Console.WriteLine($"序列化後的物件：\n{studentsString}");

List<student> objects = new List<student>();
objects = Deserialize(objects, studentsString);

Console.WriteLine("反序列化後的物件：");
foreach (Student item in objects)
{
    Console.WriteLine($"Id: {item.Id}, Name: {item.Name}, Sex: {item.Sex}");
}
```
輸出結果：
序列化後的物件：
AAEAAAD/////AQAAAAAAAAAMAgAAAEJDb25zb2xlQXBwMSwgVmVyc2lvbj0xLjAuMC4wLCBDdWx0dXJlPW5ldXRyYWwsIFB1YmxpY0tleVRva2VuPW51bGwEAQAAAHxTeXN0ZW0uQ29sbGVjdGlvbnMuR2VuZXJpYy5MaXN0YDFbW0NvbnNvbGVBcHAxLlN0dWRlbnQsIENvbnNvbGVBcHAxLCBWZXJzaW9uPTEuMC4wLjAsIEN1bHR1cmU9bmV1dHJhbCwgUHVibGljS2V5VG9rZW49bnVsbF1dAwAAAAZfaXRlbXMFX3NpemUIX3ZlcnNpb24EAAAVQ29uc29sZUFwcDEuU3R1ZGVudFtdAgAAAAgICQMAAAADAAAAAwAAAAcDAAAAAAEAAAAEAAAABBNDb25zb2xlQXBwMS5TdHVkZW50AgAAAAkEAAAACQUAAAAJBgAAAAoFBAAAABNDb25zb2xlQXBwMS5TdHVkZW50BAAAABM8SWQ+a19fQmFja2luZ0ZpZWxkFTxOYW1lPmtfX0JhY2tpbmdGaWVsZBQ8U2V4PmtfX0JhY2tpbmdGaWVsZBw8RGVzY3JpcHRpb24+a19fQmFja2luZ0ZpZWxkAAEBAQgCAAAAAQAAAAYHAAAABuW8oOS4iQYIAAAAA+eUtwYJAAAABuePremVvwEFAAAABAAAAAIAAAAGCgAAAAbmnY7lm5sGCwAAAAPlpbMGDAAAAAnlsI/nu4Tplb8BBgAAAAQAAAADAAAABg0AAAAG546L5LqUCQgAAAAGDwAAAAzlrqPkvKDlp5TlkZgL
反序列化後的物件：
Id: 1, Name: 張三, Sex: 男
Id: 2, Name: 李四, Sex: 女
Id: 3, Name: 王五, Sex: 男</student></student></student></student></t></t></list></student></student></student></student></student>

C#中實現JSON功能及物件的序列化和反序列化

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