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C#中实现JSON功能及对象的序列化和反序列化

原创 .net 作者:llnnmc 时间:2020-05-24 23:29:39 0 删除 编辑

Newtonsoft.Json程序包的引用

c#中使用json功能,需要Newtonsoft.Json程序包,可以通过NuGet程序包管理器搜索Newtonsoft.Json来安装,也可以在NuGet程序包管理器控制台下使用以下命令来安装:

install-package Newtonsoft.Json

然后引用NewTonSoft.Json命名空间。之后就可以将建立的对象转换为JSON字符串了。

将对象序列化为JSON字符串

如下创建一个类

public class Student
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string Sex { get; set; }
    public string Description { get; set; }
}

生成对象并序列化为JSON字符串

List<Student> students = new List<Student>();
students.Add(new Student { Id = 1, Name = "张三", Sex = "男", Description = "班长" });
students.Add(new Student { Id = 2, Name = "李四", Sex = "女", Description = "小组长" });
students.Add(new Student { Id = 3, Name = "王五", Sex = "男", Description = "宣传委员" });
string studentsJson = JsonConvert.SerializeObject(students);
Console.WriteLine(studentsJson);

输出结果:
[{“Id”:1,”Name”:”张三”,”Sex”:”男”,”Description”:”班长”},{“Id”:2,”Name”:”李四”,”Sex”:”女”,”Description”:”小组长”},{“Id”:3,”Name”:”王五”,”Sex”:”男”,”Description”:”宣传委员”}]

使用[JsonIgnore]特性忽略字段的序列化

有时我们可能不希望某些字段参与对象的JSON序列化,此时可以在该字段上使用[JsonIgnore]特性,对象被序列化后不会包含被忽略的字段

public class Student
{
    public int Id { get; set; }
    public string Name { get; set; }
    [JsonIgnore]
    public string Sex { get; set; }
    public string Description { get; set; }
}

输出结果:
[{“Id”:1,”Name”:”张三”,”Description”:”班长”},{“Id”:2,”Name”:”李四”,”Description”:”小组长”},{“Id”:3,”Name”:”王五”,”Description”:”宣传委员”}]

使用[JsonProperty]特性标识字段的序列化名称

有时我们可能想在对象序列化时更换字段的输出名称,譬如简化字段名称以缩短JSON字符串的长度,此时可使用[JsonProperty]特性标识字段

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; }
}

输出结果:
[{“Id”:1,”Name”:”张三”,”Desc”:”班长”},{“Id”:2,”Name”:”李四”,”Desc”:”小组长”},{“Id”:3,”Name”:”王五”,”Desc”:”宣传委员”}]

格式化输出JSON字符串

如果要将生成的JSON字符串以友好的格式化形式输出,可调用以下方法来转换

/// <summary>
/// 格式化JSON字符串
/// </summary>
/// <param name="str"></param>
/// <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;
    }
}

于是上面的JSON字符串可改用格式化的形式输出

List<Student> students = new List<Student>();
students.Add(new Student { Id = 1, Name = "张三", Sex = "男", Description = "班长" });
students.Add(new Student { Id = 2, Name = "李四", Sex = "女", Description = "小组长" });
students.Add(new Student { Id = 3, Name = "王五", Sex = "男", Description = "宣传委员" });
//string studentsJson = JsonConvert.SerializeObject(students);
string studentsJson = ConvertJsonString(JsonConvert.SerializeObject(students));
Console.WriteLine(studentsJson);

输出结果:
[
{
“Id”: 1,
“Name”: “张三”,
“Desc”: “班长”
},
{
“Id”: 2,
“Name”: “李四”,
“Desc”: “小组长”
},
{
“Id”: 3,
“Name”: “王五”,
“Desc”: “宣传委员”
}
]

JSON字符串的反序列化

以下例子将构建的JSON字符串反序列化为对象,类的定义不要使用以上描述的两个附加特性

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; }
}
string inputJsonString = @"[
{ Id: 1, Name: '张三', Sex: '男', Description: '班长' },
{ Id: 2, Name: '李四', Sex: '女', Description: '小组长' },
{ Id: 3, Name: '王五', Sex: '男', Description: '宣传委员' }
]";
List<Student> objects = JsonConvert.DeserializeObject<List<Student>>(inputJsonString);
foreach (Student item in objects)
{
Console.WriteLine($"Id: {item.Id}, Name: {item.Name}, Sex: {item.Sex}, Description: {item.Description}");
}

输出结果:
Id: 1, Name: 张三, Sex: 男, Description: 班长
Id: 2, Name: 李四, Sex: 女, Description: 小组长
Id: 3, Name: 王五, Sex: 男, Description: 宣传委员

一般对象的序列化和反序列化

有时候我们可能需要序列化一个对象到字符串,或者反序列化字符串到对象,如对一个类进行封装传输或者存储。这首先需要使用特性[Serializable]将该对象类型标记为可序列化

// 标记类型可序列化
[Serializable]
public class Student
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string Sex { get; set; }
    public string Description { get; set; }
}

一般对象的序列化和反序列化可以用以下两个方法来实现

/// <summary>
/// 序列化对象到字符串
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="obj"></param>
/// <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);
    }
}
/// <summary>
/// 反序列化字符串到对象
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="obj"></param>
/// <param name="str"></param>
/// <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;
}

以下例子使用上述两个方法实现一般对象的序列化和反序列化

List<Student> students = new List<Student>();
students.Add(new Student { Id = 1, Name = "张三", Sex = "男", Description = "班长" });
students.Add(new Student { Id = 2, Name = "李四", Sex = "女", Description = "小组长" });
students.Add(new Student { Id = 3, Name = "王五", Sex = "男", Description = "宣传委员" });
string studentsString = Serialize(students);
Console.WriteLine($"序列化后的对象:\n{studentsString}");
List<Student> objects = new List<Student>();
objects = Deserialize(objects, studentsString);
Console.WriteLine("反序列化后的对象:");
foreach (Student item in objects)
{
    Console.WriteLine($"Id: {item.Id}, Name: {item.Name}, Sex: {item.Sex}");
}

输出结果:
序列化后的对象:
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
反序列化后的对象:
Id: 1, Name: 张三, Sex: 男
Id: 2, Name: 李四, Sex: 女
Id: 3, Name: 王五, Sex: 男

来自 “ ITPUB博客 ” ,链接:http://blog.itpub.net/28974745/viewspace-2694024/,如需转载,请注明出处,否则将追究法律责任。

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