Question

我这样做是为了将JSON格式的字符串转换为VB.NET Object。

我找不到为什么它不起作用！

jsonSettingsWrapper.vb

Public Class jsonSettingsWrapper
    'Public setting As jsonSettings
    Public Property setting As jsonSettings
        Get
            Return m_setting
        End Get
        Set(value As jsonSettings)
            m_setting = value
        End Set
    End Property
    Private m_setting As jsonSettings
End Class

Public Class jsonSettings
    Public Property root_folder_path As String
        Get
            Return m_root_folder_path
        End Get
        Set(value As String)
            m_root_folder_path = value
        End Set
    End Property
    Private m_root_folder_path As String

    Public Property ignored_files As String()
        Get
            Return m_ignored_files
        End Get
        Set(value As String())
            m_ignored_files = value
        End Set
    End Property
    Private m_ignored_files As String()

    Public Property last_pack_date As String
        Get
            Return m_last_pack_date
        End Get
        Set(value As String)
            m_last_pack_date = value
        End Set
    End Property
    Private m_last_pack_date As String

    Public Property last_push_date As String
        Get
            Return m_last_push_date
        End Get
        Set(value As String)
            m_last_push_date = value
        End Set
    End Property
    Private m_last_push_date As String

    Public Property no_of_packs As Integer
        Get
            Return m_no_of_packs
        End Get
        Set(value As Integer)
            m_no_of_packs = value
        End Set
    End Property
    Private m_no_of_packs As Integer

    Public Property packs_array As packs()
        Get
            Return m_packs_array
        End Get
        Set(value As packs())
            m_packs_array = value
        End Set
    End Property
    Private m_packs_array As packs()
End Class

Public Class packs
    Public Property filename As String
        Get
            Return m_filename
        End Get
        Set(value As String)
            m_filename = value
        End Set
    End Property
    Private m_filename As String

    Public Property pack_date As String
        Get
            Return m_pack_date
        End Get
        Set(value As String)
            m_pack_date = value
        End Set
    End Property
    Private m_pack_date As String
End Class

Form1.vb的

Imports System.Web.Script.Serialization
Imports WindowsApplication1.jsonSettingsWrapper

Public Class Form1

    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        Dim ser As New JavaScriptSerializer
        Dim settingsString As String = IO.File.ReadAllText("settings.json")
        MsgBox(settingsString)
        Dim settings = ser.Deserialize(Of jsonSettingsWrapper)(settingsString)
        MsgBox(settings.setting) 'empty
        MsgBox(settings.setting.root_folder_path) 
        ' ^ ^ Error: A first chance exception of type 'System.NullReferenceException' occurred in FilesSync.exe
    End Sub

如代码注释中所述，当它尝试访问其某些值时会发生错误。任何人都可以说明为什么会发生这种情况。我在哪里做错了？

编辑：我使用的JSON是：

{"settings": {
    "root_folder_path": "ab",
    "ignored_files": [
        "cd",
        "ef"
    ],
    "last_pack_date": "12",
    "last_push_date": "21",
    "no_of_packs": 3,
    "packs_array": [
        {
            "filename": "aa",
            "pack_date": "21"
        }
    ]
}}

Answer 1

您的JSON使用属性名称＆＃34;设置＆＃34;但是你的班级使用＆＃34;设置＆＃34 ;,改变你的班级以使用正确的名字

Public Class jsonSettingsWrapper
    'Public setting As jsonSettings
    Public Property settings() As jsonSettings
        Get
            Return m_setting
        End Get
        Set(ByVal value As jsonSettings)
            m_setting = value
        End Set
    End Property
    Private m_setting As jsonSettings
End Class

或使用DataContract

将JSON字符串读取到VB .NET对象

1 个答案: