创建文件
Dim strFile As String = String.Format("C:\ErrorLog.txt", DateTime.Today.ToString("dd-MMM-yyyy"))
File.AppendAllText(strFile, String.Format("Error Message in Occured at-- {0}{1}", DateTime.Now, Environment.NewLine))
第一句话的意思是在c盘下面创建一个ErrorLog.txt的文本文档，第二句话的意思是，在这个文本文档中写入"Error Message in Occured at--后面接当前时间，每打印一句就换一行。
上面是直接从本地磁盘写，那么，如果从数据库中要读取后缀.bin的文件，然后在写入本地磁盘该如何做呢？
从数据库读取文件
'读取数据库中bin文件
Dim blobFiles As Integer = 0
Try
System.IO.Directory.CreateDirectory("C:\var\")
myCommand.CommandText = "select blobFile from evnet.join_server_firmware_version order by dttDateTime desc" '从数据库中读取存放文件字段按时间最新
Dim dr As MySqlDataReader = myCommand.ExecuteReader()
dr.Read()
Dim b(dr.GetBytes(blobFiles, 0, Nothing, 0, Integer.MaxValue) - 1) As Byte '声明b数组存放读取到的dr
dr.GetBytes(blobFiles, 0, b, 0, b.Length) '将b读取到的数存放在blobFiles中
dr.Close()
conn.Close()
conn.Open()
myCommand.CommandText = "select vchfimware_versionName from evnet.join_server_firmware_version order by dttDateTime desc"
VersionName = myCommand.ExecuteScalar
conn.Close()
If System.IO.File.Exists("C:\var\" + VersionName + ".txt") Then '判断当前c盘是否存储有该文件夹
Else
Dim fs12 As New System.IO.FileStream("C:\var\" + VersionName + ".txt ", FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.ReadWrite) '无则创建改文件
fs12.Write(b, blobFiles, b.Length) '向创建的文件中开始写，一次性写完
fs12.Close() '关闭读写操作，以免引发异常
fs12.Dispose()
End If
'======================
Catch ex As Exception
Debug.Print("#######################" & ex.StackTrace)
Debug.Print("########" & ex.Message)
Throw ex
End Try
每次只读取2014长度的字节
Dim fs As New System.IO.FileStream("C:\var\" + VersionName + ".txt", IO.FileMode.Open, IO.FileAccess.Read) Dim buffer(1023) As Byte
Dim re As New System.IO.BinaryReader(fs)
Dim numdouble As Double = (fs.Length / 1024)
num = Math.Ceiling(numdouble) '此函数用于判断是否有小数，有小数将自动取整比如：1.2将会取2，1.6将会取2
fs.Seek(i * ByNum.c, SeekOrigin.Begin)
re.Read(buffer, 0, 1024) '表示从0位开始读1024位 如果想取分组包长度可用 buffer.Length 如果想取数据则直接可取buffer
将VS中输出的debug统一放入指定的txt文件夹中
Public Const LOG_PATH As String = "C:\Users\Public\Documents\ECharge\"
If Not System.IO.Directory.Exists(Main.LOG_PATH) Then
System.IO.Directory.CreateDirectory(Main.LOG_PATH)
End If
If Not System.IO.Directory.Exists(Main.LOG_PATH & "Connect Server") Then
System.IO.Directory.CreateDirectory(Main.LOG_PATH & "Connect Server")
End If
If Not System.IO.Directory.Exists(Main.LOG_PATH & "Connect Server\Exception\") Then
System.IO.Directory.CreateDirectory(Main.LOG_PATH & "Connect Server\Exception\")
End If
If Not System.IO.Directory.Exists(Main.LOG_PATH & "Connect Server\Exception\" & Main.serverID & "\") Then
System.IO.Directory.CreateDirectory(Main.LOG_PATH & "Connect Server\Exception\" & Main.serverID & "\")
End If
Dim Str As New FileStream(Main.LOG_PATH & "Connect Server\Exception\" & Main.serverID & "\" & "DebugMessages.txt", System.IO.FileMode.Append)
Dim DebugFile As New StreamWriter(Str)
Dim Listener = New TextWriterTraceListener(DebugFile)
Debug.Listeners.Add(Listener)
Debug.AutoFlush = True
Debug.Print("----- start debug print to file")
上述代码将程序运行的debug放到c盘指定的目录，并创建一个DebguMessage.txt文档，执行后效果图如下：
VB.NET创建随机数
1 '产生随机数
2 Try
3 Dim Vchar As String = "00030,0031,00032,00033,00034,00035"
4 Dim VcArray() As String = Split(Vchar, ",") '将字符串生成数组
5 Dim VNum As String = ""
6 Dim objRandom As Random = New Random
7 objRandom.Next(0, 5)
8 VNum = VNum & VcArray(Int(objRandom.Next(0, 5))) '数组从0开始读取,后面指定读取最大界限，防止数组越界
9 MessageBox.Show(VNum)
10 Catch ex As Exception
11 Debug.Print(ex.Message)
12 Throw ex
13 End Try
VB.NET Integer类型转成byte类型并调用sort方法重新对元素排序
Public Sub setChargerStattimeStamp(ByRef StataTimeStamp As Integer)
Try
chargerStatTimeStamp = BitConverter.GetBytes(StataTimeStamp)
Dim sorts As List(Of Byte) = New List(Of Byte)(chargerStatTimeStamp)
sorts.Sort()
chargerStatTimeStamp(0) = sorts(0)
chargerStatTimeStamp(1) = sorts(1)
chargerStatTimeStamp(2) = sorts(2)
chargerStatTimeStamp(3) = sorts(3)
Catch ex As Exception
Throw ex
End Try
End Sub
VB.NET byte免拼接高级写法
Public Sub setRemoteUID(ByRef byteArray() As Byte)
Try
'D1 46 A3 6A 5E 08 04 00 01 D7 15 65 0B 94 3D 1D 原始UID：209701631069429
Array.Copy(byteArray, 0, Me.remoteUid, 0, UID_LENGTH)
Array.Resize(Me.remoteUid, UID_LENGTH)
ArrayRemove(byteArray, UID_LENGTH)
Dim id As String() = Me.remoteUid.Select(Function(byt) byt.ToString("x2")).ToArray
Dim uid As String = String.Join("-", id).ToUpper
Me.remoteUid_Value = uid
Dim id1 As String() = Me.remoteUid.Select(Function(byt) byt.ToString("x2")).ToArray
Dim uid1 As String = String.Join("", id).ToUpper
Meter_Reading.ByNum.Uid = Me.remoteUid_Value
Meter_Reading.ByNum.vchprivateID = uid1
Debug.Print("##############remoteUid_Value=" & Me.remoteUid_Value)
Debug.Print("##############vchprivateID=" & Meter_Reading.ByNum.vchprivateID)
Catch ex As Exception
Throw ex
End Try
End Sub
end
__EOF__
作 者：潇十一郎
出 处：https://www.cnblogs.com/zhangxiaoyong/p/5112793.html
