vb.net 与 XML 的操作

内容:.net与xml的小软件(100多行左右)

注意:如果转贴，请一定注明出处，以及作者

//=================================开始===============

//======================准备工作===========================

          @#　再建立项目的文件夹的bin文件夹下

          @#创建两个文件

          @#一个是"myxml.xml"

          @#一个是"myxml.mdb"

           @#这里面有一个表"users"三个字段名"nameid","age","faverity"



      @#再转到图形界面

    @#单击"工具箱"的"数据"把"OleDbConnection"," OleDbComman","DataSet","OleDbDataAdapter"

   @#拉入窗体界面

   @#依次对这几个控件进行操作

 @#我的文件夹是D:\vbproject\WindowsApplication1

  @#D:\vbproject\WindowsApplication1/bin/myxml.xml

 @#D:\vbproject\WindowsApplication1/bin/myxml.mdb

         

//======================准备结束==============

   (1)首先在机子上要有.Net FrameWork

    打开VS.NET依次展开:文件-新建-项目;

    再选择VISUAL-BASIC-项目-Windows应用程序

    

这就是所需要一个小界面

现在一步步的来写代码，完成它的功能

首先来完成添加功能:

我们目标是：通过这三个文本框(姓名，年龄，爱好)来添加到数据库中。然后再把这个数据库的表保存成XML格式

    双击"添加"按钮

   在里面写下以下这些代:(VB写的语言，不是C#)

  If TextBox1.Text <> "" And TextBox2.Text <> "" And TextBox3.Text <> "" Then

  @#在三个文本框都不为空时，执行以下操作,

   @#否则出错
            Dim strsel As String
            strsel = "select * from users where nameid=@#" & TextBox1.Text & "@#"

@#建立一个查询字符串，看要要添加的姓名，是否已在数据中存在，如果不存在就可以添加
            OleDbCommand1 = New OleDbCommand
            Me.OleDbCommand1.CommandText = strsel
            Me.OleDbCommand1.Connection = OleDbConnection1
            OleDbConnection1.Open()
            Try

 @#进行异常处理

                Dim reader As OleDbDataReader = OleDbCommand1.ExecuteReader()
                If reader.Read() Then

@#通过DataReader来读取，如果读得到，表明数据在有这个姓名存在，不添加;
                    ListBox1.Items.Add("已经有该记录!")
                Else
                    reader.Close()

@#要对数据库进行操作，首先把DataReader关掉;
                    Dim insert As String
                    insert = "insert into users(nameid,age,faverity) values(@#" & TextBox1.Text & "@#,@#" & TextBox2.Text & "@#,@#" & TextBox3.Text & "@#)"

   @#建立一个插入字符串
                    OleDbCommand1 = New OleDbCommand
                    Me.OleDbCommand1.CommandText = insert
                    Me.OleDbCommand1.Connection = Me.OleDbConnection1
                    Me.OleDbCommand1.ExecuteNonQuery()
                    ListBox1.Items.Add("添加成功!!")

        @#以下是把数据库的数据保存为XML格式
                    DataSet1 = New DataSet
                    OleDbDataAdapter1 = New OleDbDataAdapter("select * from users", OleDbConnection1)
                    OleDbDataAdapter1.Fill(DataSet1, "users")
                    DataSet1.WriteXml("myxml.xml")
                End If
            Catch ex As Exception
                ListBox1.Items.Add("Errors!")
            End Try

            OleDbConnection1.Close()
        Else
            MessageBox.Show("请输入完整!!")
        End If

   //==================接下来是对数据库进行查询===================

@#双击"查找"按钮

 @#写入以下代码

   If TextBox4.Text <> "" Then

@#还是和上面一样如果文本框为空，就不执行，如果不为空，就执行下面的操作
            ListBox1.Items.Clear()

@#首先把listBox清空
            Dim searchtext As String
            searchtext = TextBox4.Text
            OleDbConnection1.Open()
            Dim selstring As String
            selstring = "select * from users where nameid like @#%" & searchtext & "%@#"

         @# 建立查询字符串，可以支持模糊查询
            OleDbCommand1 = New OleDbCommand
            Me.OleDbCommand1.CommandText = selstring
            Me.OleDbCommand1.Connection = OleDbConnection1

@#以下几句是显示匹配的条数
            DataSet1 = New DataSet
            OleDbDataAdapter1 = New OleDbDataAdapter(selstring, OleDbConnection1)
            OleDbDataAdapter1.Fill(DataSet1, "users")
            ListBox1.Items.Add("共有" & DataSet1.Tables("users").Rows.Count & "条匹配的记录")
            ListBox1.Items.Add("-------------------------------------------------------------")
            Try

 @#进行异常处理
                Dim cmdreader As OleDbDataReader = OleDbCommand1.ExecuteReader()

                While cmdreader.Read

  @#注意这里要用while

  @#不然就无法进行循环，就只能进行一次查询
                    ListBox1.Items.Add(cmdreader("nameid").ToString())
                    ListBox1.Items.Add(cmdreader("age").ToString())
                    ListBox1.Items.Add(cmdreader("faverity").ToString())
                    ListBox1.Items.Add("----------------------------------")
                End While

                cmdreader.Close()

                OleDbConnection1.Close()
            Catch ex As Exception
                ListBox1.Items.Add("Errors")
            End Try
        Else
        End If

//================再把来ＸＭＬ文档，以ＸＭＬ形式显示在ListBox里面

 双击"ＸＭＬ文档" 写进下面这些代码:

  ListBox1.Items.Clear()

@# 清空listBox
        Dim xtr As XmlTextReader = New XmlTextReader("myxml.xml")

@#创建成一个XmlTextReader读取"myxml.xml"文档
        While xtr.Read
            Select Case (xtr.NodeType)

       @# 咱们用select case 形式来选择xml节点类型
                Case XmlNodeType.XmlDeclaration

      @#先从ListBox里写进xml声明=====xmldeclaration
                    ListBox1.Items.Add("<?xml version=@#1.0@# encoding=@#gb2312@#?>")

   @#再依次显示节点的名称，值

   @#包括根节点
                Case XmlNodeType.Element
                    ListBox1.Items.Add("<" & xtr.Name & ">")
                Case XmlNodeType.Text
                    ListBox1.Items.Add(xtr.Value)
                Case XmlNodeType.EndElement
                    ListBox1.Items.Add("</" & xtr.Name & ">")

            End Select
        End While
        xtr.Close()

 @#关闭xmlTextReader

  //========再把数据库中所有数据显示在ListBox中========

  @#双击"查看全部"按钮

 @#写入下面的一些代码:

 ListBox1.Items.Clear()

 @#这些代码大家应该可以看得懂了
        OleDbConnection1.Open()
        Dim selall As String
        selall = "select * from users"
        OleDbCommand1 = New OleDbCommand
        Me.OleDbCommand1.CommandText = selall
        Me.OleDbCommand1.Connection = OleDbConnection1
        Try
            Dim creader As OleDbDataReader = OleDbCommand1.ExecuteReader()
            While creader.Read
                ListBox1.Items.Add("name: " & creader("nameid").ToString() & "; age :" & creader("age").ToString() & "; faverity :" & creader("faverity").ToString())
            End While
            creader.Close()
        Catch ex As Exception
            ListBox1.Items.Add("Errors")
        End Try
        OleDbConnection1.Close()

  //==========================再来进完成删除按钮=================

  @#双击"删除"按钮

  @#写入以下的代码

  If TextBox4.Text <> "" Then

@#如果不为空，进行以下操作
            ListBox1.Items.Clear()

   @#先清空ListBox
            OleDbConnection1.Open()

  @# 建立连接
            Dim delstring As String
            delstring = TextBox4.Text
            Dim delsel As String
            delsel = "select * from users where nameid=@#" & delstring & "@#"

  @#创建查询字符串
            OleDbCommand1 = New OleDbCommand
            Me.OleDbCommand1.CommandText = delsel
            Me.OleDbCommand1.Connection = OleDbConnection1
            Try
                Dim selreader As OleDbDataReader = OleDbCommand1.ExecuteReader()
                If Not selreader.Read Then

  @#假如读不到，就表明数据库无此数据，无法进行删除操作
                    MessageBox.Show("数据库中无该记录!")
                Else
                    selreader.Close()

   @#要对数据进行操作，必须首把DataReader关掉
                    Dim delrecord As String
                    delrecord = "delete * from users where nameid=@#" & delstring & "@#"

   @#建立删除字符串sql语句，以上都是
                    OleDbCommand1 = New OleDbCommand
                    Me.OleDbCommand1.CommandText = delrecord
                    Me.OleDbCommand1.Connection = OleDbConnection1
                    Me.OleDbCommand1.ExecuteNonQuery()
                    MessageBox.Show("删除成功!!")

  @#再把进行删除操作的数据库，再次把数据库中数据保存成ＸＭＬ文档
                    DataSet1 = New DataSet
                    OleDbDataAdapter1 = New OleDbDataAdapter("select * from users", OleDbConnection1)
                    OleDbDataAdapter1.Fill(DataSet1, "users")
                    DataSet1.WriteXml("myxml.xml")
                End If
            Catch ex As Exception
                MessageBox.Show(ex.Message)
            Finally
                OleDbConnection1.Close()
            End Try
        Else
            MessageBox.Show("请输入你想删除的记录!")
        End If

 //======================= 重设按钮=====

  TextBox1.Text = ""
        TextBox2.Text = ""
        TextBox3.Text = ""
        ListBox1.Items.Clear()

 //============================关闭===============

            me.Close()



@#好了这个小软件完成了，有问题的话留言

@#本程序在.net framework 2003创建

@#已经进行过测试，完全可以运行

原文转自：http://www.ltesting.net