B4A 使用JDBC连接MySQL数据库
类库引用
- • jdbcSQL.jar
- • jdbcSQL.xml
- • mysql-connector-java-5.1.49-bin.jar
关键点注意
需要把
mysql-connector-java-5.1.49-bin.jar驱动文件,放到B4A安装目录下的Libraries内部类库文件夹下
码代码
#Region Project Attributes
#ApplicationLabel: JDBC连接mysql
#VersionCode: 1
#VersionName:
#SupportedOrientations: portrait
#CanInstallToExternalStorage: False
#End Region
#Region Activity Attributes
#FullScreen: False
#IncludeTitle: True
#End Region
#AdditionalJar: mysql-connector-java-5.1.49-bin
Sub Process_Globals
Private MysqlJdbc As JdbcSQL
End Sub
Sub Globals
Private tf As Boolean=False
Private WebView1 As WebView
Private Button1 As Button
Private Button2 As Button
End Sub
Sub Activity_Create(FirstTime As Boolean)
Activity.LoadLayout("Layout")
'DisableStrictMode
''-------
End Sub
Sub Activity_Resume
End Sub
Sub Activity_Pause (UserClosed As Boolean)
End Sub
Sub Button1_Click
Dim driver As String = "com.mysql.jdbc.Driver"
Dim jdbcUrl As String = "jdbc:mysql://42.193.251.120:3306/db_student"
Dim Username As String = "student"
Dim Password As String = "student"
MysqlJdbc.InitializeAsync("EventMysql", driver, jdbcUrl, Username, Password)
Wait For EventMysql_Ready (Success As Boolean)
If Success = False Then
ToastMessageShow("数据库连接失败",False)
Button1.TextColor=Colors.Red
Else
ToastMessageShow("数据库连接成功",False)
tf=True
Button1.TextColor=Colors.Green
End If
End Sub
Private Sub Button2_Click
If tf Then
Dim SenderFilter As Object = MysqlJdbc.ExecQueryAsync("SQL", "SELECT `学生ID`,`姓名`,`语文`,`数学`,`英语`,`总成绩` FROM v_allscore;", Null)
Wait For (SenderFilter) SQL_QueryComplete (Success As Boolean, rs As JdbcResultSet)
If Success Then
Dim htmltd As StringBuilder
htmltd.Initialize
Do While rs.NextRow
htmltd.Append($"<tr>"$)
htmltd.Append($"<td>${rs.GetString("学生ID")}</td>"$)
htmltd.Append($"<td>${rs.GetString("姓名")}</td>"$)
htmltd.Append($"<td>${rs.GetString("语文")}</td>"$)
htmltd.Append($"<td>${rs.GetString("数学")}</td>"$)
htmltd.Append($"<td>${rs.GetString("英语")}</td>"$)
htmltd.Append($"<td>${rs.GetString("总成绩")}</td>"$)
htmltd.Append($"<td><a href="${rs.GetString("学生ID")}">明细</a></td>"$)
htmltd.Append($"</tr>"$)
Loop
WebView1.LoadHtml(htmls(htmltd.ToString))
rs.Close
Else
Log(LastException)
End If
Else
ToastMessageShow("未连接数据库",False)
End If
End Sub
Private Sub htmls(td As String) As String
Dim html As String=$"
<html>
<head>
<style>
table{
font-size:0.8rem;
width:100%;
text-align:center;
border-collapse:collapse;
border-spacing:0;
border-left:1px solid #888;
border-top:1px solid #888;
background:#efefef;
}
th,td{
border-right:1px solid #888;
border-bottom:1px solid #888;
}
th{
font-weight:bold;
background:#ccc;
}
a{
text-decoration: none;
color: green;
}
</style>
</head>
<body>
<table>
<tr>
<th>学生ID</th>
<th>姓名</th>
<th>语文</th>
<th>数学</th>
<th>英语</th>
<th>总成绩</th>
<th>明细</th>
</tr>
${td}
</table>
</body>
</html>
"$
Return html
End Sub
Private Sub WebView1_OverrideUrl (Url As String) As Boolean
Dim res As String=Url.Replace("file:///","")
'ToastMessageShow(res,False)
Seltss(res)
Return True
End Sub
Private Sub Seltss(sid As Int)
If tf Then
Dim SenderFilter As Object = MysqlJdbc.ExecQueryAsync("SQL", $"SELECT `学生ID`,`学生名`,`生日`,`性别`,`任课教师`,`科目`,`成绩` FROM v_tsscore WHERE `学生ID` = ${sid} GROUP BY `科目`;"$, Null)
Wait For (SenderFilter) SQL_QueryComplete (Success As Boolean, rs As JdbcResultSet)
If Success Then
Dim ressb As StringBuilder
ressb.Initialize
Dim i As Int=1,sumcj As Double
Do While rs.NextRow
If i=1 Then
ressb.Append($"ID:${rs.GetString("学生ID")}${CRLF}"$)
ressb.Append($"姓名:${rs.GetString("学生名")}${CRLF}"$)
ressb.Append($"生日:${rs.GetString("生日")}${CRLF}"$)
ressb.Append($"性别:${rs.GetString("性别")}${CRLF}"$)
End If
If rs.GetString("科目")="语文" Then
ressb.Append($"语文:${rs.GetString("成绩")}${CRLF}"$)
sumcj=sumcj+rs.GetString("成绩")
End If
If rs.GetString("科目")="数学" Then
ressb.Append($"数学:${rs.GetString("成绩")}${CRLF}"$)
sumcj=sumcj+rs.GetString("成绩")
End If
If rs.GetString("科目")="英语" Then
ressb.Append($"英语:${rs.GetString("成绩")}${CRLF}"$)
sumcj=sumcj+rs.GetString("成绩")
End If
i=i+1
Loop
ressb.Append($"总成绩:${sumcj}"$)
rs.Close
MsgboxAsync(ressb.ToString,"明细")
Else
Log(LastException)
End If
Else
ToastMessageShow("未连接数据库",False)
End If
End Sub源码下载
链接：https://pan.baidu.com/s/1dSACc_F7nVbZK8H1cUgtfg?pwd=goh3
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原始发表：2022-07-25，如有侵权请联系 cloudcommunity@tencent.com 删除
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