Question

Cannot create JDBC driver of class 'org.gjt.mm.mysql.Driver' for connect URL 'null'

做Struts1.2时出错，配好数据源后Tomcat5.5一启动就报错：
Cannot create JDBC driver of class 'org.gjt.mm.mysql.Driver' for connect URL 'null'。

其中struts-config.xml内容如下：
<data-sources>
<data-source key="jdbc/mysql" type="org.apache.commons.dbcp.BasicDataSource">
<set-property property="driverClassName" value="org.gjt.mm.mysql.Driver"/>
<set-property property="url" value="jdbc:mysql://localhost:3306/field"/>
<set-property property="username" value="root"/>
<set-property property="password" value="123456"/>
<set-property property="minCount" value="10"/>
<set-property property="maxCount" value="20"/>
<set-property property="description" value="mysql"/>
<set-property property="readOnly" value="false"/>
<set-property property="autoCommit" value="true"/>
<set-property property="loginTimeout" value=""/>
</data-source>
</data-sources>
这是其中调用的代码：
public class loginAction extends Action {

@Override
public ActionForward execute(ActionMapping mapping, ActionForm form,
HttpServletRequest request, HttpServletResponse response)
throws Exception {
ActionErrors errors = new ActionErrors();
boolean isValid=false;

isValid = valid(request,(loginActionForm)form);

if(isValid){
return mapping.findForward("success");
}else {
errors.add("NameOrPassError", new ActionMessage("NameOrPassError"));
return mapping.findForward("error");
}
}

private boolean valid(HttpServletRequest request,loginActionForm loginForm){
DataSource ds = null;
Connection conn = null;
boolean b = false;

try {
ds = getDataSource(request,"jdbc/mysql");
conn = ds.getConnection();
String username = loginForm.getUsername();
String password = loginForm.getPassword();
String sqlStr = new String("select * from user where username=? and password=?");
PreparedStatement preSQLSelect = conn.prepareStatement(sqlStr,ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_READ_ONLY);

username = new String(username.getBytes("ISO-8859-1"));
password = new String(password.getBytes("ISO-8859-1"));
preSQLSelect.setString(1,username);
preSQLSelect.setString(2,password);
ResultSet rs = preSQLSelect.executeQuery();

if(rs.next()){
b = true;
request.getSession().setAttribute("userID",rs.getString("userID"));
request.getSession().setAttribute("username",rs.getString("userName"));
request.getSession().setAttribute("password",rs.getString("password"));
}

rs.close();
preSQLSelect.close();
conn.close();

} catch (SQLException e) {
e.printStackTrace();
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}

return b;
}

}
请大家帮帮忙

Answer 1

确定你的mysql驱动放在项目中了么？

1)启动Tomcat服务器，打开浏览器，输入http://localhost:8080/admin（其中localhost是名称服务器或称为主机），
进入管理界面的登陆页面，这时候请输入原来安装时要求输入的用户名和密码，登陆到管理界面，

2)选择Resources－Data sources进入配置数据源界面，选择
Data Source Actions －>选择Create New Data Source,进入配置详细信息界面
主要内容例如下：
JNDI Name: ->jdbc/mysql
Data Source URL ->jdbc:mysql://localhost:3306/test
JDBC Driver Class-> org.gjt.mm.mysql.Driver
3)修改\conf\Catalina\localhost目录下建立一个xml文件,名称为你所发布的web应用的名称．xml,(如testpool.xml)打开添加内容如下:
<?xml version="1.0" encoding="UTF-8"?>
<Context>
<Resource
name="jdbc/mysql"
type="javax.sql.DataSource"
password="123456"
driverClassName="org.gjt.mm.mysql.Driver"
maxIdle="2"
maxWait="50"
username="root"
url="jdbc:mysql://localhost:3306/test"
maxActive="4"/>

</Context>
内容同conf/server.xml中<GlobalNamingResources>
<Resource
name="jdbc/mysql"
type="javax.sql.DataSource"
password="123456"
driverClassName="org.gjt.mm.mysql.Driver"
maxIdle="2"
maxWait="50"
username="root"
url="jdbc:mysql://localhost:3306/test"
maxActive="4"/>
</GlobalNamingResources>

少了这一步会报错：Cannot create JDBC driver of class '' for connect URL 'null'
4)修改web.xml

打开%TOMCAT_HOME%\conf\web.xml或yourwebapp/web-inf/web.xml,添加以下内容：
<resource-ref>
<description>DB Connection</description>
<res-ref-name>jdbc/mysql</res-ref-name>
<res-type>javax.sql.DataSource</res-type>
<res-auth>Container</res-auth>
</resource-ref>
注意res-ref-name填写的内容要与在上文提到的JNDI Name名称一致。
到这里，配置工作就基本完成了!

5)引用JNDI时用"java:comp/env/jdbc/mysql";
建立文件测试 test.jsp：
<%@page contentType="text/html;charset=utf-8" %>
<%@page import="java.sql.*" %>
<%@page import="javax.sql.*" %>
<%@page import="javax.naming.*" %>
<html>
<head>
<title>Tomcat连接池测试</title>
</head>
<body>
<%
Context ctx=new InitialContext();
Connection conn=null;
DataSource ds=(DataSource)ctx.lookup("java:comp/env/jdbc/mysql");
conn=ds.getConnection();
Statement stmt=conn.createStatement(ResultSet.CONCUR_READ_ONLY,ResultSet.CONCUR_UPDATABLE);
ResultSet rs=stmt.executeQuery("select * from testexample");
while(rs.next()){
out.println(rs.getInt(1));
out.println(rs.getString(2));
out.println(rs.getString(3));
}
out.println("数据库操作成功！");
rs.close();
stmt.close();
conn.close();

%>
</body>
</html>

Answer 2

换个驱动的jar包，用这个mysql-connector-java-5.0.8-bin.jar

这个jar包是mysql官方的驱动jar包

驱动的名是 com.mysql.jdbc.Driver