怎么用Servlet连接mysql数据库 给个例题

package com.jsp.Database

import java.sql.*

import javax.sql.*

import java.io.*

import javax.servlet.*

import javax.servlet.http.*

import com.microsoft.jdbc.sqlserver.SQLServerDriver

public class JDBCServlet extends HttpServlet

{

/* 连接数据库属性*/

String driver

String password,url,user

/*处理doGet */

public void doGet(HttpServletRequest request,HttpServletResponse response)

throws IOException,ServletException

{

response.setContentType("text/htmlcharset=gb2312")

PrintWriter out=response.getWriter()

try

{

Connection con=getConnection()

Statement stmt=con.createStatement()

ResultSet rst=stmt.executeQuery("select * from user_info")

while(rst.next())

{

out.println(rst.getString("userid"))

out.println("<br>")

}

rst.close()

stmt.close()

con.close()

}

catch(SQLException e)

{

e.printStackTrace()

}

}

/*处理doPost请求*/

public void doPost(HttpServletRequest request,HttpServletResponse response)

throws IOException,ServletException

{

doGet(request,response)

}

public void init()throws ServletException

{

driver=getInitParameter("DRIVER")

password=getInitParameter("PASSWORD")

url=getInitParameter("URL")

user=getInitParameter("USER")

}

private Connection getConnection()

{

Connection con=null

try

{

Class.forName(driver)

con=DriverManager.getConnection(url,user,password)

}

catch(Exception e )

{

e.printStackTrace()

}

return con

}

}

======== web.xml文件配置========

<servlet>

<servlet-name>JDBCServlet</servlet-name>

<servlet-class>com.jsp.Database.JDBCServlet</servlet-class>

<init-param>

<param-name>DRIVER</param-name>

<param-value>com.microsoft.jdbc.sqlserver.SQLServerDriver</param-value>

</init-param>

<init-param>

<param-name>URL</param-name>

<param-value>jdbc:jdbc:mysql://127.0.0.1:3306/数据库名</param-value>

</init-param>

<init-param>

<param-name>USER</param-name>

<param-value>用户名</param-value>

</init-param>

<init-param>

<param-name>PASSWORD</param-name>

<param-value>密码</param-value>

</init-param>

</servlet>

<servlet-mapping>

<servlet-name>JDBCServlet</servlet-name>

<url-pattern>/init_servlet</url-pattern>

</servlet-mapping>

WEB.XML在你的tomcat/webapp/你的目录/WEB-INF/下..

或者复制tomcat/webapp/ROOT/WEB-INF/下的,,做一下修改就行了.

简单点说，主要有几个步骤：

1、确保你能连接mysql数据库（前提是有安装mysql数据库并有相应的库表）；

2、确保你能获取数据库连接（前提是有mysql的驱动程序）；

3、拥有负责数据写入的Dao类（就是用来写入数据库的java类）；

4、在servlet中利用Dao类向数据库中写入数据。

至于有没有jsp负责数据的展现，看实际需要就可以。

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