注：该servlet链接的是mySql数据库，数据库名为test_db 在运行前需要加载mySql数据库驱动
DBServlet servlet文件代码如下::
package com;
import java.io.*; //导入java.io包
import java.util.*;
import java.sql.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class DBServlet extends HttpServlet{ //定义一个继承HttpServlet的公有类
ServletConfig config=null; //定义一个ServletConfig对象
private String driverName=""; //定义私有字符串常量并初始化
private String username=""; //定义的数据库用户名
private String password=""; //定义的数据库连接密码
private String dbName=""; //定义的数据库名
private Connection conn; //初始化连接
private Statement stmt; //初始化数据库操作
ResultSet rs=null; //初始化结果集
public void init(ServletConfig config)throws ServletException{
super.init(config); //继承父类的init()方法
this.config=config; //获取配置信息
driverName=config.getInitParameter("driverName");//从配置文件中获取JDBC驱动名
username=config.getInitParameter("username"); //获取数据库用户名
password=config.getInitParameter("password"); //获取数据库连接密码
dbName=config.getInitParameter("dbName"); //获取要连接的数据库
}
public void doGet(HttpServletRequest req,HttpServletResponse resp)throws IOException,ServletException{
resp.setContentType("text/html;charset=GBK"); //设置字符编码格式
PrintWriter out=resp.getWriter(); //实例化对象，用于页面输出
out.println("<html>"); //实现生成静态Html
out.println("<head>");
out.println("<meta http-equiv=\"Content-Type\"content=\"text/html;charset=GBK\">");
out.println("<title>DataBase Connection</title>");
out.println("</head>");
out.println("<body bgcolor=\"white\">");
out.println("<center>");
String url="jdbc:mysql://127.0.0.1:3307/test_db";
try{
Class.forName("com.mysql.jdbc.Driver");
conn=DriverManager.getConnection(url,username,password);
stmt=conn.createStatement();
String sql="select * from t_food_order";
rs=stmt.executeQuery(sql);
out.println("Servlet访问数据库成功");
out.println("<table border=1 bordercolorlight=#000000>");
out.println("<tr><td width=40>序号</td>");
out.println("<td>书名</td>");
out.println("<td>城市</td>");
//out.println("<td>州</td>");
//out.println("<td>国</td></tr>");
while(rs.next()){
out.println("<tr><td>"+rs.getString(1)+"</td>");
out.println("<td>"+rs.getString(2)+"</td>");
out.println("<td>"+rs.getString(3)+"</td>");
//out.println("<td>"+rs.getString(4)+"</td>");
//out.println("<td>"+rs.getString(5)+"</td>");
out.println("<tr>");
}
out.println("</table>");
rs.close();
stmt.close();
conn.close();
}catch(Exception e){
e.printStackTrace();
out.println(e.toString());
}
out.println("</center>");
out.println("</body>");
out.println("</html>");
}
public void doPost(HttpServletRequest req,HttpServletResponse resp)throws IOException,ServletException{
this.doGet(req,resp);
}
public void destory(){
config=null;
driverName=null;
username=null;
password=null;
dbName=null;
conn=null;
stmt=null;
rs=null;
}
}
web.xml文件如下：：
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5"
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
<servlet>
<description>This is the description of my J2EE component</description>
<display-name>This is the display name of my J2EE component</display-name>
<servlet-name>DBServlet</servlet-name>
<servlet-class>com.DBServlet</servlet-class>
<init-param>
<param-name>driverName</param-name>
<param-value>com.mysql.jdbc.Driver</param-value>
</init-param>
<init-param>
<param-name>username</param-name>
<param-value>root</param-value>
</init-param>
<init-param>
<param-name>password</param-name>
<param-value>root</param-value>
</init-param>
<init-param>
<param-name>dbName</param-name>
<param-value>test_db</param-value>
</init-param>
</servlet>
<servlet>
<description>This is the description of my J2EE component</description>
<display-name>This is the display name of my J2EE component</display-name>
<servlet-name>Ka</servlet-name>
<servlet-class>com.Ka</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>DBServlet</servlet-name>
<url-pattern>/DBServlet</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>Ka</servlet-name>
<url-pattern>/Ka</url-pattern>
</servlet-mapping>
</web-app>
转自：http://www.cnblogs.com/penseur/archive/2012/05/15/2502120.html
