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使用 servlet 连接数据库

2012-02-14 20:29 281 查看

1.项目工程 web.xml 配置

<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>org.olive.DBServlet</servlet-class>
<init-param>
<param-name>driverName</param-name>
<param-value>com.microsoft.jdbc.sqlserver.SQLServerDriver</param-value>
</init-param>
<init-param>
<param-name>username</param-name>
<param-value>sa</param-value>
</init-param>
<init-param>
<param-name>password</param-name>
<param-value></param-value>
</init-param>
<init-param>
<param-name>dbName</param-name>
<param-value>pubs</param-value>
</init-param>

</servlet>

<servlet-mapping>
<servlet-name>DBServlet</servlet-name>
<url-pattern>/servlet/DBServlet</url-pattern>
</servlet-mapping>

2.servlet java文件

DBServlet.java

package org.olive;

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:microsoft:sqlserver://localhost:1433; DatabaseName=pubs";
try{
Class.forName("com.microsoft.jdbc.sqlserver.SQLServerDriver");
conn=DriverManager.getConnection(url,username,password);
stmt=conn.createStatement();
String sql="use pubs select * from publishers";
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;
}
}

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