您的位置：首页 > 数据库

通过ServletConfig加载web.xml文件来连接数据库

2016-03-27 14:47 507 查看

首先在web.xml文件配置节点

<servlet>

<servlet-name>testServlet</servlet-name>

<servlet-class>com.yd.etc.TestServlet</servlet-class>



<init-param>

<param-name>driver</param-name>

<param-value>com.mysql.jdbc.Driver</param-value>

</init-param>



<init-param>

<param-name>url</param-name>

<param-value>jdbc:mysql://localhost:3306/test</param-value>

</init-param>



<init-param>

<param-name>user</param-name>

<param-value>root</param-value>

</init-param>



<init-param>

<param-name>pass</param-name>

<param-value>123456</param-value>

</init-param>

</servlet>

<servlet-mapping>

<servlet-name>testServlet</servlet-name>

<url-pattern>/testServlet</url-pattern>

</servlet-mapping>

再通过TestServlet来连接数据库

TestServlet.java 代码：

package com.yd.etc;

import java.io.PrintStream;

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.ResultSet;

import java.sql.Statement;

import javax.servlet.ServletConfig;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

public class TestServlet extends HttpServlet {

// 重写init方法

public void init(ServletConfig config) throws ServletException {

// 重写该方法，应该首先调用父类的init()方法

super.init(config);

}

// 响应客户端请求的方法

public void service(HttpServletRequest request, HttpServletResponse response)

throws ServletException, java.io.IOException {

try {

// 获取ServletConfig对象

ServletConfig config = getServletConfig();

// 通过ServletConfig对象获取配置参数：dirver

String driver = config.getInitParameter("driver");

// 通过ServletConfig对象获取配置参数：url

String url = config.getInitParameter("url");

// 通过ServletConfig对象获取配置参数：user

String user = config.getInitParameter("user");

// 通过ServletConfig对象获取配置参数：pass

String pass = config.getInitParameter("pass");

// 注册驱动

Class.forName(driver);

// 获取数据库连接

Connection conn = DriverManager.getConnection(url, user, pass);

// 创建Statement对象

Statement stmt = conn.createStatement();

// 执行查询，获取ResuletSet对象

ResultSet rs = stmt.executeQuery("select * from user");

response.setContentType("text/html;charSet=gbk");

// 获取页面输出流

PrintStream out = new PrintStream(response.getOutputStream());

// 输出HTML标签

out.println("<html>");

out.println("<head>");

out.println("<title>访问Servlet初始化参数测试</title>");

out.println("</head>");

out.println("<body>");

out.println("<table bgcolor=\"#9999dd\" border=\"1\""

+ "width=\"480\">");

// 遍历结果集

while (rs.next()) {

// 输出结果集内容

out.println("<tr>");

out.println("<td>" + rs.getString(1) + "</td>");

out.println("<td>" + rs.getString(2) + "</td>");

out.println("</tr>");

}

out.println("</table>");

out.println("</body>");

out.println("</html>");

} catch (Exception e) {

e.printStackTrace();

}

}

}

还有种方法直接在TestServlet 类上面注解配置

@WebServlet(name="testServlet"

, urlPatterns={"/testServlet"}

, initParams={

@WebInitParam(name="driver", value="com.mysql.jdbc.Driver"),

@WebInitParam(name="url", value="jdbc:mysql://localhost:3306/test"),

@WebInitParam(name="user", value="root"),

@WebInitParam(name="pass", value="123456")})

结果和在web.xml一样；

至于效果的怎么样，期待各位一起学习

内容来自用户分享和网络整理，不保证内容的准确性，如有侵权内容，可联系管理员处理

标签：

相关文章推荐

新的分享

章节导航