mysql 监听器_Jsp连接Mysql数据库：利用Servlet监听器

可以实现Jsp连接Mysql数据库的监听器。具体实现步骤如下：

1. 在web.xml文件中定义一个监听器：

<listener>
    <listener-class>com.xxx.xxx.MySqlListener</listener-class>
</listener>

2. 编写一个实现ServletContextListener接口的监听器类MySqlListener，并在其中编写连接Mysql数据库的代码：

public class MySqlListener implements ServletContextListener {
    public void contextInitialized(ServletContextEvent event) {
        String driver = "com.mysql.jdbc.Driver";
        String url = "jdbc:mysql://localhost:3306/databaseName";
        String user = "username";
        String password = "password";
        Connection conn = null;
        try {
            Class.forName(driver);
            conn = DriverManager.getConnection(url, user, password);
            event.getServletContext().setAttribute("conn", conn);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    public void contextDestroyed(ServletContextEvent event) {
        Connection conn = (Connection) event.getServletContext().getAttribute("conn");
        try {
            conn.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

3. 在Jsp页面中使用EL表达式获取ServletContext中的Connection对象，从而连接Mysql数据库：

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<%
    Connection conn = (Connection) application.getAttribute("conn");
    PreparedStatement ps = null;
    ResultSet rs = null;
    try {
        ps = conn.prepareStatement("SELECT * FROM tableName");
        rs = ps.executeQuery();
        while (rs.next()) {
            out.print(rs.getString("columnName") + "<br/>");
        }
    } catch (SQLException e) {
        e.printStackTrace();
    } finally {
        try {
            if (rs != null) rs.close();
            if (ps != null) ps.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
%>

通过以上步骤，我们就可以在Jsp页面中连接Mysql数据库并执行SQL语句了。