JavaWeb-jdbc的mysql驱动问题

jdbc的mysql驱动问题

问题描述：mysql驱动在服务器运行时显示找不到类，在程序运行时正常。

解决办法：主要是驱动没有放对目录，将mysql驱动放到WEB-INF/lib目录下就能正常访问了

添加为库

报错信息

java.lang.RuntimeException: java.lang.ClassNotFoundException: com.mysql.jdbc.Driver

示例代码

程序

java 复制代码

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class JdbcExample {
    public static void main(String[] args) throws ClassNotFoundException {
        Class.forName("com.mysql.jdbc.Driver");
        // 数据库连接信息
        String url = "jdbc:mysql://ip:端口/数据库名?useSSL=false";
        String username = "用户名";
        String password = "密码";

        // JDBC对象
        Connection connection = null;
        Statement statement = null;
        ResultSet resultSet = null;

        try {
            // 连接数据库
            connection = DriverManager.getConnection(url, username, password);

            // 创建Statement对象
            statement = connection.createStatement();

            // 执行查询语句
            String query = "SELECT * FROM users";
            resultSet = statement.executeQuery(query);

            // 处理查询结果
            while (resultSet.next()) {
                int id = resultSet.getInt("id");
                String name = resultSet.getString("name");
                String email = resultSet.getString("age");

                System.out.println("ID: " + id);
                System.out.println("Name: " + name);
                System.out.println("age: " + email);
                System.out.println("----------------------");
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            // 关闭资源
            try {
                if (resultSet != null) {
                    resultSet.close();
                }
                if (statement != null) {
                    statement.close();
                }
                if (connection != null) {
                    connection.close();
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
}

服务器

java 复制代码

package com.chuwu.web;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.sql.*;

@WebServlet("/dome2")
public class ServletDemo2 extends HttpServlet {
    private void doMysql() throws ClassNotFoundException, SQLException {
        Class.forName("com.mysql.jdbc.Driver");
        // 数据库连接信息
        String url = "jdbc:mysql://ip:端口/数据库?useSSL=false";
        String username = "用户名";
        String password = "密码";

        // JDBC对象
        Connection connection = null;
        Statement statement = null;
        ResultSet resultSet = null;

        try {
            // 连接数据库
            connection = DriverManager.getConnection(url, username, password);

            // 创建Statement对象
            statement = connection.createStatement();

            // 执行查询语句
            String query = "SELECT * FROM users";
            resultSet = statement.executeQuery(query);

            // 处理查询结果
            while (resultSet.next()) {
                int id = resultSet.getInt("id");
                String name = resultSet.getString("name");
                String email = resultSet.getString("age");

                System.out.println("ID: " + id);
                System.out.println("Name: " + name);
                System.out.println("age: " + email);
                System.out.println("----------------------");
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            // 关闭资源
            try {
                if (resultSet != null) {
                    resultSet.close();
                }
                if (statement != null) {
                    statement.close();
                }
                if (connection != null) {
                    connection.close();
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("get请求");
        try {
            doMysql();
        } catch (ClassNotFoundException e) {
            throw new RuntimeException(e);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }

    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("post请求");
    }
}