需求在不能配置双数据源的情况下你需要连接两个数据库进行手写jdbc来进行连接数据库操作数据

jdbc工具类

这里为了方便我手写了一个工具类给你方便调用不用手写jdbc连接

package com.datanew.util;
import java.sql.*;
import java.util.ArrayList;
import java.util.HashMap;

/**
 * 原生jdbc操作数据库工具类
 */
public class JdbcUtil {

    //数据库连接：地址、用户名、密码
    private final String url;
    private final String username;
    private final String password;

    public JdbcUtil(String url, String username, String password){
        this.url = url;
        this.username = username;
        this.password = password;
    }
    public JdbcUtil(String url, String username, String password, String driver){
        this.url = url;
        this.username = username;
        this.password = password;

        try {
            /*
                同时需要引入相关驱动依赖

                1、MySQL：
                com.mysql.cj.jdbc.Driver

                2、Oracle：
                oracle.jdbc.driver.OracleDriver

                3、pgsql：
                org.postgresql.Driver

             */
            //加载驱动
            Class.forName(driver);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
    }

    /**
     * 获取 Connection 连接
     */
    private Connection getConnection() {
        Connection conn = null;
        try {
            conn= DriverManager.getConnection(url, username, password);
            conn.setAutoCommit(true);
        } catch (SQLException e) {
            System.err.println("获取Connection连接异常...");
            e.printStackTrace();
        }
        return conn;
    }

    /**
     * 关闭 Connection 连接
     */
    private void close(Connection conn){
        try {
            conn.close();
        } catch (SQLException e) {
            System.err.println("关闭Connection连接异常...");
            e.printStackTrace();
        }
    }

    /**
     * 查询
     */
    public ArrayList<HashMap<String,Object>> find(String sql, Object[] params) {
        ArrayList<HashMap<String, Object>> list = new ArrayList<>();

        //获取连接
        Connection conn = getConnection();
        PreparedStatement ps;
        ResultSet rs;

        try {
            //设置SQL、以及参数
            ps = conn.prepareStatement(sql);
            if (params != null) {
                for (int i = 0; i < params.length; i++) {
                    ps.setObject(i + 1, params[i]);
                }
            }

            //执行查询
            rs = ps.executeQuery();

            //获取查询结果
            ResultSetMetaData rm = rs.getMetaData();
            int columnCount = rm.getColumnCount();

            //封装结果集
            while (rs.next()) {
                HashMap<String, Object> map = new HashMap<>(columnCount);
                for (int i = 1; i <= columnCount; i++) {
                    String name = rm.getColumnName(i).toLowerCase();
                    Object value = rs.getObject(i);

                    map.put(name,value);
                }
                list.add(map);
            }

            //关闭连接
            close(conn);
        } catch (Exception e) {
            System.err.println("执行 jdbcUtil.find() 异常...");
            e.printStackTrace();
        }

        return list;
    }
    public HashMap<String,Object> findOne(String sql, Object[] params){
        ArrayList<HashMap<String, Object>> list = find(sql, params);
        return list.size() > 0 ? list.get(0) : null;
    }

    /**
     * 更新
     */
    private boolean update(String sql, Object[] params){
        boolean flag = false;

        //获取连接
        Connection conn = getConnection();
        PreparedStatement ps;

        try {
            //设置SQL、以及参数
            ps = conn.prepareStatement(sql);
            if (params != null) {
                for (int i = 0; i < params.length; i++) {
                    ps.setObject(i + 1, params[i]);
                }
            }

            //执行
            flag = ps.execute();
        } catch (SQLException e) {
            System.err.println("执行 jdbcUtil.update() 异常...");
            e.printStackTrace();
        }

        //关闭连接
        close(conn);

        return flag;
    }
}

测试

你可以使用一个main函数来进行测试

public static void main(String[] args) {
        //获取连接
        jdbcUtil jdbcUtil = new jdbcUtil("jdbc:mysql://localhost/jfinal_demo","root","123456");
 
        // find查询
        ArrayList<HashMap<String, Object>> list = jdbcUtil.find("select * from user", null);
        for (HashMap<String, Object> map : list) {
            System.out.println(map);
        }
 
        System.out.println("----------------------------");
 
        //update执行、findOne查询
        jdbcUtil.update("delete from user where user_id = ?", new Object[]{"4"});
        jdbcUtil.update("insert into user values (?,?)", new Object[]{"4","王麻子"});
        jdbcUtil.update("update user set user_name = ? where user_id = ?", new Object[]{"王麻子子","4"});
 
        HashMap<String, Object> map = jdbcUtil.findOne("select * from user where user_id = ?", new Object[]{"4"});
        System.out.println(map);
    }