jdbc的一个小例子

package com.itheima.a_jdbc;

import org.junit.Test;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;

public class a_hello {
    @Test
    public void f1() {
        System.out.println("hello");
    }

    @Test
    public void f2() throws Exception {
        //注册驱动
        Class.forName("com.mysql.jdbc.Driver");

        //获取连接
        Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/day07", "root", "");

        //编写sql
        String sql = "select * from category";

        //创建语句执行者
        PreparedStatement st = conn.prepareStatement(sql);

        //设置参数

        //执行sql
        ResultSet rs = st.executeQuery();

        //处理结果
        while (rs.next()) {
            System.out.println(rs.getString("cid") + "::" + rs.getString("cname"));
        }

        //释放资源
        rs.close();
        st.close();
        conn.close();
    }

}