在JDBC中利用工具类来进行更新和查询

package com.haoran.lesson2.utils;

import java.io.IOException;
import java.io.InputStream;
import java.sql.*;
import java.util.Properties;

//在该处写调用db.properties中关于连接目的数据库的基本信息
//在jdbcUtils类中进行配置文件的高内聚
public class jdbcUtils {
    private  static String driver = null;
    private  static String url = null;
    private  static String username = null;
    private  static String password = null;
    static {
        try{
            InputStream resourceAsStream = jdbcUtils.class.getClassLoader().getResourceAsStream("db.properties");
            //读取配置文件
            Properties properties = new Properties();
            properties.load(resourceAsStream);//下载资源
            driver=properties.getProperty("driver");
            url=properties.getProperty("url");
            username=properties.getProperty("username");
            password=properties.getProperty("password");

            //然后开始1,加载驱动
            Class.forName(driver);

        } catch (IOException | ClassNotFoundException e) {
            e.printStackTrace();
        }
    }


    //新建一个getConnection的方法类来实现 获取连接Connection 的功能
    public static Connection getConnection() throws SQLException {
        return DriverManager.getConnection(url,username,password);
    }



    //新建一个release的方法类来实现 释放连接资源 的功能
    public static void release(Connection conn, Statement st, ResultSet rs){
        if (rs!=null) {
            try {
                rs.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if (st!=null){
            try {
                st.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if (conn!=null){
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }

    }

}

更新：

package com.haoran.lesson2;

import com.haoran.lesson2.utils.jdbcUtils;

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

public class test {
    public static void main(String[] args) {
        Connection conn = null;
        Statement st = null;
        ResultSet rs = null;

        try {
            conn=jdbcUtils.getConnection();//直接用工具类进行数据库连接
            st=conn.createStatement();//利用数据库连接conn获得SQL的执行对象st
            String sql="INSERT INTO `users`(id,`NAME`,`PASSWORD`,`email`,`birthday`)" +
                    "VALUE (4,'xiaozhang','1234','123123123@qq.com','1902-02-08')";
            //每次对数据库进行更新操作，只是该语句发生变化即可；
            int i = st.executeUpdate(sql);
            if (i>0){
                System.out.println("插入成功");
            }
            //当上述SQL语句为select查询语句时，st.executeQuery;
            // String sql="select * from users where id = 1";
//            rs =st.executeQuery(sql);
//            while(rs.next()){
//                System.out.println(rs.getString("NAME"));
//            }
        } catch (SQLException e) {
            e.printStackTrace();
        }finally {
            jdbcUtils.release(conn,st,rs);
        }
    }
}

查询：

package com.haoran.lesson2;

import com.haoran.lesson2.utils.jdbcUtils;

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

public class testSelect {
    public static void main(String[] args) {
        Connection conn = null;
        Statement st = null;
        ResultSet rs = null;

        try {
            conn= jdbcUtils.getConnection();//直接用工具类进行数据库连接
            st=conn.createStatement();//利用数据库连接conn获得SQL的执行对象st
            String sql="select * from users where id = 1";
            rs =st.executeQuery(sql);
            while(rs.next()){
                System.out.print(rs.getString("Name"));
            }
        } catch (
                SQLException e) {
            e.printStackTrace();
        }finally {
            jdbcUtils.release(conn,st,rs);
        }
    }
}