package com.util;
import com.pojo.UserInfo;
 
import java.sql.*;
 
public class DBConnection {
 
    private static Connection conn;
 
    private static String userName = "scott";
    private static String passWord = "tiger";
    private static String url;
 
    static {
        url = "jdbc:oracle:thin:@localhost:1521:orcl";
    }
 
    public static Connection getConnection() {
 
        try {
 
            Class.forName("oracle.jdbc.OracleDriver");
            conn = DriverManager.getConnection(url, userName, passWord);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return conn;
    }
 
    //关闭资源的方法
    public static void closeResource(ResultSet rs, PreparedStatement pstmt, Connection conn) {
 
        try {
            if (null != rs) {
                rs.close();
            }
            if (null != pstmt) {
                pstmt.close();
            }
            if (null != conn) {
                conn.close();
            }
 
        } catch (SQLException e) {
            e.printStackTrace();
            System.out.println("关闭资源出现问题--");
        }
 
    }
 
    public static void main(String[] args) {
 
        ResultSet resultSet = null;
        PreparedStatement preparedStatement = null;
        Connection conn;
        DBConnection db = new DBConnection();
        conn = db.getConnection();
        String sql = "select * from userInfo ";
        try {
            preparedStatement = conn.prepareStatement(sql);
            resultSet = preparedStatement.executeQuery();
            while (resultSet.next()){
                UserInfo u = new UserInfo();
                u.setUsername(resultSet.getString("username"));
                System.out.println("用户信息： 用户名为："+ u.getUsername());
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }finally {
            closeResource(resultSet,preparedStatement,conn);
        }
 
    }
}

package com.util;
import com.pojo.UserInfo;
 
import java.sql.*;
 
public class DBConnectionMySql {
 
    private static Connection conn;
 
    private static String userName = "root";
    private static String passWord = "tiger";
    private static String url;
    private static String driver;
    static {
         url = "jdbc:mysql://localhost:3306/wlc";
         driver = "com.mysql.jdbc.Driver";
    }
 
    public static Connection getConnection() {
 
        try {
 
            Class.forName(driver);
            conn = DriverManager.getConnection(url, userName, passWord);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return conn;
    }
 
    //关闭资源的方法
    public static void closeResource(ResultSet rs, PreparedStatement pstmt, Connection conn) {
 
        try {
            if (null != rs) {
                rs.close();
            }
            if (null != pstmt) {
                pstmt.close();
            }
            if (null != conn) {
                conn.close();
            }
 
        } catch (SQLException e) {
            e.printStackTrace();
            System.out.println("关闭资源出现问题--");
        }
 
    }
 
    public static void main(String[] args) {
 
        ResultSet resultSet = null;
        PreparedStatement preparedStatement = null;
        Connection conn;
        DBConnectionMySql db = new DBConnectionMySql();
        conn = db.getConnection();
        String sql = "select * from userInfo ";
        try {
            preparedStatement = conn.prepareStatement(sql);
            resultSet = preparedStatement.executeQuery();
            while (resultSet.next()){
                UserInfo u = new UserInfo();
                u.setUsername(resultSet.getString("username"));
                System.out.println("用户信息： 用户名为："+ u.getUsername());
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }finally {
            closeResource(resultSet,preparedStatement,conn);
        }
 
    }
}