[java]

package util;

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


public class DBHelper {
    
    // 0,导入jar包
    
    // 1,数据库驱动
    private final static String driver = "com.mysql.jdbc.Driver";
    
    // 2,连接数据库的URL地址
    private final static String url ="jdbc:mysql://localhost:3306/Book?useSSL=false&allowPublicKeyRetrieval=true&serverTimezone=UTC";
    private final static String username = "root";
    private final static String password="123";
    
    private static Connection conn = null;
    
    /* 静态代码块加载驱动 */
    static {
        try {
            Class.forName(driver);
        }catch(Exception e){
            e.printStackTrace();
        }
    }
    
    /* 案例模式返回数据库连接对象 */
    public static Connection getConnection() throws SQLException {
        if(conn==null) {
            conn = DriverManager.getConnection(url, username, password);
            return conn;
        }
        return conn;
    }
    
}