java 连接数据库

public void connectSQL(){
    try {
       // 加载驱动
       Class.forName("com.mysql.cj.jdbc.Driver");
       // 连接三板斧
       String url = "jdbc:mysql://localhost:3306/test_data";
       String username = "root";
       String password = "123456";
       // 连接数据库对象
       Connection connection = DriverManager.getConnection(url,username,password);
       // 获取执行SQL的对象
       Statement statement = connection.createStatement();
       // 执行对象去执行SQL
       String sql = "select * from sys_user;";
       // 获取结果集并打印
       ResultSet resultSet = statement.executeQuery(sql);
       while (resultSet.next()){
          log.info("---------------------");
          log.info("User_Id = " + resultSet.getString("User_Id"));
          log.info("UserName = " + resultSet.getString("UserName"));
       }
    }catch (Exception e) {
       log.info(e.getMessage());
    }

}




由上可以提取出方法：

    //region 连接数据库
    public static ResultSet connectSQL(String url, String username, String password, String sql){
       try {
          // 加载驱动
          Class.forName("com.mysql.cj.jdbc.Driver");
          // 连接数据库对象
          Connection connection = DriverManager.getConnection(url,username,password);
          // 获取执行SQL的对象
          Statement statement = connection.createStatement();
          // 执行对象去执行SQL
//        String sql = "select * from sys_user;";
          // 获取结果集并打印
          return statement.executeQuery(sql);
       }catch (Exception e) {
          log.info(e.getMessage());
          return null;
       }

    }

    //endregion


使用：

// 连接三板斧
String url = "jdbc:mysql://localhost:3306/test_data";
String username = "root";
String password = "123456";
// 执行对象去执行SQL
String sql = "select * from sys_user;";
// 调用方法
ResultSet resultSet = connectSQL(url, username, password, sql);
if (resultSet != null) {
    try {
       while (resultSet.next()) {
          log.info("---------------------");
          log.info("User_Id = " + resultSet.getString("User_Id"));
          log.info("UserName = " + resultSet.getString("UserName"));
       }
    } catch (Exception e) {
       log.info(e.getMessage());
    }
}

参考：Java连接mysql数据库方法及代码（jdbc）_java连接mysql数据库的代码-CSDN博客