java获取数据库表名/字段名/注释

package com.nf.lc.sql_meta_data;

import java.sql.*;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;

/**
 * 获得数据库表的元数据
 */
public class Test{

    public static void main(String[] args) throws SQLException, ClassNotFoundException {

        HashMap computer_mall = (HashMap) getAllTableColumn();

        Set tableNames = computer_mall.keySet();
        System.out.println("一共有表：" + tableNames.size() + "张");
        for (String tableName : tableNames) {
            System.out.println("===========================\r\n");
            System.out.println("表名：" + tableName);

            // <字段名,类型>  HashMap 集合
            HashMap columnNames = (HashMap) computer_mall.get(tableName);

            Set columns = columnNames.keySet();

            for (String column : columns) {
                System.out.println("字段名：" + column + " 类型：" + columnNames.get(column));
            }

            System.out.println("===========================\r\n");
        }


    }

    public static Map getAllTableColumn () throws SQLException, ClassNotFoundException {

        String driver = "org.mariadb.jdbc.Driver";
        String url = "jdbc:mariadb://localhost:3306/test";
        String username = "root";
        String password = "root";
        Map tableNameMap = new HashMap<>();


        //加载驱动
        Class.forName(driver);

        //获得数据库连接
        Connection connection = DriverManager.getConnection(url, username, password);
        //获得元数据
        DatabaseMetaData metaData = connection.getMetaData();
        //获得表信息
        ResultSet tables = metaData.getTables(null, null, null, new String[]{"TABLE"});

        while (tables.next()) {
            Map columnNameMap = new HashMap<>(); //保存字段名

            //获得表名
            String table_name = tables.getString("TABLE_NAME");
            //通过表名获得所有字段名
            ResultSet columns = metaData.getColumns(null, null, table_name, "%");
            //获得所有字段名
            while (columns.next()) {
                //获得字段名
                String column_name = columns.getString("COLUMN_NAME");
                //获得字段类型
                String type_name = columns.getString("TYPE_NAME");
//获得字段注释   注意： 对于此列，SQL Server 始终会返回 Null。
                String remarks = columns.getString("REMARKS");
//   https://docs.microsoft.com/zh-cn/sql/connect/jdbc/reference/getcolumns-method-sqlserverdatabasemetadata?view=sql-server-2017
//                System.out.println(table_name+":"+column_name+":"+remarks);

                columnNameMap.put(column_name, type_name);
            }

            tableNameMap.put(table_name, columnNameMap);

        }

        return tableNameMap;
    }


}