package book.database;
import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Statement;
public class GetMetadata {
    public static void showDatabaseMetadata(Connection con){
        try{
            DatabaseMetaData md=con.getMetaData();
            System.out.println("数据库"+md.getURL()+"的元数据如下：");
            
            }catch (SQLException e){
                e.printStackTrace();
            }
    }
    public static void showTableMetaData(Connection con,String tableName){
        String sql="SELECT * FROM"+tableName;
        Statement sm=null;
        try{
            sm=con.createStatement();
            ResultSet rs= sm.executeQuery(sql);
            
            ResultSetMetaData md = rs.getMetaData();
            
            System.out.println("数据表"+tableName+"的元数据如下：");
            int columnCount = md.getColumnCount();
            System.out.println("column count:"+columnCount);
            System.out.println();
            StringBuffer sb =new StringBuffer("");
            sb.append("sn\tname\t\t").append("type\t\t");
            sb.append("scale\t").append("isNullable");
            System.out.println(sb);
            sb.delete(0, sb.length());
            for(int i=1;i<=columnCount;i++){
                sb.append(i).append("\t");
                sb.append(md.getColumnName(i)).append("\t\t");
                sb.append(md.getColumnTypeName(i)).append("\t\t");
                sb.append(md.getScale(i)).append("\t");
                sb.append(md.isNullable(i));
                System.out.println(sb);
                sb.delete(0,sb.length());
            }
            rs.close();
        }catch(SQLException e){
            e.printStackTrace();
        }finally{
            if (sm!= null){
                try{
                    sm.close();
                }catch(SQLException e1){
                    e1.printStackTrace();
                }
            }
        }
    }
    public static void main(String[] args) throws ClassNotFoundException,SQLException{
        String dbName = "books";
        String tableName = "book";
        String userName = "root";
        String password = "123456";
        Connection con = null;
        try{
            con = DBConnector.getMySQLConnection(null,null,null,dbName,userName,password);
            GetMetadata.showDatabaseMetadata(con);
            System.out.println();
            GetMetadata.showTableMetaData(con,tableName);
        }catch (ClassNotFoundException e1){
            throw e1;
        }catch (SQLException e2){
            throw e2;
        }finally {
            if (con != null){
                try{
                    con.close();
                }catch(SQLException e1){
                    e1.printStackTrace();
                }
            }
        }
    }
}