用JDBC获得元数据

package jdbc_preparement;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.InputStream;
import java.io.OutputStream;
import java.sql.Blob;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Statement;

public class text_preparestartment {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
      Connection con=simplecon.getConnection();
      String sql="select * from t_user";
     try {
         simple.getGeneral(sql);
        
    } catch (Exception e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

    }

}
//连接数据库
class simplecon
{
    static Connection con;
    static Connection getConnection()
    {   
        try{
            con=DriverManager.getConnection("jdbc:mysql://localhost:3306/test","数据库名","数据库密码");    
        }catch(SQLException e){
            e.printStackTrace();
        }
        return con;
    }
    static void close(AutoCloseable a)
    {
        try {
            a.close();
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}class simple
{
    static void getGeneral(String sql)
    {
        Connection con=simplecon.getConnection();
        try {
            PreparedStatement ps=con.prepareStatement(sql);
            ResultSetMetaData re=ps.getMetaData();  //获得元数据
            int count=re.getColumnCount();          //返回列数
            for(int i=1;i<=count;i++)               //返回列类型
            {
                System.out.print(re.getColumnTypeName(i)+" ");
            }
            System.out.println();
            for(int i=1;i<=count;i++)             //返回列名
            {
                System.out.print(re.getColumnLabel(i)+" ");
            }
            System.out.println();
            
            //执行sql查询
            ResultSet re2=ps.executeQuery();  //返回查询结果
            while(re2.next())
            {
            
                for(int i=1;i<=count;i++)
              {
                System.out.print(re2.getString(i)+" ");
              }
                System.out.println();
            }
            
            simplecon.close(ps);
            simplecon.close(re2);
            
            
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}