使用DatabaseMetaDate获取数据库信息

import java.sql.*;
public class GetDBInfo
{
  public GetDBInfo()
  {
  }

  public static void main(String[] args)
  {
  try{
    Class.forName("com.microsoft.jdbc.sqlserver.SQLServerDriver").newInstance();
    String url="dbc:oracle:thin:@localhost:1521:orcl";
    String user="system";
    String pass="******";
    String s;
    Connection con=DriverManager.getConnection(url,user,pass);
        DatabaseMetaData dbmd=con.getMetaData();
    s = dbmd.getDriverName();
    System.out.println("驱动程序的名称是: "+s);
    System.out.println(" ");

    s = dbmd.getDatabaseProductName();
    System.out.println ("数据库名称是："+s);
    System.out.println(" ");

    ResultSet rs = dbmd.getSchemas();
    System.out.println("模式名有：");
    while(rs.next())
      System.out.print("  "+rs.getString(1));
      System.out.println();
      
     s = dbmd.getSQLKeywords();
    System.out.println("SQL中的关键词为: "+s);
    System.out.println(" ");

    int max=dbmd.getMaxColumnNameLength();
    System.out.println ("列名的最大长度可以是："+max);
    System.out.println(" ");

    max = dbmd.getMaxTableNameLength();
    System.out.println ("表名的最大长度可以是："+max);
    System.out.println(" ");

    max = dbmd.getMaxColumnsInSelect();
    System.out.println ("一个select 子句所能返回的最多列数列名的最大长度可是是："+max);
    System.out.println(" ");

    max = dbmd.getMaxTablesInSelect();
    System.out.println ("一个SELECT语句最多可以访问多少个表："+max);
    System.out.println(" ");


    max = dbmd.getMaxColumnsInTable();
    System.out.println ("表中允许的最多列数："+max);
    System.out.println(" ");

    max = dbmd.getMaxConnections();
    System.out.println ("并发访问的用户个数："+max);
    System.out.println(" ");

    max = dbmd.getMaxStatementLength();
    System.out.println ("SQL语句最大允许的长度："+max);
    System.out.println(" ");

    s = dbmd.getNumericFunctions();
    System.out.println("数据库的所有数学函数的列表: "+s);
    System.out.println(" ");

    s = dbmd.getStringFunctions();
    System.out.println("数据库的所有字符串函数的列表: "+s);
    System.out.println(" ");

    s = dbmd.getSystemFunctions();
    System.out.println("数据库的所有系统函数的列表: "+s);
    System.out.println(" ");

    s = dbmd.getTimeDateFunctions();
    System.out.println("数据库的所有日期时间函数的列表: "+s);
    System.out.println(" ");

    rs = dbmd.getTypeInfo();
    while(rs.next())
      {
        System.out.print(" 数据类型名："+rs.getString(1));
        System.out.print("  数据类型："+ rs.getString(2));
        System.out.print("  精度："+   rs.getString(3));
        System.out.println("  基数："+   rs.getString(18));
      }
      System.out.println(" ");

    s = dbmd.getURL();
    System.out.println("此数据库的url: "+s);
    System.out.println(" ");

    s = dbmd.getUserName();
    System.out.println("此数据库的用户: "+s);
    System.out.println(" ");
//好像要注意是大写
    String [ ] t = { "TABLE", "VIEW" };
    rs = dbmd.getTables(null, "HR", "%", t);
    while(rs.next()){
      System.out.print("目录名："+rs.getString(1));
      System.out.print(" 模式名："+rs.getString(2));
      System.out.print(" 表名："+rs.getString(3));
      System.out.print(" 表的类型："+rs.getString(4));
      System.out.println(" 注释："+rs.getString(5));
      }
      System.out.println(" ");

    rs = dbmd.getPrimaryKeys(null, "HR","EMPLOYEES");
    while(rs.next()){
      System.out.print("目录名："+rs.getString(1));
      System.out.print(" 模式名："+rs.getString(2));
      System.out.print(" 表名："+rs.getString(3));
      System.out.print(" 列名顺序号："+rs.getString(4));
      System.out.print(" 列名顺序号："+rs.getString(5));
      System.out.println(" 主键名："+rs.getString(6));
      }
      System.out.println(" ");

     rs = dbmd.getTableTypes();
     System.out.println(" 表的类型有：");
     while(rs.next())
       System.out.print("  "+ rs.getString(1));
       System.out.println();
       System.out.println(" ");

     rs = dbmd.getColumns(null, "HR", "EMPLOYEES", "%");
     System.out.println(" 表名 "+" 列名 "+"  数据类型"+" 本地类型名"+" 列的大小"+ " 小数位数"+" 数据基数"+" 是否可空"+" 索引号");
     while(rs.next()){
      System.out.print(rs.getString(3)+" ");
      System.out.print(rs.getString(4)+" ");
      System.out.print(rs.getString(5)+" ");
      System.out.print(rs.getString(6)+" ");
      System.out.print(rs.getString(7)+" ");
      System.out.print(rs.getString(9)+" ");
      System.out.print(rs.getString(10)+" ");
      System.out.print(rs.getString(11)+" ");
      System.out.println(rs.getString(17)+" ");
      }
      System.out.println(" ");

      rs = dbmd.getIndexInfo(null, "HR", "EMPLOYEES", false, false);

       System.out.println(" 表名"+" 索引名"+" 索引类型"+" 索引列名"+" 索引顺序"+ " 小数位数"+" 数据基数"+" 是否可空"+" 索引号");
      while(rs.next()){
      System.out.print(rs.getString(3)+" ");
      System.out.print(rs.getString(6)+" ");
      System.out.print(rs.getString(7)+" ");
      System.out.print(rs.getString(9)+" ");
      System.out.println(rs.getString(10)+" ");
      }
      System.out.println(" ");
    
    rs.close();
       con.close();
    }
    catch(Exception e){System.out.println(e);}
    new GetDBInfo();
  }
}