JDBC系列教程之十二：DatabaseMetaData(数据库的元数据信息)和ParameterMetaData(参数的元数据信息)

DBMD.java

package com.hyneng.jdbc;

import java.sql.DatabaseMetaData;

import java.sql.SQLException;

/**

* 2010-10-08

* @author HuangYineng

*/

public class DBMD {

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

      java.sql.Connection conn = JdbcUtils.getConnection();

      DatabaseMetaData dbmd =  conn.getMetaData();

      System.out.println("db name: " +  dbmd.getDatabaseProductName());

      System.out.println("tx: " + dbmd.supportsTransactions());

      conn.close();

   }

}

ParameterMetaTest.java

package com.hyneng.jdbc;

import java.sql.Connection;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.SQLException;

/**

* 2010-10-08

* @author HuangYineng

*/

public class ParameterMetaTest {

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

      Object[] params = new Object[] { "hyneng",75f };

      read("select * from user where name=? and  money > ?", params);

   }

   static void read(String sql, Object[]  params) throws SQLException {

      Connection conn = null;

      PreparedStatement ps = null;

      ResultSet rs = null;

      try {

          conn = JdbcUtils.getConnection();

          ps = conn.prepareStatement(sql);

//         ParameterMetaData pmd =  ps.getParameterMetaData();

//         int count = pmd.getParameterCount();

          for (int i = 1; i <= params.length; i++) {

          // System.out.print(pmd.getParameterClassName(i) + "\t");

          // System.out.print(pmd.getParameterType(i) + "\t");

          // System.out.println(pmd.getParameterTypeName(i));

             ps.setObject(i, params[i - 1]);

          }

          rs = ps.executeQuery();

          while (rs.next()) {

             System.out.println(rs.getInt("id") + "\t"

                 + rs.getString("name") + "\t" + rs.getDate("birthday")

                 + "\t" + rs.getFloat("money"));

          }

      } finally {

          JdbcUtils.free(rs, ps,  conn);

      }

   }

}