连接数据库：注意if() 和while()的区别

package test;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import org.testng.annotations.Test;

public class NewTestTest
{
@Test
  public void f() throws SQLException, ClassNotFoundException
  {  

 String driverName="com.microsoft.sqlserver.jdbc.SQLServerDriver"; 
 String url="jdbc:sqlserver://10.181.57.36:1433;DatabaseName=CAXO_V34_TEST";
 String username = "caxo_v34_test" ;   
 String password = "caxo_v34_test" ;               
 try
 {
  Class.forName(driverName).newInstance();
 }
 catch (InstantiationException e)
 {
  e.printStackTrace();
 } catch (IllegalAccessException e)
 {
  e.printStackTrace();
 }
 Connection con = DriverManager.getConnection(url,username,password);
 Statement stmt=con.createStatement();
 ResultSet rs= stmt.executeQuery("select * from PROD_USERMASTER t where t.USER_CP_ID= 'publish' and t.USER_NAME_CN like '%吴小%'");
 while(rs.next())
  {//rs.next();
   System.out.println(rs.getRow());
   System.out.println(rs.getString("USER_NAME_CN"));
  }      
         
  if(rs.next())
  {   
      String name = rs.getString("USER_NAME_CN") ;   
      System.out.println(rs.getString(1)+"/**/"+name); // 此方法比较高效   
  }
   
  if(rs != null)
  {   // 关闭记录集   
      try{   
              rs.close() ;   
          }
      catch(SQLException e)
          {   
              e.printStackTrace() ;   
          }   
  }   
  if(stmt != null)
  {   // 关闭声明   
      try
      {   
          stmt.close() ;   
      }
      catch(SQLException e)
      {   
         e.printStackTrace() ;   
      }   
  }   
  if(con != null)
  {  // 关闭连接对象   
     try
     {   
        con.close() ;   
     }
     catch(SQLException e)
     {   
        e.printStackTrace() ;   
     }   
  }      
  }
}