servletconnect.java

J2EE编程实例

import java.net.*;
import java.io.*;
import java.sql.*;
import javax.servlet.*;
import javax.servlet.http.*;

public class ServletConnect extends HttpServlet
  {
   public void service(ServletRequest rq,ServletResponse rp) throws ServletException,IOException
     {
      Connection con = null;    //定义数据库连接对象
      Statement stmt = null;    //定义数据库声明对象
      ResultSet rset = null;    //定义记录结果集对象
      String sSQLCmd = null;    //存放T-SQL语句
      String Recordset1 = null; 
      String Recordset2 = null;
      String Recordset3 = null;
      String ResponseStr = null;
      String ResponseStr_chs = null;
      rp.setContentType("text/html");   //定义反馈信息的输出格式
      ServletOutputStream out = rp.getOutputStream(); //定义输出流对象
      
      sSQLCmd = rq.getParameter("ssqlcmd");

      if (sSQLCmd == null || sSQLCmd.length() < 1)
        {
         /* 如果前天提交的查询命令有错误，则返回error */
         out.print("error");
        }
      else
        {
         /* 开始查询，并将查询结果反馈给前台的Applet */
         try
           {
            /* 利用JDBC-ODBC桥建立数据库连接 */
            DriverManager.registerDriver(new sun.jdbc.odbc.JdbcOdbcDriver());
            con = DriverManager.getConnection("jdbc:odbc:DemoDB","demo","demo");
            stmt = con.createStatement ();
            rset = stmt.executeQuery (sSQLCmd);

            while(rset.next())
              {
               Recordset1 = rset.getString(1); 
               Recordset2 = rset.getString(2);
               Recordset3 = rset.getString(3);
               Recordset1 = (Recordset1 == null) ? "不限" : Recordset1;
               Recordset2 = (Recordset2 == null) ? "不限" : Recordset2;
               Recordset3 = (Recordset3 == null) ? "不限" : Recordset3;
               ResponseStr = Recordset1 + "," + Recordset2 + "," + Recordset3;
               ResponseStr_chs = new String(ResponseStr.getBytes("iso-8859-1"));   //转换中文字符
               System.out.print("<" + ResponseStr + "> ... ");
               out.print(ResponseStr_chs);
               System.out.print("... has been sent.\n");
              }
            rset.close();
            con.close();
           }

         catch(SQLException e)
           {
            System.out.println("!程序在运行是出现例外：" + e.toString());
           }
        }
     }
  }