query2.java

来自「java web 开发,Java Xml 编程指南书籍源码」· Java 代码 · 共 55 行

// servlet Query2 as second 3tier example

import javax.servlet.*;  // communicate with client
import javax.servlet.http.*; 
import java.util.Enumeration;   // 

import MyNa.utils.Logger;  // saves admin/debug info to file
import MyNa.utils.Env;   // basic package
import MyNa.utils.DBHandler;   // communicate with database
import java.sql.SQLException;   // thrown by LookerUpper
import MyNa.utils.HtmlWrapper; // sends HTML to client.
import java.io.IOException; // thrown by HtmlWrapper


public class Query2 extends HttpServlet { 

  Logger lg=null; 
  DBHandler dbH=null; String iniFile = "MyNa/EnvIni/Query2";

  public void init(ServletConfig cfg) throws ServletException{
    super.init(cfg);
     try{
      lg=new Logger(); lg.clearLog(); lg.logIt("Query2.init()");
      Env dbEnv=new Env(iniFile+".ini");
      dbH=new DBHandler(dbEnv);
    }catch(Exception ex){ex.printStackTrace(); lg.logIt("Query2",ex);}
  }

  public void destroy() { //  try to close up.
   lg.logIt("Query2.destroy()");
   try{if(dbH!=null) dbH.close();}
   catch(SQLException ex){
    lg.logIt("Query2 close",ex);
    }
  }

  public void doGet (HttpServletRequest req, 
                     HttpServletResponse res)
          throws ServletException, IOException{
   HtmlWrapper W=new HtmlWrapper(res.getWriter());
   try{
     res.setContentType("text/html");
     Env queryData=new Env(req);
     Env result=dbH.getQueryResult(queryData);
     W.wrapEnvResultPage(result);
     }catch(Exception ex){
      lg.logIt("doGet: ",ex);
      W.wrapPage("doGet failure",""+ex); return;}
  }


}