mainservlet.java

一个基于MVC模式的经典的分页设计

package com.nicho;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import oracle.jdbc.OracleDriver;

public class MainServlet extends HttpServlet {

	
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		response.setContentType("text/html;charset=GBK");
		
		
		  int shownum=4;
		  int totalpage=0;
		 
		 UseBean ub1=new UseBean();
		
		
	  try{   
		     int totalrow=ub1.getTotalrow();
		  
		 
			     new OracleDriver();
		         String url="jdbc:oracle:thin:@localhost:1521:tombo";
		         String sql="select *  from (select row_.*,rownum rownum_ from(select" +
		        		" * from emp order by empno)row_ where rownum<=?) where rownum_>?";
		       
			     Connection con=DriverManager.getConnection(url, "scott", "tiger");
		 	     PreparedStatement pst=con.prepareStatement(sql);
		 	    
				    if(totalrow%shownum==0){
				    	totalpage=totalrow/shownum;
				    	
				    }else{
				    	
				    	totalpage=totalrow/shownum+1;
				    }
				  
		 	      if(request.getParameter("page")==null){
                      int page=1;
                      int currpage=1;
                      
				     pst.setInt(1, shownum);
					 pst.setInt(2, 0);
					 request.setAttribute("page", page);
			        request.setAttribute("currpage",page);
					 request.setAttribute("total_page", totalpage);
		 	      }
		 	      else {
		 	    	 int page=Integer.parseInt(request.getParameter("page"));
		 	    	 
		 	 	   
					 if(page>totalpage||page<=0){
						 request.getRequestDispatcher("erro.jsp").forward(request, response);
						 
					 }
		 	   	          pst.setInt(1, shownum*page);
				          pst.setInt(2,shownum*(page-1));
				     	    request.setAttribute("page", page);
					        request.setAttribute("currpage",page);
							 request.setAttribute("total_page", totalpage);
		 	    	  
		 	      }
					 
					ResultSet rt=pst.executeQuery();
					List list=new ArrayList();
					while(rt.next()){
						 UseBean ub=new UseBean();
						ub.setEmpno(rt.getString("empno"));
						ub.setEname(rt.getString("ename"));
						ub.setSal(rt.getString("sal"));
						ub.setJob(rt.getString("job"));
						
						list.add(ub);
						
					}
					request.setAttribute("list", list);
					rt.close();
					pst.close();
					con.close();
					 
					 request.getRequestDispatcher("showall.jsp").forward(request, response);
		
		  } catch(Exception e){
			  e.printStackTrace();
			  
		}
		
		
	
		
	}

	
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
             
		   this.doGet(request, response);
	
	}

}