DAO设计模式&&struts分页

 今天在网上看了dao设计模式和一个struts分页方法，自己将他们结合起来写了一个程序实例以加深对他们的理解和运用。

程序实例如下：

首先用mysql创建一个person表，sql语句为：

create table person
(
pid int auto_increment,
pname varchar(20),
primary key (pid)
);

insert into person(pname) values('x');
insert into person(pname) values('y');
insert into person(pname) values('z');
insert into person(pname) values('a');
insert into person(pname) values('b');
insert into person(pname) values('c');
insert into person(pname) values('d');
insert into person(pname) values('e');
insert into person(pname) values('f');
insert into person(pname) values('g');
insert into person(pname) values('h');
insert into person(pname) values('k');
insert into person(pname) values('j');
insert into person(pname) values('l');

dao工厂类DAOFactory.java如下：

/Abstract class DAO Factory
public abstract class DAOFactory ...{

  // List of DAO types supported by the factory
  public static final int MYSQL=1;
  //...

  // There will be a method for each DAO that can be 
  // created. The concrete factories will have to 
  // implement these methods.
  public abstract PersonDAO getPersonDAO();
  // ...

  public static DAOFactory getDAOFactory(
      int whichFactory) ...{
  
    switch (whichFactory) ...{
      case MYSQL: 
          return new MysqlDAOFactory();
      //...
      default: 
          return null;
    }
  }
}

MysqlDAOFactory.java代码如下：

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;

public class MysqlDAOFactory extends DAOFactory...{
     private static final String DRIVER=
        "com.mysql.jdbc.Driver";
      private static final String DBURL=
        "jdbc:mysql://localhost/daotest?user=root&password=101213&useUnicode=true&characterEncoding=gb2312";

      // method to create Cloudscape connections
      public static Connection createConnection() ...{
        // Use DRIVER and DBURL to create a connection
        // Recommend connection pool implementation/usage
          Connection conn=null;
          try...{
              Class.forName(DRIVER).newInstance();
              conn= DriverManager.getConnection(DBURL);
          }catch(Exception e)...{
              e.printStackTrace();
          }
          return conn;
      }
      
      public static void closeAll(Connection conn, Statement stmt, ResultSet rs) ...{
            if (rs != null) ...{
                try ...{
                    rs.close();
                } catch (Exception e) ...{
                    System.out.println("close resultset failed." + e.getMessage());
                }
            }
            if (stmt != null) ...{
                try ...{
                    stmt.close();
                } catch (Exception e) ...{
                    System.out.println("close statement failed." + e.getMessage());
                }
            }
            if (conn != null) ...{
                try ...{
                    conn.close();
                } catch (Exception e) ...{
                    System.out.println("close connection failed." +  e.getMessage());
                }
            }
        }
      
      public PersonDAO getPersonDAO() ...{
        // CloudscapeCustomerDAO implements CustomerDAO
        return new MysqlPersonDAO();
      }

}

dao接口PersonDAO.java如下：

import java.util.Collection;

import javax.sql.RowSet;

public interface PersonDAO ...{
      public int insertPerson(String pname);
      public boolean deletePerson(int pid);
      public Person findPerson(int pid);
      public boolean updatePerson(Person p);
      //public RowSet selectCustomersRS();
      public Collection selectCustomersTO(String sql,int startIndex,int recordPerPage);
      //...
    }

执行此接口的MysqlPersonDAO.java如下：

/CloudscapeCustomerDAO implementation of the 
//CustomerDAO interface. This class can contain all
//Cloudscape specific code and SQL statements. 
//The client is thus shielded from knowing 
//these implementation details.

//import java.sql.*;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.Collection;

//import javax.sql.RowSet;

public class MysqlPersonDAO implements 
 PersonDAO ...{
    
    private int totalPerson=0;

   public int getTotalPerson() ...{
        return totalPerson;
    }

    public void setTotalPerson(int totalPerson) ...{
        this.totalPerson = totalPerson;
    }

public MysqlPersonDAO() ...{
 // initialization 
       }

// The following methods can use
// CloudscapeDAOFactory.createConnection() 
// to get a connection as required

public int insertPerson(String pname) ...{
 // Implement insert customer here.
 // Return newly created customer number
 // or a -1 on error
    return 0;
}

public boolean deletePerson(int pid) ...{
 // Implement delete customer here
 // Return true on success, false on failure
    return false;
}

public Person findPerson(int pid) ...{
 // Implement find a customer here using supplied
 // argument values as search criteria
 // Return a Transfer Object if found,
 // return null on error or if not found
    return null;
}

public boolean updatePerson(Person p) ...{
 // implement update record here using data
 // from the customerData Transfer Object
 // Return true on success, false on failure or
 // error
    return false;
}

//public RowSet selectCustomersRS() {
 // implement search customers here using the
 // supplied criteria.
 // Return a RowSet. 
    //return null;
//}

 public Collection selectCustomersTO(String sql,int startIndex,int recordPerPage) ...{
 // implement search customers here using the
 // supplied criteria.
 // Alternatively, implement to return a Collection 
 // of Transfer Objects.
     ArrayList pList=new ArrayList();
     Connection conn=null;
     Statement stmt=null;
     ResultSet rs=null;
     try...{
         conn=MysqlDAOFactory.createConnection();
         stmt=conn.createStatement();
         rs=stmt.executeQuery(sql);
         rs.last();
         totalPerson=rs.getRow();
         rs.absolute(startIndex);//将指针移动到此 ResultSet 对象的给定行编号
         for(int i=0;i<recordPerPage;i++)...{
             Person p=new Person();
             p.setPid(rs.getInt("pid"));
             p.setPname(rs.getString("pname"));
             pList.add(p);
             rs.next();
         }
     }catch(SQLException e)...{
         e.printStackTrace();
     }finally...{
         MysqlDAOFactory.closeAll(conn, stmt, rs);
     }
    return pList;
  }
//...
}

与数据库表对应的Person.java类如下：

public class Person implements java.io.Serializable...{
    private int pid;
    private String pname;
    
    public Person()...{
        
    }
    
    public Person(int pid,String pname)...{
        this.pid=pid;
        this.pname=pname;
    }

    public int getPid() ...{
        return pid;
    }

    public void setPid(int pid) ...{
        this.pid = pid;
    }

    public String getPname() ...{
        return pname;
    }

    public void setPname(String pname) ...{
        this.pname = pname;
    }
    
    

}

分页处理类PageInfo.java如下：

/用于记录分页的记录
import java.io.Serializable;

public class PageInfo implements Serializable ...{

    private int recordCountNumber = 0; // 总记录数

    private int pageCountNumber = 0; // 总页数

    private int recordPerPage = 0; // 每页记录数

    private int currentPage = 0; // 当前页数

    private int previousPageNumber = 0; // 当前页的前一页数

    private int nextPageNumber = 0; // 当前页的后一页数

    public PageInfo() ...{
    }
    
    public int getRecordCountNumber() ...{
        return this.recordCountNumber;
    }

    public int getPageCountNumber() ...{
        if (recordCountNumber == 0)
            return 0;
        if (recordPerPage == 0)
            return 1;
        if (this.recordCountNumber % this.recordPerPage == 0) ...{
            this.pageCountNumber = this.recordCountNumber / this.recordPerPage;
        } else ...{
            this.pageCountNumber = (this.recordCountNumber / this.recordPerPage) + 1;
        }
        return this.pageCountNumber;
    }

    public int getRecordPerPage() ...{
        return this.recordPerPage;
    }
    public void setRecordPerPage(int recordPerPage)...{
        this.recordPerPage=recordPerPage;
    }

    public int getCurrentPage() ...{
        return this.currentPage;
    }

    public int getLastPageNumber() ...{
        return this.pageCountNumber;
    }

    public int getPreviousPageNumber() ...{
        this.previousPageNumber = this.currentPage - 1;
        return this.previousPageNumber;
    }

    public int getNextPageNumber() ...{
        this.nextPageNumber = this.currentPage + 1;
        return this.nextPageNumber;
    }

    public void setCurrentPage(int currentPage) ...{
        this.currentPage = currentPage;
    }

    public void setRecordCountNumber(int recordCountNumber) ...{
        this.recordCountNumber = recordCountNumber;
    }
    
}

getPerson.jsp代码如下：

<%...@ page language="java" pageEncoding="GB18030"%>

<%...@ taglib uri="/WEB-INF/struts-html.tld" prefix="html" %>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html:html>
  <head>
    
    <title>getPerson.jsp</title>

    <meta http-equiv="pragma" content="no-cache">
    <meta http-equiv="cache-control" content="no-cache">

  </head>
  
  <body>
    <form action="getPerson.do?method=showFirst" method="post">
    <html:submit>得到人员信息</html:submit>
    </form>
  </body>
</html:html>

响应jsp的GetPersonAction.java继承DispatchAction，写了五个方法（showFirst，showPrivious，showNext，showLast，showRandom），分别显示第一页，上一页，下一页，最后一页和任意一页，其实只需要showRandom一个方法就可以了，不过它要从jsp页面得到一个参数，即要显示的是第几页。而前四个方法不需要。具体代码如下：

import java.util.Collection;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;
import org.apache.struts.actions.DispatchAction;

import dao.DAOFactory;
import dao.MysqlPersonDAO;
import dao.PageInfo;
import dao.PersonDAO;

/** *//** 
 * MyEclipse Struts
 * Creation date: 07-28-2007
 * 
 * XDoclet definition:
 * @struts.action input="/getPerson.jsp" validate="true"
 */
public class GetPersonAction extends DispatchAction ...{
    /**//*
     * Generated Methods
     */

    
    public ActionForward showFirst(ActionMapping mapping, ActionForm form,
            HttpServletRequest request, HttpServletResponse response) ...{
        // TODO Auto-generated method stub
        DAOFactory mysqlFactory =   
              DAOFactory.getDAOFactory(DAOFactory.MYSQL);
        PersonDAO pDAO = 
              mysqlFactory.getPersonDAO();
        String sql="select * from person";
        HttpSession session=request.getSession();
        PageInfo pInfo=(PageInfo)session.getAttribute("pageinfo");
        if(pInfo==null)...{
        pInfo=new PageInfo();
        pInfo.setRecordPerPage(10);
        }
        Collection pList=pDAO.selectCustomersTO(sql, 1, pInfo.getRecordPerPage());
        pInfo.setRecordCountNumber(((MysqlPersonDAO)pDAO).getTotalPerson());
        pInfo.setCurrentPage(1);
        session.setAttribute("pageinfo", pInfo);
        request.setAttribute("plist", pList);
        
        return mapping.findForward("personInfo");
    }
    
    public ActionForward showPrivious(ActionMapping mapping, ActionForm form,
            HttpServletRequest request, HttpServletResponse response) ...{
        // TODO Auto-generated method stub
        DAOFactory mysqlFactory =   
              DAOFactory.getDAOFactory(DAOFactory.MYSQL);
        PersonDAO pDAO = 
              mysqlFactory.getPersonDAO();
        String sql="select * from person";
        HttpSession session=request.getSession();
        PageInfo pInfo=(PageInfo)session.getAttribute("pageinfo");
        Collection pList=pDAO.selectCustomersTO(sql, (pInfo.getPreviousPageNumber()-1) *
                pInfo.getRecordPerPage()+1, pInfo.getRecordPerPage());
        pInfo.setRecordCountNumber(((MysqlPersonDAO)pDAO).getTotalPerson());
        pInfo.setCurrentPage(pInfo.getPreviousPageNumber());
        session.setAttribute("pageinfo", pInfo);
        request.setAttribute("plist", pList);
        
        return mapping.findForward("personInfo");
    }
    
    public ActionForward showNext(ActionMapping mapping, ActionForm form,
            HttpServletRequest request, HttpServletResponse response) ...{
        // TODO Auto-generated method stub
        DAOFactory mysqlFactory =   
              DAOFactory.getDAOFactory(DAOFactory.MYSQL);
        PersonDAO pDAO = 
              mysqlFactory.getPersonDAO();
        String sql="select * from person";
        HttpSession session=request.getSession();
        PageInfo pInfo=(PageInfo)session.getAttribute("pageinfo");
        Collection pList=pDAO.selectCustomersTO(sql, pInfo.getCurrentPage()*pInfo.getRecordPerPage(), pInfo.getRecordPerPage());
        pInfo.setRecordCountNumber(((MysqlPersonDAO)pDAO).getTotalPerson());
        pInfo.setCurrentPage(pInfo.getNextPageNumber());
        session.setAttribute("pageinfo", pInfo);
        request.setAttribute("plist", pList);
        
        return mapping.findForward("personInfo");
    }
    
    public ActionForward showLast(ActionMapping mapping, ActionForm form,
            HttpServletRequest request, HttpServletResponse response) ...{
        // TODO Auto-generated method stub
        DAOFactory mysqlFactory =   
              DAOFactory.getDAOFactory(DAOFactory.MYSQL);
        PersonDAO pDAO = 
              mysqlFactory.getPersonDAO();
        String sql="select * from person";
        HttpSession session=request.getSession();
        PageInfo pInfo=(PageInfo)session.getAttribute("pageinfo");
        Collection pList=pDAO.selectCustomersTO(sql, (pInfo.getPageCountNumber()-1) *
                pInfo.getRecordPerPage()+1, pInfo.getRecordPerPage());
        pInfo.setRecordCountNumber(((MysqlPersonDAO)pDAO).getTotalPerson());
        pInfo.setCurrentPage(pInfo.getLastPageNumber());
        session.setAttribute("pageinfo", pInfo);
        request.setAttribute("plist", pList);
        
        return mapping.findForward("personInfo");
    }
    
    public ActionForward showRandom(ActionMapping mapping, ActionForm form,
            HttpServletRequest request, HttpServletResponse response) ...{
        // TODO Auto-generated method stub
        DAOFactory mysqlFactory =   
              DAOFactory.getDAOFactory(DAOFactory.MYSQL);
        PersonDAO pDAO = 
              mysqlFactory.getPersonDAO();
        String pageNumber=request.getParameter("pageNumber");
        int page=Integer.parseInt(pageNumber);
        String sql="select * from person";
        HttpSession session=request.getSession();
        PageInfo pInfo=(PageInfo)session.getAttribute("pageinfo");
        Collection pList=pDAO.selectCustomersTO(sql, (page-1) *
                pInfo.getRecordPerPage()+1, pInfo.getRecordPerPage());
        pInfo.setRecordCountNumber(((MysqlPersonDAO)pDAO).getTotalPerson());
        pInfo.setCurrentPage(page);
        session.setAttribute("pageinfo", pInfo);
        request.setAttribute("plist", pList);
        
        return mapping.findForward("personInfo");
    }
    
    
}

显示数据信息页面personInfo.jsp如下：

<%...@ page language="java" pageEncoding="GB18030"%>
<%...@ page import="dao.PageInfo" %>

<%...@ taglib uri="/WEB-INF/struts-bean.tld" prefix="bean" %>
<%...@ taglib uri="/WEB-INF/struts-html.tld" prefix="html" %>
<%...@ taglib uri="/WEB-INF/struts-logic.tld" prefix="logic" %>
<%...@ taglib uri="/WEB-INF/struts-tiles.tld" prefix="tiles" %>

<%...
  PageInfo pinfo=(PageInfo)session.getAttribute("pageinfo");
  int pageCount=pinfo.getPageCountNumber();
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html:html>
  <head>
    
    <title>personInfo.jsp</title>

    <meta http-equiv="pragma" content="no-cache">
    <meta http-equiv="cache-control" content="no-cache">
    <meta http-equiv="expires" content="0">    
    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
    <meta http-equiv="description" content="This is my page">
    <!--
    <link rel="stylesheet" type="text/css" href="styles.css">
    -->
    
    <script type="text/javascript">...
    function pageSelected()...{
    document.form1.pageNumber.selectedIndex=<%=pinfo.getCurrentPage()-1 %>;
    }
    function formSubmit()...{
    document.form1.submit();
    }
    </script>

  </head>
  
  <body onLoad="pageSelected()">
  
    <center>
    <table>
    <caption>人员信息</caption>
    <tr>
    <td>编号</td>
    <td>姓名</td>
    </tr>
    <logic:present name="plist">
    <logic:iterate id="person" name="plist">
    <tr>
    <td>
    <bean:write name="person" property="pid"/>
    </td>
    <td>
    <bean:write name="person" property="pname"/>
    </td>
    </tr>
    </logic:iterate>
    </logic:present>
    </table>
    <table>
    <tr>
    <td>
    共<bean:write name="pageinfo" property="recordCountNumber" scope="session"/>条记录
    </td>
    <td>
    共<bean:write name="pageinfo" property="pageCountNumber" scope="session"/>页
    </td>
    <td>
    当前第<bean:write name="pageinfo" property="currentPage" scope="session"/>页
    </td>
    <td>
    <html:link href="/DAOTest/getPerson.do?method=showFirst"> 首页 </html:link>
    </td>
    <td>
    <logic:equal name="pageinfo" property="currentPage" value="1">
    上一页
    </logic:equal>
    <logic:notEqual name="pageinfo" property="currentPage" value="1">
    <html:link href="/DAOTest/getPerson.do?method=showPrivious">
    上一页
    </html:link>
    </logic:notEqual>
    </td>
    <td>
    <logic:equal name="pageinfo" property="currentPage" value="<%=String.valueOf(pageCount) %>">
    下一页
    </logic:equal>
    <logic:notEqual name="pageinfo" property="currentPage" value="<%=String.valueOf(pageCount) %>">
    <html:link href="/DAOTest/getPerson.do?method=showNext">
    下一页
    </html:link>
    </logic:notEqual>
    </td>
    <td>
    <html:link href="/DAOTest/getPerson.do?method=showLast"> 尾页</html:link>
    </td>
    <td>
    <form action="/DAOTest/getPerson.do?method=showRandom" method="post" name="form1">
    <select name="pageNumber" onChange="formSubmit()">
    <%...
     for(int i=1;i<=pageCount;i++){
     %>
   <option value="<%=i %>">
   --第<%=i %>页--
   </option>
    <%...} %>
    </select>
    </form>
    <td>
    </table>
    </center>
  </body>
</html:html>

struts-config.xml如下：

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE struts-config PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 1.1//EN" "http://jakarta.apache.org/struts/dtds/struts-config_1_1.dtd">

<struts-config>
  <data-sources />
  <form-beans />
  <global-exceptions />
  <global-forwards />
  <action-mappings >
    <action
      input="/getPerson.jsp"
      path="/getPerson"
      parameter="method"
      type="com.iss.struts.action.GetPersonAction">
      <forward name="personInfo" path="/personInfo.jsp" />
    </action>

  </action-mappings>

  <message-resources parameter="com.iss.struts.ApplicationResources" />
</struts-config>