Java in Action - Struts分页显示1

    说道Struts自然是不能离开MVC模式,分页显示也是如此.我不知道我的算法是不是算好的,也希望看过的朋友能发表一下自己的看法,下面简单阐述一下主要的开发思路:

1)建立适当的模型组件,对应你要查询数据库中的表,这部分由熟悉的JavaBean来充当.并在其中建立数据库查询方法,该方法需要一个java.sql.Conntection类型的参数,并返回一个ArrayList,在本例中为Book.java,另外还有一个数据库连接的Bean是SqlBean.java.

2)建立分页所需要的模型组件,也是用JavaBean,通过Book提供的ArrayList来构造,这里用的是PageBean.java.

3)建立控制器组件,这部分由Struts的Action来实现,主要负责实例化Book,并利用返回的ArrayList对象,构造PageBean,以及接收由视图传递来的action参数,从而在PageBean对象中调用不同的方法,该方法返回Book[]对象,最后将Book[]和PageBean放入到request中.本Action为PageListAction.java.

4)建立视图组件,这部分JSP来实现,为了不出现JAVA代码,使用Struts提供的标签库,主要负责从Request中取出刚刚放入的对象,通过反复调用Action以及action参数,而实现分页显示,是pagetest.jsp.

5)建立并配置struts-config.xml和web.xml文件.

6)建立数据库.

我对代码进行了实现,调试通过.如果大家有更好的用Struts实现分页显示的算法可以给我留言,代码如下:

struts-config.xml文件如下,这里配置了一个接收haha的请求提交给PageListAction

               type="page.PageListAction"

               scope="request">

……………………………………………………………………………….

Web.xml文件如下,这里配置了Web的信息,基本都是由Eclipse完成的

      action

      org.apache.struts.action.ActionServlet

         application

         ApplicationResources

         config

         /WEB-INF/struts-config.xml

         debug

         2

         detail

         2

      2

      action

      *.do

     index.jsp

…………………………………………………………………………

这个是控制器Action类

package page;

import org.apache.struts.action.*;

import javax.servlet.http.*;

import bean.Book;

import java.util.*;

import javax.sql.DataSource;

public class PageListAction extends Action {

    ArrayList arrayList=new ArrayList();

    PageBean pd;

    public ActionForward execute(ActionMapping mapping,

                                 ActionForm form,

                                 HttpServletRequest request,

                                 HttpServletResponse response)

    throws Exception {

        String action;

        action=request.getParameter("action");

        if(action==null||action.equals("null")) {

            try {

                arrayList=Book.getAllBook();

            }

            catch(Exception e) {

                e.printStackTrace();

            }

            pd=new PageBean(arrayList);

            Book[] books=pd.getBooks();

            request.setAttribute("result",books);

            request.setAttribute("page",pd);

        }

        else {

            if(action=="nextPage"||action.equals("nextPage")) {

                Book[] books=pd.getNextPage();

                request.setAttribute("result",books);

                request.setAttribute("page",pd);

            }

            if(action=="previousPage"||action.equals("previousPage")) {

                Book[] books=pd.getPreviousPage();

                request.setAttribute("resule",books);

                request.setAttribute("page",pd);

            }

        }

        return mapping.findForward("success");

    }

}

………………………………………………………………………………….

这个是pagebean类,主要负责分页算法和逻辑处理

package page;

import bean.Book;

import java.util.*;

public class PageBean {

    int currentPage=1;//当前页数

    public int totalPages=0;//总页数

    int pageRecorders=2;//每页显示数

    int totalRows=0;//总数据数

    int pageStartRow=0;//每页的起始数

    int pageEndRow;//每页的终止数

    boolean hasNextPage=false;//是否有下一页

    boolean hasPreviousPage=false;//是否有前一页

    ArrayList arrayList;

    Iterator it;

    public PageBean(ArrayList arrayList) {

        this.arrayList=arrayList;

        totalRows=arrayList.size();

        it=arrayList.iterator();

        hasPreviousPage=false;

        currentPage=1;

        if((totalRows%pageRecorders)==0) {

            totalPages=totalRows/pageRecorders;

        }

        else {

            totalPages=totalRows/pageRecorders+1;

        }

        if(currentPage>=totalPages) {

            hasNextPage=false;

        }

        else {

            hasNextPage=true;

        }

        if(totalRows

            this.pageStartRow=0;

            this.pageEndRow=totalRows;

        }

        else {

            this.pageStartRow=0;

            this.pageEndRow=pageRecorders;

        }

    }

    public void setCurrentPage(int currentPage) {

        this.currentPage=currentPage;

    }

    public void setPageRecorders(int pageRecorders) {

        this.pageRecorders=pageRecorders;

    }

    public void setHasNextPage(boolean hasNextPage) {

        this.hasNextPage=hasNextPage;

    }

    public void setHasPreviosPage(boolean hasPreviosPage) {

        this.hasPreviousPage=hasPreviousPage;

    }

    public String getCurrentPage() {

        return this.toString(currentPage);

    }

    public String getTotalPages() {

        return this.toString(totalPages);

    }

    public String getTotalRow() {

        return this.toString(totalRows);

    }

    public int getPageRecorders() {

        return pageRecorders;

    }

    public int getPageEndRow() {

        return pageEndRow;

    }

    public int getPageStartRow() {

        return pageStartRow;

    }

    public boolean isHasNextPage() {

        return hasNextPage;

    }

    public boolean isHasPreviousPage() {

        return hasPreviousPage;

    }

    public Book[] getNextPage() {

        currentPage=currentPage+1;

        if((currentPage-1)>0) {

            hasPreviousPage=true;

        }

        else {

            hasPreviousPage=false;

        }

        if(currentPage>=totalPages) {

            hasNextPage=false;

        }

        else {

            hasNextPage=true;

        }

        Book[] books=getBooks();

        return books;

    }

    public Book[] getPreviousPage() {

        currentPage=currentPage-1;

        if(currentPage==0) {

            currentPage=1;

        }

        if(currentPage>=totalPages) {

            hasNextPage=false;

        }

        else {

            hasNextPage=true;

        }

        if((currentPage-1)>0) {

            hasPreviousPage=true;

        }

        else {

            hasPreviousPage=false;

        }

        Book[] books=getBooks();

        return books;

    }

    public Book[] getBooks() {

        if(currentPage*pageRecorders

            pageEndRow=currentPage*pageRecorders;

            pageStartRow=pageEndRow-pageRecorders;

        }

        else {

            pageEndRow=totalRows;

            pageStartRow=pageRecorders*(totalPages-1);

        }

        Book[] books=new Book[pageEndRow-pageStartRow+1];

        int j=0;

        for(int i=pageStartRow;i

            Book book=(Book)arrayList.get(i);

            books[j++]=book;

        }

        return books;

    }

    public String toString(int temp) {

        String str=Integer.toString(temp);

        return str;

    }

}

……………………………………………………………………………….

Book类,负责查询数据库,把结果放到一个ArrayList中

package bean;

import java.sql.*;

import java.util.ArrayList;

public class Book {

    private String bookname;

    private String author;

    private String price;

    public Book(String name,String author,String price) {

        this.bookname=name;

        this.author=author;

        this.price=price;

    }

    public void setBookname(String bookname) {

        this.bookname=bookname;

    }

    public void setAuthor(String Author) {

        this.author=author;

    }

    public void setPrice(String price) {

        this.price=price;

    }

    public String getBookname() {

        return bookname;

    }

    public String getAuthor() {

        return author;

    }

    public String getPrice() {

        return price;

    }

    public static ArrayList getAllBook() throws Exception {

        String sql="select * from book";

        SqlBean sq=new SqlBean();

        ArrayList arrayList=new ArrayList();

        try

        {

            ResultSet resultSet=sq.select(sql);

            while(resultSet.next()) {

                String name=resultSet.getString("name");

                String author=resultSet.getString("author");

                String price=resultSet.getString("price");

                Book book=new Book(name,author,price);

                arrayList.add(book);

            }

            resultSet.close();

        }

        catch(SQLException e)

        {

            System.out.println("数据库错误"+e.toString());

        }

        return arrayList;

    }

}

………………………………………………………………………………..

这个是SqlBook,负责和数据库建立一个连接的Bean

package bean;

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.ResultSet;

import java.sql.Statement;

public class SqlBean {

    String url="jdbc:microsoft:sqlserver://localhost:1433;DatabaseName=eBookStore";

    Connection con=null;

    Statement sta=null;

    public SqlBean() {

        try

        {

            Class.forName("com.microsoft.jdbc.sqlserver.SQLServerDriver");

            con=DriverManager.getConnection(url,"sa","");

            sta=con.createStatement();

        }

        catch(Exception e)

        {

            System.out.println("连接错误"+e.toString());

        }

    }

    public ResultSet select(String selects) throws Exception

    {

        return sta.executeQuery(selects);

    }

}

…………………………………………………………………………

这个是负责显示分页的JSP页.pagetest.jsp

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

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

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

<%@ page contentType="text/html;charset=gb2312"%>

        nextPage

        previousPage

             共分页显示,当前是

                 页.

…………………………………………………………………………………

这个是首页的JSP页面,只有一个连接.提交一个haha.do的请求

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

<%@ page contentType="text/html;charset=gb2312" language="java"%>

    GotoPage