struts 分页显示

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

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE struts-config PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 1.2//EN" "http://struts.apache.org/dtds/struts-config_1_2.dtd">

<struts-config>

<action-mappings>

<action path="/haha"

type="page.PageListAction"

scope="request">

<forward name="success" path="/pagetest.jsp"/>

</action>

</action-mappings>

<message-resources parameter="ApplicationResources" />

</struts-config>

……………………………………………………………………………….

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

<?xml version="1.0" encoding="UTF-8"?>

<web-app xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="2.4" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">

<servlet>

<servlet-name>action</servlet-name>

<servlet-class>org.apache.struts.action.ActionServlet</servlet-class>

<init-param>

<param-name>application</param-name>

<param-value>ApplicationResources</param-value>

</init-param>

<init-param>

<param-name>config</param-name>

<param-value>/WEB-INF/struts-config.xml</param-value>

</init-param>

<init-param>

<param-name>debug</param-name>

<param-value>2</param-value>

</init-param>

<init-param>

<param-name>detail</param-name>

<param-value>2</param-value>

</init-param>

<load-on-startup>2</load-on-startup>

</servlet>

<servlet-mapping>

<servlet-name>action</servlet-name>

<url-pattern>*.do</url-pattern>

</servlet-mapping>

<welcome-file-list>

<welcome-file>index.jsp</welcome-file>

</welcome-file-list>

</web-app>

…………………………………………………………………………

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<pageRecorders) {

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<totalRows) {

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<pageEndRow;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"%>

<html:html locale="true">

<head>

</head>

<body>

<table border="1">

<tr><th>书名</th><th>作者</th><th>价格</th></tr>

<logic:present name="result">

<logic:iterate id="book" name="result" type="bean.Book">

<logic:present name="book">

<tr>

<td><bean:write name="book" property="bookname"/></td>

<td><bean:write name="book" property="author"/></td>

<td><bean:write name="book" property="price"/></td>

</tr>

</logic:present>

</logic:iterate>

</logic:present>

</table>

<logic:present name="page">

<logic:equal name="page" property="hasNextPage" value="true">

<html:link page="/haha.do?action=nextPage">nextPage</html:link>

</logic:equal>

<logic:equal name="page" property="hasPreviousPage" value="true">

<html:link page="/haha.do?action=previousPage">previousPage</html:link>

</logic:equal>

共分<bean:write name="page" property="totalPages"/>页显示,当前是

<bean:write name="page" property="currentPage"/>页.

</logic:present>

</body>

</html:html>

…………………………………………………………………………………

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"%>

<html:html>

<head>

</head>

<body>

<html:link action="haha.do">GotoPage</html:link>

</body>

</html:html>