[原创]彻底解决Struts分页显示

彻底解决Struts分页显示

作者：李敏强  eMail: [e-mail]

学习Struts已经有2个多月了，前几天群里的朋友问我Struts分页显示的问题，觉得好像与在jsp中的差不多，但还是遇到了这样那样的问题，好不容易花了几天时间把问题都搞清楚，觉得还是写点东西跟大家分享一下的好！

至于Struts的语法这里就不多介绍了，不懂的朋友可以先看网上的其他文章。

 

一 开发环境

Elicpse+Struts Studio+SqlServer2000+Tomcat。

 

二 开发思路

既然讲的是Struts，那自然离不了MVC，分页显示也是如此。

1 建立适当的模型组件，对应你要查询数据库中的表。这部分由我们熟悉的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

2 建立分页所需要的模型组件，也是由javaBean来充当，通过由Book中提供的ArrayList来构造。本例中为 PageBean.java.。

3建立控制器组件，这部分由Struts 中的Action来实现。主要负责将实例化Book，并利用返回的ArrayList对象，构造PageBean。以及接收由视图传递而来的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request中。本例中为PageListAction.java。

4建立视图组件，这部分由jsp来充当，为了不出现java 代码，我们使用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PageListAction以及action参数，而实现分页显示。本例中为pagetest.jsp.

5 建立并配置struts-config.xml。

6 建立数据库。

 

三 实例代码

1 Book.java

 

package bean;

import java.sql.*;

import java.util.ArrayList;

/**

 * @作者 李敏强

 * Struts分页显示数据Bean，对应数据库中Book表

 */

public class Book {

       private String bookname; //书名

       private String author;   //作者

       private String price;    //价格

      

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

       this.bookname=name;

       this.author=author;

       this.price=price;

}

 

       public String getAuthor() {

              return author;

       }

 

       public void setAuthor(String author) {

              this.author = author;

       }

 

       public String getBookname() {

              return bookname;

       }

 

       public void setBookname(String bookname) {

              this.bookname = bookname;

       }

      

       public String getPrice(){

           return this.price;    

       }

      

       public void setPrice(String price){

           this.price=price;    

       }

      

       public static ArrayList getAllBook(Connection connection){

               String sql="select * from book";

               ArrayList arrayList = new ArrayList();

               try{

               Statement statement = connection.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,ResultSet.CONCUR_READ_ONLY);

               ResultSet resultSet = statement.executeQuery(sql);         

         System.out.println("BookBean 数据查询已完成！");

                  while(resultSet.next())

                  {           

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

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

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

                    System.out.println("开始数据封装：name="+name+"author="+author+"price="+price);

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

                    arrayList.add(book);

                  }

                      connection.close();

                      resultSet.close();

               }catch(SQLException e)

               {

                    System.out.println("数据库异常"+e.toString());

               }

 

                  return arrayList;

       }

}

 

2 PageBean.java

package page;

import bean.Book;

import java.util.*;

/**

 * @作者 李敏强

 * Struts分页显示逻辑Bean

 */

public class PageBean {

 

       int currentPage=1;  //当前页

public      int totalPages=0;  //总页数

       int pageRecorders=5;//每页5条数据

       int totalRows=0;  //总数据数

       int pageStartRow=0;//每页的起始数

       int pageEndRow=0;  //每页显示数据的终止数

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

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

       ArrayList arrayList;

       Iterator it;

public PageBean(){}

      

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;  

    }

 

}

 

       /**

        * @return Returns the currentPage.

        */

       public String getCurrentPage() {

              return this.toString(currentPage);

       }

       /**

        * @param currentPage The currentPage to set.

        */

       public void setCurrentPage(int currentPage) {

              this.currentPage = currentPage;

       }

       /**

        * @return Returns the pageRecorders.

        */

       public int getPageRecorders() {

              return pageRecorders;

       }

       /**

        * @param pageRecorders The pageRecorders to set.

        */

       public void setPageRecorders(int pageRecorders) {

              this.pageRecorders = pageRecorders;

       }

       /**

        * @return Returns the pageEndRow.

        */

       public int getPageEndRow() {

              return pageEndRow;

       }

       /**

        * @return Returns the pageStartRow.

        */

       public int getPageStartRow() {

              return pageStartRow;

       }

       /**

        * @return Returns the totalPages.

        */

       public String getTotalPages() {

      

              return this.toString(totalPages);

       }

       /**

        * @return Returns the totalRows.

        */

       public String getTotalRows() {

              return this.toString(totalRows);

       }

       /**

        * @return Returns the hasNextPage.

        */

       public boolean isHasNextPage() {

              return hasNextPage;

       }

       /**

        * @param hasNextPage The hasNextPage to set.

        */

       public void setHasNextPage(boolean hasNextPage) {

              this.hasNextPage = hasNextPage;

       }

       /**

        * @return Returns the hasPreviousPage.

        */

       public boolean isHasPreviousPage() {

              return hasPreviousPage;

       }

       /**

        * @param hasPreviousPage The hasPreviousPage to set.

        */

       public void setHasPreviousPage(boolean hasPreviousPage) {

              this.hasPreviousPage = hasPreviousPage;

       }

public Book[] getNextPage(){

      

       currentPage=currentPage+1;

       System.out.println("PageBean.getNextPage()正在执行；");

       System.out.println("参数currentPage="+currentPage);

 

       if((currentPage-1)>0)

       {

              hasPreviousPage=true;  

       }

    else

    {

           hasPreviousPage=false; 

    }

      

       if(currentPage>=totalPages)

       {

              hasNextPage=false;      

       }

       else

       {

              hasNextPage=true;

       }

       System.out.println("参数hasNextPage="+hasNextPage);

       System.out.println("准备执行PageBean.getBooks()");

       Book[] books=getBooks();

       this.description();

      

       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();

       this.description();

       return books;

}

 

public Book[] getBooks(){

       System.out.println("pageBean.getBooks（）开始执行；");

      

      

       if(currentPage*pageRecorders判断是否为最后一页

              pageEndRow=currentPage*pageRecorders;

           pageStartRow=pageEndRow-pageRecorders;

       }

       else{

              pageEndRow=totalRows;

              pageStartRow=pageRecorders*(totalPages-1);

       }

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

      

       System.out.println("pageStartRow="+pageStartRow);

       System.out.println("pageEndRow="+pageEndRow);

        int j=0; 

       for(int i=pageStartRow;i

       {

      

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

        books[j++]=book;

      

       }

       System.out.println("要显示的页面数据已经封装,具体信息如下：");

       this.description();

       return books;

}

 

public String toString(int temp)

{

String str=Integer.toString(temp);

return str;

}

 

public void description()

{

 

   String description="共有数据数:"+this.getTotalRows()+

 

   "共有页数: "+this.getTotalPages() +

 

   "当前页数为:"+this.getCurrentPage()+

  

   " 是否有前一页: "+this.isHasPreviousPage() +

 

   " 是否有下一页:"+this.isHasNextPage()+

 

   " 开始行数:"+this.getPageStartRow()+

 

   " 终止行数:"+this.getPageEndRow();

 

   System.out.println(description);

 

}

}

 

3  PageListAction.java

package page;

import org.apache.struts.action.*;

import javax.servlet.http.*;

import comm.Constants;

 

import bean.Book;

import java.util.*;

import javax.sql.DataSource;

/**

 * @author 李敏强

 * Struts分页显示Action

 */

public class PageListAction extends Action {

 

       public PageListAction(){}

       ArrayList arrayList=new ArrayList();

    PageBean pb;

      

       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")){ //第一次读取数据

             try{

                    DataSource datasource=this.getDataSource(request,Constants.DATASOURCE_KEY);                

                    arrayList=Book.getAllBook(datasource.getConnection());

                    System.out.println("第一步，数据已经成功传递到Action，action="+action);

               }catch(Exception e){

                      e.printStackTrace();

                          System.out.println("数据库连接出现异常");

                      }

            

               pb=new PageBean(arrayList);

          Book[] books=pb.getBooks();

          pb.description();

          request.setAttribute("result",books);

          request.setAttribute("page",pb);

 

                  

             }

             else

             {

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

                    {

                           System.out.println("参数action="+action);

                           System.out.println("函数pb.getNextPage()准备执行");

                           Book[]books=pb.getNextPage();

                           request.setAttribute("page",pb);

                           request.setAttribute("result",books);

 

            

                    }

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

                    {

                           System.out.println("参数action="+action);

                           System.out.println("函数pb.getPreviouspage()准备执行");

                           Book[] books=pb.getPreviouspage();  

                           request.setAttribute("page",pb);

                        request.setAttribute("result",books);

 

                   

                    }

             }

              return (mapping.findForward("success"));

        }   

}

 

4 pagetest.jsp

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

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

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

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

<%@ taglib uri="/WEB-INF/struts-logic.tld" prefix="logic" %>
<%@ taglib uri="/WEB-INF/struts-bean.tld" prefix="bean" %>
<%@ taglib uri="/WEB-INF/struts-html.tld" prefix="html" %>
<%@ page contentType="text/html; charset=gb2312" language="java"%>

<html:html locale="true">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
</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:equal name="page" property="hasNextPage" value="true">
<html:link page="/page.do?action=nextPage">nextPage</html:link>
</logic:equal>
<logic:equal name="page" property="hasPreviousPage" value="true">
<html:link page="/page.do?action=previousPage">PreviousPage</html:link>
</logic:equal>

共有数据总数<bean:write name="page" property="totalRows"/>;
共分<bean:write name="page" property="totalPages"/>页,当前是第
<bean:write name="page" property="currentPage"/>页

</body>
</html:html>

 

5 struts-config.xml

<?xml version="1.0" encoding="ISO-8859-1" ?>

<!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>
  <data-source key="dataSource" type="org.apache.commons.dbcp.BasicDataSource">
   <set-property property="driverClassName" value="com.microsoft.jdbc.sqlserver.SQLServerDriver"/>
   <set-property property="url" value="jdbc:microsoft:sqlserver://127.0.0.1:1433;DatabaseName=eBookStore;SelectMethod=cursor"/>
   <set-property property="username" value="limq"/>
   <set-property property="password" value="1"/>
   <set-property property="maxActive" value="10"/>
   <set-property property="maxWait" value="5000"/>
   <set-property property="defaultAutoCommit" value="true"/>
   <set-property property="defaultReadOnly" value="false"/>
  </data-source>
 </data-sources>
  <form-beans>
  </form-beans>
  <global-forwards>
  </global-forwards>
  <action-mappings>
  <action path="/page" type="page.PageListAction" scope="request">
  <forward name="success" path="/pagetest.jsp"/>
  </action>
  </action-mappings>
  <controller>
  </controller>
</struts-config>

6 建立eBookStore数据库，以及表book（name,author,parce）;其中数据的配置可以根据你的不同情况在struts-config.xml中而定。

 

7 Constants.java

 

package comm;

 

/**

 * this interface provides the constant string for applicator constant

 */

public class Constants {

        /**

          * name of the User Object in HttpSession

          */

         public static String USER_KEY="user";

         /**

          * dataSource name

          */

         public static String DATASOURCE_KEY="dataSource";

}

 

好了，全部代码我已经贴完了，难免有不妥的地方，如果您有好的意见或者建议请跟我联系，在下将感激不尽！！ [e-mail]