一 開發環境

Elicpse+Struts Studio+SqlServer2000+Tomcat。

二 開發思路

既然講的是Struts，那自然離不了MVC，分頁顯示也是如此。

1 建立適當的模型組件，對應你要查詢數據庫中的表。這部分由我們熟悉的javaBean來充當。并在其中建立數據庫查詢方法，該方法需要一個java.sql.Conntection類型的參數，并返回一個ArrayList。在本例中為 Book.java

2 建立分頁所需要的模型組件，也是由javaBean來充當，通過由Book中提供的ArrayList來構造。本例中為 PageBean.java.。

3建立控制器組件，這部分由Struts 中的Action來實現。主要負責將實例化Book，并利用返回的ArrayList對象，構造PageBean。以及接收由視圖傳遞而來的action參數。從而在PageBean對象中調用不同的方法，該方法返回Book[] 對象。最后將 Book[]和PageBean放入request中。本例中為PageListAction.java。

4建立視圖組件，這部分由jsp來充當，為了不出現java 代碼，我們使用Struts提供的標簽庫，主要負責從request中取出剛剛放入的對象，通過反復調用PageListAction以及action參數，而實現分頁顯示。本例中為pagetest.jsp.

5 建立并配置struts-config.xml。

6 建立數據庫。

三 實例代碼

1 Book.java

package bean;
import java.sql.*;
import java.util.ArrayList;
/**
 * @作者 李敏強
 * Struts分頁顯示數據Bean，對應數據庫中Book表
 */
public class Book {
 private String bookname; //書名
 private String author;   //作者
 private String price;    //價格
 
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 數據查詢已完成！");
      while(resultSet.next())
      { 
        String name = resultSet.getString("name");
        String author = resultSet.getString("author");
        String price = resultSet.getString("price");
        System.out.println("開始數據封裝：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("數據庫異常"+e.toString());
   }

      return arrayList;
 }
}

2 PageBean.java

package page;
import bean.Book;
import java.util.*;
/**
 * @作者 李敏強
 * Struts分頁顯示邏輯Bean
 */
public class PageBean {

 int currentPage=1;  //當前頁
public int totalPages=0;  //總頁數
 int pageRecorders=5;//每頁5條數據
 int totalRows=0;  //總數據數
 int pageStartRow=0;//每頁的起始數
 int pageEndRow=0;  //每頁顯示數據的終止數
 boolean hasNextPage=false; //是否有下一頁
 boolean hasPreviousPage=false; //是否有前一頁
 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<pageRecorders)
    {
    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()正在執行；");
 System.out.println("參數currentPage="+currentPage);

 if((currentPage-1)>0)
 {
  hasPreviousPage=true;
 }
    else
    {
     hasPreviousPage=false;
    }
 
 if(currentPage>=totalPages)
 {
  hasNextPage=false;
 }
 else
 {
  hasNextPage=true;
 }
 System.out.println("參數hasNextPage="+hasNextPage);
 System.out.println("準備執行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（）開始執行；");
 
 
 if(currentPage*pageRecorders<totalRows){//判斷是否為最后一頁
  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<pageEndRow;i++)
 {
 
  Book book=(Book)arrayList.get(i);
  books[j++]=book;
 
 }
 System.out.println("要顯示的頁面數據已經封裝,具體信息如下：");
 this.description();
 return books;
}

public String toString(int temp)
{
String str=Integer.toString(temp);
return str;
}

public void description()
{

   String description="共有數據數:"+this.getTotalRows()+

   "共有頁數: "+this.getTotalPages() +

   "當前頁數為:"+this.getCurrentPage()+
  
   " 是否有前一頁: "+this.isHasPreviousPage() +

   " 是否有下一頁:"+this.isHasNextPage()+

   " 開始行數:"+this.getPageStartRow()+

   " 終止行數:"+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 李敏強
 * Struts分頁顯示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")){ //第一次讀取數據
try{
DataSource datasource=this.getDataSource(request,Constants.DATASOURCE_KEY);   
arrayList=Book.getAllBook(datasource.getConnection());
System.out.println("第一步，數據已經成功傳遞到Action，action="+action);
   }catch(Exception e){
          e.printStackTrace();
  System.out.println("數據庫連接出現異常");
      }
  
     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("參數action="+action);
  System.out.println("函數pb.getNextPage()準備執行");
  Book[]books=pb.getNextPage();
  request.setAttribute("page",pb);
 request.setAttribute("result",books);  
    }
if(action=="previousPage" || action.equals("previousPage"))
  {
  System.out.println("參數action="+action);
  System.out.println("函數pb.getPreviouspage()準備執行");
  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"%>

<html:html locale="true">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
</head>
<body>

<table border="1">
<tr><th>書名</th><th>作者</th><th>價格</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>
共有數據總數<bean:write name="page" property="totalRows"/>;
共分<bean:write name="page" property="totalPages"/>頁,當前是第
<bean:write name="page" property="currentPage"/>頁
</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數據庫，以及表book（name,author,parce）;其中數據的配置可以根據你的不同情況在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";
}