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blog名称:四裤全输的小窝～～
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 [Struts][转]解决Struts分页显示
文章收藏, 网上资源, 软件技术, 电脑与网络 四裤全输 发表于 2006/10/23 13:24:00
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转自：http://www.micromms.com/?do=fetchByDate&dYear=2006&dMonth=10&dDay=9一 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.javapackage 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<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<totalRows){//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<pageEndRow;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.javapackage 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"%>
<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";}
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