| 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> |
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