struts2 分页

public List getList(int pageSize, int pageNow) {
//获取分页数据List list = * ;//我用的sqlserverString sql = "select top 10 * from testwhere username like '%badpeas%' and id not in (select top 0 id from test order by id)order by id";return list;}
public int getCount() {
//我用的sqlserverString sql = "select count(*) from region where username like '%badpeas%'";//得到总数据条数int count = *;return count;}
================================Test类(封装数据)
public class Test(){private int id;private String username;private password;//省略seter, geter方法.}
================================show.jsp
  NO姓名密码.   
      上一页 上一页下一页 下一页[page: /]
 
================================ShowAction.java
private int pageNow = 1 ; //初始化为1,默认从第一页开始显示 private int pageSize = 5 ; //每页显示5条记录 private int count; //总页数private List testList;
//省略seter, geter
public String execute() throws Exception {count = (dao.getCount()-1)/pageSize+1; //得到总页数testList = dao.getList(pageSize, pageNow); //得到listif (testList == null)testList = new ArrayList();return SUCCESS;}

   在开发web程序时，从数据库中取出来的数据一般都要分页显示在页面上，分页显示的方法非常多，有人写自定义标签，用自己写的标签进行分页显示，我个人觉得这是一种比较好的方法。下面是我用Struts2做的一个分页显示实例，基本的思路是：把数据库表中的每一行数据封装成一个对象，用一个返回类型为List的方法返回这些对象，接着在Struts2的action里面定义一个List属性，用这个List来接收从数据库中查询出来并进行了封装的那些对象，然后通过Struts2的标签遍历List里的每个对象，并把这些对象里所包含的属性取出来展现在页面上。下面是具体的步骤：

所用工具：JDK1.6 + MyEclipse6.0 + Tomcat6.0 + MySQL5.0 + struts 2.0.11

1、新建一个web工程,导入struts2中相应的jar包和mysql数据驱动包。

2、编写web.xml文件，其代码如下：

 

<?xml version="1.0" encoding="UTF-8"?><web-app version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"><filter><filter-name>struts2</filter-name><filter-class>org.apache.struts2.dispatcher.FilterDispatcher</filter-class></filter><filter-mapping><filter-name>struts2</filter-name><url-pattern>/*</url-pattern></filter-mapping><welcome-file-list><welcome-file>index.jsp</welcome-file></welcome-file-list></web-app>                  

3、建一个数据库表，用于保存学员信息：

drop database if exists page;create database page ;use page;create table student (   stu_id integer auto_increment,   stuName varchar(255) not null,   address varchar(255) not null,   stuPhone varchar(255)not null,   primary key(stu_id));insert into student(stuName,address,stuPhone) values('杨华林','长沙','13787825190');insert into student(stuName,address,stuPhone) values('李明清','天津','13787525190');insert into student(stuName,address,stuPhone) values('李小华','大连','13788451190');insert into student(stuName,address,stuPhone) values('郑小明','苏州','13787052188');insert into student(stuName,address,stuPhone) values('杨一新','西安','13787851190');insert into student(stuName,address,stuPhone) values('王新任','广州','13787056460');insert into student(stuName,address,stuPhone) values('谢小华','深圳','13787075550');insert into student(stuName,address,stuPhone) values('王建明','厦门','13788853690');insert into student(stuName,address,stuPhone) values('秦一生','北京','13788689236');insert into student(stuName,address,stuPhone) values('田翠林','杭州','13787655150');insert into student(stuName,address,stuPhone) values('陈小明','广州','13787623668');

4、编写PageDAO类，该类用于从数据库中取出所有的学员信息，把这些学员信息封装成一个Student对象并将
   其放入List中。

package org.hnylj.util;import java.sql.Connection;import java.sql.DriverManager;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;import java.util.ArrayList;import java.util.List;public class PageDAO {private Connection conn ;private PreparedStatement pstmt ;private ResultSet rs ;private static final String DRIVER = "com.mysql.jdbc.Driver" ;private static final String URL = "jdbc:mysql://localhost:3306/page" ;private static final String USERNAME = "root" ;private static final String PASSWORD = "123" ;private Student student ;//数据库连接public synchronized Connection getConnection () {try {Class.forName (DRIVER) ;conn = DriverManager.getConnection (URL,USERNAME,PASSWORD) ;} catch (ClassNotFoundException e) {e.printStackTrace () ;return null ;} catch (SQLException e) {e.printStackTrace () ;return null ;} return conn ;}    //分页查询  public List<Student> queryByPage (int pageSize, int pageNow) {  List<Student> list = new ArrayList<Student> () ;  try {    if (this.getConnection()!=null && pageSize>0 && pageNow>0) {    pstmt = this.getConnection().prepareStatement(      "select * from student order by stu_id limit "+(pageNow*pageSize-pageSize)+","+pageSize    );    rs = pstmt.executeQuery () ;        while (rs.next()) {    student = new Student () ;    student.setStu_id (rs.getInt(1)) ;    student.setStuName (rs.getString(2)) ;    student.setAddress (rs.getString(3)) ;    student.setStuPhone (rs.getString(4)) ;    list.add (student) ;    }    }  } catch(SQLException e) {  e.printStackTrace() ;  }  return list ;  }}                  

5、由于要对数据库中的学员信息进行封装，所以需要编写一个JavaBean,即Student类：

package org.hnylj.util;public class Student {private int stu_id ;private String stuName ;private String address ;private String stuPhone ;public Student () {}public int getStu_id () {return stu_id ;}public void setStu_id (int stu_id) {this.stu_id = stu_id ;}public String getStuName () {return stuName ;}public void setStuName (String stuName) {this.stuName = stuName ;}public String getAddress () {return address ;}public void setAddress (String address) {this.address = address ;}public String getStuPhone () {return stuPhone ;}public void setStuPhone (String stuPhone) {this.stuPhone = stuPhone ;}}

至此底层的代码就写好了。接下来我们需要编写web层的代码。

6、编写web层的jsp文件，分别有index.jsp,show.jsp和error.jsp，其代码分别如下：

<%@ page language="java" pageEncoding="UTF-8"%><%@ taglib uri="/struts-tags" prefix="s"%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html><head><title>Struts2实现分页显示</title></head><body>   <div align="center">      <s:a href="show.action">进入查看学员列表</s:a>   </div></body></html>

<%@ page language="java" pageEncoding="UTF-8"%><%@ taglib uri="/struts-tags" prefix="s"%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html>  <head>    <title>Struts2实现分页显示</title>  </head>  <body>  <div align="center">  <table border="1">    <tr>   <th>学号</th>   <th>姓名</th>   <th>地址</th>   <th>电话</th>    </tr><s:iterator value="students">   <tr>      <td><s:property value="stu_id"/></td>      <td><s:property value="stuName"/></td>      <td><s:property value="address"/></td>      <td><s:property value="stuPhone"/></td>   </tr></s:iterator>  </table>     <s:url id="url_pre" value="show.action">         <s:param name="pageNow" value="pageNow-1"></s:param>     </s:url>     <s:url id="url_next" value="show.action">         <s:param name="pageNow" value="pageNow+1"></s:param>     </s:url>       <s:a href="%{url_pre}">上一页</s:a>          <s:iterator value="students" status="status">        <s:url id="url" value="show.action">            <s:param name="pageNow" value="pageNow"/>        </s:url>     </s:iterator>     <s:a href="%{url_next}">下一页</s:a>   </div>  </body></html>

<%@ page language="java" pageEncoding="UTF-8"%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html>  <head>    <title>发生错误</title>  </head>    <body>      业务逻辑发生异常,请稍候再试。。。。。。  </body></html>

7、编写struts2的action来拦截用户的请求：

 

package org.hnylj.web;import java.util.List;import org.hnylj.util.PageDAO;import org.hnylj.util.Student;import com.opensymphony.xwork2.ActionSupport;public class ShowAction extends ActionSupport {private List<Student> students ;private int pageNow = 1 ; //初始化为1,默认从第一页开始显示    private int pageSize = 5 ; //每页显示5条记录    private PageDAO pageDAO = new PageDAO () ;public List<Student> getStudents() {return students;}public void setStudents(List<Student> students) {this.students = students;}public int getPageNow() {return pageNow;}public void setPageNow(int pageNow) {this.pageNow = pageNow;}public int getPageSize() {return pageSize;}public void setPageSize(int pageSize) {this.pageSize = pageSize;}public String execute() throws Exception {students = pageDAO.queryByPage(pageSize, pageNow) ;return SUCCESS ;}}

8、配置struts.xml文件，即action和响应结果页面之间的映射：

<?xml version="1.0" encoding="UTF-8" ?><!DOCTYPE struts PUBLIC    "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"    "http://struts.apache.org/dtds/struts-2.0.dtd"><struts><package name="struts2" namespace="/" extends="struts-default"><action name="show" class="org.hnylj.web.ShowAction"><result name="success">show.jsp</result><result name="error">error.jsp</result></action></package></struts>

至此所有的工作已经完成，接下来部署整个web工程到tomcat的webapps目录下，启动tomcat，在浏览器地址栏输入http://localhost:8080/项目名称/index.jsp，回车即可看到一个链接，点击该链接即可看到一个可以进行上一页和下一页的学员信息列表。

    该应用有一些不足之处，以后再完善一下，如果大家有比较好的分页方法，希望能提供一些好的建议，大家一起学习，共同进步！