struts2分页实现

原创

赵士杰 2023-05-06 17:34:09 博主文章分类：struts ©著作权

文章标签 Java Struts SQL JSP MySQL 文章分类 Java 后端开发

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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：

Xml代码

<?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> 



<?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：

Sql代码

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'); 


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。 

Java代码 

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 ; 

 } 

} 



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： 


Java代码 

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 ; 

 } 

} 


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：

Java代码

<%@ 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"> 

 <s:a href="show.action">进入查看学员列表</s:a> 

 </div> 

 </body> 

</html>Java代码 

<%@ 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"%> 

<%@ 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>Java代码 

<%@ 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> 


<%@ 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：

Java代码

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 ; 

 } 

} 


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：

Java代码

<?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> 


<?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。