struts2分页实现

在开发web程序时，从数据库中提取的数据通常显示在页面上。有很多方法可以显示分页。有些人写自定义标签，用自己的标签显示分页。就我个人而言，我认为这是一个更好的方法。以下是我用Struts2做的一个分页显示实例。基本思路是将数据库表中的每一行数据包装成一个对象，然后通过返回类型为List返回这些对象 Struts2的action定义了一个List属性，用这个List接收从数据库中查询并包装的对象，然后通过Struts2的标签遍布List中的每个对象，并在页面上显示这些对象中包含的属性。具体步骤如下： 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="https://www.tulingxueyuan.cn/d/file/p/20230508/v5xlvq5yc4f"  xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee  https://www.tulingxueyuan.cn/d/file/p/20230508/gercllsezy3  <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="https://www.tulingxueyuan.cn/d/file/p/20230508/v5xlvq5yc4f"  xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee  https://www.tulingxueyuan.cn/d/file/p/20230508/gercllsezy3  <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、用于保存学生信息的数据库表： 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"，"137845190"; insert into student(stuName,address,stuPhone) values苏州，郑小明，'13787052188'); insert into student(stuName,address,stuPhone) values"杨一新"，"西安"，"1378785190"; insert into student(stuName,address,stuPhone) values"王新任"，"广州"，"137870560"; 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"，"13785390"; insert into student(stuName,address,stuPhone) values"秦一生"，"北京"，"1378889236"; 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"，"137845190"; insert into student(stuName,address,stuPhone) values"郑小明"，"苏州"，"1378705218"; 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"，"137870560"; insert into student(stuName,address,stuPhone) values"谢小华"，"深圳"，"13787550"; 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"，"1378889236"; insert into student(stuName,address,stuPhone) values"田翠林"，"杭州"，"137875150"; insert into student(stuName,address,stuPhone) values"陈小明"，"广州"，"137876268";4、编写Pagedao类，这类用于从数据库中取出所有学生信息，并将这些学生信息封装成Student 对象并将 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、因为要包装数据库中的学生信息，所以要写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 ;  } }

到目前为止，底层的代码已经写好了。接下来，我们需要编写web层的代码。 6、用index编写web层的jsp文件.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>  <p align="center">  <s:a href="show.action">查看学生列表</s:a>  </p>  </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>  <p align="center">  <s:a href="show.action">查看学生列表</s:a>  </p>  </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>  <p 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>  </p>  </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>  <p 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>  </p>  </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>  业务逻辑异常，请稍后再试试。。。。。。。  </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>  业务逻辑异常，请稍后再试试。。。。。。。  </body> </html>

7、编写struts2的action拦截用户请求：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  private int pageSize = 5 ; ///每页显示5个记录  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  private int pageSize = 5 ; ///每页显示5个记录  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与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" ?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>

到目前为止，所有的工作都已经完成。接下来，将整个web项目部署到tomcat的webaps目录中，启动tomcat，并在浏览器地址栏中输入 http://localhost:8080/项目名称/index.jsp，回车后可以看到一个链接，点击这个链接就可以看到一个学生信息列表，可以进行上一页和下一页。