struts2分页实现

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。