javabean+servlet+jsp实现分页

前端实现用ligerUI实现分页，感觉用框架确实简单，闲着无聊，模拟着liger的分页界面实现了一遍（只要是功能，样式什么无视）

这里用基础的三层架构+servlet+jsp实现，思路很简单，把所有分页相关信息写入到一个pagebean类里面，service返回这个bean类，每次分页查询时都从该bean里查找信息。只是其中的细节问题比较繁琐，如边界处理（前端和后台边界都要处理），下拉框跳转后要显示当前页等等

这是ligerUI实现的分页样式（实现过程我的上一篇博客有写）

模拟实现过程：

目录结构

数据库（mysql）

model层,一个数据库对应的model（Blog），还有一个pageBean(BlogPage)

import java.sql.Date;

public class Blog {
    private int id;
    private int category_id;
    private String title;
    private String content;
    private Date created_time;
　　//getter和setter方法
    @Override
    public String toString() {
        return "Blog [id=" + id + ", category_id=" + category_id + ", title=" + title + ", content=" + content
                + ", created_time=" + created_time + "]";
    }
}

public class BlogPage {
    private List<Blog> pagerecord;//每页记录
    private int pageno;//当前页
    private int pagenostart;//每页开始索引
    private int pagesize=5;//每页多少数据
    private int totalrecord;//总记录数
    private int totalpage;//总页数

    public BlogPage(int pageno,int totalrecord){
        //pageno totalrecord都可以当做已有信息
        this.totalrecord=totalrecord;
        //计算总页数
        totalpage=(totalrecord%pagesize==0)?totalrecord/pagesize:totalrecord/pagesize+1;
        //pageno的边界处理
        if(pageno<=1)
            this.pageno=1;
        else if(pageno>=totalpage)
            this.pageno=totalpage;
        else
            this.pageno=pageno;
        //计算每页开始索引，即每页第一个数据的索引，用于分页查询
        pagenostart=(this.pageno-1)*pagesize;
    }
    public int getPagenostart() {
        return pagenostart;
    }
    public void setPagenostart(int pagenostart) {
        this.pagenostart = pagenostart;
    }
    public List<Blog> getPagerecord() {
        return pagerecord;
    }
    public void setPagerecord(List<Blog> pagerecord) {
        this.pagerecord = pagerecord;
    }
    public int getPageno() {
        return pageno;
    }
    public void setPageno(int pageno) {
        this.pageno = pageno;
    }
    public int getPagesize() {
        return pagesize;
    }
    public void setPagesize(int pagesize) {
        this.pagesize = pagesize;
    }
    public int getTotalrecord() {
        return totalrecord;
    }
    public void setTotalrecord(int totalrecord) {
        this.totalrecord = totalrecord;
    }
    public int getTotalpage() {
        return totalpage;
    }
    public void setTotalpage(int totalpage) {
        this.totalpage = totalpage;
    }
}

dao层

JDBCUtil封装了jdbc的连接和释放操作

public class JDBCUtil {
    private static String url = "jdbc:mysql://localhost:3306/blogs_stu";
    private static String username = "root";
    private static String password = "";
    static {
        try {
            Class.forName("com.mysql.jdbc.Driver");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    public static Connection getConnection(){
        Connection conn;
        try {
            conn= DriverManager.getConnection(url, username, password);
            return conn;
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return null;
    }
    public static void release(ResultSet rs,PreparedStatement ps,Connection conn){
        if(rs!=null){
            try {
                rs.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if(ps!=null){
            try {
                ps.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if(conn!=null){
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
}

public class BlogDao {
    //每页的记录，传入每页开始索引和每页大小用于分页，即limit的两个参数（mysql分页用limit）
    public List<Blog> getPageRecord(int pagenostart, int pagesize) {
        Connection conn = JDBCUtil.getConnection();
        PreparedStatement ps = null;
        ResultSet rs = null;
        String sql = "select * from blog limit ?,?";
        List<Blog> list = new ArrayList<Blog>();
        try {
            ps = conn.prepareStatement(sql);
            ps.setInt(1, pagenostart);
            ps.setInt(2, pagesize);
            rs = ps.executeQuery();
            while (rs.next()) {
                Blog blog = new Blog();
                blog.setId(rs.getInt("id"));
                blog.setCategory_id(rs.getInt("category_id"));
                blog.setTitle(rs.getString("title"));
                blog.setContent(rs.getString("content"));
                blog.setCreated_time(rs.getDate("created_time"));
                list.add(blog);
            }
            return list;
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            JDBCUtil.release(rs, ps, conn);
        }
        return null;
    }
    //总记录数
    public int getTotal() {
        Connection conn = JDBCUtil.getConnection();
        PreparedStatement ps = null;
        ResultSet rs = null;
        try {
            ps = conn.prepareStatement("select count(*) from blog");
            rs = ps.executeQuery();
            if (rs.next()) {
                return rs.getInt(1);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            JDBCUtil.release(rs, ps, conn);
        }
        return 0;
    }
}

service层

public class BlogService {
    BlogDao blogDao = new BlogDao();
    //返回pagebean,所有分页需要的信息都去pagebean里查找
    public BlogPage findPageRecord(int pageno) {
        int totalrecord = blogDao.getTotal();
        BlogPage blogpage = new BlogPage(pageno, totalrecord);
        List<Blog> list = blogDao.getPageRecord(blogpage.getPagenostart(),blogpage.getPagesize());
        blogpage.setPagerecord(list);
        return blogpage;
    }
}

servlet类

@WebServlet("/BlogSplitServlet")
public class BlogSplitServlet extends HttpServlet {
    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        response.setContentType("text/html; charset=utf-8");
        String pagenostr=request.getParameter("pageno");
        //首次访问servletpagenostr为null，给一个初始值，即默认访问第一页
        int pageno=1;
        if(pagenostr!=null)
            pageno=Integer.parseInt(pagenostr);
        BlogService service=new BlogService();
        BlogPage blogPage=service.findPageRecord(pageno);
        request.setAttribute("blogPage", blogPage);
        request.getRequestDispatcher("/blogPage.jsp").forward(request, response);
    }
    public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }
}

这样所有的分页信息就封装到pagebean里了

jsp实现只需要将pagebean里的信息取出来就行了

下面给出我的jsp实现（模拟ligerUI）

<%@ page language="java" contentType="text/html; charset=utf-8"
    pageEncoding="utf-8"%>
<%@page import="java.util.*,model.Blog,model.BlogPage"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>Insert title here</title>
<script type="text/javascript">
    window.onload = function() {
        //保证select的option与当前页显示一致
        select = document.getElementById("select");
        pageno = ‘${blogPage.pageno}‘;
        select.options[pageno - 1].selected = ‘selected‘;
    }
    //select下拉列表跳转
    function selectjump() {
        var pageno = select.selectedIndex + 1;
        window.location.href = "http://localhost/jspPageSplit/BlogSplitServlet?pageno="
                + pageno;
    }
    //text跳转，onblur事件，输入框失去焦点是发生
    function textjump() {
        var pageno = document.getElementById("text").value;
        window.location.href = "http://localhost/jspPageSplit/BlogSplitServlet?pageno="
                + pageno;
    }
</script>
</head>
<body>
    <%
        BlogPage blogPage = (BlogPage) request.getAttribute("blogPage");
        List<Blog> list = blogPage.getPagerecord();
        // 尾页填充空白行，若不填充，尾页表格tr行数与前面不一致很难看
        if (list.size() < blogPage.getPagesize()) {
            for (int i = list.size(); i < blogPage.getPagesize(); i++)
                list.add(null);
        }
    %>
    <div style="width: 50%; height: 400px">
        <table border="1" cellspacing="0" width="100%" bgcolor="#CEF0C5">
            <tr height="40px">
                <td>id</td><td>标题</td><td>内容</td><td>创建时间</td>
            </tr>
            <%
                for (Blog blog : list) {
                    if (blog != null) {
            %>
            <tr height="50px">
                <td width="10%"><%=blog.getId()%></td>
                <td width="20%"><%=blog.getTitle()%></td>
                <td width="40%"><%=blog.getContent()%></td>
                <td width="30%"><%=blog.getCreated_time()%></td>
            </tr>
            <!-- 尾页空白行填充 -->
            <%} else {%>
            <tr height="50px">
                <td width="10%"></td>
                <td width="20%"></td>
                <td width="40%"></td>
                <td width="30%"></td>
            </tr>
            <%}}%>
        </table>
        <div style="height:50px;background-color: #4B7DB3;line-height: 40px;">
        &nbsp;&nbsp;
        <!-- select下拉框 -->
        <select id="select">
            <%for (int i = 1; i <= blogPage.getTotalpage(); i++) {%>
            <option onclick="selectjump()"><%=i%></option>
            <%}%>
        </select>
        <a href="${pageContext.request.contextPath}/BlogSplitServlet?pageno=1">首页</a>
        <a href="${pageContext.request.contextPath}/BlogSplitServlet?pageno=<%=blogPage.getPageno()-1<1?blogPage.getPageno():blogPage.getPageno()-1%>">上一页</a>&nbsp;&nbsp;
        <input type="text" id="text" size="1px" value="${blogPage.pageno}" onblur="textjump()">/${blogPage.totalpage}
        <a href="${pageContext.request.contextPath}/BlogSplitServlet?pageno=<%=blogPage.getPageno()+1>blogPage.getTotalpage()?blogPage.getPageno():blogPage.getPageno()+1%>">下一页</a>
        <a href="${pageContext.request.contextPath}/BlogSplitServlet?pageno=<%=blogPage.getTotalpage()%>">尾页</a>
        <div style="float: right;">
        显示从${blogPage.pagenostart+1}到${blogPage.pageno==blogPage.totalpage?blogPage.totalrecord:blogPage.pagesize},
        共${blogPage.totalrecord}条. 每页显示${blogPage.pagesize}条
        </div>
        </div>
    </div>
</body>
</html>

这是最后的样子，样式粗略的调了下，功能跟ligerUI默认的分页一模一样

实际运用中可以根据需求编写jsp页面，但是后台代码基本是通用的