mysql分页查询

public class User {
    private int id;
    private String name;
    private BigDecimal salary;

    public User() {
    }

    public User(int id, String name, BigDecimal salary) {
        this.id = id;
        this.name = name;
        this.salary = salary;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public BigDecimal getSalary() {
        return salary;
    }

    public void setSalary(BigDecimal salary) {
        this.salary = salary;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", name=‘" + name + ‘\‘‘ +
                ", salary=" + salary +
                ‘}‘;
    }
}

public class PageUtil {
    private int firstPage =1; //首页
    private int prePage; //上一页
    private int nextPage; //下一页
    private int totalPage; //末页/总页数
    private int curPage; //当前页
    private List datas; //需要显示的数据
    private int curSize =9; //每页显示的数据
    private int totalSize; // 总的记录数

    public int getFirstPage() {
        return firstPage;
    }
    public void setFirstPage(int firstPage) {
        this.firstPage = firstPage;
    }
    public int getPrePage() {
        return this.getCurPage()==this.getFirstPage()?this.getFirstPage():this.getCurPage()-1;
    }
    public void setPrePage(int prePage) {
        this.prePage = prePage;
    }
    public int getNextPage() {
        return this.getCurPage()==this.getTotalPage()?this.getTotalPage():this.getCurPage()+1;
    }
    public void setNextPage(int nextPage) {
        this.nextPage = nextPage;
    }
    public int getTotalPage() {
        return this.getTotalSize()%this.getCurSize()==0?this.getTotalSize()/this.getCurSize():this.getTotalSize()/this.getCurSize()+1;
    }
    public void setTotalPage(int totalPage) {
        this.totalPage = totalPage;
    }
    public int getCurPage() {
        return curPage;
    }
    public void setCurPage(int curPage) {
        this.curPage = curPage;
    }
    public List getDatas() {
        return datas;
    }
    public void setDatas(List datas) {
        this.datas = datas;
    }
    public int getCurSize() {
        return curSize;
    }
    public void setCurSize(int curSize) {
        this.curSize = curSize;
    }
    public int getTotalSize() {
        return totalSize;
    }
    public void setTotalSize(int totalSize) {
        this.totalSize = totalSize;
    }
}

public class UserDao {
   public int queryCount(){
       QueryRunner runner = new QueryRunner(getSource(),true);
       Long query = null;
       try {
            query = (Long) runner.query("select count(*) from user", new ScalarHandler());
       } catch (SQLException e) {
           e.printStackTrace();
       }
       System.out.println(query);
       return query.intValue();
   }
    public List queryAll(int pageNo, int pageSize){
        QueryRunner runner = new QueryRunner(getSource(), true);
        BeanListHandler<User> handler = new BeanListHandler<>(User.class);
        List<User> result = null;
        try {
            String sql = "select id,name,salary from user limit ?,?";
            result = runner.query(sql, handler,(pageNo-1)*pageSize,pageSize);
        } catch (SQLException e) {
            e.printStackTrace();
            throw new RuntimeException("获取查询数据失败",e);
        }
     
        return result;
    }
}

public class UserService {
    public List queryAll(int pageNo, int pageSize){
        List page =  new UserDao().queryAll(pageNo,pageSize);
        return page;
    }

    public int queryCount(){
        return new UserDao().queryCount();
    }
}

@WebServlet("/user")
public class UserServlet extends HttpServlet {
    UserService service = new UserService();
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        PageUtil pageUtil = new PageUtil();
        //计算总记录数
        pageUtil.setTotalSize(service.queryCount());
        //计算当前页
        String curpage = req.getParameter("curpage");
        if (curpage == null || curpage.equals("")){
            curpage = "1";
        }
        pageUtil.setCurPage(Integer.parseInt(curpage));
        //计算每页显示的数据
        pageUtil.setDatas(service.queryAll(pageUtil.getCurPage(),pageUtil.getCurSize()));
        req.setAttribute("page",pageUtil);
        req.getRequestDispatcher("WEB-INF/index.jsp").forward(req,resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req,resp);
    }
}

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%--
  Created by IntelliJ IDEA.
  User: Administrator
  Date: 2019/9/17
  Time: 20:50
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
    <meta http-equiv="pragma" content="no-cache">
    <meta http-equiv="cache-control" content="no-cache">
    <meta http-equiv="expires" content="0">
    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
    <meta http-equiv="description" content="This is my page">
</head>
<body>
<table border="1px" cellspacing="0" cellpadding="5">
    <tr>
        <th>编号</th>
        <th>姓名</th>
        <th>工资</th>
    </tr>
    <c:forEach items="${page.datas}" var="pa">
        <tr>
            <td>${pa.id}</td>
            <td>${pa.name}</td>
            <td>${pa.salary}</td>
        </tr>
    </c:forEach>
</table>
<a href="<c:url value=‘/user?curpage=${page.firstPage}‘ />">首页</a>
<a href="<c:url value=‘/user?curpage=${page.prePage}‘ />">下一页</a>
<a href="<c:url value=‘/user?curpage=${page.nextPage}‘ />">上一页</a>
<a href="<c:url value=‘/user?curpage=${page.totalPage}‘ />">尾页</a>
<form action="<c:url value=‘/user‘ />">
    跳转到 <input type="text" name="curpage" size="2"/>页 <input value="跳转" type="submit"/>
</form>
跳转到 <input type="text" name="pageno" id="pagenoId" size="2"/>页 <input value="跳转" type="button" οnclick="tiaozhuan()"/>
当前为${page.curPage }页 /共有${page.totalPage }页 每页有${page.curSize }数据 总记录数${page.totalSize } 

<script type="text/javascript">
    function tiaozhuan() {
        var pageid = document.getElementById("pagenoId");
        var url = "<c:url value=‘/user?curpage="+pageid+"‘ />";
        window.location.href = url;
    }
</script>
</body>
</html>