Currently, there are two commonly used pagination implementation methods:
1. Modify SQL every time you turn a page, and pass relevant parameters to SQL to check the data of this page in the database in real time and display it.
2. Check all the data of a table in the database, and then get some data and display them through processing in the business logic.
For a simple management system with a small amount of data, the first implementation method is relatively easy to use less code to realize the pagination 1 function. This article is also to introduce this method for you:
Code snippet:
1, Page java
package com.cm.contract.common;
import org.apache.commons.lang.StringUtils;
import org.apache.commons.lang.builder.ToStringBuilder;
/** Paging class
* @author FENGWEI
* @date 2016-5-23
*/
public class Page implements java.io.Serializable{
private static final long serialVersionUID = 1L;
// before 1 page
private Boolean hasPrePage;
// after 1 page
private Boolean hasNextPage;
// How many items are displayed per page : The default 20 article
private Long everyPage = 20L;
// Total number of pages
private Long totalPage;
// Current page number : By default the first 1 page
private Long currentPage = 1L;
// Start the subscript
private Long beginIndex;
// The end of the subscript
private Long endinIndex;
// How many pieces altogether
private Long totalCount;
// Sort the column name
private String sortName;
// Order status
private String sortState;
// Ordering information
private String sortInfo;
// Whether the sorting
private Boolean sort = false;
private String defaultInfo = " ";
public String getDefaultInfo() {
return defaultInfo;
}
public void setDefaultInfo(String defaultInfo) {
this.defaultInfo = defaultInfo;
}
public String getSortInfo() {
return sortInfo;
}
public void setSortInfo(String sortInfo) {
this.sortInfo = sortInfo;
}
public String getSortName() {
return sortName;
}
public void setSortName(String sortName) {
setPageSortState(sortName);
}
public String getSortState() {
return sortState;
}
public void setSortState(String sortState) {
this.sortState = sortState;
}
public Page() {
}
/**
* The commonly used , For calculating paging
* */
public Page(Long totalRecords){
this.totalCount = totalRecords;
setTotalPage(getTotalPage(totalRecords));
}
/**
* Use when setting how many bars to display per page
* */
public Page(Long everyPage,Long totalRecords){
this.everyPage = everyPage;
this.totalCount = totalRecords;
setTotalPage(getTotalPage(totalRecords));
}
/**
* @param state Status code
* @param value Go to page number or set how many columns to display per page or sort column names
*/
public void pageState(int index,String value) {
sort = false;
switch (index) {
case 0 :setEveryPage(Long.parseLong(value));break;
case 1 :first();break;
case 2: previous();break;
case 3: next();break;
case 4: last();break;
case 5: sort = true;sort(value);break;
case 6 :// To the specified number of pages
setCurrentPage(Long.parseLong(value));
break;
}
}
/**
* The former 1 page
*/
private void first() {
currentPage = 1L;
}
private void previous() {
currentPage--;
}
private void next() {
currentPage++;
}
private void last() {
currentPage = totalPage;
}
private void sort(String sortName) {
// Set sort state
setPageSortState(sortName);
}
/**
* Total page count
* */
private Long getTotalPage(Long totalRecords) {
Long totalPage = 0L;
everyPage = everyPage == null ? 10L : everyPage;
if (totalRecords % everyPage == 0)
totalPage = totalRecords / everyPage;
else {
totalPage = totalRecords / everyPage + 1;
}
return totalPage;
}
public Long getBeginIndex() {
this.beginIndex = (currentPage - 1) * everyPage;
return this.beginIndex;
}
public void setBeginIndex(Long beginIndex) {
this.beginIndex = beginIndex;
}
public Long getCurrentPage() {
this.currentPage = currentPage == 0 ? 1 : currentPage;
return this.currentPage;
}
public void setCurrentPage(Long currentPage) {
if(0 == currentPage){
currentPage = 1L;
}
this.currentPage = currentPage;
}
public Long getEveryPage() {
this.everyPage = everyPage == 0 ? 10 : everyPage;
return this.everyPage;
}
public void setEveryPage(Long everyPage) {
this.everyPage = everyPage;
}
public Boolean getHasNextPage() {
this.hasNextPage = (currentPage != totalPage) && (totalPage != 0);
return this.hasNextPage;
}
public void setHasNextPage(Boolean hasNextPage) {
this.hasNextPage = hasNextPage;
}
public Boolean getHasPrePage() {
this.hasPrePage = currentPage != 1;
return this.hasPrePage;
}
public void setHasPrePage(Boolean hasPrePage) {
this.hasPrePage = hasPrePage;
}
public Long getTotalPage() {
return this.totalPage;
}
public void setTotalPage(Long totalPage) {
if(this.currentPage > totalPage){
this.currentPage = totalPage;
}
this.totalPage = totalPage;
}
public Long getTotalCount() {
return this.totalCount;
}
public void setTotalCount(Long totalCount) {
setTotalPage(getTotalPage(totalCount));
this.totalCount = totalCount;
}
@Override
public String toString() {
return ToStringBuilder.reflectionToString(this);
}
/**
* Set sort state
* */
private void setPageSortState(String newPageSortName){
// Determines if the previous sort field is empty
if(StringUtils.isEmpty(sortName)){
// The default sort is ascending
this.sortState = PageUtil.ASC;
this.sortInfo = PageUtil.PAGE_ASC;
}else{
if(StringUtils.equalsIgnoreCase(newPageSortName, sortName)){
// judge sortState Sort state value
if(StringUtils.equalsIgnoreCase(sortState, PageUtil.ASC)){
this.sortState = PageUtil.DESC;
this.sortInfo = PageUtil.PAGE_DESC;
}else{
this.sortState = PageUtil.ASC;
this.sortInfo = PageUtil.PAGE_ASC;
}
}else{
// The default
this.sortState = PageUtil.ASC;
this.sortInfo = PageUtil.PAGE_ASC;
}
}
sortName = newPageSortName.toLowerCase();
}
public Boolean isSort() {
return sort;
}
public void setSort(Boolean sort) {
this.sort = sort;
}
public Long getEndinIndex() {
this.endinIndex = (currentPage) * everyPage;
return endinIndex;
}
public void setEndinIndex(Long endinIndex) {
this.endinIndex = endinIndex;
}
}2.PageState.java
package com.cm.contract.common;
import org.apache.commons.lang.StringUtils;
/** Paging state class
* @author FENGWEI
* @date 2016-5-23
*/
public enum PageState {
/**
* Set how many bars to display per page
* */
SETPAGE,
/**
* Home page
* */
FIRST,
/**
* forward 1 page
* */
PREVIOUS,
/**
* backward 1 page
* */
NEXT,
/**
* At the end of the page
* */
LAST,
/**
* The sorting
* */
SORT,
/**
* To page one
* */
GOPAGE;
/**
* @param value The index name
* @return Returns the index index
*/
public static int getOrdinal(String value) {
int index = -1;
if (StringUtils.isEmpty(value)) {
return index;
}
String newValue = StringUtils.trim(value).toUpperCase();
try {
index = valueOf(newValue).ordinal();
} catch (IllegalArgumentException e) {}
return index;
}
}3.PageUtil.java
/**
* Paging utility class
* @author FENGWEI
* @date 2016-5-23
*/
public class PageUtil {
public static final String ASC = "asc";
public static final String DESC = "desc";
public static final String PAGE_DESC = " left ";
public static final String PAGE_ASC = " write ";
public static final String PAGE_NULL = " ";
public static final String SESSION_PAGE_KEY = "page";
/**
* Initializes the split page class
* @param initPageSql Non-paged queries SQL
* @param totalCount Total number of rows
* @param index Paging state
* @param value Only when you set how many bars to display per page , Values are not NULL, For the other NULL
*/
public static Page inintPage(Long totalCount,Integer index,String value,Page sessionPage){
Page page = null;
if(index < 0){
page = new Page(totalCount);
}else{
/** How many items are displayed per page */
Long everPage = null == value ? 10 : Long.parseLong(value);
/** To obtain Session The paging class in , Easy to save page paging state */
page = sessionPage;
page.setEveryPage(everPage);
page.setTotalCount(totalCount);
}
return page;
}
/**
* When page click: home page , before 1 page , after 1 page , At the end of the page , The sorting , Paging to the number of pages
* @param index Paging state
* @param value Sort the field name or to page number
*/
public static Page execPage(int index,String value,Page sessionPage){
Page page = sessionPage;
/** Call method for paging calculation */
page.pageState(index,value);
return page;
}
}4.DefaultController.java this part can be used flexibly
package com.cm.contract.common;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import org.springframework.web.bind.annotation.ModelAttribute;
/**
* Extract common request and response Title:DefaultController Descrption:
*
* @author FENGWEI
* @date 2016-5-6 In the afternoon 3:30:32
*/
public class DefaultController {
/**
* oracel the 3 Layer paging statement Subclasses before presenting the data , Do paging computation !
*
* @param querySql
* Of the query SQL statements , No paging
* @param totalCount
* According to the query SQL The total number of bars obtained
* @param columnNameDescOrAsc
* The column name + The sorting way : ID DESC or ASC
*/
protected Page executePage(HttpServletRequest request, Long totalCount) {
if (null == totalCount) {
totalCount = 0L;
}
/** Page state , This state is native to paging , Nothing to do with business */
String pageAction = request.getParameter("pageAction");
String value = request.getParameter("pageKey");
/** Gets subscripts to determine the paging state */
int index = PageState.getOrdinal(pageAction);
Page page = null;
/**
* index < 1 only 2 Kind of state 1 When first invoked , There is no value of zero in the paging state class NULL return -1 2 When the page sets how many bars to display per page :
* index=0, When how many items are displayed per page , The paging class is recalculated
* */
Page sessionPage = getPage(request);
if (index < 1) {
page = PageUtil.inintPage(totalCount, index, value, sessionPage);
} else {
page = PageUtil.execPage(index, value, sessionPage);
}
setSession(request, page);
return page;
}
private Page getPage(HttpServletRequest request) {
Page page = (Page) request.getSession().getAttribute(
PageUtil.SESSION_PAGE_KEY);
if (page == null) {
page = new Page();
}
return page;
}
private void setSession(HttpServletRequest request, Page page) {
request.getSession().setAttribute(PageUtil.SESSION_PAGE_KEY, page);
}
}Usage:
5,Controller.java
/**
* model Added paging conditions
* executePage The method is written in the utility class
* @param model
*/
@Controller
public class CMLogController extends DefaultController {
@RequestMapping("index.do")
public ModelAndView userInto(ModelMap model, String username) {
nameStr = username;
model.addAttribute("username", nameStr);
// Number of pages
Long totalCount = logService.pageCounts(model);
// Paging display
Page page = executePage(request, totalCount);
if (page.isSort()) {
model.put("orderName", page.getSortName());
model.put("descAsc", page.getSortState());
} else {
model.put("orderName", "logtime");
model.put("descAsc", "desc");
}
model.put("startIndex", page.getBeginIndex());
model.put("endIndex", page.getEndinIndex());
ModelAndView mv = new ModelAndView();
// Paging query
logList = logService.pageList(model);
mv.addObject("logList", logList);
mv.setViewName("/jsp/log");
return mv;
}}6. Several query statements in maybatis
// Paging query
<select id="pageList" parameterType="map" resultMap="BaseResultMap">
select ttt.* from(select tt.*,rownum rn from(select * from CM_LOG
<where>
<if test="username != null and username != ''">
<!--
Special remind 1 Next, $ It's just string concatenation, So be very careful sql Injection problem.
Used at development time : $, Convenient debugging sql, Post time use : #
-->
and username like '%${username}%'
</if>
<if test="type != null and type != ''">
<!--
Special remind 1 Next, $ It's just string concatenation, So be very careful sql Injection problem.
Used at development time : $, Convenient debugging sql, Post time use : #
-->
AND TYPE = #{type,jdbcType=VARCHAR}
</if>
</where>
order by ${orderName} ${descAsc} )tt)ttt
<where>
<if test="startIndex != null and startIndex != ''">
rn > ${startIndex}
</if>
<if test="endIndex != null and endIndex != ''">
<![CDATA[ and rn <= ${endIndex} ]]>
</if>
</where>
</select>
// Number of pages
<select id="pageCounts" parameterType="map" resultType="long">
select count(*) from CM_LOG
<where>
<if test="username != null and username != ''">
and username like '%${username}%'
</if>
</where>
</select>7. Front desk page index.jsp
// Simply add it to the page layout div
//username For the condition
// <jsp:param name="url" value="/log/index.do?"/> No strings attached The question mark has to be there
<body >
<div align="right" style="height: 20">
<jsp:include page="/jsp/page.jsp">
<jsp:param name="url" value="/log/index.do?username=${username }"/>
</jsp:include>
</div>
</body >8, Page.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<c:set var="page" value="${sessionScope.page}" />
<c:set var="path" value="${pageContext.request.contextPath}" />
<c:set var="url" value="${param.url}" />
<c:set var="urlParams" value="${param.urlParams}" />
<c:set var="pathurl" value="${path}/${url}" />
<tr>
<td colspan="5">
${urlParams }
A total of ${page.totalCount} records A total of ${page.totalPage} page Each page shows ${page.everyPage} article
The current first ${page.currentPage} page
<c:choose>
<c:when test="${page.hasPrePage eq false}">
<< Home page < On the page
</c:when>
<c:otherwise>
<a href="${pathurl}&pageAction=first${urlParams}"><< Home page </a>
<a href="${pathurl}&pageAction=previous${urlParams}" />< on 1 page </a>
</c:otherwise>
</c:choose>
||
<c:choose>
<c:when test="${page.hasNextPage eq false}">
On the next page > back >>
</c:when>
<c:otherwise>
<a href="${pathurl}&pageAction=next${urlParams}"> Under the 1 page > </a>
<a href="${pathurl}&pageAction=last${urlParams}"> At the end of the page >></a>
</c:otherwise>
</c:choose>
<SELECT name="indexChange" id="indexChange"
onchange="getCurrentPage(this.value);">
<c:forEach var="index" begin="1" end="${page.totalPage}" step="1">
<option value="${index}" ${page.currentPage eq index ? "selected" : ""}>
The first ${index} page
</option>
</c:forEach>
</SELECT>
Each page shows :<select name="everyPage" id="everyPage" onchange="setEveryPage(this.value);">
<c:forEach var="pageCount" begin="5" end="${page.totalCount}" step="5">
<option value="${pageCount}" ${page.everyPage eq pageCount ? "selected" : ""}>
${pageCount} article
</option>
</c:forEach>
</select>
</td>
</tr>
<div style='display: none'>
<a class=listlink id="indexPageHref" href='#'></a>
</div>
<script>
function getCurrentPage(index){
var a = document.getElementById("indexPageHref");
a.href = '${pathurl}&pageAction=gopage&pageKey='+index+'${urlParams}';
a.setAttribute("onclick",'');
a.click("return false");
}
function setEveryPage(everyPage){
var a = document.getElementById("indexPageHref");
var currentPage = document.getElementById('indexChange').value;
a.href = '${pathurl}&pageAction=setpage&pageKey='+everyPage+'${urlParams}';
a.setAttribute("onclick",'');
a.click("return false");
}
function sortPage(sortName){
var a = document.getElementById("indexPageHref");
a.href = '${pathurl}&pageAction=sort&pageKey='+sortName+'${urlParams}';
a.setAttribute("onclick",'');
a.click("return false");
}
</script>