通过先前的文章：【Spring Boot】MyBatis引入 分页插件pagehelper
知道如何使用分页插件pagehelper，现在对这个分页插件再简单包装一下，使它使用起来更方便，自带分页条：
1、分页条类（输出分页字符串：首页、上一页、下一页、尾页）：
package com.wenjianbao.codepub.model.page;
import cn.hutool.core.net.url.UrlBuilder;
import cn.hutool.core.net.url.UrlQuery;
import cn.hutool.core.util.ArrayUtil;
import cn.hutool.core.util.NumberUtil;
import com.wenjianbao.codepub.helper.PageURLHelper;
import java.util.Map;
/**
* 分页条类（输出分页字符串：首页、上一页、下一页、尾页）
*/
public class Pagination {
private int pageNum = 1; // 【必填】当前分页数
private int pageSize = 10; // 【必填】每页记录数
private int totalPages = 0; // 【必填】总共分页数
private long totalSize = 0; // 【必填】总记录数
private int[] pageSizeOption = {10, 20, 30, 40, 50}; // 每页记录数 下拉选择项
private int maxPages = 0; // 最大能显示的分页数（比如说，本来总共有250页，但是想让它只显示前50页）
private int columnPages = 5; // 分页栏显示的页数
private String basePageUrl = "";
/**
* 构造方法
*/
public Pagination() {
init();
}
/**
* 初始化
*/
private void init() {
// 基础的URL构造器
UrlBuilder urlBuilder = UrlBuilder.of(PageURLHelper.getPageUrl());
Map<CharSequence, CharSequence> urlParams = urlBuilder.getQuery().getQueryMap();
UrlQuery urlQuery = new UrlQuery();
String[] deleteParams = {"pageNum", "pageSize"};
for (Map.Entry<CharSequence, CharSequence> entry : urlParams.entrySet()) {
if (!ArrayUtil.contains(deleteParams, entry.getKey())) {
urlQuery.add(entry.getKey(), entry.getValue());
}
}
basePageUrl = urlBuilder.setQuery(urlQuery).toString();
// 总页数
if (maxPages > 0 && maxPages < totalPages) {
totalPages = maxPages;
}
// 校正当前页，不能越界
pageNum = NumberUtil.max(pageNum, 1);
pageNum = NumberUtil.min(pageNum, totalPages);
}
private String makeUrl(int pageNum) {
UrlBuilder urlBuilder = UrlBuilder.ofHttp(basePageUrl);
urlBuilder.addQuery("pageNum", String.valueOf(pageNum));
return urlBuilder.toString();
}
private String makeUrl(int pageNum, int pageSize) {
UrlBuilder urlBuilder = UrlBuilder.ofHttp(basePageUrl);
urlBuilder.addQuery("pageNum", String.valueOf(pageNum));
urlBuilder.addQuery("pageSize", String.valueOf(pageSize));
return urlBuilder.toString();
}
/**
* 获取分页字符串
*/
public String getPageStr() {
StringBuilder pageSb = new StringBuilder();
int offset = NumberUtil.ceilDiv(columnPages, 2) - 1;
int from = 0;
int to = 0;
if (totalPages < columnPages) {
from = 1;
to = totalPages;
} else {
from = pageNum - offset;
to = from + columnPages - 1;
if (from < 1) {
from = 1;
to = columnPages;
} else if (to > totalPages) {
from = totalPages - columnPages + 1;
to = totalPages;
}
}
// 首页
if (from > 1) {
pageSb.append("<li><a href=\"")
.append(makeUrl(1, pageSize))
.append("\" class=\"first\">首页</a></li>");
}
// 上一页
if (pageNum > 1) {
pageSb.append("<li><a href=\"")
.append(makeUrl(pageNum - 1, pageSize))
.append("\" class=\"prev\">上一页</a></li>");
}
// 中间数字页
for (int i = from; i <= to; i++) {
if (i == pageNum) {
pageSb.append("<li class=\"active\"><a>")
.append(i)
.append("</a></li>");
} else {
pageSb.append("<li><a href=\"")
.append(makeUrl(i, pageSize))
.append("\">")
.append(i)
.append("</a></li>");
}
}
// 下一页
if (pageNum < totalPages) {
pageSb.append("<li><a href=\"")
.append(makeUrl(pageNum + 1, pageSize))
.append("\" class=\"next\">下一页</a></li>");
}
// 末页
if (to < totalPages) {
pageSb.append("<li><a href=\"")
.append(makeUrl(totalPages, pageSize))
.append("\" class=\"last\">末页</a></li>");
}
// 每页记录数 下拉框
StringBuilder pageSizeSb = new StringBuilder();
pageSizeSb.append("<li>总共<strong>")
.append(totalSize)
.append("</strong>条记录，每页显示<select #onchange#>#option#</select>条记录 </li>");
// 下拉框 onChange事件
StringBuilder onchangeSb = new StringBuilder();
onchangeSb.append(" onchange=\"location.href='")
.append(makeUrl(1))
.append("&pageSize=' + this.value\" ");
StringBuilder optionSb = new StringBuilder();
for (int size : pageSizeOption) {
String selectedStr = "";
if (pageSize == size) {
selectedStr = " selected=\"selected\" ";
}
optionSb.append("<option value=\"")
.append(size)
.append("\" ")
.append(selectedStr)
.append(">")
.append(size)
.append("</option>")
;
}
String pageSizeStr = pageSizeSb.toString()
.replace("#onchange#", onchangeSb.toString())
.replace("#option#", optionSb.toString());
return "<ul class=\"pagination clearfix\">"
+ pageSizeStr
+ pageSb.toString()
+ "</ul>";
}
public int getPageNum() {
return pageNum;
}
public void setPageNum(int pageNum) {
this.pageNum = pageNum;
}
public int getPageSize() {
return pageSize;
}
public void setPageSize(int pageSize) {
this.pageSize = pageSize;
}
public int getTotalPages() {
return totalPages;
}
public void setTotalPages(int totalPages) {
this.totalPages = totalPages;
}
public long getTotalSize() {
return totalSize;
}
public void setTotalSize(long totalSize) {
this.totalSize = totalSize;
}
public int[] getPageSizeOption() {
return pageSizeOption;
}
public void setPageSizeOption(int[] pageSizeOption) {
this.pageSizeOption = pageSizeOption;
}
public int getMaxPages() {
return maxPages;
}
public void setMaxPages(int maxPages) {
this.maxPages = maxPages;
}
public int getColumnPages() {
return columnPages;
}
public void setColumnPages(int columnPages) {
this.columnPages = columnPages;
}
}
2、分页查询结果封装类
package com.wenjianbao.codepub.model.page;
import com.github.pagehelper.PageInfo;
import java.util.List;
/**
* 分页查询结果封装类
*/
public class PageResult<T> {
private final PageInfo<T> pageInfo;
private final Pagination pagination;
/**
* 构造方法
*/
public PageResult(List<T> list) {
this.pageInfo = new PageInfo<>(list);
this.pagination = new Pagination();
this.pagination.setPageNum(getPageNum());
this.pagination.setPageSize(getPageSize());
this.pagination.setTotalPages(getTotalPages());
this.pagination.setTotalSize(getTotalSize());
}
/**
* 快捷生成分页结果类
*/
public static <T> PageResult<T> of(List<T> list) {
return new PageResult<>(list);
}
/**
* 当前页分页数
*/
public int getPageNum() {
return this.pageInfo.getPageNum();
}
/**
* 每页记录数
*/
public int getPageSize() {
return this.pageInfo.getPageSize();
}
/**
* 总记录数
*/
public long getTotalSize() {
return this.pageInfo.getTotal();
}
/**
* 总共分页数
*/
public int getTotalPages() {
return this.pageInfo.getPages();
}
/**
* 分页条
*/
public String getPageStr() {
return this.pagination.getPageStr();
}
/**
* 分页数据列表
*/
public List<T> getList() {
return this.pageInfo.getList();
}
}
使用示例：
// 设置分页信息 PageHelper.startPage(pageNum, pageSize); // 分页查询博文 List<Blog> blogList = blogMapper.selectPage(); // 获取分页信息 PageResult<Blog> pageResult = PageResult.of(blogList); // 输出分页信息 System.out.println(pageResult.getPageNum()); // 当前页分页数 System.out.println(pageResult.getPageSize()); // 每页记录数 System.out.println(pageResult.getTotalSize()); // 总记录数 System.out.println(pageResult.getTotalPages()); // 总共分页数 System.out.println(pageResult.getPageStr()); // 分页条 System.out.println(pageResult.getList()); // 分页数据列表