springboot实现分页功能的完整代码
作者:Starbright.
1.分页功能的作用
分页功能作为各类网站和系统不可或缺的部分(例如百度搜索结果的分页等),当一个页面数据量大的时候分页作用就体现出来的,其作用有以下5个。
(1)减少系统资源的消耗
(2)提高数据库的查询性能
(3)提升页面的访问速度
(4)符合用户的浏览习惯
(5)适配页面的排版
2.建立测试数据库
由于需要实现分页功能,所需的数据较多
DROP TABLE IF EXISTS tb_user; CREATE TABLE tb_user ( id int(11) NOT NULL AUTO_INCREMENT COMMENT '主键id', name varchar(100) NOT NULL DEFAULT '' COMMENT '登录名', password varchar(100) NOT NULL DEFAULT '' COMMENT '密码', PRIMARY KEY (id) USING BTREE ) ENGINE = InnoDB CHARACTER SET = utf8; insert into tb_user (id,name,password) value (1,'C','123456'), (2,'C++','123456'), (3,'Java','123456'), (4,'Python','123456'), (5,'R','123456'), (6,'C#','123456'); insert into tb_user (id,name,password) value (7,'test1','123456'); insert into tb_user (id,name,password) value (8,'test2','123456'); insert into tb_user (id,name,password) value (9,'test3','123456'); insert into tb_user (id,name,password) value (10,'test4','123456'); insert into tb_user (id,name,password) value (11,'test5','123456'); insert into tb_user (id,name,password) value (12,'test6','123456'); insert into tb_user (id,name,password) value (13,'test7','123456'); insert into tb_user (id,name,password) value (14,'test8','123456'); insert into tb_user (id,name,password) value (15,'test9','123456'); insert into tb_user (id,name,password) value (16,'test10','123456'); insert into tb_user (id,name,password) value (17,'test11','123456'); insert into tb_user (id,name,password) value (18,'test12','123456'); insert into tb_user (id,name,password) value (19,'test13','123456'); insert into tb_user (id,name,password) value (20,'test14','123456'); insert into tb_user (id,name,password) value (21,'test15','123456'); insert into tb_user (id,name,password) value (22,'test16','123456'); insert into tb_user (id,name,password) value (23,'test17','123456'); insert into tb_user (id,name,password) value (24,'test18','123456'); insert into tb_user (id,name,password) value (25,'test19','123456'); insert into tb_user (id,name,password) value (26,'test20','123456'); insert into tb_user (id,name,password) value (27,'test21','123456'); insert into tb_user (id,name,password) value (28,'test22','123456'); insert into tb_user (id,name,password) value (29,'test23','123456'); insert into tb_user (id,name,password) value (30,'test24','123456'); insert into tb_user (id,name,password) value (31,'test25','123456'); insert into tb_user (id,name,password) value (32,'test26','123456'); insert into tb_user (id,name,password) value (33,'test27','123456'); insert into tb_user (id,name,password) value (34,'test28','123456'); insert into tb_user (id,name,password) value (35,'test29','123456'); insert into tb_user (id,name,password) value (36,'test30','123456'); insert into tb_user (id,name,password) value (37,'test31','123456'); insert into tb_user (id,name,password) value (38,'test32','123456'); insert into tb_user (id,name,password) value (39,'test33','123456'); insert into tb_user (id,name,password) value (40,'test34','123456'); insert into tb_user (id,name,password) value (41,'test35','123456'); insert into tb_user (id,name,password) value (42,'test36','123456'); insert into tb_user (id,name,password) value (43,'test37','123456'); insert into tb_user (id,name,password) value (44,'test38','123456'); insert into tb_user (id,name,password) value (45,'test39','123456'); insert into tb_user (id,name,password) value (46,'test40','123456'); insert into tb_user (id,name,password) value (47,'test41','123456'); insert into tb_user (id,name,password) value (48,'test42','123456'); insert into tb_user (id,name,password) value (49,'test43','123456'); insert into tb_user (id,name,password) value (50,'test44','123456'); insert into tb_user (id,name,password) value (51,'test45','123456');
3.分页功能返回的结果封装
新建一个util包并在包中新建Result通用结果类,代码如下:
package ltd.newbee.mall.entity; public class User { private Integer id; private String name; private String password; public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } }
后端接口返回的数据会根据以上格式进行数据封装,包括业务码、返回信息、实际的数据结果。这个格式是开发人员自行设置的,如果有其他更好的方案也可以进行适当的调整。
在util包中新建PageResult通用结果类,代码如下:
package ltd.newbee.mall.util; import java.util.List; /** * 分页工具类 */ public class PageResult { //总记录数 private int totalCount; //每页记录数 private int pageSize; //总页数 private int totalPage; //当前页数 private int currPage; //列表数据 private List<?> list; /** * * @param totalCount 总记录数 * @param pageSize 每页记录数 * @param currPage 当前页数 * @param list 列表数据 */ public PageResult(int totalCount, int pageSize, int currPage, List<?> list) { this.totalCount = totalCount; this.pageSize = pageSize; this.currPage = currPage; this.list = list; this.totalPage = (int) Math.ceil((double) totalCount / pageSize); } public int getTotalCount() { return totalCount; } public void setTotalCount(int totalCount) { this.totalCount = totalCount; } public int getPageSize() { return pageSize; } public void setPageSize(int pageSize) { this.pageSize = pageSize; } public int getTotalPage() { return totalPage; } public void setTotalPage(int totalPage) { this.totalPage = totalPage; } public int getCurrPage() { return currPage; } public void setCurrPage(int currPage) { this.currPage = currPage; } public List<?> getList() { return list; } public void setList(List<?> list) { this.list = list; } }
4.分页功能代码具体实现
4.1数据层
在UserDao接口中新增两个方法findUsers()和getTotalUser(),代码如下所示:
/** * 返回分页数据列表 * * @param pageUtil * @return */ List<User> findUsers(PageQueryUtil pageUtil); /** * 返回数据总数 * * @param pageUtil * @return */ int getTotalUser(PageQueryUtil pageUtil);
在UserMapper.xml文件中新增这两个方法的映射语句,代码如下所示:
<!--分页--> <!--查询用户列表--> <select id="findUsers" parameterType="Map" resultMap="UserResult"> select id,name,password from tb_user order by id desc <if test="start!=null and limit!=null"> limit #{start}.#{limit} </if> </select> <!--查询用户总数--> <select id="getTotalUser" parameterType="Map" resultType="int"> select count(*) from tb_user </select>
4.2业务层
新建service包,并新增业务类UserService,代码如下所示:
import ltd.newbee.mall.dao.UserDao; import ltd.newbee.mall.entity.User; import ltd.newbee.mall.util.PageResult; import ltd.newbee.mall.util.PageQueryUtil; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Service; import java.util.List; @Service public class UserService { @Autowired private UserDao userDao; public PageResult getUserPage(PageQueryUtil pageUtil){ //当前页面中的数据列表 List<User> users = userDao.findUsers(pageUtil); //数据总条数,用于计算分页数据 int total = userDao.getTotalUser(pageUtil); //分页信息封装 PageResult pageResult = new PageResult(users,total,pageUtil.getLimit(),pageUtil.getPage()); return pageResult; } }
首先根据当前页面和每页条数查询当前页的数据集合,然后调用select count(*)语句查询数据的总条数用于计算分页数据,最后将获取的数据封装到PageResult对象中并返回给控制层。
4.3控制层
在controller包中新建PageTestController类,用于实现分页请求的处理并返回查询结果,代码如下所示:
@RestController @RequestMapping("users") public class PageTestController { @Autowired private UserService userService; //分页功能测试 @RequestMapping(value = "/list",method = RequestMethod.GET) public Result list(@RequestParam Map<String,Object> params){ Result result = new Result(); if (StringUtils.isEmpty(params.get("page"))||StringUtils.isEmpty(params.get("limit"))){ //返回错误码 result.setResultCode(500); //错误信息 result.setMessage("参数异常!"); return result; } //封装查询参数 PageQueryUtil queryParamList = new PageQueryUtil(params); //查询并封装分页结果集 PageResult userPage = userService.getUserPage(queryParamList); //返回成功码 result.setResultCode(200); result.setMessage("查询成功"); //返回分页数据 result.setData(userPage); return result; } }
分页功能的交互流程:前端将所需页码和条数参数传输给后端,后端在接收分页请求后对分页参数进行计算,并利用MySQL的limit关键字查询对应的记录,在查询结果被封装后返回给前端。在TestUserControler类上使用的是@RestController注解,该注解相当于@ResponseBody+@Controller的组合注解。
5.jqGrid分页插件
jqGrid是一个用来显示网格数据的jQuery插件。开发人员通过使用jqGrid可以轻松实现前端页面与后台数据的Ajax异步通信并实现分页功能。同时,jqGrid是一款代码开源的分页插件,源码也一直处于迭代更新的状态中。
下载地址:jqGrid
下载jqGrid后解压文件,将解压的文件直接拖进项目的static目录下
以下是jqGrid实现分页的步骤:
首先,在前端页面代码中引入jqGrid分页插件所需的源文件,代码如下所示:
<link href="plugins/jqgrid-5.8.2/ui.jqgrid-bootstrap4.css" rel="external nofollow" rel="stylesheet"/> <!--jqGrid依赖jQuery,因此需要先引入jquery.min.js文件,下方地址为字节跳动提供的cdn地址--> <script src="http://s3.pstatp.com/cdn/expire-1-M/jquery/3.3.1/jquery.min.js"></script> <!--grid.locale-cn.js为国际化所需的文件,-cn表示中文--> <script src="plugins/jqgrid-5.8.2/grid.locale-cn.js"></script> <script src="plugins/jqgrid-5.8.2/jquery.jqGrid.min.js"></script>
其次,在页面中需要展示分页数据的区域添加用于jqGrid初始化的代码:
<!--jqGrid必要DOM,用于创建表格展示列表数据--> <table id="jqGrid" class="table table-bordered"></table> <!--jqGrid必要DOM,分页信息区域--> <div id="jqGridPager"></div>
最后,调用jqGrid分页插件的jqGrid()方法渲染分页展示区域,代码如下所示:
jqGrid()方法中的参数及含义如图所示。
jqGrid前端页面测试:
在resources/static目中新建jqgrid-page-test.html文件,代码如下所示:
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>jqGrid分页测试</title> <!--引入bootstrap样式文件--> <link rel="stylesheet" href="/static/bootstrap-5.3.0-alpha3-dist/css/bootstrap.css" rel="external nofollow" /> <link href="jqGrid-5.8.2/css/ui.jqgrid-bootstrap4.css" rel="external nofollow" rel="stylesheet"/> </head> <body> <div style="margin: 24px;"> <!--数据展示列表,id为jqGrid--> <table id="jqGrid" class="table table-bordered"></table> <!--分页按钮展示区--> <div id="jqGridPager"></div> </div> </body> <!--jqGrid依赖jQuery,因此需要先引入jquery.min.js文件,下方地址为字节跳动提供的cdn地址--> <script src="http://s3.pstatp.com/cdn/expire-1-M/jquery/3.3.1/jquery.min.js"></script> <!--grid.locale-cn.js为国际化所需的文件,-cn表示中文--> <script src="plugins/jqgrid-5.8.2/grid.locale-cn.js"></script> <script src="plugins/jqgrid-5.8.2/jquery.jqGrid.min.js"></script> <script src="jqgrid-page-test.js"></script> </html>
jqGrid初始化
在resources/static目录下新建jqgrid-page-test.js文件,代码如下所示:
$(function () { $("#jqGrid").jqGrid({ url: 'users/list', datatype: "json", colModel: [ {label: 'id',name: 'id', index: 'id', width: 50, hidden: true,key:true}, {label: '登录名',name: 'name',index: 'name', sortable: false, width: 80}, {label: '密码字段',name: 'password',index: 'password', sortable: false, width: 80} ], height: 485, rowNum: 10, rowList: [10,30,50], styleUI: 'Bootstrap', loadtext: '信息读取中...', rownumbers: true, rownumWidth: 35, autowidth: true, multiselect: true, pager: "#jqGridPager", jsonReader:{ root: "data.list", page: "data.currPage", total: "data.totalCount" }, prmNames:{ page: "page", rows: "limit", order: "order" }, gridComplete: function () { //隐藏grid底部滚动条 $("#jqGrid").closest(".ui-jqgrid-bdiv").css({"overflow-x": "hidden"}); } }); $(window).resize(function () { $("jqGrid").setGridWidth($(".card-body").width()); }); });
总结
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