mybaties分页原理 mybatis如何实现分页,有几种方式

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一、MyBatisPlusConfig中配置分页插件

/*** 配置分页插件* @return page*/@Beanpublic PaginationInterceptor paginationInterceptor(){PaginationInterceptor paginationInterceptor = new PaginationInterceptor();// 开启 count 的 join 优化,只针对部分 left joinpaginationInterceptor.setCountSqlParser(new JsqlParserCountOptimize(true));return paginationInterceptor;}

【mybaties分页原理 mybatis如何实现分页,有几种方式】1. 分页实现的原理
Mybatis-plus分页插件使用的是IPage进行分页。IPage内部原理是基于拦截器，拦截的是方法以及方法中的参数。判断是否是查询操作，如果是查询操作，才会进入分页的处理逻辑。进入分页逻辑处理后，拦截器会通过反射获取该方法的参数进行判断是否存在IPage对象的实现类。如果不存在则不进行分页，存在则将该参数赋值给IPage对象，然后进行拼接sql的处理完成分页操作。

二、统一结果集1. 创建返回码定义类

public class ResultCode {/*** 成功**/public final static int OK = 20000;/*** 失败**/public final static int ERROR = 20001;/*** 用户名或密码错误**/public final static int LOGIN_ERROR = 20002;/*** 权限不足**/public final static int ACCESS_ERROR = 20003;/*** 远程调用失败**/public final static int REMOTE_ERROR = 20004;/*** 重复操作**/public final static int REPEAT_ERROR = 20005;}

2. 创建结果集类

@[email protected](value = "http://www.mnbkw.com/jxjc/168754/全局统一返回结果")public class R implements Serializable {public final static String OK_MSG = "请求成功";public final static String FAIL_MSG = "请求失败";@ApiModelProperty(value = "http://www.mnbkw.com/jxjc/168754/是否成功")private boolean success;@ApiModelProperty(value = "http://www.mnbkw.com/jxjc/168754/返回码")private Integer code;@ApiModelProperty(value = "http://www.mnbkw.com/jxjc/168754/返回消息")private String message;@ApiModelProperty(value = "http://www.mnbkw.com/jxjc/168754/返回数据")private Object data;@ApiModelProperty(value = "http://www.mnbkw.com/jxjc/168754/总条数")private Long total;@ApiModelProperty(value = "http://www.mnbkw.com/jxjc/168754/分页信息")private PageInfo pageInfo;@Datapublic static class PageInfo {@ApiModelProperty("当前页")protected int currentPage;@ApiModelProperty("页大小")protected int pageSize;@ApiModelProperty("总记录数")protected long totalCount;@ApiModelProperty("总页数")protected long totalPage;public PageInfo() {}@ConstructorProperties({"currentPage", "pageSize", "totalCount", "totalPage"})public PageInfo(int currentPage, int pageSize, long totalCount, long totalPage) {this.currentPage = currentPage;this.pageSize = pageSize;this.totalCount = totalCount;this.totalPage = totalPage;}}private R(){}private R(int code, String msg, Object data) {this.code = code;this.message = msg;if (data instanceof Page<?>) {Page<?> page = (Page<?>) data;this.total = page.getTotal();this.data = http://www.mnbkw.com/jxjc/168754/page.getRecords();this.pageInfo = new PageInfo((int)page.getCurrent(), (int)page.getSize(), page.getTotal(), page.getPages());} else {this.data = data;}}public static R ok(){R r = new R();r.setSuccess(true);r.setCode(ResultCode.OK);r.setMessage("成功");return r;}public static R ok(Object data) {return new R(ResultCode.OK, OK_MSG, data);}public static R ok(String msg, Object data) {return new R(ResultCode.OK, msg, data);}public static R error(){R r = new R();r.setSuccess(false);r.setCode(ResultCode.ERROR);r.setMessage("失败");return r;}public static R error(String msg) {return new R(ResultCode.ERROR, msg, null);}public static R error(int errorCode, String msg) {return new R(errorCode, msg, null);}public R message(String message){this.setMessage(message);return this;}public R code(Integer code){this.setCode(code);return this;}public R data(Object data){this.setData(data);return this;}}

三、编写分页接口1. 先编写查询类
代码如下：

@Datapublic class MemberQueryVo extends BasePageEntity{@ApiModelProperty(value = "http://www.mnbkw.com/jxjc/168754/用户名")private String userName;}

2. service层
先定义一个查询分页的接口，在实现类里做相关处理

@Servicepublic class MemberServiceImpl extends ServiceImpl<MemberMapper, Member> implements MemberService {@Overridepublic IPage<Member> listMemberPage(MemberQueryVo queryVo) {IPage<Member> page = new Page<>(queryVo.getCurrentPage(),queryVo.getCurrentPage());//条件查询LambdaQueryWrapper<Member> queryWrapper = new LambdaQueryWrapper<Member>();if (StringUtils.isNotBlank(queryVo.getUserName())) {queryWrapper.like(Member::getUserName, queryVo.getUserName());}return baseMapper.selectPage(page,queryWrapper);}}

3. controller层
编写分页接口，代码如下：

@ApiOperation(value = "http://www.mnbkw.com/jxjc/168754/分页用户列表")@GetMapping(value = "http://www.mnbkw.com/getPage")public R listPage(MemberQueryVo queryVo){IPage<Member> page = memberService.listMemberPage(queryVo);return R.ok(page);}

4. 接口测试
直接通过swagger生成的api接口页面进行测试，当前页、每页参数传1时，返回的分页信息里，总数是两条，只返回了一条数据。说明分页成功。

在进行条件查询的时候，也成功查询对应数据。

总结
感谢大家的阅读，上就是今天要讲的内容，本文简单介绍了如何配置分页插件、以及分页的原理。如有不足之处，纯属能力有限，还请多多包涵。