mybatis的分页查询可以通过PageHelper插件实现

在数据库中我们使用分页查询的sql语句为：
select * from 表名 [where 条件] limit (page-1)*pageSize, pageSize;
page: 当前页码
pageSize: 每页显示的条数。

但是当我们使用PageHelper插件后页码什么的都不用我们计算 我们可以通过直接使用它里面的函数得到我们想要的。如：总条数 总页数 当前页面呈现的数据

使用步骤:
第一步：在pom.xml中引入依赖

<dependency><groupId>repMaven.com.github.pagehelper</groupId><artifactId>pagehelper</artifactId><version>5.3.0</version>
</dependency>

第二步:在conf.xml中设置PageHelper拦截器

<plugins><plugin interceptor="com.github.pagehelper.PageInterceptor"></plugin>
</plugins>

注意：

第三步:在测试类(单元测试)中测试:

    @Testpublic void testFindAll() throws Exception{Reader rd = Resources.getResourceAsReader("conf.xml");SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(rd);SqlSession session = factory.openSession();UserDao userDao = session.getMapper(UserDao.class);//pageNum:当前页 pageSize:每页显示几条数据PageHelper.startPage(1,2);List<User> user = userDao.findAll();PageInfo<User> pageInfo = new PageInfo<User>(user);System.out.println("总条数:"+pageInfo.getTotal());System.out.println("总页数:"+pageInfo.getPages());System.out.println("当前页码对应的数据:"+pageInfo.getList());session.close();}

数据库为:

/*Navicat Premium Data TransferSource Server         : MichinaishSource Server Type    : MySQLSource Server Version : 80011Source Host           : localhost:3306Source Schema         : mybatisTarget Server Type    : MySQLTarget Server Version : 80011File Encoding         : 65001Date: 06/06/2022 19:16:07
*/SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;-- ----------------------------
-- Table structure for tbl_user02
-- ----------------------------
DROP TABLE IF EXISTS `tbl_user02`;
CREATE TABLE `tbl_user02`  (`id` bigint(20) NOT NULL AUTO_INCREMENT COMMENT '主键ID',`name` varchar(30) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL COMMENT '姓名',`pwd` varchar(50) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL COMMENT '密码',`email` varchar(50) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL COMMENT '邮箱',PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT = 8 CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Dynamic;-- ----------------------------
-- Records of tbl_user02
-- ----------------------------
INSERT INTO `tbl_user02` VALUES (6, '张三', '123', 'zs@qq.com');
INSERT INTO `tbl_user02` VALUES (7, '李四', '123', 'ls@qq.com');
INSERT INTO `tbl_user02` VALUES (9, 'ac', '123', 'ac@qq.com');
INSERT INTO `tbl_user02` VALUES (10, 'bc', '123', 'bc@qq.com');
INSERT INTO `tbl_user02` VALUES (11, 'cc', '123', 'cc@qq.com');
INSERT INTO `tbl_user02` VALUES (12, 'dc', '123', 'dc@qq.com');SET FOREIGN_KEY_CHECKS = 1;