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Mybatis 分页查询

Mybatis 分页查询

作者: Maggieq8324 | 来源:发表于2019-08-26 13:20 被阅读0次

    该篇博客记录采用pagehelper分页插件实现Mybatis分页功能

    一、依赖
    • pom.xml
    <!-- pagehelper -->
    <dependency>
        <groupId>com.github.pagehelper</groupId>
        <artifactId>pagehelper-spring-boot-starter</artifactId>
        <version>1.2.5</version>
    </dependency>
    
    二、配置
    • application.yml
    # pagehelper
    pagehelper:
       helperDialect: mysql
       reasonable: true
       supportMethodsArguments: true
    params: count=countSql
    
    • CURD通用接口封装
    public interface CurdService<T> {
        /**
         * 分页查询
         * 这里统一封装了分页请求和结果,避免直接引入具体框架的分页对象, 如MyBatis或JPA的分页对象
         * 从而避免因为替换ORM框架而导致服务层、控制层的分页接口也需要变动的情况,替换ORM框架也不会
         * 影响服务层以上的分页接口,起到了解耦的作用
         * @param pageRequest 自定义,统一分页查询请求
         * @return PageResult 自定义,统一分页查询结果
         */
        PageResult findPage(PageRequest pageRequest);
    }
    
    • 分页请求封装
    public class PageRequest {
        /**
         * 当前页码
         */
        private int pageNum = 1;
        /**
         * 每页数量
         */
        private int pageSize = 10;
        /**
         * 查询参数
         */
        private Map<String, Object> params = new HashMap<>();
        
        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 Map<String, Object> getParams() {
            return params;
        }
        public void setParams(Map<String, Object> params) {
            this.params = params;
        }
        public Object getParam(String key) {
            return getParams().get(key);
        }
    }
    
    • 分页结果封装
    public class PageResult {
        /**
         * 当前页码
         */
        private int pageNum;
        /**
         * 每页数量
         */
        private int pageSize;
        /**
         * 记录总数
         */
        private long totalSize;
        /**
         * 页码总数
         */
        private int totalPages;
        /**
         * 分页数据
         */
        private List<?> content;
        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 long getTotalSize() {
            return totalSize;
        }
        public void setTotalSize(long totalSize) {
            this.totalSize = totalSize;
        }
        public int getTotalPages() {
            return totalPages;
        }
        public void setTotalPages(int totalPages) {
            this.totalPages = totalPages;
        }
        public List<?> getContent() {
            return content;
        }
        public void setContent(List<?> content) {
            this.content = content;
        }
    }
    
    • 分页助手封装
    public class MybatisPageHelper {
    
        public static final String findPage = "findPage";
        
        /**
         * 分页查询, 约定查询方法名为 “findPage” 
         * @param pageRequest 分页请求
         * @param mapper Dao对象,MyBatis的 Mapper  
         * @param args 方法参数
         * @return
         */
        public static PageResult findPage(PageRequest pageRequest, Object mapper) {
            return findPage(pageRequest, mapper, findPage);
        }
        
        /**
         * 调用分页插件进行分页查询
         * @param pageRequest 分页请求
         * @param mapper Dao对象,MyBatis的 Mapper  
         * @param queryMethodName 要分页的查询方法名
         * @param args 方法参数
         * @return
         */
        @SuppressWarnings({ "unchecked", "rawtypes" })
        public static PageResult findPage(PageRequest pageRequest, Object mapper, String queryMethodName, Object... args) {
            // 设置分页参数
            int pageNum = pageRequest.getPageNum();
            int pageSize = pageRequest.getPageSize();
            PageHelper.startPage(pageNum, pageSize);
            // 利用反射调用查询方法
            Object result = ReflectionUtils.invoke(mapper, queryMethodName, args);
            return getPageResult(pageRequest, new PageInfo((List) result));
        }
    
        /**
         * 将分页信息封装到统一的接口
         * @param pageRequest 
         * @param page
         * @return
         */
        private static PageResult getPageResult(PageRequest pageRequest, PageInfo<?> pageInfo) {
            PageResult pageResult = new PageResult();
            pageResult.setPageNum(pageInfo.getPageNum());
            pageResult.setPageSize(pageInfo.getPageSize());
            pageResult.setTotalSize(pageInfo.getTotal());
            pageResult.setTotalPages(pageInfo.getPages());
            pageResult.setContent(pageInfo.getList());
            return pageResult;
        }
    }
    
    • HTTP返回结果封装
    public class HttpResult {
        private int code = 200;
        private String msg;
        private Object data;
        
        public static HttpResult error() {
            return error(HttpStatus.SC_INTERNAL_SERVER_ERROR, "未知异常,请联系管理员");
        }
        public static HttpResult error(String msg) {
            return error(HttpStatus.SC_INTERNAL_SERVER_ERROR, msg);
        }
        public static HttpResult error(int code, String msg) {
            HttpResult r = new HttpResult();
            r.setCode(code);
            r.setMsg(msg);
            return r;
        }
        public static HttpResult ok(String msg) {
            HttpResult r = new HttpResult();
            r.setMsg(msg);
            return r;
        }
        public static HttpResult ok(Object data) {
            HttpResult r = new HttpResult();
            r.setData(data);
            return r;
        }
        public static HttpResult ok() {
            return new HttpResult();
        }
        public int getCode() {
            return code;
        }
        public void setCode(int code) {
            this.code = code;
        }
        public String getMsg() {
            return msg;
        }
        public void setMsg(String msg) {
            this.msg = msg;
        }
        public Object getData() {
            return data;
        }
        public void setData(Object data) {
            this.data = data;
        }
    }
    
    三、实现
    • SysUserController.java
    @RestController
    @RequestMapping("/user")
    public class SysUserController {
    
        @Autowired
        private SysUserService sysUserService;
        
        @PostMapping(value="/findPage")
        public HttpResult findPage(@RequestBody PageRequest pageRequest) {
            return HttpResult.ok(sysUserService.findPage(pageRequest));
        }
    }
    
    • SysUserService.java
    public interface SysUserService extends CurdService<SysUser> {
    
    }
    
    • SysUserMapper.java
    public interface SysUserMapper {
        List<SysUser> findPage();
    }
    
    • SysUserServiceImpl.java
    //经过对分页查询业务的封装,只需调用MybatisPageHelper.findPage(pageRequest, sysUserMapper)即可实现分页查询功能
    @Service
    public class SysUserServiceImpl implements SysUserService {
    
        @Autowired
        private SysUserMapper sysUserMapper;
        
        @Override
        public PageResult findPage(PageRequest pageRequest) {
            return MybatisPageHelper.findPage(pageRequest, sysUserMapper);
        }
    }
    
    • SysUserMapper.xml
    <?xml version="1.0" encoding="UTF-8"?>
    <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
    <mapper namespace="com.coisini.admin.mapper.SysUserMapper">
      <resultMap id="BaseResultMap" type="com.coisini.admin.entity.SysUser">
        <id column="id" jdbcType="BIGINT" property="id" />
        <result column="name" jdbcType="VARCHAR" property="name" />
        <result column="nick_name" jdbcType="VARCHAR" property="nickName" />
        <result column="avatar" jdbcType="VARCHAR" property="avatar" />
        <result column="password" jdbcType="VARCHAR" property="password" />
        <result column="salt" jdbcType="VARCHAR" property="salt" />
        <result column="email" jdbcType="VARCHAR" property="email" />
        <result column="mobile" jdbcType="VARCHAR" property="mobile" />
        <result column="status" jdbcType="TINYINT" property="status" />
        <result column="dept_id" jdbcType="BIGINT" property="deptId" />
        <result column="create_by" jdbcType="VARCHAR" property="createBy" />
        <result column="create_time" jdbcType="TIMESTAMP" property="createTime" />
        <result column="last_update_by" jdbcType="VARCHAR" property="lastUpdateBy" />
        <result column="last_update_time" jdbcType="TIMESTAMP" property="lastUpdateTime" />
        <result column="del_flag" jdbcType="TINYINT" property="delFlag" />
      </resultMap>
      <sql id="Base_Column_List">
        id, name, nick_name, avatar, password, salt, email, mobile, status, dept_id, create_by, 
        create_time, last_update_by, last_update_time, del_flag
      </sql>
      <select id="findPage" resultMap="BaseResultMap">
        select u.*, (select d.name from sys_dept d where d.id = u.dept_id) deptName from sys_user u
      </select>
    </mapper>
    
    四、测试
    在这里插入图片描述

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