mybatis分页插件的使用（电商项目前端动态查询排序）

记得之前写过的各种各样的分页，每次编写分页逻辑都得浪费很长时间，还得调试，经常出问题。实际项目中可能会用到分页比较多的情况。可以使用拦截器分页（尚未研究）,下面推荐mybatis的pagehepler插件

maven导包（第一个是肯定用到的）

<!-- mybatis pager -->    <dependency>      <groupId>com.github.pagehelper</groupId>      <artifactId>pagehelper</artifactId>      <version>4.1.0</version>    </dependency>    <dependency>      <groupId>com.github.miemiedev</groupId>      <artifactId>mybatis-paginator</artifactId>      <version>1.2.17</version>    </dependency>    <dependency>      <groupId>com.github.jsqlparser</groupId>      <artifactId>jsqlparser</artifactId>      <version>0.9.4</version>    </dependency>

分页方法的实现：

//分页方法    public ServerResponse<PageInfo> getProductList(int pageNum,int pageSize){        //startPage - start        PageHelper.startPage(pageNum,pageSize);        //填充自己的sql逻辑             //查询所有的产品        List<Product> productList = productMapper.selectList();             //将所有产品换成一个vo的对象        List<ProductListVo> productListVoList = Lists.newArrayList();        for (Product product:productList){            ProductListVo productListVo = assembleProductListVo(product);            productListVoList.add(productListVo);        }        //pagehelper收尾        PageInfo pageResult = new PageInfo(productList);        pageResult.setList(productListVoList);        return ServerResponse.createBySuccess(pageResult);    }

上面代码 pageResult = new PageInfo（productList）;这里写productListVoList也是ok的，但是前提是要保证mybatispagehelper和volist的分页是一致的。在处理vo逻辑的时候和mapper查出来的是一样的。size  

如果是同一个list，set方法可以不写的

下面粘贴一下pageInfo的源码：

/* * The MIT License (MIT) * * Copyright (c) 2014 [e-mail] * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN * THE SOFTWARE. */package com.github.pagehelper;import java.io.Serializable;import java.util.Collection;import java.util.List;/** * 对Page<E>结果进行包装 * <p/> * 新增分页的多项属性，主要参考:http://bbs.csdn.net/topics/360010907 * * @author liuzh/abel533/isea533 * @version 3.3.0 * @since 3.2.2 * 项目地址 : http://git.oschina.net/free/Mybatis_PageHelper */@SuppressWarnings({"rawtypes", "unchecked"})public class PageInfo<T> implements Serializable {    private static final long serialVersionUID = 1L;    //当前页    private int pageNum;    //每页的数量    private int pageSize;    //当前页的数量    private int size;    //排序    private String orderBy;    //由于startRow和endRow不常用，这里说个具体的用法    //可以在页面中"显示startRow到endRow 共size条数据"    //当前页面第一个元素在数据库中的行号    private int startRow;    //当前页面最后一个元素在数据库中的行号    private int endRow;    //总记录数    private long total;    //总页数    private int pages;    //结果集    private List<T> list;    //第一页    private int firstPage;    //前一页    private int prePage;    //下一页    private int nextPage;    //最后一页    private int lastPage;    //是否为第一页    private boolean isFirstPage = false;    //是否为最后一页    private boolean isLastPage = false;    //是否有前一页    private boolean hasPreviousPage = false;    //是否有下一页    private boolean hasNextPage = false;    //导航页码数    private int navigatePages;    //所有导航页号    private int[] navigatepageNums;    public PageInfo() {    }    /**     * 包装Page对象     *     * @param list     */    public PageInfo(List<T> list) {        this(list, 8);    }    /**     * 包装Page对象     *     * @param list          page结果     * @param navigatePages 页码数量     */    public PageInfo(List<T> list, int navigatePages) {        if (list instanceof Page) {            Page page = (Page) list;            this.pageNum = page.getPageNum();            this.pageSize = page.getPageSize();            this.orderBy = page.getOrderBy();            this.pages = page.getPages();            this.list = page;            this.size = page.size();            this.total = page.getTotal();            //由于结果是>startRow的，所以实际的需要+1            if (this.size == 0) {                this.startRow = 0;                this.endRow = 0;            } else {                this.startRow = page.getStartRow() + 1;                //计算实际的endRow（最后一页的时候特殊）                this.endRow = this.startRow - 1 + this.size;            }        } else if (list instanceof Collection) {            this.pageNum = 1;            this.pageSize = list.size();            this.pages = 1;            this.list = list;            this.size = list.size();            this.total = list.size();            this.startRow = 0;            this.endRow = list.size() > 0 ? list.size() - 1 : 0;        }        if (list instanceof Collection) {            this.navigatePages = navigatePages;            //计算导航页            calcNavigatepageNums();            //计算前后页，第一页，最后一页            calcPage();            //判断页面边界            judgePageBoudary();        }    }    /**     * 计算导航页     */    private void calcNavigatepageNums() {        //当总页数小于或等于导航页码数时        if (pages <= navigatePages) {            navigatepageNums = new int[pages];            for (int i = 0; i < pages; i++) {                navigatepageNums[i] = i + 1;            }        } else { //当总页数大于导航页码数时            navigatepageNums = new int[navigatePages];            int startNum = pageNum - navigatePages / 2;            int endNum = pageNum + navigatePages / 2;            if (startNum < 1) {                startNum = 1;                //(最前navigatePages页                for (int i = 0; i < navigatePages; i++) {                    navigatepageNums[i] = startNum++;                }            } else if (endNum > pages) {                endNum = pages;                //最后navigatePages页                for (int i = navigatePages - 1; i >= 0; i--) {                    navigatepageNums[i] = endNum--;                }            } else {                //所有中间页                for (int i = 0; i < navigatePages; i++) {                    navigatepageNums[i] = startNum++;                }            }        }    }    /**     * 计算前后页，第一页，最后一页     */    private void calcPage() {        if (navigatepageNums != null && navigatepageNums.length > 0) {            firstPage = navigatepageNums[0];            lastPage = navigatepageNums[navigatepageNums.length - 1];            if (pageNum > 1) {                prePage = pageNum - 1;            }            if (pageNum < pages) {                nextPage = pageNum + 1;            }        }    }    /**     * 判定页面边界     */    private void judgePageBoudary() {        isFirstPage = pageNum == 1;        isLastPage = pageNum == pages;        hasPreviousPage = pageNum > 1;        hasNextPage = pageNum < pages;    }    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 getSize() {        return size;    }    public void setSize(int size) {        this.size = size;    }    public String getOrderBy() {        return orderBy;    }    public void setOrderBy(String orderBy) {        this.orderBy = orderBy;    }    public int getStartRow() {        return startRow;    }    public void setStartRow(int startRow) {        this.startRow = startRow;    }    public int getEndRow() {        return endRow;    }    public void setEndRow(int endRow) {        this.endRow = endRow;    }    public long getTotal() {        return total;    }    public void setTotal(long total) {        this.total = total;    }    public int getPages() {        return pages;    }    public void setPages(int pages) {        this.pages = pages;    }    public List<T> getList() {        return list;    }    public void setList(List<T> list) {        this.list = list;    }    public int getFirstPage() {        return firstPage;    }    public void setFirstPage(int firstPage) {        this.firstPage = firstPage;    }    public int getPrePage() {        return prePage;    }    public void setPrePage(int prePage) {        this.prePage = prePage;    }    public int getNextPage() {        return nextPage;    }    public void setNextPage(int nextPage) {        this.nextPage = nextPage;    }    public int getLastPage() {        return lastPage;    }    public void setLastPage(int lastPage) {        this.lastPage = lastPage;    }    public boolean isIsFirstPage() {        return isFirstPage;    }    public void setIsFirstPage(boolean isFirstPage) {        this.isFirstPage = isFirstPage;    }    public boolean isIsLastPage() {        return isLastPage;    }    public void setIsLastPage(boolean isLastPage) {        this.isLastPage = isLastPage;    }    public boolean isHasPreviousPage() {        return hasPreviousPage;    }    public void setHasPreviousPage(boolean hasPreviousPage) {        this.hasPreviousPage = hasPreviousPage;    }    public boolean isHasNextPage() {        return hasNextPage;    }    public void setHasNextPage(boolean hasNextPage) {        this.hasNextPage = hasNextPage;    }    public int getNavigatePages() {        return navigatePages;    }    public void setNavigatePages(int navigatePages) {        this.navigatePages = navigatePages;    }    public int[] getNavigatepageNums() {        return navigatepageNums;    }    public void setNavigatepageNums(int[] navigatepageNums) {        this.navigatepageNums = navigatepageNums;    }    @Override    public String toString() {        final StringBuffer sb = new StringBuffer("PageInfo{");        sb.append("pageNum=").append(pageNum);        sb.append(", pageSize=").append(pageSize);        sb.append(", size=").append(size);        sb.append(", startRow=").append(startRow);        sb.append(", endRow=").append(endRow);        sb.append(", total=").append(total);        sb.append(", pages=").append(pages);        sb.append(", list=").append(list);        sb.append(", firstPage=").append(firstPage);        sb.append(", prePage=").append(prePage);        sb.append(", nextPage=").append(nextPage);        sb.append(", lastPage=").append(lastPage);        sb.append(", isFirstPage=").append(isFirstPage);        sb.append(", isLastPage=").append(isLastPage);        sb.append(", hasPreviousPage=").append(hasPreviousPage);        sb.append(", hasNextPage=").append(hasNextPage);        sb.append(", navigatePages=").append(navigatePages);        sb.append(", navigatepageNums=");        if (navigatepageNums == null) sb.append("null");        else {            sb.append('[');            for (int i = 0; i < navigatepageNums.length; ++i)                sb.append(i == 0 ? "" : ", ").append(navigatepageNums[i]);            sb.append(']');        }        sb.append('}');        return sb.toString();    }}

在电商平台中的使用：前端搜索动态排序业务

@controller层

@RequestMapping("list.do")    @ResponseBody    public ServerResponse<PageInfo> list(@RequestParam(value = "keyword",required = false) String keyword,                                         @RequestParam(value = "categroyId",required = false)Integer categroyId,                                         @RequestParam(value = "pageNum",defaultValue = "1") Integer pageNum,                                         @RequestParam(value = "pageSize",defaultValue = "10") Integer pageSize,                                         @RequestParam(value = "orderBy",defaultValue = "") String orderBy){       return iProductService.getProductByKeywordCategroy(keyword,categroyId,pageNum,pageSize,orderBy);    }

@service层

public ServerResponse<PageInfo> getProductByKeywordCategroy(String keyword,Integer categroyId,Integer pageNum,Integer pageSize,String orderBy){        if (StringUtils.isBlank(keyword) && categroyId == null){            return ServerResponse.createByErrorMessage(ResponseCode.ILLEGAL_ARGUMENT.getCode(),ResponseCode.ILLEGAL_ARGUMENT.getDesc());        }        List<Integer> categroyIdList = new ArrayList<Integer>();        if (categroyId!=null){            Category category = categoryMapper.selectByPrimaryKey(categroyId);            if (category == null && StringUtils.isBlank(keyword)){                //没有该分类，并且还没有关键字，这时候返回一个空的结果集不报错                PageHelper.startPage(pageNum,pageSize);                List<ProductListVo> productListVoList = Lists.newArrayList();                PageInfo pageInfo = new PageInfo(productListVoList);                return ServerResponse.createBySuccess(pageInfo);            }            categroyIdList = iCategroyService.selectCategroyAndChildrenById(category.getId()).getData();        }        if (StringUtils.isNotBlank(keyword)){            keyword = new StringBuilder().append("%").append(keyword).append("%").toString();        }        PageHelper.startPage(pageNum,pageSize);        //排序处理,动态排序，和前端约定的        if (StringUtils.isNotBlank(orderBy)){            if (Const.ProductListOrderBy.PRICE_ASC_DESC.contains(orderBy)){                String[] orderByArray = orderBy.split("_");                PageHelper.orderBy(orderByArray[0] +" "+orderByArray[1]);            }        }        List<Product> productList = productMapper.selectByNameAndProductIds(StringUtils.isBlank(keyword)?null:keyword,categroyIdList.size()==0?null:categroyIdList);        List<ProductListVo> productListVoList = Lists.newArrayList();        for (Product product:productList){            ProductListVo productListVo = assembleProductListVo(product);            productListVoList.add(productListVo);        }        PageInfo pageInfo = new PageInfo(productList);        pageInfo.setList(productListVoList);        return ServerResponse.createBySuccess(pageInfo);    }

const公共类（和前端约定配置：price_desc降序   price_asc升序）：

public interface ProductListOrderBy{        Set<String> PRICE_ASC_DESC = Sets.newHashSet("price_desc","price_asc");    }

mybatis Dao层接口

List<Product> selectByNameAndProductIds(@Param("productName") String productName,@Param("categroyIdList")List<Integer> categroyIdList);

mybatis xml实现：

<select id="selectByNameAndProductIds" resultMap="BaseResultMap" parameterType="map">    select    <include refid="Base_Column_List"/>    from mmall_product    where status = 1    <if test="productName!=null">      and name like #{productName}    </if>    <if test="categroyIdList!=null">      and category_id in      <foreach collection="categroyIdList" open="(" close=")" separator="," item="item" index="index">          #{item}      </foreach>    </if>  </select>