springboot+mybatis分页插件pageHelper的配置与使用

1、在pom文件里面加入pageHelper分页jar包依赖：

<dependency>
   <groupId>com.github.pagehelper</groupId>
   <artifactId>pagehelper</artifactId>
   <version>4.2.1</version>
</dependency>
2、在mybatis配置文件中加入pageHelper分页插件：

//配置分页插件，详情请查阅官方文档
PageHelper pageHelper = new PageHelper();
Properties properties = new Properties();
properties.setProperty("pageSizeZero", "true");//分页尺寸为0时查询所有纪录不再执行分页
properties.setProperty("reasonable", "true");//页码<=0 查询第一页，页码>=总页数查询最后一页
properties.setProperty("supportMethodsArguments", "true");//支持通过 Mapper 接口参数来传递分页参数
pageHelper.setProperties(properties);

//添加插件
sqlSessionFactoryBean.setPlugins(new Interceptor[]{pageHelper});

3、业务层代码：

//pageHelper组件进行分页
Page<CloudProductBO> page = PageHelper.offsetPage(pageNo, pageSize);
cloudProductDao.queryProductByCondition(param);
List<CloudProductBO> result = page.getResult();
PageInfo pageInfo = new PageInfo(result);
return pageInfo;

pageHelper类下面的SQL语句进行自动分页，page.getResult()的结果就是分页查询的结果，pageInfo是分页组件，直接返还给前台，里面有分页插件，下面就是pageInfo类。

public class PageInfo<T> implements Serializable {
    private static final long serialVersionUID = 1L;
    private int pageNum;
    private int pageSize;
    private int size;
    private String orderBy;
    private int startRow;
    private int endRow;
    private long total;
    private int pages;
    private List<T> list;
    private int prePage;
    private int nextPage;
    private boolean isFirstPage;
    private boolean isLastPage;
    private boolean hasPreviousPage;
    private boolean hasNextPage;
    private int navigatePages;
    private int[] navigatepageNums;
    private int navigateFirstPage;
    private int navigateLastPage;

    public PageInfo() {
        this.isFirstPage = false;
        this.isLastPage = false;
        this.hasPreviousPage = false;
        this.hasNextPage = false;
    }

    public PageInfo(List<T> list) {
        this(list, 8);
    }

    public PageInfo(List<T> list, int navigatePages) {
        this.isFirstPage = false;
        this.isLastPage = false;
        this.hasPreviousPage = false;
        this.hasNextPage = false;
        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();
            if(this.size == 0) {
                this.startRow = 0;
                this.endRow = 0;
            } else {
                this.startRow = page.getStartRow() + 1;
                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 = (long)list.size();
            this.startRow = 0;
            this.endRow = list.size() > 0?list.size() - 1:0;
        }

        if(list instanceof Collection) {
            this.navigatePages = navigatePages;
            this.calcNavigatepageNums();
            this.calcPage();
            this.judgePageBoudary();
        }

    }

    private void calcNavigatepageNums() {
        int startNum;
        if(this.pages <= this.navigatePages) {
            this.navigatepageNums = new int[this.pages];

            for(startNum = 0; startNum < this.pages; ++startNum) {
                this.navigatepageNums[startNum] = startNum + 1;
            }
        } else {
            this.navigatepageNums = new int[this.navigatePages];
            startNum = this.pageNum - this.navigatePages / 2;
            int endNum = this.pageNum + this.navigatePages / 2;
            int i;
            if(startNum < 1) {
                startNum = 1;

                for(i = 0; i < this.navigatePages; ++i) {
                    this.navigatepageNums[i] = startNum++;
                }
            } else if(endNum > this.pages) {
                endNum = this.pages;

                for(i = this.navigatePages - 1; i >= 0; --i) {
                    this.navigatepageNums[i] = endNum--;
                }
            } else {
                for(i = 0; i < this.navigatePages; ++i) {
                    this.navigatepageNums[i] = startNum++;
                }
            }
        }

    }

    private void calcPage() {
        if(this.navigatepageNums != null && this.navigatepageNums.length > 0) {
            this.navigateFirstPage = this.navigatepageNums[0];
            this.navigateLastPage = this.navigatepageNums[this.navigatepageNums.length - 1];
            if(this.pageNum > 1) {
                this.prePage = this.pageNum - 1;
            }

            if(this.pageNum < this.pages) {
                this.nextPage = this.pageNum + 1;
            }
        }

    }

    private void judgePageBoudary() {
        this.isFirstPage = this.pageNum == 1;
        this.isLastPage = this.pageNum == this.pages;
        this.hasPreviousPage = this.pageNum > 1;
        this.hasNextPage = this.pageNum < this.pages;
    }

    public int getPageNum() {
        return this.pageNum;
    }

    public void setPageNum(int pageNum) {
        this.pageNum = pageNum;
    }

    public int getPageSize() {
        return this.pageSize;
    }

    public void setPageSize(int pageSize) {
        this.pageSize = pageSize;
    }

    public int getSize() {
        return this.size;
    }

    public void setSize(int size) {
        this.size = size;
    }

    public String getOrderBy() {
        return this.orderBy;
    }

    public void setOrderBy(String orderBy) {
        this.orderBy = orderBy;
    }

    public int getStartRow() {
        return this.startRow;
    }

    public void setStartRow(int startRow) {
        this.startRow = startRow;
    }

    public int getEndRow() {
        return this.endRow;
    }

    public void setEndRow(int endRow) {
        this.endRow = endRow;
    }

    public long getTotal() {
        return this.total;
    }

    public void setTotal(long total) {
        this.total = total;
    }

    public int getPages() {
        return this.pages;
    }

    public void setPages(int pages) {
        this.pages = pages;
    }

    public List<T> getList() {
        return this.list;
    }

    public void setList(List<T> list) {
        this.list = list;
    }

    /** @deprecated */
    @Deprecated
    public int getFirstPage() {
        return this.navigateFirstPage;
    }

    /** @deprecated */
    @Deprecated
    public void setFirstPage(int firstPage) {
        this.navigateFirstPage = firstPage;
    }

    public int getPrePage() {
        return this.prePage;
    }

    public void setPrePage(int prePage) {
        this.prePage = prePage;
    }

    public int getNextPage() {
        return this.nextPage;
    }

    public void setNextPage(int nextPage) {
        this.nextPage = nextPage;
    }

    /** @deprecated */
    @Deprecated
    public int getLastPage() {
        return this.navigateLastPage;
    }

    /** @deprecated */
    @Deprecated
    public void setLastPage(int lastPage) {
        this.navigateLastPage = lastPage;
    }

    public boolean isIsFirstPage() {
        return this.isFirstPage;
    }

    public void setIsFirstPage(boolean isFirstPage) {
        this.isFirstPage = isFirstPage;
    }

    public boolean isIsLastPage() {
        return this.isLastPage;
    }

    public void setIsLastPage(boolean isLastPage) {
        this.isLastPage = isLastPage;
    }

    public boolean isHasPreviousPage() {
        return this.hasPreviousPage;
    }

    public void setHasPreviousPage(boolean hasPreviousPage) {
        this.hasPreviousPage = hasPreviousPage;
    }

    public boolean isHasNextPage() {
        return this.hasNextPage;
    }

    public void setHasNextPage(boolean hasNextPage) {
        this.hasNextPage = hasNextPage;
    }

    public int getNavigatePages() {
        return this.navigatePages;
    }

    public void setNavigatePages(int navigatePages) {
        this.navigatePages = navigatePages;
    }

    public int[] getNavigatepageNums() {
        return this.navigatepageNums;
    }

    public void setNavigatepageNums(int[] navigatepageNums) {
        this.navigatepageNums = navigatepageNums;
    }

    public int getNavigateFirstPage() {
        return this.navigateFirstPage;
    }

    public int getNavigateLastPage() {
        return this.navigateLastPage;
    }

    public void setNavigateFirstPage(int navigateFirstPage) {
        this.navigateFirstPage = navigateFirstPage;
    }

    public void setNavigateLastPage(int navigateLastPage) {
        this.navigateLastPage = navigateLastPage;
    }

    public String toString() {
        StringBuffer sb = new StringBuffer("PageInfo{");
        sb.append("pageNum=").append(this.pageNum);
        sb.append(", pageSize=").append(this.pageSize);
        sb.append(", size=").append(this.size);
        sb.append(", startRow=").append(this.startRow);
        sb.append(", endRow=").append(this.endRow);
        sb.append(", total=").append(this.total);
        sb.append(", pages=").append(this.pages);
        sb.append(", list=").append(this.list);
        sb.append(", prePage=").append(this.prePage);
        sb.append(", nextPage=").append(this.nextPage);
        sb.append(", isFirstPage=").append(this.isFirstPage);
        sb.append(", isLastPage=").append(this.isLastPage);
        sb.append(", hasPreviousPage=").append(this.hasPreviousPage);
        sb.append(", hasNextPage=").append(this.hasNextPage);
        sb.append(", navigatePages=").append(this.navigatePages);
        sb.append(", navigateFirstPage").append(this.navigateFirstPage);
        sb.append(", navigateLastPage").append(this.navigateLastPage);
        sb.append(", navigatepageNums=");
        if(this.navigatepageNums == null) {
            sb.append("null");
        } else {
            sb.append('[');

            for(int i = 0; i < this.navigatepageNums.length; ++i) {
                sb.append(i == 0?"":", ").append(this.navigatepageNums[i]);
            }

            sb.append(']');
        }

        sb.append('}');
        return sb.toString();
    }
}

4、持久层SQL：

跟普通查询一样，不需要加入页数参数，pageHelper分页插件自动进行分页，至于原理能力有限暂时解释不了。

5、加到服务器中的jar包

因为我的本地有maven项目管理工具，服务器中没有maven这样的工具，还需要加入这个jar包才能形成依赖，才可以进行使用。