PageInfo类，用来封装查询出的结果，查询出的结果集合即为list。

package com.github.pagehelper;

/**

@SuppressWarnings({“rawtypes”, “unchecked”})
public class PageInfo 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;

//前一页
private int prePage;
//下一页
private int nextPage;

//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;
//导航条上的第一页
private int navigateFirstPage;
//导航条上的最后一页
private int navigateLastPage;

/**
* 包装Page对象
*
* @param list
*/
public PageInfo(List 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) {
        navigateFirstPage = navigatepageNums[0];
        navigateLastPage = 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;
}

@Deprecated
// firstPage就是1, 此函数获取的是导航条上的第一页, 容易产生歧义
public int getFirstPage() {
    return navigateFirstPage;
}

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

@Deprecated
// 请用getPages()来获取最后一页, 此函数获取的是导航条上的最后一页, 容易产生歧义.
public int getLastPage() {
    return navigateLastPage;
}

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

public int getNavigateFirstPage() {
    return navigateFirstPage;
}

public int getNavigateLastPage() {
    return navigateLastPage;
}

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

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

@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(“, prePage=”).append(prePage);
sb.append(“, nextPage=”).append(nextPage);
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(“, navigateFirstPage”).append(navigateFirstPage);
sb.append(“, navigateLastPage”).append(navigateLastPage);
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();
}
}