public class PageInfo<T> implements Serializable {

    private static final long serialVersionUID = 1L;

    /**
     * 当前页码数
     */
    private int pageNum;
    /**
     * 每页显示的记录数
     */
    private int pageSize;
    /**
     * 分页下标
     */
    private int limitIndex;
    /**
     * 开始行号
     */
    private long startRow;
    /**
     * 结束行号
     */
    private long endRow;
    /**
     * 总记录数
     */
    private long rows;
    /**
     * 总页码数
     */
    private int pages;
    /**
     * 首页页码
     */
    private int firstPage;
    /**
     * 上一页页码
     */
    private int previousPage;
    /**
     * 下一页页码
     */
    private int nextPage;
    /**
     * 尾页页码
     */
    private int lastPage;
    /**
     * 是否有上一页
     */
    private boolean hasPreviousPage = false;
    /**
     * 是否有下一页
     */
    private boolean hasNextPage = false;
    /**
     * 是否为首页
     */
    private boolean ifFirstPage = false;
    /**
     * 是否为最后一页
     */
    private boolean ifLastPage = false;

    // 分页显示的页数，比如在页数上显示1，2，3，4，5.start就是1，end就是5
    private int start = 1;
    private int end = 5;
    private int[] navigation;

    // 存放本次分页查询出来的数据
    private List<T> list;


    public static PageInfo pageInfoBuild(long rows) {
        int curPage = ServletUtils.getParameterToInt(ProjectConstants.PAGE_NUM);
        int pageRow = ServletUtils.getParameterToInt(ProjectConstants.PAGE_SIZE);
        return new PageInfo(curPage, pageRow, rows);
    }

    public static PageInfo pageInfoBuild(int curPage, long rows) {
        int pageRow = ServletUtils.getParameterToInt(ProjectConstants.PAGE_SIZE);
        return new PageInfo(curPage, pageRow, rows);
    }

    public static PageInfo pageInfoBuild(int curPage, int pageRow, long rows) {
        return new PageInfo(curPage, pageRow, rows);
    }

    public PageInfo(int curPage, int pageRow, long rows) {
        // 当前页码
        this.pageNum = curPage;
        // 每页显示的记录数
        this.pageSize = pageRow;
        // 总记录数
        this.rows = rows;
        // 分页下标
        this.limitIndex = (this.pageNum - 1) * this.pageSize;
        // 总页码数
        this.pages = (int) Math.ceil(this.rows * 1.0 / this.pageSize);
        // 当前页码大于总页码数时，当前页码=总页码数
        if (this.pageNum > this.pages) {
            this.pageNum = this.pages;
        }
        // 开始行号
        this.startRow = (this.pageNum * this.pageSize) - (this.pageSize - 1);
        // 结束行号
        this.endRow = this.pageNum * this.pageSize;
        //当结束行号>总行数时，结束行号=总行数
        if (this.endRow > rows) {
            this.endRow = rows;
        }
        //设置首页
        this.firstPage = 1;
        //设置尾页
        this.lastPage = this.pages;
        //是否为第一页
        this.ifFirstPage = this.pageNum == this.firstPage;
        //是否为最后一页
        this.ifLastPage = this.pageNum == this.lastPage;
        // 设置上一页
        if (this.pageNum > 1) {
            this.hasPreviousPage = true;
            this.previousPage = this.pageNum - 1;
        }
        // 设置下一页
        if (this.pageNum < this.pages) {
            this.hasNextPage = true;
            this.nextPage = this.pageNum + 1;
        }

        // 显示页数的算法
        if (this.pages <= 5) {// 总页数小于5页
            this.end = this.pages;
        } else {
            // 总页数是大于5的，那么就要根据当前是第几页来判断显示的start和end
            this.start = pageNum - 2;
            this.end = pageNum + 2;

            if (start <= 0) {
                this.start = 1;
                this.end = 5;
            }
            if (end > this.pages) {
                this.end = this.pages;
                this.start = end - 4;
            }
        }
        int temp = 0;
        navigation = new int[(end - start) + 1];
        for (int x = start; x <= end; x++) {
            navigation[temp] = x;
            temp++;
        }
    }

    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 getLimitIndex() {
        return limitIndex;
    }

    public void setLimitIndex(int limitIndex) {
        this.limitIndex = limitIndex;
    }

    public long getStartRow() {
        return startRow;
    }

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

    public long getEndRow() {
        return endRow;
    }

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

    public long getRows() {
        return rows;
    }

    public void setRows(long rows) {
        this.rows = rows;
    }

    public int getPages() {
        return pages;
    }

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


    public int getFirstPage() {
        return firstPage;
    }

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

    public int getPreviousPage() {
        return previousPage;
    }

    public void setPreviousPage(int previousPage) {
        this.previousPage = previousPage;
    }

    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 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 boolean isIfFirstPage() {
        return ifFirstPage;
    }

    public void setIfFirstPage(boolean ifFirstPage) {
        this.ifFirstPage = ifFirstPage;
    }

    public boolean isIfLastPage() {
        return ifLastPage;
    }

    public void setIfLastPage(boolean ifLastPage) {
        this.ifLastPage = ifLastPage;
    }

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

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

    public int getStart() {
        return start;
    }

    public void setStart(int start) {
        this.start = start;
    }

    public int getEnd() {
        return end;
    }

    public void setEnd(int end) {
        this.end = end;
    }

    public int[] getNavigation() {
        return navigation;
    }

    public void setNavigation(int[] navigation) {
        this.navigation = navigation;
    }

    @Override
    public String toString() {
        return "PageInfo{" +
                "pageNum=" + pageNum +
                ", pageSize=" + pageSize +
                ", limitIndex=" + limitIndex +
                ", startRow=" + startRow +
                ", endRow=" + endRow +
                ", rows=" + rows +
                ", pages=" + pages +
                ", firstPage=" + firstPage +
                ", previousPage=" + previousPage +
                ", nextPage=" + nextPage +
                ", lastPage=" + lastPage +
                ", hasPreviousPage=" + hasPreviousPage +
                ", hasNextPage=" + hasNextPage +
                ", ifFirstPage=" + ifFirstPage +
                ", ifLastPage=" + ifLastPage +
                ", start=" + start +
                ", end=" + end +
                ", navigation=" + Arrays.toString(navigation) +
                ", list=" + list +
                '}';
    }
}