基于Java的学科竞赛管理系统

package org.uscp.vo; import java.io.UnsupportedEncodingException; import java.net.URLEncoder; import java.util.HashMap; import java.util.List; import java.util.Map; public class Pagination<T> { public static final int DEFAULT_PAGE_SIZE = 10; public static final String PAGINATION = "pagination"; class Config{ /** * 指定页面跳转时接收跳转页数的param变量 */ public String page = "page"; /** * 指定跳转的路径 */ public String path = ""; /** * 指定分页时的查询参数 */ public Map<String,String> queryParams = new HashMap<String,String>(); } /** * 分页的配置 */ private Config config = new Config(); /** * 使用默认的构造函数后必须调用 reBuild(long,long)方法 */ public Pagination(){ } public void reBuild(long currentPage,long total,int pageSize){ this.currentPage = currentPage; this.total = total; this.lastPage = total % pageSize == 0 ? total/pageSize : (total/pageSize + 1); this.hasMore = this.currentPage < this.lastPage; } /** * 自定义配置的构造函数 * @param currentPage * @param total */ public Pagination(long currentPage,long total){ reBuild(currentPage,total,this.pageSize); } public Pagination(long currentPage,long total,Map<String,String> queryParams){ this(currentPage, total); if(null != queryParams){ config.queryParams = queryParams; } } /** * 自定义配置的构造函数 * @param page * @param path * @param queryParams */ public Pagination(long currentPage,long total,String page,String path,Map<String,String> queryParams){ this(currentPage, total,queryParams); if(null != page){ config.page = page; } if(null != path){ config.path = path; } } private List<T> items; /** * 当前页数 */ private long currentPage; /** * 最后一页页码 */ private long lastPage; /** * 总记录数 */ private long total; /** * 默认每页5个 */ private int pageSize = DEFAULT_PAGE_SIZE; private boolean hasMore; public List<T> getItems() { return items; } public void setItems(List<T> items) { this.items = items; } public int getPageSize() { return pageSize; } public long getCurrentPage(){ return currentPage; } public Map<String,String> getQueryParams(){ return config.queryParams; } public long getTotal(){ return total; } public void setPageSize(int pageSize) { this.pageSize = pageSize; //这里根据pageSize重新计算分页个数及是否有下一页 this.lastPage = total % pageSize == 0 ? total/pageSize : (total/pageSize + 1); this.hasMore = this.currentPage < this.lastPage; } /** * 是否有分页 * @return */ private boolean hasPages(){ return !(1 == this.currentPage && !this.hasMore); } /** * 生成一个禁用的按钮 * @param text * @return */ private String getDisabledTextWrapper(String text){ return "<li class='disabled'><span>" + text + "</span></li>"; } /** * 生成一个激活的按钮 * @param text * @return */ private String getActivePageWrapper(String text){ return "<li class='active'><span>" + text + "</span></li>"; } /** * 生成省略号按钮 * @return */ private String getDots(){ return this.getDisabledTextWrapper("..."); } /** * 生成一个可点击的按钮 * @param url * @param page * @return */ private String getAvailablePageWrapper(String url,String page){ return "<li><a href='" +url + "'>" + page + "</a></li>"; } /** * 生成普通页码按钮 * @param url * @param page * @return */ private String getPageLinkWrapper(String url,String page){ if(page.equals(String.valueOf(this.currentPage))){ return this.getActivePageWrapper(page); } return this.getAvailablePageWrapper(url, page); } /** * 批量生成页码按钮. * @param urls * @return */ private String getUrlLinks(Map<Long,String> urls){ StringBuilder builder = new StringBuilder(""); if(null != urls && urls.size() > 0){ for(Long page : urls.keySet()){ builder.append(this.getPageLinkWrapper(urls.get(page), String.valueOf(page))); } } return builder.toString(); } /** * 创建一组分页链接 * @param start * @param end * @return * @throws UnsupportedEncodingException */ private Map<Long,String> getUrlRange(long start, long end) throws UnsupportedEncodingException{ Map<Long,String> urls = new HashMap<Long,String>(); for(long page = start;page<=end;page++){ urls.put(page, this.getUrl(page)); } return urls; } /** * 获取页码对应的链接 * @param page * @return * @throws UnsupportedEncodingException */ private String getUrl(long page) throws UnsupportedEncodingException{ if(page<0){ page = 1; } //组合查询参数 StringBuilder urlBuilder = new StringBuilder(); if(null != config.path){ urlBuilder.append(config.path); } urlBuilder.append("?page=").append(page); if(config.queryParams.size() > 0){ for(String param : config.queryParams.keySet()){ urlBuilder.append("&").append(param).append("=").append(URLEncoder.encode(config.queryParams.get(param),"utf-8")); } } return urlBuilder.toString(); } /** * 页码按钮 * @return string * @throws UnsupportedEncodingException */ private String getLinks() throws UnsupportedEncodingException{ int size = 3; int window = size * 2; Map<Long,String> first = null; Map<Long,String> slide = null; Map<Long,String> last = null; if(this.lastPage < window + 6){ first = this.getUrlRange(1, this.lastPage); }else if(this.currentPage <= window){ first = this.getUrlRange(1, window+2); last = this.getUrlRange(this.lastPage -1 , this.lastPage); }else if(this.currentPage > (this.lastPage - window)){ first = this.getUrlRange(1, 2); last = this.getUrlRange(this.lastPage -(window+2) , this.lastPage); }else{ first = this.getUrlRange(1, 2); slide = this.getUrlRange(this.currentPage - size, this.currentPage + size); last = this.getUrlRange(this.lastPage -1 , this.lastPage); } StringBuilder builder = new StringBuilder(); if(first.size() > 0){ builder.append(this.getUrlLinks(first)); } if(null != slide && slide.size() > 0){ builder.append(this.getDots()); builder.append(this.getUrlLinks(slide)); } if(null != last && last.size()>0){ builder.append(this.getDots()); builder.append(this.getUrlLinks(last)); } return builder.toString(); } /** * 上一页按钮 * @return * @throws UnsupportedEncodingException */ private String getPreviousButton() throws UnsupportedEncodingException{ String character = "&laquo;"; if(this.currentPage <= 1){ return this.getDisabledTextWrapper(character); } String url = this.getUrl(this.currentPage - 1); return this.getPageLinkWrapper(url, character); } /** * 下一页按钮 * @return * @throws UnsupportedEncodingException */ private String getNextButton() throws UnsupportedEncodingException{ String character = "&raquo;"; if(!this.hasMore){ return this.getDisabledTextWrapper(character); } String url=this.getUrl(this.currentPage + 1); return this.getPageLinkWrapper(url, character); } /** * 渲染分页html * @return */ public String getRender(){ if(this.hasPages()){ StringBuilder builder = new StringBuilder("<ul class='pagination'>"); try{ builder.append(this.getPreviousButton()); builder.append(this.getLinks()); builder.append(this.getNextButton()); } catch(UnsupportedEncodingException e){ e.printStackTrace(); } builder.append("</ul>"); return builder.toString();