基于SSM框架的学生信息管理系统源码.zip

package com.student.common.utils; import javax.servlet.http.HttpServletRequest; import javax.servlet.jsp.JspException; import javax.servlet.jsp.JspWriter; import javax.servlet.jsp.tagext.TagSupport; import java.io.IOException; import java.util.Map; /** * 显示格式：首页 上一页 1 2 3 4 5下一页 尾页 */ public class NavigationTag extends TagSupport { static final long serialVersionUID = 2372405317744358833L; /** * request 中用于保存Page<E> 对象的变量名,默认为“page” */ private String bean = "page"; /** * 分页跳转的url地址,此属性必须 */ private String url = null; /** * 显示页码数量 */ private int number = 5; @Override public int doStartTag() throws JspException { JspWriter writer = pageContext.getOut(); HttpServletRequest request = (HttpServletRequest) pageContext.getRequest(); Page page = (Page) request.getAttribute(bean); if (page == null) return SKIP_BODY; url = resolveUrl(url, pageContext); try { // 计算总页数 int pageCount = page.getTotal() / page.getSize(); if (page.getTotal() % page.getSize() > 0) { pageCount++; } writer.print("<nav><ul class=\"pagination\">"); //首页链接路径 String homeUrl = append(url, "page", 1); //末页链接路径 String backUrl = append(url, "page", pageCount); // 显示“上一页”按钮 if (page.getPage() > 1) { String preUrl = append(url, "page", page.getPage() - 1); preUrl = append(preUrl, "rows", page.getSize()); writer.print("<li><a href=\"" + homeUrl + "\">" + "首页</a></li>"); writer.print("<li><a href=\"" + preUrl + "\">" + "上一页</a></li>"); } else { writer.print("<li class=\"disabled\"><a href=\"#\">" + "首页 </a></li>"); writer.print("<li class=\"disabled\"><a href=\"#\">" + "上一页 </a></li>"); } // 显示当前页码的前2页码和后两页码 // 若1 则 1 2 3 4 5, 若2 则 1 2 3 4 5, 若3 则1 2 3 4 5, // 若4 则 2 3 4 5 6 ,若10 则 8 9 10 11 12 int indexPage =1; if(page.getPage() - 2 <=0){ indexPage=1; }else if(pageCount-page.getPage() <=2){ indexPage=pageCount-4; }else{ indexPage= page.getPage() - 2; } for (int i= 1;i <= number && indexPage <= pageCount;indexPage++,i++){ if (indexPage == page.getPage()) { writer.print("<li class=\"active\"><a href=\"#\">" + indexPage +"<spanclass=\"sr-only\"></span></a></li>"); continue; } String pageUrl = append(url, "page", indexPage); pageUrl = append(pageUrl, "rows", page.getSize()); writer.print("<li><a href=\"" + pageUrl + "\">" + indexPage + "</a></li>"); } // 显示“下一页”按钮 if (page.getPage() < pageCount) { String nextUrl = append(url, "page", page.getPage() + 1); nextUrl = append(nextUrl, "rows", page.getSize()); writer.print("<li><a href=\"" + nextUrl + "\">" + "下一页</a></li>"); writer.print("<li><a href=\"" + backUrl + "\">" + "尾页</a></li>"); } else { writer.print("<li class=\"disabled\"><a href=\"#\">" + "下一页</a></li>"); writer.print("<li class=\"disabled\"><a href=\"#\">" + "尾页</a></li>"); } writer.print("</nav>"); } catch (IOException e) { e.printStackTrace(); } return SKIP_BODY; } private String append(String url, String key, int value) { return append(url, key, String.valueOf(value)); } /** * 为url 参加参数对儿 */ private String append(String url, String key, String value) { if (url == null || url.trim().length() == 0) { return ""; } if (url.indexOf("?") == -1) { url = url + "?" + key + "=" + value; } else { if (url.endsWith("?")) { url = url + key + "=" + value; } else { url = url + "&amp;" + key + "=" + value; } } return url; } /** * 为url 添加翻页请求参数 */ private String resolveUrl(String url, javax.servlet.jsp.PageContext pageContext) throws JspException { Map params = pageContext.getRequest().getParameterMap(); for (Object key : params.keySet()) { if ("page".equals(key) || "rows".equals(key)){ continue; } Object value = params.get(key); if (value == null){ continue; } if (value.getClass().isArray()) { url = append(url, key.toString(), ((String[]) value)[0]); } else if (value instanceof String) { url = append(url, key.toString(), value.toString()); } } return url; } public String getBean() { return bean; } public void setBean(String bean) { this.bean = bean; } public String getUrl() { return url; } public void setUrl(String url) { this.url = url; } public void setNumber(int number) { this.number = number; } }