javaEE JSP，自定義標籤庫，自定義分頁條標籤
阿新 • • 發佈：2018-12-11
WEB-INF/tld/commons.tld（自定義標籤庫的描述）：
<?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE taglib PUBLIC "-//Sun Microsystems, Inc.//DTD JSP Tag Library 1.2//EN" "http://java.sun.com/dtd/web-jsptaglibrary_1_2.dtd"> <taglib> <tlib-version>2.0</tlib-version> <jsp-version>1.2</jsp-version> <short-name>common</short-name> <uri>http://xxx.cn/common/</uri> <display-name>Common Tag</display-name> <description>Common Tag library</description> <tag> <name>page</name> <tag-class>com.xxx.common.utils.NavigationTag</tag-class> <body-content>JSP</body-content> <description>create navigation for paging</description> <attribute> <name>bean</name> <rtexprvalue>true</rtexprvalue> </attribute> <attribute> <name>number</name> <rtexprvalue>true</rtexprvalue> </attribute> <attribute> <name>url</name> <required>true</required> <rtexprvalue>true</rtexprvalue> </attribute> </tag> </taglib>
NavigationTag.java（標籤處理類,繼承TagSupport類）：
package com.xxx.common.utils; import java.io.IOException; import java.util.Map; import javax.servlet.http.HttpServletRequest; import javax.servlet.jsp.JspException; import javax.servlet.jsp.JspWriter; import javax.servlet.jsp.tagext.TagSupport; /** * 顯示格式 上一頁 1 2 3 4 5 下一頁 */ public class NavigationTag extends TagSupport { //繼承TagSupport類 static final long serialVersionUID = 2372405317744358833L; /** * request 中用於儲存Page<E> 物件的變數名,預設為“page” */ private String bean = "page"; /** * 分頁跳轉的url地址,此屬性必須 */ private String url = null; /** * 顯示頁碼數量 */ 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 { //計算總頁數 int pageCount = page.getTotal() / page.getSize(); if (page.getTotal() % page.getSize() > 0) { pageCount++; } writer.print("<nav><ul class=\"pagination\">"); //顯示“上一頁”按鈕 if (page.getPage() > 1) { String preUrl = append(url, "page", page.getPage() - 1); preUrl = append(preUrl, "rows", page.getSize()); writer.print("<li><a href=\"" + preUrl + "\">上一頁</a></li>"); } else { writer.print("<li class=\"disabled\"><a href=\"#\">上一頁</a></li>"); } //顯示當前頁碼的前2頁碼和後兩頁碼 //若1 則 1 2 3 4 5, 若2 則 1 2 3 4 5, 若3 則1 2 3 4 5, //若4 則 2 3 4 5 6 ,若10 則 8 9 10 11 12 int indexPage = (page.getPage() - 2 > 0)? page.getPage() - 2 : 1; for(int i=1; i <= number && indexPage <= pageCount; indexPage++, i++) { if(indexPage == page.getPage()) { writer.print( "<li class=\"active\"><a href=\"#\">"+indexPage+"<span class=\"sr-only\">(current)</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>"); } //顯示“下一頁”按鈕 if (page.getPage() < pageCount) { String nextUrl = append(url, "page", page.getPage() + 1); nextUrl = append(nextUrl, "rows", page.getSize()); writer.print("<li><a href=\"" + nextUrl + "\">下一頁</a></li>"); } else { writer.print("<li class=\"disabled\"><a href=\"#\">下一頁</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)); } /** * 為url 參加引數對兒 * * @param url * @param key * @param value * @return */ 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 + "&" + key + "=" + value; } } return url; } /** * 為url 新增翻頁請求引數 * * @param url * @param pageContext * @return * @throws javax.servlet.jsp.JspException */ private String resolveUrl(String url, javax.servlet.jsp.PageContext pageContext) throws JspException{ //UrlSupport.resolveUrl(url, context, pageContext) 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; } /** * @return the bean */ public String getBean() { return bean; } /** * @param bean the bean to set */ public void setBean(String bean) { this.bean = bean; } /** * @return the url */ public String getUrl() { return url; } /** * @param url the url to set */ public void setUrl(String url) { this.url = url; } public void setNumber(int number) { this.number = number; } }
Demo.jsp（使用自定義標籤庫）：
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%> <%@ taglib prefix="my" uri="http://xxx.cn/common/"%> <!-- 引入自定義標籤庫 --> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta charset="utf-8"> <title>demo</title> </head> <body> <form action="" method="post" > <table class="table"> <thead> <tr> <th>ID</th> <th>客戶名稱</th> <th>客戶來源</th> <th>客戶所屬行業</th> <th>客戶級別</th> <th>固定電話</th> <th>手機</th> <th>操作</th> </tr> </thead> <tbody> <c:forEach items="${page.rows}" var="row"> <tr> <td>${row.cust_id}</td> <td>${row.cust_name}</td> <td>${row.cust_source}</td> <td>${row.cust_industry}</td> <td>${row.cust_level}</td> <td>${row.cust_phone}</td> <td>${row.cust_mobile}</td> <td> <a href="#" onclick="editCustomer(${row.cust_id})">修改</a> <a href="#" onclick="deleteCustomer(${row.cust_id})">刪除</a> </td> </tr> </c:forEach> </tbody> </table> <div> <!-- 分頁條;自定義的標籤。 --> <my:page url="${pageContext.request.contextPath }/customer/list.action" /> <!-- 自定義標籤庫 --> </div> </form> </body> </html>
Page.java（用到的分頁類）：
package com.xxx.common.utils;
import java.util.List;
public class Page<T> {
private int total; //總記錄數
private int page; //當前頁數
private int size; //每頁顯示條數
private List<T> rows;
public int getTotal() {
return total;
}
public void setTotal(int total) {
this.total = total;
}
public int getPage() {
return page;
}
public void setPage(int page) {
this.page = page;
}
public int getSize() {
return size;
}
public void setSize(int size) {
this.size = size;
}
public List<T> getRows() {
return rows;
}
public void setRows(List<T> rows) {
this.rows = rows;
}
}