自定义Tag标签的编写

最新推荐文章于 2025-06-18 00:15:00 发布

atrueman123

最新推荐文章于 2025-06-18 00:15:00 发布

阅读量4k

点赞数

CC 4.0 BY-SA版权

分类专栏： JAVA天地文章标签： string integer 文档 border exception jsp

本文链接：https://blog.youkuaiyun.com/atrueman123/article/details/5216715

JAVA天地专栏收录该内容

17 篇文章

订阅专栏

由于工程项目的需要，自己开发了一个分页的标签：

package com.xxx.eclanswers.utils; import javax.servlet.jsp.JspException; import javax.servlet.jsp.JspWriter; import org.apache.taglibs.standard.tag.el.core.ExpressionUtil; import org.springframework.util.StringUtils; import org.springframework.web.servlet.tags.RequestContextAwareTag; public class PaginationTag extends RequestContextAwareTag { /** * @author patrick.hung */ private static final long serialVersionUID = 1L; public String itemsTotal = null; public String currentNO = null; public String itemsPage = null; public String paginationUrlParam=null; private String _paginationUrlParam=""; private Integer _itemsPage = 2; private Integer _currentNO = 1; private Integer _itemsTotal = 0; private void evaluateExprssions() throws JspException { _itemsTotal = (Integer) ExpressionUtil.evalNotNull("Pagination", "itemsTotal", itemsTotal, Integer.class, this, pageContext); if (StringUtils.hasText(currentNO)) { _currentNO = (Integer) ExpressionUtil.evalNotNull("Pagination", "currentNO", currentNO, Integer.class, this, pageContext); } if (StringUtils.hasText(itemsPage)) { _itemsPage = (Integer) ExpressionUtil.evalNotNull("Pagination", "itemsPage", itemsPage, Integer.class, this, pageContext); } if(StringUtils.hasText(paginationUrlParam)) { _paginationUrlParam=(String)ExpressionUtil.evalNotNull("Pagination", paginationUrlParam, paginationUrlParam, String.class, this, pageContext); } } @Override protected int doStartTagInternal() throws Exception { evaluateExprssions(); int elements = _itemsTotal; int pageNO = elements / _itemsPage + (elements % _itemsPage == 0 ? 0 : 1); JspWriter writer = pageContext.getOut(); StringBuffer sb = new StringBuffer(500); sb.append("<mce:style type=/"text/css/"></mce:style><style type=/"text/css/" mce_bogus="1">a.hcl:link,a.hcl:visited, a.hcl:active { color:#3666d4; font:13px/1.231 arial,helvetica,clean,sans-serif; font-family: arial, helvetica, 'bitstream vera sans', clean, sans-serif; border: 1px solid #ccdbe4; margin:0 5px 0 0; padding:2px 8px; text-align:center; text-decoration:none; }a.hcl:hover{color:#FFFFFF;background-color: #66FFFF;background:#3666d4;border-color:#2b55af;}a.hcl_cur:link,a.hcl_cur:visited, a.hcl_cur:active {color:#3666d4;font:13px/1.231 arial,helvetica,clean,sans-serif;font-family: arial, helvetica, 'bitstream vera sans', clean, sans-serif; border: 0px solid #ccdbe4;margin:0 5px 0 0;padding:2px 8px;text-align:center;text-decoration:none;font-weight: bold;}</style>"); if (pageNO < 4) {// the scene of the page smaller than 4. sb.append(buildPrev(_currentNO)); sb.append(processLogic(_currentNO, pageNO, -1)); } else if (pageNO > 3 && pageNO < 7) {// the scene of the page between // 3 and 7. sb.append(buildPrev(_currentNO)); if (_currentNO > 3 && _currentNO < 7) { sb.append(processLogic(_currentNO, pageNO, -1)); } else if(_currentNO<4){ sb.append(processLogic(_currentNO, pageNO, 4)); } } else if (pageNO > 6 && pageNO < 10) {// the scene of the page between 6 and 10. sb.append(buildPrev(_currentNO)); if (_currentNO > 6 && _currentNO < 10) { sb.append(processLogic(_currentNO, pageNO, -1)); } else if (_currentNO > 3 && _currentNO < 7) {//It must be in between 1 and 7. sb.append(processLogic(_currentNO, pageNO, 7)); } else { sb.append(processLogic(_currentNO, pageNO, 4)); } } else {// the scene of pageNO smaller than 10 sb.append(buildPrev(_currentNO)); if (_currentNO > 9) { for (int i = _currentNO - 8; i < _currentNO; i++) { sb.append(buildHref(i, String.valueOf(i),"hcl") + " "); } sb.append(buildHref(_currentNO, String.valueOf(_currentNO),"hcl_cur")); if (_currentNO < pageNO) {// 判断是否还有下一页 sb.append(buildHref(_currentNO + 1, "Next>","hcl")); } } else if (_currentNO < 10 && _currentNO > 6) { sb.append(processLogic(_currentNO, pageNO, 10)); } else if (_currentNO < 7 && _currentNO > 3) { sb.append(processLogic(_currentNO, pageNO, 7)); } else { if (_currentNO < 4) { sb.append(processLogic(_currentNO, pageNO, 4)); } } } writer.append(sb.toString()); writer.flush(); return 0; } /** * execute building the list of page * @param currentNO * @param pageNO * @param endpage <p>please fill the last page number * @return */ private String processLogic(int currentNO,int pageNO,int endpage) { StringBuffer sb=new StringBuffer(100); int endPage=pageNO+1; if(endpage!=-1) { endPage=endpage; } for (int i = 1; i < currentNO; i++) { sb.append(buildHref(i, String.valueOf(i),"hcl") + " "); } sb.append(buildHref(currentNO, String.valueOf(currentNO),"hcl_cur"));//for current page,make use 'hcl_cur' style for (int i = currentNO + 1; i < endPage; i++) { sb.append(buildHref(i, String.valueOf(i),"hcl") + " "); } if (currentNO<pageNO) {// 判断是否还有下一页 sb.append(buildHref(_currentNO + 1, "Next>","hcl")); } return sb.toString(); } private String buildHref(int t, String s,String styleId) { StringBuffer sb = new StringBuffer(30); sb.append("<a class='"); sb.append(styleId); sb.append("' href="?"); if(StringUtils.hasText(paginationUrlParam)) { sb.append(_paginationUrlParam).append("&pageNo=").append(t).append("" mce_href="?"); if(StringUtils.hasText(paginationUrlParam)) { sb.append(_paginationUrlParam).append("&pageNo=").append(t).append("">"); } sb.append(s); sb.append("</a>"); return sb.toString(); }; private String buildPrev(int currentNO) { String str = ""; if (currentNO != 1) { str = buildHref(currentNO - 1, "<Prev","hcl") + " "; } return str; }; private String buildNext(int currentNO) { String str = ""; str = buildHref(_currentNO + 1, "Next>","hcl"); return str; } // private String makeUrl(int t) { // StringBuffer sb=new StringBuffer(20); // if(StringUtils.hasText(paginationUrlParam)) { // sb.append(_paginationUrlParam).append("&pageNo=").append(t).append("'>"); // } // return sb.toString(); // } public String getItemsTotal() { return itemsTotal; } public void setItemsTotal(String itemsTotal) { this.itemsTotal = itemsTotal; } public String getCurrentNO() { return currentNO; } public void setCurrentNO(String currentNO) { this.currentNO = currentNO; } public String getItemsPage() { return itemsPage; } public void setItemsPage(String itemsPage) { this.itemsPage = itemsPage; } public String getPaginationUrlParam() { return paginationUrlParam; } public void setPaginationUrlParam(String paginationUrlParam) { this.paginationUrlParam = paginationUrlParam; } }

其中：itemsTotal 、currentNO、itemsPage三个属性是冒出来的，在标签中要提供输入的值。前面带有“_”号的变量是本地变量，通过evaluateExprssions()函数转化的。

主要的是要覆写RequestContextAwareTag类doStartTagInternal方法。

配置部分：

编写tld文件，使其作为引入标签时使用。

新建一tld文档，内容如下：

<?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>1.0</tlib-version> <jsp-version>1.2</jsp-version> <short-name>eclanswers</short-name> <uri>http://eclanswers.xxxxxx.com/tags</uri> <tag> <name>pagination</name> <tag-class>com.ecl.eclanswers.utils.PaginationTag</tag-class> <body-content>JSP</body-content> <description>display operation with per page by this tag</description> <attribute> <name>itemsTotal</name> <required>true</required> <rtexprvalue>true</rtexprvalue> </attribute> <attribute> <name>currentNO</name> <required>true</required> <rtexprvalue>true</rtexprvalue> </attribute> <attribute> <name>itemsPage</name> <required>true</required> <rtexprvalue>true</rtexprvalue> </attribute> <attribute> <name>paginationUrlParam</name> <required>true</required> <rtexprvalue>true</rtexprvalue> </attribute> </tag> </taglib>

把需要的属性，比如itemsTotal 、currentNO、itemsPage这三个在该文档中标注出来。

对该tld文档进行加载是通过web.xml来加载的，只需在web.xml中配置如下：

<taglib> <taglib-uri>http://eclanswers.xxxxxx.com/tags</taglib-uri> <taglib-location>/WEB-INF/tld/eclanswers.tld（你自己的tld文档路径）</taglib-location> </taglib>

在前台jsp页面中像使用其他spring标签时一样，即可。