JSP自定义标签案例分析_JSP编程_

 public class MyReferer extends BodyTagSupport { private String site; private String back; public String getSite() { return site; } public void setSite(String site) { this.site = site; } public String getBack() { return back; } public void setBack(String back) { this.back = back; } public int doEndTag() throws JspException { // 获取JSP上下文环境对象 PageContext pageContext = this.pageContext; // 获取到request对象 HttpServletRequest request = (HttpServletRequest)pageContext.getRequest(); // 判断 String header = request.getHeader("referer"); if(header != null && header.startsWith(getSite())){ // 执行后续的页面 return Tag.EVAL_PAGE; }else{ // 页面的重定向 HttpServletResponse response = (HttpServletResponse)pageContext.getResponse(); try { response.sendRedirect(getBack()); } catch (IOException e) { e.printStackTrace(); } // 不执行 return Tag.SKIP_PAGE; } } } 

1.0jnbreferercn.itcast.custom.MyRefereremptysitetruetruebacktruetrue

<%@taglib uri="/WEB-INF/referer.tld" prefix="my"%>

<%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %> 大于  小于 

 public class ChooseTag extends SimpleTagSupport { private boolean tag = true; public boolean isTag() { return tag; } public void setTag(boolean tag) { this.tag = tag; } // 遇到标签自动执行 public void doTag() throws JspException, IOException { // 获取标签体对象 JspFragment body = this.getJspBody(); // 执行标签体 body.invoke(null); super.doTag(); } }

 public class WhenTag extends SimpleTagSupport { private boolean test; public boolean isTest() { return test; } public void setTest(boolean test) { this.test = test; } // 遇到标签自动执行 public void doTag() throws JspException, IOException { // 获取父元素 ChooseTag choose = (ChooseTag)this.getParent(); // 获取父元素的标记变量值 boolean parent = choose.isTag(); // 判断 if( parent && this.isTest() ){ // 执行标签体 JspFragment body = this.getJspBody(); body.invoke(null); } super.doTag(); } }

 public class OtherwiseTag extends SimpleTagSupport { // 遇到标签自动执行 public void doTag() throws JspException, IOException { // 获取父元素 ChooseTag choose = (ChooseTag)this.getParent(); // 获取父元素的标记变量值 boolean parent = choose.isTag(); // 判断 if(parent){ // 执行标签体 JspFragment body = this.getJspBody(); body.invoke(null); } super.doTag(); } }

1.0jnbchoosecn.itcast.tags.ChooseTagscriptless  JSP2.0方式 whencn.itcast.tags.WhenTagscriptlesstesttruetrueotherwisecn.itcast.tags.OtherwiseTagscriptless

<%@taglib uri="/WEB-INF/ifelse.tld" prefix="jnb"%> 小于  大于