JSP自定义标签 foreach select

续集（上篇博客地址）

上篇博客地址

①foreach

foreach助手类

package com.tanle.jsp;

import java.util.Iterator;
import java.util.List;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.BodyTagSupport;

public class ForeachTag extends BodyTagSupport{
	private List<Object> items;
	private String var;
	private String varStatus;//保存index ,count对象属性
	
	public static class Status{
		public int index=0;

		public int getIndex() {
			return index;
		}

		public void setIndex(int index) {
			this.index = index;
		}
		public int getCount() {
			
			return this.index+1;
		}
		void increment() {
			this.index++;
		}
	}
	
	
	
	
	
	
	public String getVarStatus() {
		return varStatus;
	}
	public void setVarStatus(String varStatus) {
		this.varStatus = varStatus;
	}
	public List<Object> getItems() {
		return items;
	}
	public void setItems(List<Object> items) {
		this.items = items;
	}
	public String getVar() {
		return var;
	}
	public void setVar(String var) {
		this.var = var;
	}
	
	
	@Override
	public int doStartTag() throws JspException {
		// TODO Auto-generated method stub
		if(null!=varStatus && !"".equals(varStatus)) {
			pageContext.setAttribute(varStatus, new Status());
		}
		if(null!=items && 0!=items.size()) {
			Iterator<Object> it = items.iterator();
			Object next = it.next();
			pageContext.setAttribute(var, next);
			pageContext.setAttribute("it", it);
			return EVAL_BODY_INCLUDE;
		}
		
		return doStartTag();
	}
	@Override
	public int doAfterBody() throws JspException {
		// TODO Auto-generated method stub
		Iterator<Object> it = (Iterator<Object>) pageContext.getAttribute("it");
		while(it.hasNext()) {
			if(null!=varStatus && !"".equals(varStatus)) {
				Status status = (com.tanle.jsp.ForeachTag.Status) pageContext.getAttribute(varStatus);
				status.increment();
				pageContext.setAttribute(varStatus, status);
			}
			Object next = it.next();
			pageContext.setAttribute(var, next);

			return EVAL_BODY_AGAIN;
		}
		return super.doAfterBody();
	}
}

foreach的tld文件设置

 <tag>
    <name>forEach</name>
    <tag-class>com.tanle.jsp.ForeachTag</tag-class>
    <body-content>JSP</body-content>
  	<attribute>
  		<name>items</name>
  		<required>true</required>
  		<rtexprvalue>true</rtexprvalue>
  	</attribute>
  	<attribute>
  		<name>var</name>
  		<required>true</required>
  		<rtexprvalue>false</rtexprvalue>
  	</attribute>
  	<attribute>
  		<name>varStatus</name>
  		<required>false</required>
  		<rtexprvalue>false</rtexprvalue>
  	</attribute>
  </tag>

界面显示

	<t:forEach items="${names }" var="n" varStatus="s">
		<li>${n },${s.index },${s.count }</li>
	</t:forEach>	

②select

select助手类

package com.tanle.jsp;

import java.lang.reflect.InvocationTargetException;
import java.util.List;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.tagext.BodyTagSupport;

import org.apache.commons.beanutils.PropertyUtils;

public class SelectTag extends BodyTagSupport{
	
	private List<Object> items;
	
	private String name;
	
	private String valueKey;//保存option中value的key
	
	private String textKey;//保存option中text文本的key

	private String cssStyle;
	
	private String headKey;
	private String headValue;
	private String selectedOptionValue;
	
	
	
	public String getSelectedOptionValue() {
		return selectedOptionValue;
	}

	public void setSelectedOptionValue(String selectedOptionValue) {
		this.selectedOptionValue = selectedOptionValue;
	}

	public String getHeadKey() {
		return headKey;
	}

	public void setHeadKey(String headKey) {
		this.headKey = headKey;
	}

	public String getHeadValue() {
		return headValue;
	}

	public void setHeadValue(String headValue) {
		this.headValue = headValue;
	}

	public String getCssStyle() {
		return cssStyle;
	}

	public void setCssStyle(String cssStyle) {
		this.cssStyle = cssStyle;
	}

	public List<Object> getItems() {
		return items;
	}

	public void setItems(List<Object> items) {
		this.items = items;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public String getValueKey() {
		return valueKey;
	}

	public void setValueKey(String valueKey) {
		this.valueKey = valueKey;
	}

	public String getTextKey() {
		return textKey;
	}

	public void setTextKey(String textKey) {
		this.textKey = textKey;
	}
	
	@Override
	public int doStartTag() throws JspException {
		// TODO Auto-generated method stub
		JspWriter out = pageContext.getOut();
		try {
			String html = toHtml();
			out.print(html);
		} catch (Exception e) {
			// TODO: handle exception
			throw new RuntimeException();
		}
		
		return super.doStartTag();
	}
	private String toHtml() throws Exception{
		StringBuffer sb=new StringBuffer();
		//<select name="" style="">
		sb.append("<select name='"+name+"'");
		sb.append(" style='"+cssStyle+"'");
		sb.append(">");
		//<option value=""></option>
		if(null!=items && 0!=items.size()) {
			if(null!=headKey && !"".equals(headKey.trim())) {
				sb.append("<option value='"+headKey+"'>"+headValue+"</option>");
			}
			Object value=null;
			Object text=null;
			for (Object object : items) {
				//反射
				value=PropertyUtils.getProperty(object, valueKey);
				text=PropertyUtils.getProperty(object, textKey);
				if(value.toString().equals(selectedOptionValue.trim())) {
					sb.append("<option selected value='"+value+"'>"+text+"</option>");

				}else {
					sb.append("<option value='"+value+"'>"+text+"</option>");

				}
			}
		}
		
		sb.append("</select>");
		
		return sb.toString();
	}
}

select的tld文件设置

 <tag>
    <name>select</name>
    <tag-class>com.tanle.jsp.SelectTag</tag-class>
    <body-content>empty</body-content>
  	<attribute>
  		<name>items</name>
  		<required>true</required>
  		<rtexprvalue>true</rtexprvalue>
  	</attribute>
  	<attribute>
  		<name>name</name>
  		<required>false</required>
  		<rtexprvalue>false</rtexprvalue>
  	</attribute>
  	<attribute>
  		<name>valueKey</name>
  		<required>true</required>
  		<rtexprvalue>false</rtexprvalue>
  	</attribute>
  	<attribute>
  		<name>textKey</name>
  		<required>true</required>
  		<rtexprvalue>false</rtexprvalue>
  	</attribute>
  	<attribute>
  		<name>cssStyle</name>
  		<required>false</required>
  		<rtexprvalue>false</rtexprvalue>
  	</attribute>
  	
  	<attribute>
  		<name>selectedOptionValue</name>
  		<required>false</required>
  		<rtexprvalue>false</rtexprvalue>
  	</attribute>
  </tag>

界面显示

<%
	List<Dept> li=new ArrayList<Dept>();
	li.add(new Dept(1,"教质部"));
	li.add(new Dept(2,"教学部"));
	li.add(new Dept(3,"财务部"));
	li.add(new Dept(4,"就业部"));
	request.setAttribute("li", li);
	%>
	<t:select items="${li
	 }" valueKey="deptId" textKey="deptName" cssStyle="" selectedOptionValue=""/>

③总结

感谢观看，有什么不足之处欢迎指正.