JSP迭代标签

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1. 新建LoopTag类，代码如下：

package bid.zhazhapan.fims.tag;import java.io.IOException;import java.util.Collection;import java.util.Iterator;import javax.servlet.jsp.JspException;import javax.servlet.jsp.tagext.BodyTagSupport;public class LoopTag extends BodyTagSupport {    private String name;// 迭代出的对象在pageContext中的名字    private Collection collection;// 需要迭代的集合对象    private Iterator it;// 需要迭代的对象    private String type;// 在迭代器中对象的类型    public void setName(String name) {        this.name = name;    }    public void setType(String type) {        this.type = type;    }    // 将页面中的集合对象传入到程序中    public void setCollection(Collection collection) {        this.collection = collection;        // 生成迭代对象        if (collection.size() > 0) {            it = collection.iterator();        }    }    public int doStartTag() throws JspException {        // 如果集合没有内容，不执行标签体        if (it == null) {            return this.SKIP_BODY;        }        return this.EVAL_BODY_INCLUDE;    }    public int doAfterBody() throws JspException {        if (it.hasNext()) {            //在这里自定义输出的内容            pageContext.setAttribute(name, "<br/>" + it.next());            return this.EVAL_BODY_AGAIN;// 此返回值将反复调用此方法        }        return this.SKIP_BODY;    }    public int doEndTag() throws JspException {        if (bodyContent != null) {            try {                bodyContent.writeOut(bodyContent.getEnclosingWriter());            } catch (IOException e) {                throw new JspException("IO Error " + e.getMessage());            }        }        return this.EVAL_PAGE;    }}

2. 新建LoopTEI类，代码如下：

package bid.zhazhapan.fims.tag;import javax.servlet.jsp.tagext.TagData;import javax.servlet.jsp.tagext.TagExtraInfo;import javax.servlet.jsp.tagext.VariableInfo;public class LoopTEI extends TagExtraInfo {    // 覆盖方法，定义脚本变量的信息    public VariableInfo[] getVariableInfo(TagData data) {        return new VariableInfo[] { new  VariableInfo(data.getAttributeString("name"), data.getAttributeString("type"), true, VariableInfo.NESTED)};    }}

3. 新建“mytag.tld“xml配置文件（如何配置xml文件），内容如下：

<?xml version="1.0" encoding="UTF-8"?><javaee:taglib version="2.1" xmlns:javaee="http://java.sun.com/xml/ns/javaee" xmlns:xml="http://www.w3.org/XML/1998/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-jsptaglibrary_2_1.xsd ">  <javaee:tlib-version>1.0</javaee:tlib-version>  <javaee:short-name>demo</javaee:short-name>  <javaee:uri>/demo</javaee:uri>  <javaee:tag>    <javaee:name>loop</javaee:name>    <javaee:tag-class>bid.zhazhapan.fims.tag.LoopTag</javaee:tag-class>    <javaee:tei-class>bid.zhazhapan.fims.tag.LoopTEI</javaee:tei-class>    <javaee:body-content>JSP</javaee:body-content>    <javaee:attribute>        <javaee:name>name</javaee:name>        <javaee:required>true</javaee:required>        <javaee:rtexprvalue>true</javaee:rtexprvalue>    </javaee:attribute>    <javaee:attribute>        <javaee:name>type</javaee:name>        <javaee:required>true</javaee:required>        <javaee:rtexprvalue>true</javaee:rtexprvalue>    </javaee:attribute>    <javaee:attribute>        <javaee:name>collection</javaee:name>        <javaee:required>true</javaee:required>        <javaee:rtexprvalue>true</javaee:rtexprvalue>    </javaee:attribute>  </javaee:tag></javaee:taglib>

4. 测试标签，新建test.jsp，代码如下：

<%@page import="java.util.ArrayList"%><%@ page language="java" contentType="text/html; charset=ISO-8859-1"    pageEncoding="ISO-8859-1"%><%@ taglib uri="WEB-INF/tlds/mytag.tld" prefix="mytag"%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>Insert title here</title></head><body>    <%        ArrayList ary = new ArrayList();        ary.add("apple");        ary.add("microsoft");        ary.add("google");    %>    <mytag:loop name="col" type="String" collection="<%=ary%>">${col }</mytag:loop></body></html>

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