JSP迭代标签

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, "
"
+ 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:


<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>1.0javaee:tlib-version>
  <javaee:short-name>demojavaee:short-name>
  <javaee:uri>/demojavaee:uri>
  <javaee:tag>
    <javaee:name>loopjavaee:name>
    <javaee:tag-class>bid.zhazhapan.fims.tag.LoopTagjavaee:tag-class>
    <javaee:tei-class>bid.zhazhapan.fims.tag.LoopTEIjavaee:tei-class>
    <javaee:body-content>JSPjavaee:body-content>
    <javaee:attribute>
        <javaee:name>namejavaee:name>
        <javaee:required>truejavaee:required>
        <javaee:rtexprvalue>truejavaee:rtexprvalue>
    javaee:attribute>
    <javaee:attribute>
        <javaee:name>typejavaee:name>
        <javaee:required>truejavaee:required>
        <javaee:rtexprvalue>truejavaee:rtexprvalue>
    javaee:attribute>
    <javaee:attribute>
        <javaee:name>collectionjavaee:name>
        <javaee:required>truejavaee:required>
        <javaee:rtexprvalue>truejavaee: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"%>

<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title heretitle>
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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