使用jsp自定义标签库实现数据列表显示模拟cms4j中的标签库效果

来源：互联网发布：gxsec软件编辑：程序博客网时间：2024/06/04 17:58

文章标题：使用jsp自定义标签库实现数据列表显示模拟cms4j中的标签库效果

作者： javaboy2012
Email：yanek@163.com
qq: 1046011462

cms4j中调用方式:

下面例子实现类似效果:

运行效果:

具体如下:

jsp调用代码：

<%@ page language="java" import="java.util.*,com.yanek.cms.vo.*" pageEncoding="UTF-8"%>
<%@ taglib uri="/tags/my-cms" prefix="myTag" %>
<body>
<myTag:articleListTag cateid="1">

    <%=article_info.getId() %>------
            <%=article_info.getTitle() %> <br>

            ${article_info.id }---- ${article_info.title }<br>

</myTag:articleListTag>
<hr>

<myTag:articleListTag cateid="2">

    <%=article_info.getId() %>------
            <%=article_info.getTitle() %> <br>

            ${article_info.id }---- ${article_info.title }<br>

</myTag:articleListTag>
</body>
</html>

标签库定义

<tag>

<name>articleListTag</name>

<tag-class>com.yanek.cms.tag.ArticleTag</tag-class>

<body-content>jsp</body-content>

      <variable>
        <name-given>article_info</name-given>
        
        <variable-class>com.yanek.cms.tag.Article</variable-class>
        <declare>true</declare>
        <scope>NESTED</scope>
      </variable>

       <attribute>
        <name>cateid</name>
        <required>true</required>
       </attribute>

</tag>

标签库类

package com.yanek.cms.tag;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

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

public class ArticleTag extends BodyTagSupport {

private Iterator it;// 要迭代的对象
private int cateid; // 文章类别id

public final static String name = "article_info";

@Override
public int doEndTag() throws JspException {
  try {
   if (bodyContent != null) {
    bodyContent.writeOut(bodyContent.getEnclosingWriter());
   }
  } catch (IOException e) {
   e.printStackTrace();

}
return EVAL_PAGE;
}

@Override
public int doStartTag() throws JspException {

  //这里根据文章分类,构造不同的列表数据,实际可以根据数据库获取
  List<Article> articles = new ArrayList<Article>();
  if (cateid == 1) {
   articles.add(new Article(1, "asp"));

   articles.add(new Article(2, "jsp"));
  } else {
   articles.add(new Article(3, "php"));

   articles.add(new Article(4, "java"));
  }
  it = articles.iterator();

if (it == null) {
return SKIP_BODY;

  } else {
   return continueNext();
  }
}

private int continueNext() {
  if (it.hasNext()) {
   pageContext.setAttribute(name, it.next(), pageContext.PAGE_SCOPE);
   return EVAL_BODY_TAG;
  } else {

return SKIP_BODY;
}
}

@Override
public int doAfterBody() {
return continueNext();
}

public int getCateid() {
return cateid;
}

public void setCateid(int cateid) {
this.cateid = cateid;
}

}

标签库引用实体类

package com.yanek.cms.tag;

public class Article {

private int id;
private String title;
public int getId() {
  return id;
}
public void setId(int id) {
  this.id = id;
}
public String getTitle() {
  return title;
}
public void setTitle(String title) {
  this.title = title;
}
public Article(int id, String title) {
  super();
  this.id = id;
  this.title = title;
}

public Article() {
  super();
  this.id = id;
  this.title = title;
}

}

几点说明：标签调用是显示list中对象时采用的脚本变量名字article_info 是在标签库定义文件和标签库类中定义的，如下

<variable>
        <name-given>article_info</name-given>
        
        <variable-class>com.yanek.cms.tag.Article</variable-class>
        <declare>true</declare>
        <scope>NESTED</scope>
      </variable>

标签库类中
public final static String name = "article_info";
pageContext.setAttribute(name, it.next(), pageContext.PAGE_SCOPE);

显示列表中对象的方式有2种方式：

调用类的方法：在eclipse中可以方法提示。

<%=article_info.getId() %>---- <%=article_info.getTitle() %>

jstl显示：

${article_info.id }---- ${article_info.title }