jsp通过自定义标签库实现数据列表显示的方法

前端技术 2023/09/02 JSP

本文实例讲述了jsp通过自定义标签库实现数据列表显示的方法。分享给大家供大家参考，具体如下：

1. 定义标签库类 UserListTag.java

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;
import com.yanek.cms.vo.UserInfo;
public class UserListTag extends BodyTagSupport {
 private String name;// 一个属性名
 private Iterator it;// 要迭代的对象
 private int cateid; // 用户类别id
 @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 {
 //这里根据用户类型,构造不同的列表数据,实现可以根据数据库获取
 List<UserInfo> users = new ArrayList<UserInfo>();
 if (cateid == 1) {
  users.add(new UserInfo(\"张三\", 20, \"Zhangsan@163.com\"));
  users.add(new UserInfo(\"李四\", 30, \"Lisi@sina.com\"));
 } else {
  users.add(new UserInfo(\"王五\", 33, \"Wangwu@qq.com\"));
  users.add(new UserInfo(\"赵六\", 33, \"zhaoliu@qq.com\"));
 }
 it = users.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 String getName() {
 return name;
 }
 public void setName(String name) {
 this.name = name;
 }
 public int getCateid() {
 return cateid;
 }
 public void setCateid(int cateid) {
 this.cateid = cateid;
 }
}

2. 在WEB-INF目录下 新建标签库描述文件my_cms_tag.tld：

my_cms_tag.tld

<?xml version=\"1.0\" encoding=\"UTF-8\"?>
<!DOCTYPE taglib PUBLIC \"-//Sun Microsystems, Inc.//DTD JSP Tag Library 1.1//EN\" \"http://java.sun.com/j2ee/dtds/web-jsptaglibrary_1_1.dtd\">
<taglib>
<tlibversion>1.0</tlibversion>
<jspversion>1.0</jspversion>
<shortname>cms</shortname>
<uri>http://www.58tech.cn/mystruts/tags-cms</uri>
<!-- userListTag start -->
  <tag>
    <name>userListTag</name>
    <tag-class>com.yanek.cms.tag.UserListTag</tag-class>
    <body-content>jsp</body-content>
   <variable>
    <!--<name-given>user_info</name-given>-->
    <name-from-attribute>name</name-from-attribute>
    <variable-class>com.yanek.cms.vo.UserInfo</variable-class>
    <declare>true</declare>
    <scope>NESTED</scope>
   </variable>
    <attribute>
    <name>name</name>
    <required>true</required>
    </attribute>
    <attribute>
    <name>cateid</name>
    <required>true</required>
    </attribute>
</tag>
<!-- userListTag end -->
</taglib>

3. web.xml配置

<?xml version=\"1.0\" encoding=\"UTF-8\"?>
<web-app version=\"2.5\" 
 xmlns=\"http://java.sun.com/xml/ns/javaee\"
 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-app_2_5.xsd\">
 <welcome-file-list>
  <welcome-file>index.jsp</welcome-file>
 </welcome-file-list>
 <taglib>
   <taglib-uri>/tags/my-cms</taglib-uri>
   <taglib-location>/WEB-INF/my_cms_tag.tld</taglib-location>
 </taglib>
</web-app>

4. jsp调用

<%@ page language=\"java\" import=\"java.util.*,com.yanek.cms.vo.*\" pageEncoding=\"UTF-8\"%>
<%@ taglib uri=\"/tags/my-cms\" prefix=\"myTag\" %>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+\"://\"+request.getServerName()+\":\"+request.getServerPort()+path+\"/\";
%>
<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">
<html>
 <head>
  <base href=\"<%=basePath%>\">
  <title>My JSP \'test.jsp\' starting page</title>
 <meta http-equiv=\"pragma\" content=\"no-cache\">
 <meta http-equiv=\"cache-control\" content=\"no-cache\">
 <meta http-equiv=\"expires\" content=\"0\">  
 <meta http-equiv=\"keywords\" content=\"keyword1,keyword2,keyword3\">
 <meta http-equiv=\"description\" content=\"This is my page\">
 <!--
 <link rel=\"stylesheet\" type=\"text/css\" href=\"styles.css\">
 -->
 </head>
 <body>
<table width=\'500px\' border=\'1\' align=\'center\'>
  <tr>
    <td width=\'20%\'>UserName</td>
    <td width=\'20%\'>Age</td>
    <td>Email</td>
  </tr>
<myTag:userListTag name=\"user_info1\" cateid=\"1\"> 
    <tr>
      <td><%=user_info1.getUserName() %></td>
      <td><%=user_info1.getAge() %></td>
      <td><%=user_info1.getEmail() %>
      </td>
    </tr> 
</myTag:userListTag>
</table>
<hr>
<table width=\'500px\' border=\'1\' align=\'center\'>
  <tr>
    <td width=\'20%\'>UserName</td>
    <td width=\'20%\'>Age</td>
    <td>Email</td>
  </tr>
<myTag:userListTag name=\"user_info2\" cateid=\"2\">
    <tr>
      <td><%=user_info2.getUserName() %></td>
      <td><%=user_info2.getAge() %></td>
      <td><%=user_info2.getEmail() %>
      </td>
    </tr> 
</myTag:userListTag>
</table>
 </body>
</html>

实体类定义

package com.yanek.cms.vo;
public class UserInfo {
 private int age;
 private String userName;
 private String email;
 public int getAge() {
 return age;
 }
 public void setAge(int age) {
 this.age = age;
 }
 public String getUserName() {
 return userName;
 }
 public void setUserName(String userName) {
 this.userName = userName;
 }
 public String getEmail() {
 return email;
 }
 public void setEmail(String email) {
 this.email = email;
 }
 public UserInfo(String userName,int age, String email) {
 super();
 this.age = age;
 this.userName = userName;
 this.email = email;
 }
 public UserInfo() {
 }
}

运行效果如下图 （URL输入：http://127.0.0.1:8080/TestCMS/page/userlist.jsp）

完整实例代码代码点击此处本站下载。

希望本文所述对大家Android程序设计有所帮助。

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