java 自定义标签库_jsp通过自定义标签库实现数据列表显示的方法

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 users = new ArrayList();

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

1.0

1.0

cms

http://www.58tech.cn/mystruts/tags-cms

userListTag

com.yanek.cms.tag.UserListTag

jsp

name

com.yanek.cms.vo.UserInfo

true

NESTED

name

true

cateid

true

3. web.xml配置

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">

index.jsp

/tags/my-cms

/WEB-INF/my_cms_tag.tld

4. jsp调用

String path = request.getContextPath();

String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";

%>

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。