Javaweb崔希凡---Day13---自定义标签---MVC

Carmen_W

于 2019-02-26 14:59:08 发布

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分类专栏： javaweb 文章标签： javaweb MVC 自定义标签

本文链接：https://blog.youkuaiyun.com/xw_Summer/article/details/87927160

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12 篇文章

订阅专栏

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JSTL标签库

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4　core标签库常用标签

自定义标签

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HelloTag.java

public class HelloTag implements SimpleTag {
	private JspTag parent;
	private PageContext pageContext;
	private JspFragment jspBody;
	
	public void doTag() throws JspException, IOException {
		pageContext.getOut().print("Hello Tag!!!");
	}
	public void setParent(JspTag parent) {
		this.parent = parent;
	}
	public JspTag getParent() {
		return this.parent;
	}
	public void setJspContext(JspContext pc) {
		this.pageContext = (PageContext) pc;
	}
	public void setJspBody(JspFragment jspBody) {
		this.jspBody = jspBody;
	}
}

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hello.tld

MVC

1　MVC设计模式

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JavaWeb经典三层框架

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三层的HELLOWORLD程序：

domain：

package cn.itcast.domain;

/**
 * 把数据库中查询出的结果保存到这个对象中。
 * @author cxf
 *
 */
public class User {
	private String username;
	private String password;
	public User(String username, String password) {
		this.username = username;
		this.password = password;
	}
	public User() {
		super();
		// TODO Auto-generated constructor stub
	}
	public String getUsername() {
		return username;
	}
	public void setUsername(String username) {
		this.username = username;
	}
	public String getPassword() {
		return password;
	}
	public void setPassword(String password) {
		this.password = password;
	}
	@Override
	public String toString() {
		return "User [username=" + username + ", password=" + password + "]";
	}
}

dao:

package cn.itcast.dao;

import cn.itcast.domain.User;

public class UserDao {
	/*
	 * 把xml中的数据查询出来之后，封装到user对象中，然后返回
	 */
	public User find() {
		return new User("zhangSan", "123"); 
	}
}

service :

package cn.itcast.service;

import cn.itcast.dao.UserDao;
import cn.itcast.domain.User;

public class UserService {
	// service层依赖dao层
	private UserDao userDao = new UserDao();
	
	/*
	 * service的查询，需要使用dao来完成！
	 */
	public User find() {
		return userDao.find();
	}
}

servlet :

package cn.itcast.web.servlet;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import cn.itcast.domain.User;

import cn.itcast.service.UserService;

public class UserServlet extends HttpServlet {
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		/*
		 * 在servlet中依赖service，然后通过service完成功能，把结果保存到request中
		 * 转发到jsp显示。
		 */
		UserService userService = new UserService();
		User user = userService.find();
		
		request.setAttribute("user", user);
		
		request.getRequestDispatcher("/show.jsp").forward(request, response);
	}
}

index.jsp :

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%
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 'index.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>
<a href="<c:url value='/UserServlet'/>">点击这里查看</a>
  </body>
</html>

show.jsp :

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
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 'show.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>
用户名：${user.username }<br/>
密　码：${user.password }<br/>
  </body>
</html>