JavaWeb基础 ServletContext get/setAttribute 保存与读取数据

Posted 2020-10-11

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       javaEE：7           
       javaSE：1.8
          JSTL：1.2.2  
      server：tomcat 8.5
    explorer：Firefox        
             os：windows7 x64
            ide：MyEclipse 2017

工程目录结构

 

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" version="3.1">

	<servlet>
		<servlet-name>SavaDataServletContext</servlet-name>
		<servlet-class>jizuiku.web.servlet.SavaDataServletContext</servlet-class>
	</servlet>
	<servlet-mapping>
		<servlet-name>SavaDataServletContext</servlet-name>
		<url-pattern>/SavaDataServletContext</url-pattern>
	</servlet-mapping>

	<servlet>
		<servlet-name>ReadDataServletContext</servlet-name>
		<servlet-class>jizuiku.web.servlet.ReadDataServletContext</servlet-class>
	</servlet>
	<servlet-mapping>
		<servlet-name>ReadDataServletContext</servlet-name>
		<url-pattern>/ReadDataServletContext</url-pattern>
	</servlet-mapping>

	
</web-app>

 

ReadDataServletContext类的代码

package jizuiku.web.servlet;

import java.io.IOException;

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * ServletContext 读取数据
 * 
 * @author 给最苦
 * @version V17.10.21
 */
public class ReadDataServletContext extends HttpServlet {

	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;

	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		// TODO Auto-generated method stub
		System.out.println("读取数据");
		
		ServletContext application = this.getServletContext();
		String nameValue = (String)application.getAttribute("name");
		System.out.println(nameValue);
	}
	
	@Override
	protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		// TODO Auto-generated method stub
		super.doPost(req, resp);
	}
}

 

SavaDataServletContext类

package jizuiku.web.servlet;

import java.io.IOException;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * ServletContext 保存数据
 * 
 * @author 给最苦
 * @version V17.10.21
 * */
public class SavaDataServletContext extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		ServletContext application = this.getServletContext();
		application.setAttribute("name", "给最苦");
		// 如果再次对name赋值的话，会覆盖
		application.setAttribute("name", "博客园");
		
		System.out.println("数据成功保存在ServletContext中");
	}

	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		doGet(request, response);
	}

}

 

效果展示

 

 

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