通过ServletContext实现Servlet之间共享数据

最新推荐文章于 2023-06-28 23:54:06 发布

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最新推荐文章于 2023-06-28 23:54:06 发布

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分类专栏： javaweb Servlet 文章标签： ServletContext

本文链接：https://blog.youkuaiyun.com/wangyanming123/article/details/52259806

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本文通过两个Servlet实例演示了如何使用ServletContext对象在应用范围内设置属性并获取这些属性。首先在一个Servlet中设置了一个字符串属性，在另一个Servlet中读取这个属性并输出。

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ServletContext 是应用级域对象。

web.xml文件：

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.0"
    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_3_0.xsd">
  <servlet>
  	<!-- 定义Sevlet:给Servlet取个名字 -->
    <servlet-name>ServletDemo</servlet-name>
    <servlet-class>com.neu.ServletDemo</servlet-class>
  </servlet>
  <servlet>
    <servlet-name>ServletDemo2</servlet-name>
    <servlet-class>com.neu.ServletDemo2</servlet-class>
  </servlet>


  <servlet-mapping>
  	<!-- 映射Servlet:给Servlet一个访问地址 -->
    <servlet-name>ServletDemo</servlet-name>
    <url-pattern>/hello</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>ServletDemo2</servlet-name>
    <url-pattern>/servlet/ServletDemo2</url-pattern>
  </servlet-mapping>

</web-app>

ServletDemo.java文件：

package com.neu;

import java.io.IOException;
import java.util.Enumeration;

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

public class ServletDemo extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		
		ServletContext sc = getServletContext();
		sc.setAttribute("p", "ppp");
		response.getWriter().write("OK");
	}

	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		doGet(request, response);
	}
	
}

ServletDemo2.java文件：

package com.neu;

import java.io.IOException;
import java.io.PrintWriter;

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

public class ServletDemo2 extends HttpServlet {

	
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		ServletContext sc = getServletContext();
		String value = (String)sc.getAttribute("p");
		response.getWriter().write(value);
	}


	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		
	}

}

运行及结果：