Servlet ServletContext

最新推荐文章于 2024-11-06 01:05:47 发布

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最新推荐文章于 2024-11-06 01:05:47 发布

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本文链接：https://blog.youkuaiyun.com/phone13144830339/article/details/78903794

package cn.et;

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;

public class ExampleServlet1 extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
   
    public ExampleServlet1() {
        super();
    }

	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		/*ServletContext代表当前Web应用，作用整个应用程序*/
		//ServletConfig 维护了ServletContext的引用
		ServletContext servletContext1 = this.getServletConfig().getServletContext();
		ServletContext servletContext2 = this.getServletContext();
		//servletContext1与servletContext2是同一个对象
		System.out.println(servletContext1==servletContext2);
	}

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

}

package cn.et;

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;


public class ExampleServlet2 extends HttpServlet {
	private static final long serialVersionUID = 1L;

    public ExampleServlet2() {
        super();
    }

	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		ServletContext servletContext = this.getServletContext();
		String data = "数据信息";
		//将data数据设入Context作用域中
		servletContext.setAttribute("data", data);
		//设入Context中的数据，其他Servlet也能通过ServletContext对象获取数据,可用于数据交流
		String value = (String)servletContext.getAttribute("data");
		response.getOutputStream().write(("Hello Servlet "+value).getBytes());
	}
	
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		doGet(request, response);
	}

}

package cn.et;

import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;

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


public class ExampleServlet3 extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    public ExampleServlet3() {
        super();
    }

	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		//读取资源文件(.properties)
		//“/”代表当前Web应用(服务器中的应用目录)
		InputStream in = this.getServletContext().getResourceAsStream("/WEB-INF/classes/jdbc.properties");
		Properties props = new Properties();
		props.load(in);
		/*driverClass=oracle.jdbc.OracleDriver
	    url=jdbc:oracle:thin:@localhost:1521:orcl
	    usernames=scott
	    password=tiger*/
		String driverClass = props.getProperty("driverClass");
		String url = props.getProperty("url");
		String usernames = props.getProperty("usernames");
		String password = props.getProperty("password");
		System.out.println(driverClass);
		System.out.println(url);
		System.out.println(usernames);
		System.out.println(password);
		//请求转发
		RequestDispatcher rd = this.getServletContext().getRequestDispatcher("/index.html");
		rd.forward(request, response);
	}
	
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		doGet(request, response);
	}

}

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
  <display-name>ServletExample3_ServletContext</display-name>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>
  </welcome-file-list>
  <servlet>
    <description></description>
    <display-name>ExampleServlet1</display-name>
    <servlet-name>ExampleServlet1</servlet-name>
    <servlet-class>cn.et.ExampleServlet1</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>ExampleServlet1</servlet-name>
    <url-pattern>/ExampleServlet1</url-pattern>
  </servlet-mapping>
  <servlet>
    <description></description>
    <display-name>ExampleServlet2</display-name>
    <servlet-name>ExampleServlet2</servlet-name>
    <servlet-class>cn.et.ExampleServlet2</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>ExampleServlet2</servlet-name>
    <url-pattern>/ExampleServlet2</url-pattern>
  </servlet-mapping>
  <servlet>
    <description></description>
    <display-name>ExampleServlet3</display-name>
    <servlet-name>ExampleServlet3</servlet-name>
    <servlet-class>cn.et.ExampleServlet3</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>ExampleServlet3</servlet-name>
    <url-pattern>/ExampleServlet3</url-pattern>
  </servlet-mapping>
</web-app>

index.html

<html>
	<body>
		HTML页面
	</body>
</html>

jdbc.properties文件，放在src目录下

#driverClass=com.mysql.jdbc.Driver
#url=jdbc:mysql://192.168.14.103:3306/myself
#usernames=root
#password=123456
driverClass=oracle.jdbc.OracleDriver
url=jdbc:oracle:thin:@localhost:1521:orcl
usernames=scott
password=tiger