Servlet——Session、ServletConfig、ServletContext

Session的使用

1、取得session对象

req.getSession()方法

2、取得sessionId

getId()方法

3、设置session的最大空闲时间

setMaxInactiveInterval()

4、强制session失效

invalidate()

范例：

package com.zgy.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 javax.servlet.http.HttpSession;

public class TestSessionServlet extends HttpServlet{

@Override

protected void doGet(HttpServletRequest req, HttpServletResponse resp)

throws ServletException, IOException {

HttpSession session = req.getSession();

resp.getWriter().println(session.getId());

session.setMaxInactiveInterval(3);

}

}

八、ServletConfig

1、ServletConfig 一般用于处理该servlet在配置文件中的配置信息

范例：

package com.zgy.servlet;

import java.io.IOException;

import java.util.Enumeration;

import javax.servlet.ServletConfig;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

public class TestServletConfig extends HttpServlet{

@Override

protected void doGet(HttpServletRequest req, HttpServletResponse resp)

throws ServletException, IOException {

ServletConfig config = this.getServletConfig();

resp.getWriter().println(config.getInitParameter("a"));

resp.getWriter().println(config.getServletName());

Enumeration<?> e = config.getInitParameterNames();

while(e.hasMoreElements()){

resp.getWriter().println(e.nextElement());

}

resp.getWriter().println(config.getClass());

}

}

九、ServletContext对象

范例：

package com.zgy.servlet;

import java.io.IOException;

import java.util.Date;

import java.util.Set;

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 TestServletContext extends HttpServlet{

@Override

protected void doGet(HttpServletRequest req, HttpServletResponse resp)

throws ServletException, IOException {

ServletContext sc = this.getServletContext();

resp.getWriter().println(sc.getInitParameter("aa"));

//sc.setAttribute("c", new Date());

String str = sc.getRealPath("index.jsp");

resp.getWriter().println("realpath:"+str);

Set<String> set = sc.getResourcePaths("/WEB-INF");

for(String s : set){

resp.getWriter().println(s);

}

}

}