一、使用DI注入的方式

<a href="<%=request.getContextPath()%>/servletObj_1">DI注入的方式</a>

controller

package com.controller.servletobj;

import java.io.PrintWriter;

import javax.servlet.ServletContext;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.servlet.ModelAndView;

@Controller
public class ServletObj_1 {
@Autowired
private HttpServletRequest request;
@Autowired
private HttpServletResponse response;
@Autowired
private HttpSession session;
@Autowired
private ServletContext servletContext;

@RequestMapping(value = "/servletObj_1")
public ModelAndView exuecte() throws Exception {
response.setContentType("text/html");
String contextPath = request.getContextPath();
String sessionID = session.getId();
String indexPath = servletContext.getRealPath("/index.jsp");
PrintWriter out = response.getWriter();

out.println("contextPath = " + contextPath+"<br/><br/>");
out.println("sessionID = " + sessionID+"<br/><br/>");
out.println("indexPath = " + indexPath+"<br/><br/>");

out.flush();
out.close();

return null;
}
}

二、形参传入的方式：ServletContext不能通过形参的方式注入，

<a href="<%=request.getContextPath()%>/servletObj_2">形参传入的方式</a>

controller

package com.controller.servletobj;

import java.io.PrintWriter;

import javax.servlet.ServletContext;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.servlet.ModelAndView;

@Controller
public class ServletObj_2 {

@RequestMapping(value = "/servletObj_2")
public ModelAndView exuecte(HttpServletRequest request,
HttpServletResponse response, HttpSession session) throws Exception {
response.setContentType("text/html");
/**
* ServletContext不能通过形参的方式注入，
*
* 通过其他对象来进行获取。
*/
ServletContext servletContext = request.getServletContext();
String contextPath = request.getContextPath();
String sessionID = session.getId();
String indexPath = servletContext.getRealPath("/index.jsp");
PrintWriter out = response.getWriter();

out.println("contextPath = " + contextPath + "<br/><br/>");
out.println("sessionID = " + sessionID + "<br/><br/>");
out.println("indexPath = " + indexPath + "<br/><br/>");

out.flush();
out.close();

return null;
}
}

• ServletContext不能通过形参的方式注入，

三、拦截器的方式：只能注入ServletContextAware和ServletConfigAware接口

<a href="<%=request.getContextPath()%>/servletObj_3">拦截器的方式</a>

controller

package com.controller.servletobj;

import java.io.PrintWriter;

import javax.servlet.ServletConfig;
import javax.servlet.ServletContext;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.context.ServletConfigAware;
import org.springframework.web.context.ServletContextAware;
import org.springframework.web.servlet.ModelAndView;

/**
* 通过拦截器来注入,只能注入ServletContextAware和ServletConfigAware接口
*
*/
@Controller
public class ServletObj_3 implements ServletContextAware, ServletConfigAware {
private ServletContext servletContext;
private ServletConfig servletConfig;

@Override
public void setServletContext(ServletContext servletContext) {
this.servletContext = servletContext;
}

@Override
public void setServletConfig(ServletConfig servletConfig) {
this.servletConfig = servletConfig;

}

@RequestMapping(value = "/servletObj_3")
public ModelAndView exuecte(HttpServletRequest request,
HttpServletResponse response, HttpSession session) throws Exception {
response.setContentType("text/html");
String contextPath = request.getContextPath();
String sessionID = session.getId();
String indexPath = this.servletContext.getRealPath("/index.jsp");
PrintWriter out = response.getWriter();

out.println("contextPath = " + contextPath + "<br/><br/>");
out.println("sessionID = " + sessionID + "<br/><br/>");
out.println("indexPath = " + indexPath + "<br/><br/>");

out.flush();
out.close();

return null;
}

}