Action间接、直接访问Servlet API

谁践踏了优雅 2024-02-17 23:59 54阅读 0赞

一、间接访问：

需要经常访问的Servlet API就是HttpServletRequest 、HttpSession 、ServletContext三个类，分别代表着jsp内置对象的request、session、application

struts2 提供一个类ActionContext（当前Action上下文对象，通过这个类可以访问Servlet API。包含以下几个常用方法：

Map getApplication();

static ActionContext Context();

Map getParameters();

Map getSesstion();

void set Apptioncatoin(Map application)；

案例1：用户登录验证：

longin2.jsp页面：

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
    <%@ taglib prefix = "s" uri = "/struts-tags" %>
    <%
    String path = request.getContextPath();
    String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
    %>
    
    <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
    <html>
      <head>
        <base href="<%=basePath%>">
        
        <title>My JSP 'login2.jsp' starting page</title>
        
    	<meta http-equiv="pragma" content="no-cache">
    	<meta http-equiv="cache-control" content="no-cache">
    	<meta http-equiv="expires" content="0">    
    	<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
    	<meta http-equiv="description" content="This is my page">
    	
    
      </head>
      
      <body>
        <s:form action = "login2" method = "post">
          <s:textfield name = "username" label = "用户名"></s:textfield>
          <s:password name = "password" label = "密码"></s:password><br><br>
          <s:submit value = "提交"></s:submit>
        </s:form>
      </body>
    </html>

Action：LoginActoin2页面：

package com.action;
    
    import com.opensymphony.xwork2.ActionContext;
    import com.opensymphony.xwork2.ActionSupport;
    
    public class LoginAction2 extends ActionSupport{
      private String username;
      private String password;
      
      public String execute() {
    	  ActionContext actionContext = ActionContext.getContext(); //静态方法；
    	  if(username.equals("admin") && password.equals("admin")){
    		  actionContext.getSession().put("username", username);
    		  actionContext.getSession().put("password", password);
    		  return SUCCESS;
    	  }
    	return LOGIN;
      }
      
    public String getUsername() {
    	return username;
    }
    public void setUsername(String username) {
    	this.username = username;
    }
    public String getPassword() {
    	return password;
    }
    public void setPassword(String password) {
    	this.password = password;
    }
      
    }

welcome2.jsp页面：

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
    <%@ taglib prefix = "s" uri = "/struts-tags" %>
    <%
    String path = request.getContextPath();
    String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
    %>
    
    <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
    <html>
      <head>
        <base href="<%=basePath%>">
        
        <title>My JSP 'welcome2.jsp' starting page</title>
        
    	<meta http-equiv="pragma" content="no-cache">
    	<meta http-equiv="cache-control" content="no-cache">
    	<meta http-equiv="expires" content="0">    
    	<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
    	<meta http-equiv="description" content="This is my page">
    	
    
      </head>
      
      <body>
       欢迎<s:property value = "#session.username"/>访问此页面！
      </body>
    </html>

二、直接访问：

方式1）：实现相应的接口

ServletContextAware : 实现该接口的Action可以直接访问ServletContext 对象，Action 必须提供该接口的void setServletContext(ServletContext servletcontext)方法

ServletRequestAware :

ServlerResponseAware:

SessionAware:

修改以上Action中的代码：

package com.action;
    
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpSession;
    
    import org.apache.struts2.interceptor.ServletRequestAware;
    
    import com.opensymphony.xwork2.ActionContext;
    import com.opensymphony.xwork2.ActionSupport;
    
    public class LoginAction2 extends ActionSupport implements ServletRequestAware{
      private String username;
      private String password;
      private HttpServletRequest servletRequest;
      
      public String execute() {
          HttpSession session = servletRequest.getSession();
    	  if(username.equals("admin") && password.equals("admin")){
    		  session.setAttribute("username", username);
    		  session.setAttribute("password", password);
    		  return SUCCESS;
    	  }
    	return LOGIN;
      }
      
    public String getUsername() {
    	return username;
    }
    public void setUsername(String username) {
    	this.username = username;
    }
    public String getPassword() {
    	return password;
    }
    public void setPassword(String password) {
    	this.password = password;
    }
    
    public HttpServletRequest getServletRequest() {
    	return servletRequest;
    }
    
    public void setServletRequest(HttpServletRequest servletRequest) {
    	this.servletRequest = servletRequest;
    }//要使用HttpServletRequest对象，必须实现该方法
    
    
      
    }

方式2）struts2提供了ServletActionContext类：（直接访问中最常用，代码简洁）

有以下几个静态方法：

static PageContext getPageContext() ;取得Web应用的PageContext对象

static HttpServletRequest getRequest();…………

static HttpServletResponse gerResponse;…………

static ServletContext geteServletContext();…………

修改Action代码：

public class LoginAction2 extends ActionSupport{
      private String username;
      private String password;
      
      public String execute() {
    	  if(username.equals("admin") && password.equals("admin")){
    		  ServletActionContext.getRequest().getSession().setAttribute("username", username);
    		  return SUCCESS;
    	  }
    	return LOGIN;
      }