Struts2(八)訪問Servlet API

2019-11-14 23:32:14

字體：大中小

來源：轉載

供稿：網友

Struts2(八)訪問Servlet API一、Struts2中的Servlet API1.1、struts2的Action實現了MVC中C層的作用

針對請求用戶顯示不同的信息

登錄后段保存用戶信息 ----session

保存當前在線人數等功能---application

1.2、傳統的Servlet API類型

HttpServletRequest

HttpSession

ServletContext

1.3、Struts2中將傳統的Servlet API類型被處理成Map類型

訪問更方便

不依賴傳統Servlet API 類型--解耦合

二、ActionContext

所在包com.opensymphony.xwork2

ActionContext被稱為Action上下文或者Action環境

ActionContext，提供每個Action運行時與之相關的所有信息

訪問Servlet API

ActionContext類提供getContext（）方法獲得實例

通過ActionContext類的實例可獲得Map類型的請求，會話等

通過Put（）和Get（）方法在Map類型的對象中存取數據

二、簡單例子

web.xml中添加

 <filter>        <filter-name>struts2</filter-name>        <filter-class>org.apache.struts2.dispatcher.ng.filter.StrutsPRepareAndExecuteFilter</filter-class>    </filter>    <filter-mapping>        <filter-name>struts2</filter-name>        <url-pattern>/*</url-pattern>    </filter-mapping>

<%@ page language="java" contentType="text/html; charset=UTF-8"    pageEncoding="UTF-8"%><%    String path = request.getContextPath();    String basePath = request.getScheme() + "://"            + request.getServerName() + ":" + request.getServerPort()            + path + "/";%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><base href="<%=basePath %>>"><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>登錄頁面</title></head><body><form action="user01.action" method="post"><table><tr><td>用戶名:<input name="username"/></td></tr><tr><td>用戶名:<input type="passWord" name="password"/></td></tr><tr><td><input type="submit" value="提交"/><input type="reset" value="重置"/></td></tr></table></form></body></html>

loginSuccess.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"    pageEncoding="UTF-8"%><%@ taglib prefix="s" uri="/struts-tags"%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>登錄成功頁面</title></head><body><h1>jsp方式取值:</h1><%=request.getAttribute("linkaddress") %><br/><%=session.getAttribute("uname") %><br/><%=application.getAttribute("online") %><br/><h1>EL表達式取值:</h1>${request.linkaddress }<br/>${session.uname }<br/>${application.online }<br/><h1>struts取值:</h1><!-- 推薦使用這種 --><s:property value="#request.linkaddress"/><br/><!--  使用attr取值不推薦--><s:property value="#attr.linkaddress"/><br/><s:property value="#session.uname"/><br/><s:property value="#attr.uname"/><br/><s:property value="#application.online"/><br/><s:property value="#attr.online"/><br/><s:debug/></body></html>

UserAction3.java

package com.pb.web.action;import java.util.Map;import com.opensymphony.xwork2.ActionContext;import com.opensymphony.xwork2.ActionSupport;public class UserAction3 extends ActionSupport {        private String username;    private String password;    private Map<String , Object> request;    private Map<String , Object> session;    private Map<String , Object> application;        public String login(){        ActionContext ac=ActionContext.getContext();        request=(Map<String, Object>) ac.get("request");        session=ac.getSession();        application=ac.getApplication();        if(this.getUsername().equals("accp")&&this.getPassword().equals("accp")){            request.put("linkaddress", "這次的登錄地點:SZ");            session.put("uname", username);            application.put("online", "當前在線人數：xxxx");            System.out.println(request.get("linkaddress"));            System.out.println(session.get("uname"));            System.out.println(application.get("online"));                        return SUCCESS;        }        return INPUT;                            }                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 Map<String, Object> getRequest() {        return request;    }    public void setRequest(Map<String, Object> request) {        this.request = request;    }    public Map<String, Object> getSession() {        return session;    }    public void setSession(Map<String, Object> session) {        this.session = session;    }    public Map<String, Object> getApplication() {        return application;    }    public void setApplication(Map<String, Object> application) {        this.application = application;    }        }

struts.xml

<struts>    <constant name="struts.enable.DynamicMethodInvocation" value="false" />    <constant name="struts.devMode" value="true" />    <package name="default" namespace="/" extends="struts-default">    <action name="user01" class="com.pb.web.action.UserAction3" method="login">    <result name="success">/loginSuccess.jsp</result>    <result name="input">/login.jsp</result>    </action>    </package></struts>

三、IOC方式獲取Servlet API對象

更改以上的代碼

<%@ page language="java" contentType="text/html; charset=UTF-8"    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" "http://www.w3.org/TR/html4/loose.dtd"><html><head><base href="<%=basePath %>>"><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>登錄頁面</title></head><body><!-- <form action="user01.action" method="post"> --><form action="user02.action" method="post"><table><tr><td>用戶名:<input name="username"/></td></tr><tr><td>用戶名:<input type="password" name="password"/></td></tr><tr><td><input type="submit" value="提交"/><input type="reset" value="重置"/></td></tr></table></form><s:property value="#session.msg"/></body></html>

loginSuccess.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"    pageEncoding="UTF-8"%><%@ taglib prefix="s" uri="/struts-tags"%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>登錄成功頁面</title></head><body><h1>jsp方式取值:</h1><%=request.getAttribute("linkaddress") %><br/><%=session.getAttribute("uname") %><br/><%=application.getAttribute("online") %><br/><h1>EL表達式取值:</h1>${request.linkaddress }<br/>${session.uname }<br/>${application.online }<br/><h1>struts取值:</h1><!-- 推薦使用這種 --><s:property value="#request.linkaddress"/><br/><!--  使用attr取值不推薦--><s:property value="#attr.linkaddress"/><br/><s:property value="#session.uname"/><br/><s:property value="#attr.uname"/><br/><s:property value="#application.online"/><br/><s:property value="#attr.online"/><br/><s:debug/></body></html>

UserAction2.java

package com.pb.web.action;import java.util.Map;import org.apache.struts2.interceptor.ApplicationAware;import org.apache.struts2.interceptor.RequestAware;import org.apache.struts2.interceptor.SessionAware;import com.opensymphony.xwork2.ActionSupport;public class UserAction2 extends ActionSupport implements RequestAware,        SessionAware, ApplicationAware {    private static final long serialVersionUID = 1L;    //屬性要有getter、setter方法    private String username;    private String password;    //request,session,application不需要getter、setter方法    private Map<String , Object> request;    private Map<String , Object> session;    private Map<String , Object> application;        public String login(){                if(this.getUsername().equals("accp")&&this.getPassword().equals("accp")){            request.put("linkaddress", "這次的登錄地點:SZ");            session.put("uname", username);            application.put("online", "當前在線人數：xxxx");            System.out.println(request.get("linkaddress"));            System.out.println(session.get("uname"));            System.out.println(application.get("online"));                        return SUCCESS;        }        session.put("msg", "用戶名或者密碼不正確！");        return INPUT;                            }        //使用struts2提供接口來生成application,session,request對象，    @Override    public void setApplication(Map<String, Object> application) {        this.application=application;    }    @Override    public void setSession(Map<String, Object> session) {        this.session=session;    }    @Override    public void setRequest(Map<String, Object> request) {        this.request=request;    }    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;    }}

struts.xml

<action name="user02" class="com.pb.web.action.UserAction2" method="login">    <result name="success"  type="dispatcher">/loginSuccess.jsp</result>    <result name="input" type="redirect">/login.jsp</result>    </action>

使用傳統的方式獲取Servlet API

實現ServletRequestAware接口

package com.pb.web.action;import javax.servlet.ServletContext;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpSession;import org.apache.struts2.ServletActionContext;import org.apache.struts2.interceptor.ServletRequestAware;import org.apache.struts2.util.ServletContextAware;import com.opensymphony.xwork2.ActionSupport;public class UserAction04 extends ActionSupport implements ServletRequestAware,        ServletContextAware {    private String username;    private String password;    private HttpServletRequest request;    private HttpSession session;    private ServletContext application;    public String login() {        // 獲取對象        session = request.getSession();        // 保存數據        request.setAttribute("loginAddress", "您本次登錄地點是：北京");        session.setAttribute("username", username);        application.setAttribute("online", "當前在線人數：XXX");        // 獲取數據        System.out.println(request.getAttribute("loginAddress"));        System.out.println(session.getAttribute("username"));        System.out.println(application.getAttribute("online"));        return SUCCESS;    }    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;    }    @Override    public void setServletRequest(HttpServletRequest request) {        this.request = request;    }    @Override    public void setServletContext(ServletContext application) {        this.application = application;    }}

或者使用時直接獲取對象

package com.pb.web.action;import javax.servlet.ServletContext;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpSession;import org.apache.struts2.ServletActionContext;import com.opensymphony.xwork2.ActionSupport;public class UserAction03 extends ActionSupport {    private String username;    private String password;    private HttpServletRequest request;    private HttpSession session;    private ServletContext application;    public String login() {        // 獲取對象        request = ServletActionContext.getRequest();        session = request.getSession();        application = ServletActionContext.getServletContext();        // 保存數據        request.setAttribute("loginAddress", "您本次登錄地點是：北京");        session.setAttribute("username",username);        application.setAttribute("online","當前在線人數：XXX");        // 獲取數據        System.out.println(request.getAttribute("loginAddress"));        System.out.println(session.getAttribute("username"));        System.out.println(application.getAttribute("online"));        return SUCCESS;    }    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;    }}

上一篇：使用jdbc實現簡單的mvc模式的增刪改查

下一篇：設計模式原則之單一職責原則