Struts2学习_第一个案例

目标：使用Struts2作为控制器，写一个demo处理请求。

    /hello.action-->StrutsPrepareAndExecuteFilter-->Action -->Result-->/hello.jsp

• 搭建Struts2环境：在maven工程中添加jar包定义

<dependency>
    <groupId>org.apache.struts</groupId>
    <artifactId>struts2-core</artifactId>
    <version>2.5.13</version>
</dependency>

• 实现过程

        1.  在web.xml中配置StrutsPrepareAndExecuteFilter（总过滤器）

<filter>
    <filter-name>strutsmvc</filter-name>
    <filter-class>
    org.apache.struts2.dispatcher.filter.StrutsPrepareAndExecuteFilter
    </filter-class>
    <!-- 默认加载struts.xml配置文件 -->
</filter>
<filter-mapping>
    <filter-name>strutsmvc</filter-name>
    <url-pattern>*.action</url-pattern>
</filter-mapping>

        2. 引入struts.xml文件（处理具体请求）

<!DOCTYPE struts PUBLIC
"-//Apache Software Foundation//DTD Struts Configuration 2.5//EN"
"http://struts.apache.org/dtds/struts-2.5.dtd">
<struts>
  
</struts>

         3. 编写Action和jsp

public class HelloAction {
    //方法名默认execute,无参
    public String execute(){
        System.out.println("执行HelloAction处理");
        return "success";//与<result name="success">定义的name属性一致
    }
}

         4. 在struts.xml中添加处理具体请求的配置

<!-- 必须继承struts-default，否则不能使用Result -->
<package name="demo1" extends="struts-default">
    <!-- name指定请求名、class指定Action类名、method指定Action方法名 -->
    <action name="hello" class="cn.xdl.action.HelloAction" method="execute">
        <!--name指定Action方法返回值、type指定Result组件类型  -->
        <result name="success" type="dispatcher">/hello.jsp</result>
    </action>
</package>

补充：

• 通过属性接收页面传值和向页面传值
• 更改默认的.action扩展名；在struts.xml中定义

<constant name="struts.action.extension" value="do,,"/>

• 获取使用request、session、application等对象

1. 通过ActionContext对象获取，返回Map类型对象（Struts2提供了RequestMap、SessionMap、ApplicationMap封装，封装了Servlet中的HttpServletRequest、HttpSession、ServletContext）
   

ActionContext ac = ActionContext.getContext();
Map<String,Object> sessionMap = ac.getSession();
sessionMap.put("user", username);

    2. 通过ServletActionContext对象获取原有Servlet类型

HttpServletRequest httpRequest = ServletActionContext.getRequest();
HttpSession httpSession = httpRequest.getSession();
httpSession.setAttribute("user", username);

    3. 使用Aware接口注入对象

public class BaseAction  implements SessionAware,RequestAware,ApplicationAware
,ServletRequestAware,ServletResponseAware,ServletContextAware{

	Map<String,Object> session;
	Map<String,Object> request;
	Map<String,Object> application;
	HttpServletRequest httpRequest;
	HttpServletResponse response;
	ServletContext httpApplication;
	
	//创建Action对象时会自动执行setSession
	public void setSession(Map<String, Object> session) {
		this.session = session;
	}
	public void setRequest(Map<String, Object> request) {
		this.request = request;
	}
	public void setApplication(Map<String, Object> application) {
		this.application = application;
	}
	public void setServletRequest(HttpServletRequest request) {
		this.httpRequest = request;
	}
	public void setServletResponse(HttpServletResponse response) {
		this.response = response;
	}
	public void setServletContext(ServletContext context) {
		this.httpApplication = context;
	}
}