struts2 使用Map类型的request, session, application

红太狼 2022-06-03 22:46 197阅读 0赞

在Action类中可以通过ActionContext对象获得request, session, application, 给3个对象分别设置key和value， 在另一个jsp界面中访问key对应的值

程序入口由index.jsp进入, 在struts.xml中寻找名为action的action标签

struts.xml, 找到TestAction类

<struts>
        <package name="demo" extends="struts-default" namespace="/">
            <action name="action" class="action.TestAction">
                <result name="success">Hello.jsp</result>
            </action>
        </package>
    </struts>

action类, 通过ActionContext 设置kv， 并在execute()返回SUCCESS， 让result标签与其对应

public class TestAction extends ActionSupport{ 
        Map<String, Object> request;
        Map<String, Object> session;
        Map<String, Object> application;
    
        public TestAction() {
            ActionContext context = ActionContext.getContext();
            request = (Map<String, Object>) context.get("request");
            session = (Map<String, Object>) context.get("session");
            application = (Map<String, Object>) context.get("application");
        }
    
        @Override
        public String execute() throws Exception {
            request.put("info", "reqValue");
            session.put("info", "sesValue");
            application.put("info", "appValue");
            System.out.println("结果"+request.get("info"));
            return Action.SUCCESS;
        }
    }

Hello.jsp 显示值

--------------------

上面的action，定义了3个作用域， 若是action很多， 在每个action类中都写这样重复的代码很不好， 这时候可以自定义类，我们叫他BaseAction

public class BaseAction implements RequestAware,ApplicationAware,SessionAware{ 
        protected Map<String, Object> session;
        protected Map<String, Object>   application;
        protected Map<String, Object> request;
    
        @Override
        public void setSession(Map<String, Object> arg0) {
            // TODO Auto-generated method stub
            this.session=arg0;
        }
    
        @Override
        public void setApplication(Map<String, Object> arg0) {
            // TODO Auto-generated method stub
            this.application=arg0;
        }
    
        @Override
        public void setRequest(Map<String, Object> arg0) {
            // TODO Auto-generated method stub
            this.request=arg0;
    
        }
    }

这时候再来修改TestAction， 同样能达到上面的效果

public class TestAction extends BaseAction{ 
    
        public TestAction() {
        }
    
        public String execute(){
            request.put("info", "reqValue");
            session.put("info", "sesValue");
            application.put("info", "appValue");
            System.out.println("结果"+request.get("info"));
            return Action.SUCCESS;
        }
    }