gwt之mvc4g - 码农教程

Mvc4g是一个简单的框架来实现的GWT应用程序的MVC模式。

主要思想

其主要思想是，以减轻开发人员的工作，以单独的视图从模型。该框架是一个XML文件，将允许开发人员告诉视图发射事件时要执行什么样的行动需要配置。

框架如何工作

具体步骤如下图

事件是创建活动的视图控制器。事件包含两部分信息：执行的动作的名称对象传递到行动

UserBean user = new UserBean();
user.setName("John Smith");
new Event("CreateUser", user);

控制器控制器接收事件，并根据事件动作的名称，执行的行动。例如，如果您有以下事件触发：

Event e =newEvent("doOperation","+");

以下Mvc4g配置文件：

<actionname="doOperation"class="com.mvc4g.example.client.OperationAction"/>

然后控制器调用以下行动的实例：

com.mvc4g.example.client.OperationAction

要创建一个视图，你需要：实施com.mvc4g.client.ViewInterface 有一个默认的构造视图可以创建事件和火灾控制器调用的handleEvent函数。

Event e =newEvent("doOperation","+");
controller.handleEvent(e);

详细的示例

Action

package com.mvc4g.example.client;

import com.mvc4g.client.ActionInterface;
import com.mvc4g.client.Controller;

public class OperationAction implements ActionInterface {
        
        private int value = 0;

        @Override
        public void execute(Controller controller, Object form) {

                //Execute action
                String operation = (String) form;
                if("+".equals(operation)){
                        value++;
                }
                else if("-".equals(operation)){
                        value--;
                }
                
                //Update the view
                ((SimpleCalculatorView)controller.getView("mainView")).updateScreen(Integer.toString(value));

        }

}

view

package com.mvc4g.example.client;

import com.google.gwt.event.dom.client.ClickEvent;
import com.google.gwt.event.dom.client.ClickHandler;
import com.google.gwt.user.client.ui.Button;
import com.google.gwt.user.client.ui.Composite;
import com.google.gwt.user.client.ui.HorizontalPanel;
import com.google.gwt.user.client.ui.RootPanel;
import com.google.gwt.user.client.ui.TextBox;
import com.google.gwt.user.client.ui.VerticalPanel;
import com.mvc4g.client.Controller;
import com.mvc4g.client.Event;
import com.mvc4g.client.ViewInterface;

public class SimpleCalculatorView extends Composite implements ViewInterface {
        
        private Controller controller = null;
        private TextBox screen = new TextBox();
        
        public SimpleCalculatorView(){
                
                screen.setWidth("50px"); screen.setEnabled(false); screen.setText("0");
                
                Button add = new Button("+1");
                add.addClickHandler(new ClickHandler(){
                        @Override
                        public void onClick(ClickEvent event) {
                                //Create and fire event to the controller
                                Event e = new Event("doOperation", "+");
                                controller.handleEvent(e);                              
                        }                       
                });
                
                Button less = new Button("-1");
                less.addClickHandler(new ClickHandler(){
                        @Override
                        public void onClick(ClickEvent event) {
                                //Create and fire event to the controller
                                Event e = new Event("doOperation", "-");
                                controller.handleEvent(e);                              
                        }                       
                });
                
                HorizontalPanel buttons = new HorizontalPanel();
                buttons.add(add); buttons.add(less);
                
                VerticalPanel mainPanel = new VerticalPanel();
                mainPanel.add(screen);mainPanel.add(buttons);
                
                RootPanel.get().add(mainPanel);
                
        }
        
        public void updateScreen(String value){
                screen.setText(value);
        }

        @Override
        public void setController(Controller controller) {
                this.controller = controller;
        }
        
}

控制层

要创建一个动作，你需要：实施com.mvc4g.client.ActionInterface 有一个默认的构造要执行一个动作，控制器调用的动作执行功能。它在这个功能，你需要的代码行为的行动。要更新视图，动作可以检索到控制器，由控制器调用getView功能感谢。为了获取正确的观点，行动需要给视图的名称。

例如，如果你有以下调用：

controller.getView("mainView")

以下Mvc4g配置文件：

<viewname="mainView"class="com.mvc4g.example.client.SimpleCalculatorView"/>

您将检索的有以下几种观点的实例：

com.mvc4g.example.client.SimpleCalculatorView

Action

package com.mvc4g.example.client;

import com.mvc4g.client.ActionInterface;
import com.mvc4g.client.Controller;

public class OperationAction implements ActionInterface {
        
        private int value = 0;

        @Override
        public void execute(Controller controller, Object form) {

                //Execute action
                String operation = (String) form;
                if("+".equals(operation)){
                        value++;
                }
                else if("-".equals(operation)){
                        value--;
                }
                
                //Update the view
                ((SimpleCalculatorView)controller.getView("mainView")).updateScreen(Integer.toString(value));

        }

}

view

package com.mvc4g.example.client;

import com.google.gwt.event.dom.client.ClickEvent;
import com.google.gwt.event.dom.client.ClickHandler;
import com.google.gwt.user.client.ui.Button;
import com.google.gwt.user.client.ui.Composite;
import com.google.gwt.user.client.ui.HorizontalPanel;
import com.google.gwt.user.client.ui.RootPanel;
import com.google.gwt.user.client.ui.TextBox;
import com.google.gwt.user.client.ui.VerticalPanel;
import com.mvc4g.client.Controller;
import com.mvc4g.client.Event;
import com.mvc4g.client.ViewInterface;

public class SimpleCalculatorView extends Composite implements ViewInterface {
        
        private Controller controller = null;
        private TextBox screen = new TextBox();
        
        public SimpleCalculatorView(){
                
                screen.setWidth("50px"); screen.setEnabled(false); screen.setText("0");
                
                Button add = new Button("+1");
                add.addClickHandler(new ClickHandler(){
                        @Override
                        public void onClick(ClickEvent event) {
                                //Create and fire event to the controller
                                Event e = new Event("doOperation", "+");
                                controller.handleEvent(e);                              
                        }                       
                });
                
                Button less = new Button("-1");
                less.addClickHandler(new ClickHandler(){
                        @Override
                        public void onClick(ClickEvent event) {
                                //Create and fire event to the controller
                                Event e = new Event("doOperation", "-");
                                controller.handleEvent(e);                              
                        }                       
                });
                
                HorizontalPanel buttons = new HorizontalPanel();
                buttons.add(add); buttons.add(less);
                
                VerticalPanel mainPanel = new VerticalPanel();
                mainPanel.add(screen);mainPanel.add(buttons);
                
                RootPanel.get().add(mainPanel);
                
        }
        
        public void updateScreen(String value){
                screen.setText(value);
        }

        @Override
        public void setController(Controller controller) {
                this.controller = controller;
        }
        
}