我的MVC架構————GothaMVC（3）view層的實現

眾所周知現在的前端模板有很多，像JSP，FreeMarker，Velocity等。
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所以view層的代碼，在我這裡的核心在於策略模式的實現。
首先，我們寫一個view層的介面

package viewTemplate;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import modelWrapper.Model;public interface IView {    void viewRender(Model m,HttpServletRequest req,HttpServletResponse resp);}

然後，依照策略模式，我們需要定義一個“錦囊”來放置各種策略。

package viewTemplate;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import modelWrapper.Model;public class ViewContext {    //這裡用來放置需要的view    private IView view;    //屬性注入    public ViewContext(IView view){        this.view=view;    }    public void render(Model m,HttpServletRequest req,HttpServletResponse resp){        view.viewRender(m,req, resp);    }}

接下來，我們書寫JSP的view形式的代碼

package viewTemplate;import java.io.IOException;import java.util.Set;import javax.servlet.ServletException;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import modelWrapper.Model;public class Jsp implements IView {    @Override    public void viewRender(Model model,HttpServletRequest req, HttpServletResponse resp) {         if(model!=null){                Set<String> keys=model.getModel().keySet();                for(String key:keys){                    req.setAttribute(key, model.getModel().get(key));                }            }            try {                req.getRequestDispatcher(model.getView()).forward(req, resp);            } catch (ServletException | IOException e) {                e.printStackTrace();            }    }}

然後，是FreeMarker和velocity的代碼。我懶得去寫了，你們自己填空吧，當然也可以自己去擴充IView介面去實現其他你們喜歡的模板，哈哈。

package viewTemplate;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import modelWrapper.Model;public class FreeMarker implements IView {    @Override    public void viewRender(Model m,HttpServletRequest req, HttpServletResponse resp) {    }}

package viewTemplate;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import modelWrapper.Model;public class Velocity implements IView {    @Override    public void viewRender(Model m,HttpServletRequest req, HttpServletResponse resp) {    }}

最後還沒完，我們需要建立一個工廠來維護這些類

package viewTemplate;public class ViewFactory {//原廠模式    public static ViewContext getView(IView view){        return new ViewContext(view);    }    public static Jsp getJsp(){        return new Jsp();    }    public static FreeMarker getFreeMarker(){        return new FreeMarker();    }    public static Velocity getVelocity(){        return new Velocity();    }}