自定义MVC工作原理【一】

什么是MVC

MVC全名是Model View Controller，是模型(model)－视图(view)－控制器(controller)的缩写，
它是一种软件设计典范，用一种业务逻辑、数据、界面显示分离的方法组织代码

MVC结构

V
jsp/ios/android
C
servlet/action
M
实体域模型(名词)
过程域模型(动词)

自定义MVC工作原理图

利用MVC模式写一个算术

先写一个cal实体类

public class Cal {
private String num1;
private String num2;
public String getNum1() {
return num1;
}
public void setNum1(String num1) {
this.num1 = num1;
}
public String getNum2() {
return num2;
}
public void setNum2(String num2) {
this.num2 = num2;
}
public Cal(String num1, String num2) {
super();
this.num1 = num1;
this.num2 = num2;
}
public Cal() {
super();
}

}

写一个主控制器

//主控制器
public class DispatcherServlet extends HttpServlet{

private Map<String, Action> actionMap = new HashMap<>();
public void init() {
actionMap.put("/addCal", new AddCalAction());
actionMap.put("/delCal", new DelCalAction());
actionMap.put("/mulCal", new MulCalAction());
actionMap.put("/divCal", new DivCalAction());
}

@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doPost(req, resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
init();
String uri = req.getRequestURI();
uri = uri.substring(uri.lastIndexOf("/"), uri.lastIndexOf("."));
Action action = actionMap.get(uri);
action.execute(req, resp);

}
}

写一个子控制器

//子控制器:处理业务逻辑
public interface Action {
void execute(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException ;
}

**AddCalAction **

public class AddCalAction implements Action{

@Override
public void execute(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
String num1 = req.getParameter("num1");
String num2 = req.getParameter("num2");
req.setAttribute("res", Integer.valueOf(num1)+Integer.valueOf(num2));
req.getRequestDispatcher("calRes.jsp").forward(req, resp);

}

}

**DelCalAction **

public class DelCalAction implements Action{

@Override
public void execute(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
String num1 = req.getParameter("num1");
String num2 = req.getParameter("num2");
req.setAttribute("res", Integer.valueOf(num1)-Integer.valueOf(num2));
req.getRequestDispatcher("calRes.jsp").forward(req, resp);

}

}

**DivCalAction **

public class DivCalAction implements Action{

@Override
public void execute(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
String num1 = req.getParameter("num1");
String num2 = req.getParameter("num2");
req.setAttribute("res", Integer.valueOf(num1)/Integer.valueOf(num2));
req.getRequestDispatcher("calRes.jsp").forward(req, resp);

}

}

**MulCalAction **

public class MulCalAction implements Action{

@Override
public void execute(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
String num1 = req.getParameter("num1");
String num2 = req.getParameter("num2");
req.setAttribute("res", Integer.valueOf(num1) * Integer.valueOf(num2));
req.getRequestDispatcher("calRes.jsp").forward(req, resp);

}

}