Custom MVC framework implementation

Catalog

One 、 The central controller dynamically loads the storage sub controller

Two 、 Optimization of parameter passing encapsulation

3、 ... and 、 Return value page Jump optimization

Four 、 The framework configuration file is variable

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One 、 The central controller dynamically loads the storage sub controller

        Last shared to , How do we optimize the creation of different objects to facilitate coding when we want to implement different functions MVC Framework optimization , But it's not convenient enough, so let's continue to optimize ：

Question 1 ： Each initialization of the central controller shall be manually added

Analyze and solve ：

1. adopt XML Modeling we can know , Final configModel The object will contain config.xml Information of all sub controllers in

2. At the same time, in order to solve the problem that the central controller can dynamically load and save the information of sub controllers , So we just need to introduce congigModel Objects can also be initialized

        So we need to use our XML Knowledge of modeling ：

config.xml：

<?xml version="1.0" encoding="UTF-8"?>
<config>
	<action path="/book" type="com.zq.Servlet.BookAction">
		<forward name="failed" path="/login.jsp" redirect="false" />
		<forward name="success" path="/main.jsp" redirect="true" />
	</action>
</config>

Yes DispatcherServlet To transform ：

package com.zq.framework;

import java.io.IOException;


import java.util.HashMap;
import java.util.Map;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 *  The central controller 
 *  Main functions ： Accept browser requests   , Find the corresponding handler 
 * @author  Zhang Qiang 
 *
 * 2022 year 6 month 25 On the afternoon of Sunday 2:32:46
 */
@WebServlet("*.action")
public class DispatcherServlet extends HttpServlet{
	private Map<String, Action> actions = new HashMap<String, Action>();
	
	// Through modeling, we can know the final ConfigModel The object will contain config.xml All self-control information in 
	
	private ConfigModel ConfigModel;
	// When the program starts, it will be executed once 
	@Override
	public void init() throws ServletException {
//		actions.put("/book", new BookAction());
//		actions.put("/order", new OrederAction());
		try {
			ConfigModel= ConfigModelFactory.bulid();
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

	@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 {
		String uri = req.getRequestURI();
		// To get /book 
		uri=uri.substring(uri.lastIndexOf("/"),uri.lastIndexOf("."));
		//Action action = actions.gaet(uri);
		
		// Compared with the previous one from map Get sub controllers from the collection , Currently, you need to obtain config.xml The full pathname in , Then reflect instantiation 
		ActionModel actionModel = ConfigModel.pop(uri);
		if(actionModel == null) {
			throw new RuntimeException("action  To configure   error ");
		}
		String type = actionModel.getType();// The full pathname in the configuration file  action Full pathname of the sub controller 
		try {
			Action action = (Action) Class.forName(type).newInstance();//action Example 
			action.execute(req, resp);
		} catch (Exception e) {
			e.printStackTrace();
		} 
	}
}

  Page code ：Demo01：

	<h2> Optimize </h2>
	<a href="${pageContext.request.contextPath}/book.action?methodName=add"> increase </a>
	<a href="${pageContext.request.contextPath}/book.action?methodName=del"> Delete </a>
	<a href="${pageContext.request.contextPath}/book.action?methodName=update"> modify </a>
	<a href="${pageContext.request.contextPath}/book.action?methodName=check"> see </a>
	<a href="${pageContext.request.contextPath}/book.action?methodName=load"> The echo </a>

  By doing this, we can realize that we only need to modify... Without changing any code XML The configuration file can be used to add sub controllers

---

Two 、 Optimization of parameter passing encapsulation

        Question two ： We pass too many parameters. Can we not use req.getp Directly get the passed parameters ？

Demo1： We use add For example, we passed three parameters bid、bname、price

	<h2> Parameter transfer optimization </h2>
	<a href="${pageContext.request.contextPath }/book.action?methodName=add&bid=989898&bname=laoliu&price=89"> increase </a>
	<a href="${pageContext.request.contextPath}/book.action?methodName=del"> Delete </a>
	<a href="${pageContext.request.contextPath}/book.action?methodName=update"> modify </a>
	<a href="${pageContext.request.contextPath}/book.action?methodName=check"> see </a>
	<a href="${pageContext.request.contextPath}/book.action?methodName=load"> The echo </a>

To build a com.zq.entity My bag Build a... In it Book The entity class

package com.zq.entity;

public class book {
	private int bid;
	private String bname;
	private float price;
	
	public int getBid() {
		return bid;
	}
	public void setBid(int bid) {
		this.bid = bid;
	}
	public String getBname() {
		return bname;
	}
	public void setBname(String bname) {
		this.bname = bname;
	}
	public float getPrice() {
		return price;
	}
	public void setPrice(float price) {
		this.price = price;
	}
	@Override
	public String toString() {
		return "Book [bid=" + bid + ", bname=" + bname + ", price=" + price + "]";
	}
}

        Before optimization add Method ：

package com.zq.Servlet;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.zq.entity.book;
import com.zq.framework.Action;
import com.zq.framework.ActionSupport;

public class BookAction extends ActionSupport {
	
	private void load(HttpServletRequest request, HttpServletResponse response) {
		System.out.println(" In the same Servlet in , Call to query a single method ");
	}
	
	private void check(HttpServletRequest request, HttpServletResponse response) {
			System.out.println(" In the same Servlet in , Call the method of view ");
	}

	private void update(HttpServletRequest request, HttpServletResponse response) {
			System.out.println(" In the same Servlet in , Call the modified method ");
		
	}

	private void del(HttpServletRequest request, HttpServletResponse response) {
			System.out.println(" In the same Servlet in , Call the deleted method ");
		
	}

	private void add(HttpServletRequest request, HttpServletResponse response) {
		String bid = request.getParameter("bid");
		String bname = request.getParameter("bname");
		String price = request.getParameter("price");
		book book = new book();
		book.setBid(Integer.valueOf(bid));
		book.setBname(bname);
		book.setPrice(Float.valueOf(price));
		System.out.println(" Using a servlet Call in  add  Method "+book);
		
	}
}

          If we pass a lot of values, we need to accept a lot of repeated code, so we optimize it ：

  Optimize BookAction：

package com.zq.Servlet;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.zq.entity.book;
import com.zq.framework.Action;
import com.zq.framework.ActionSupport;
import com.zq.framework.ModelDriven;

public class BookAction extends ActionSupport implements ModelDriven<book>{
	
	private book book = new book();
	
	private void list(HttpServletRequest req, HttpServletResponse resp) {
		System.out.println(" Using a servlet Call in  list  Method ");
	}
	
	private void load(HttpServletRequest req, HttpServletResponse resp) {
		System.out.println(" Using a servlet Call in  list  Method ");
	}
	
	private void edit(HttpServletRequest req, HttpServletResponse resp) {
		System.out.println(" Using a servlet Call in  edit  Method ");
	}
 
	private void del(HttpServletRequest req, HttpServletResponse resp) {
		System.out.println(" Using a servlet Call in  del  Method ");
	}
 
	private void add(HttpServletRequest req, HttpServletResponse resp) {
//		String bid = req.getParameter("bid");
//		String bname = req.getParameter("bname");
//		String price = req.getParameter("price");
		//Book book = new Book();
//		book.setBid(Integer.valueOf(bid));
//		book.setBname(bname);
//		book.setPrice(Float.valueOf(price));
		System.out.println(" Using a servlet Call in  add  Method "+book);
	}
 
	@Override
	public book getModel() {
		return book;
	}
}

Create an interface ModelDriven：

package com.zq.entity;

public class book {
	private int bid;
	private String bname;
	private float price;
	
	public int getBid() {
		return bid;
	}
	public void setBid(int bid) {
		this.bid = bid;
	}
	public String getBname() {
		return bname;
	}
	public void setBname(String bname) {
		this.bname = bname;
	}
	public float getPrice() {
		return price;
	}
	public void setPrice(float price) {
		this.price = price;
	}
	@Override
	public String toString() {
		return "Book [bid=" + bid + ", bname=" + bname + ", price=" + price + "]";
	}
}

  reform  DispatcherServlet：

package com.zq.framework;

import java.io.IOException;


import java.util.HashMap;
import java.util.Map;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.beanutils.BeanUtils;

/**
 *  The central controller 
 *  Main functions ： Accept browser requests   , Find the corresponding handler 
 * @author  Zhang Qiang 
 *
 * 2022 year 6 month 25 On the afternoon of Sunday 2:32:46
 */
@WebServlet("*.action")
public class DispatcherServlet extends HttpServlet{
	private Map<String, Action> actions = new HashMap<String, Action>();
	
	// Through modeling, we can know the final ConfigModel The object will contain config.xml All self-control information in 
	
	private ConfigModel ConfigModel;
	// When the program starts, it will be executed once 
	@Override
	public void init() throws ServletException {
//		actions.put("/book", new BookAction());
//		actions.put("/order", new OrederAction());
		try {
			ConfigModel= ConfigModelFactory.bulid();
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

	@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 {
		String uri = req.getRequestURI();
		// To get /book 
		uri=uri.substring(uri.lastIndexOf("/"),uri.lastIndexOf("."));
		//Action action = actions.gaet(uri);
		
		// Compared with the previous one from map Get sub controllers from the collection , Currently, you need to obtain config.xml The full pathname in , Then reflect instantiation 
		ActionModel actionModel = ConfigModel.pop(uri);
		if(actionModel == null) {
			throw new RuntimeException("action  To configure   error ");
		}
		String type = actionModel.getType();// The full pathname in the configuration file  action Full pathname of the sub controller 
		try {
			Action action = (Action) Class.forName(type).newInstance();//action Example 
			if(action instanceof ModelDriven) {
				// So it can be transformed downward 
				ModelDriven md = (ModelDriven)action;
				//model refer to bookAction Medium book Class instance 
				Object model = md.getModel();
				// to model Property assignment in , To accept the front end jsp Parameters passed   req.getParameterMap()
				//PropertyUtils.getIndexedProperty(bean, name)  Take a value from an object 
				
				// Encapsulate all front-end parameter values into entity classes 
				BeanUtils.populate(model, req.getParameterMap());
				
			}
			action.execute(req, resp);
		} catch (Exception e) {
			e.printStackTrace();
		} 
	}
}

---

3、 ... and 、 Return value page Jump optimization

        Question 3 ： After we implement the function, we will need to jump to the page. But can we not add duplicate code but realize the jump function ？

        The solution is to put our jump path in the same way XML In profile
Reform the sub controller ：

package com.zq.framework;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 *  Sub controller 
 *  The corresponding handler 
 * @author  Zhang Qiang 
 *
 * 2022 year 6 month 25 On the afternoon of Sunday 2:34:21
 */
public interface Action {
	String execute(HttpServletRequest request, HttpServletResponse response);
}

ForwardModel：

package com.zq.framework;

/**
 *  Corresponding forward label 
 * @author yang 
 *
 * @date 2022 year 6 month 15 The morning of 9:05:38
 */
public class ForwardModel {
	private String name;
	private String path;
	private boolean redirect;
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getPath() {
		return path;
	}
	public void setPath(String path) {
		this.path = path;
	}
	public boolean getRedirect() {
		return redirect;
	}
	public void setRedirect(boolean b) {
		this.redirect = b;
	}
	
	public boolean isRedirect() {
		return redirect;
	}

	
}

ActionSupport：

package com.zq.framework;

import java.lang.reflect.Method;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class ActionSupport implements Action {
	
	@Override
	public String execute(HttpServletRequest request, HttpServletResponse response) {
		String methodName = request.getParameter("methodName");
//		methodName May be add/del/edit/list/load/xxx/yyy/aaa...
//		 What method does the front desk transfer , Call the corresponding method of the current class 
		try {
			Method m = this.getClass().getDeclaredMethod(methodName, HttpServletRequest.class,HttpServletResponse.class);
			m.setAccessible(true);
//			 Call the... Of the current class instance methodName Method 
			return (String) m.invoke(this, request,response);
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return null; 
	}
}

 DispatcherServlet：

package com.zq.framework;

import java.io.IOException;


import java.util.HashMap;
import java.util.Map;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.beanutils.BeanUtils;

/**
 *  The central controller 
 *  Main functions ： Accept browser requests   , Find the corresponding handler 
 * @author  Zhang Qiang 
 *
 * 2022 year 6 month 25 On the afternoon of Sunday 2:32:46
 */
@WebServlet("*.action")
public class DispatcherServlet extends HttpServlet{
	private Map<String, Action> actions = new HashMap<String, Action>();
	
	// Through modeling, we can know the final ConfigModel The object will contain config.xml All self-control information in 
	
	private ConfigModel ConfigModel;
	// When the program starts, it will be executed once 
	@Override
	public void init() throws ServletException {
//		actions.put("/book", new BookAction());
//		actions.put("/order", new OrederAction());
		try {
			ConfigModel= ConfigModelFactory.bulid();
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

	@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 {
		String uri = req.getRequestURI();
		// To get /book 
		uri=uri.substring(uri.lastIndexOf("/"),uri.lastIndexOf("."));
		//Action action = actions.gaet(uri);
		
		// Compared with the previous one from map Get sub controllers from the collection , Currently, you need to obtain config.xml The full pathname in , Then reflect instantiation 
		ActionModel actionModel = ConfigModel.pop(uri);
		if(actionModel == null) {
			throw new RuntimeException("action  To configure   error ");
		}
		String type = actionModel.getType();// The full pathname in the configuration file  action Full pathname of the sub controller 
		try {
			Action action = (Action) Class.forName(type).newInstance();//action Example 
			if(action instanceof ModelDriven) {
				// So it can be transformed downward 
				ModelDriven md = (ModelDriven)action;
				//model refer to bookAction Medium book Class instance 
				Object model = md.getModel();
				// to model Property assignment in , To accept the front end jsp Parameters passed   req.getParameterMap()
				//PropertyUtils.getIndexedProperty(bean, name)  Take a value from an object 
				
				// Encapsulate all front-end parameter values into entity classes 
				BeanUtils.populate(model, req.getParameterMap());
				

//				 Before formally calling this method  book The attributes in the are assigned 
				String result = action.execute(req,resp);
				ForwardModel forwardModel = actionModel.pop(result);
//				if(forwardModel == null)
//					throw new RuntimeException("forward config error");
//				/bookList.jsp /index.jsp
				String path = forwardModel.getPath();
				// Get the configuration to be forwarded 
				boolean redirect = forwardModel.isRedirect();
				if(redirect)
					resp.sendRedirect(path);
				else
				req.getRequestDispatcher(path).forward(req, resp);
			}
			action.execute(req, resp);
		} catch (Exception e) {
			e.printStackTrace();
		} 
	}
}

        But if we test now to see if we can jump to the interface, there should be a case that the path loses the project name

          The solution is to modify again  DispatcherServlet：

// Get the configuration to be forwarded
            boolean redirect = forwardModel.isRedirect();
            if(redirect)
                resp.sendRedirect(req.getServletContext().getContextPath()+path);
            else
            req.getRequestDispatcher(path).forward(req, resp);

---

Four 、 The framework configuration file is variable

          Question 4 : If we change XML What about the file name of the configuration file ？
Revise it  DispatcherServlet：

package com.zq.framework;

import java.io.IOException;


import java.util.HashMap;
import java.util.Map;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.beanutils.BeanUtils;

/**
 *  The central controller 
 *  Main functions ： Accept browser requests   , Find the corresponding handler 
 * @author  Zhang Qiang 
 *
 * 2022 year 6 month 25 On the afternoon of Sunday 2:32:46
 */
@WebServlet("*.action")
public class DispatcherServlet extends HttpServlet{
	private Map<String, Action> actions = new HashMap<String, Action>();
	
	// Through modeling, we can know the final ConfigModel The object will contain config.xml All self-control information in 
	
	private ConfigModel ConfigModel;
	// When the program starts, it will be executed once 
	@Override
	public void init() throws ServletException {
//		actions.put("/book", new BookAction());
//		actions.put("/order", new OrederAction());
		try {
			// Configure address 
			//getInitParameter The function of is to get web.xml Medium servlet Information configuration parameters 
			String configLocation = this.getInitParameter("configLocation");
			if(configLocation == null || "".equals(configLocation))
				ConfigModel = ConfigModelFactory.bulid();
			else
				ConfigModel = ConfigModelFactory.bulid(configLocation);
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

	@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 {
		String uri = req.getRequestURI();
		// To get /book 
		uri=uri.substring(uri.lastIndexOf("/"),uri.lastIndexOf("."));
		//Action action = actions.gaet(uri);
		
		// Compared with the previous one from map Get sub controllers from the collection , Currently, you need to obtain config.xml The full pathname in , Then reflect instantiation 
		ActionModel actionModel = ConfigModel.pop(uri);
		if(actionModel == null) {
			throw new RuntimeException("action  To configure   error ");
		}
		String type = actionModel.getType();// The full pathname in the configuration file  action Full pathname of the sub controller 
		try {
			Action action = (Action) Class.forName(type).newInstance();//action Example 
			if(action instanceof ModelDriven) {
				// So it can be transformed downward 
				ModelDriven md = (ModelDriven)action;
				//model refer to bookAction Medium book Class instance 
				Object model = md.getModel();
				// to model Property assignment in , To accept the front end jsp Parameters passed   req.getParameterMap()
				//PropertyUtils.getIndexedProperty(bean, name)  Take a value from an object 
				
				// Encapsulate all front-end parameter values into entity classes 
				BeanUtils.populate(model, req.getParameterMap());
				

//				 Before formally calling this method  book The attributes in the are assigned 
				String result = action.execute(req,resp);
				ForwardModel forwardModel = actionModel.pop(result);
//				if(forwardModel == null)
//					throw new RuntimeException("forward config error");
//				/bookList.jsp /index.jsp
				String path = forwardModel.getPath();
				// Get the configuration to be forwarded 
				boolean redirect = forwardModel.isRedirect();
				if(redirect)
					resp.sendRedirect(path);
				else
				req.getRequestDispatcher(path).forward(req, resp);
			}
			action.execute(req, resp);
		} catch (Exception e) {
			e.printStackTrace();
		} 
	}
}

web.xml：

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" version="3.1">
  <display-name>t280_mvc</display-name>
  <servlet>
  	<servlet-name>mvc</servlet-name>
  	<servlet-class>com.cdl.framework.DispatcherServlet</servlet-class>
 	<init-param>
 		<param-name>configLaction</param-name>
 		<param-value>/wuyanzu2</param-value>
 	</init-param>
  </servlet>
  <servlet-mapping>
  	<servlet-name>mvc</servlet-name>
  	<url-pattern>*.action</url-pattern>
  </servlet-mapping>
</web-app>

take config.xml->wuyanzu2.xml

In this case, even if we modify the name of the configuration file ourselves, there will be no problem