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Mvc进阶（下）

2023-10-23 25
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简介： Mvc进阶（下）

1.前言

虽然前面文章深入解析Java自定义MVC框架的原理与实现讲述了Mvc框架，但是那只能算是比较低级的，还能够再优化，接下来我会再优化3次代码，让代码更为简洁，通用。

2.上次代码弊端

虽然简化了代码，但是代码并不 能够通用，MVC这种东西，最终是要打包成jar架包的，可是上一篇文章的代码优化并不能够打包成架包，现在开始第一次优化。

1.利用xml建模反射优化

1.XMl文件

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE config
[<!ELEMENT config (action*)>
<!ELEMENT action (forward*)>
<!ATTLIST action 
path CDATA #REQUIRED
type CDATA #IMPLIED
>
]
>
  <!--
    config标签:可以包含0~N个action标签
  -->
<config>
  <!--
    action标签:可以饱含0~N个forward标签 path:以/开头的字符串,并且值必须唯一 非空 ,子控制器对应的路径
    type:字符串,非空，子控制器的完整类名
  -->
  <action path="/book" type="com.niyin.com.BookAction">
    <forward name="list" path="/res.jsp" redirect="true" />
    <forward name="tolist" path="/res.jsp" redirect="false" />
  </action>
  <action path="/order" type="com.niyin.com.Orderaction">
    <forward name="success" path="/index.jsp" redirect="true" />
    <forward name="failed" path="/register.jsp" redirect="false" />
  </action>
  <action path="/bookAction" type="test.BookAction">
    <forward name="add" path="/bookAdd.jsp" redirect="true" />
    <forward name="del" path="/reg.jsp" redirect="false" />
    <forward name="list" path="/list.jsp" redirect="false" />
    <forward name="upd" path="/login.jsp" redirect="false" />
  </action>
  <action path="/loginAction" type="test.action.LoginAction">
    <forward name="a" path="/index.jsp" redirect="false" />
    <forward name="b" path="/welcome.jsp" redirect="true" />
  </action>
</config>

2.对xml建模

package model;
import java.util.HashMap;
import java.util.Map;
public class ActionModel {
  private String path;
  private String type;
  private Map<String ,ForwardModel>fmp=new HashMap<String ,ForwardModel>();
  public String getType() {
    return type;
  }
  public void setType(String type) {
    this.type = type;
  }
  public String getPath() {
    return path;
  }
  public void setPath(String path) {
    this.path = path;
  }
  public void push(ForwardModel forwardModel) {
    fmp.put(forwardModel.getName(), forwardModel);
  }
  public  ForwardModel pop(String name) {
    return fmp.get(name);
  }
}
package model;
import java.util.HashMap;
import java.util.Map;
public class ConfigModel {
private Map<String,ActionModel>aMap=new HashMap<String,ActionModel>();
public void push(ActionModel actionModel) {
  aMap.put(actionModel.getPath(), actionModel);
}
public ActionModel pop(String path) {
  return aMap.get(path);
}
public static void main(String[] args) throws Exception {
  ConfigModel configModel =new ConfigMOdelFactory().build();
  ActionModel actionModel=configModel.pop("/loginAction");
  ForwardModel forwardModel =actionModel.pop("b");
  System.out.println(forwardModel.getPath());
}
}
package model;
import java.io.InputStream;
import java.util.List;
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;
public class ConfigMOdelFactory {
  public static ConfigModel build() throws Exception {
    ConfigModel configModel = new ConfigModel();
    InputStream in = ConfigMOdelFactory.class.getResourceAsStream("/config.xml");
    SAXReader sr = new SAXReader();
    Document doc = sr.read(in);
    List<Element> actionsEles = doc.selectNodes("/config/action");
    for (Element element : actionsEles) {
      // System.out.println(element.asXML());
      ActionModel actionmodel = new ActionModel();
      actionmodel.setPath(element.attributeValue("path"));
      actionmodel.setType(element.attributeValue("type"));
      List<Element> forwardEles = element.selectNodes("forward");
      for (Element forwardEle : forwardEles) {
        // System.out.println(forwardEle.asXML());
        ForwardModel forwardModel = new ForwardModel();
        forwardModel.setName(forwardEle.attributeValue("name"));
        forwardModel.setPath(forwardEle.attributeValue("path"));
        forwardModel.setRedirect(!"false".equals(forwardEle.attributeValue("redirect")));
        actionmodel.push(forwardModel);
      }
      configModel.push(actionmodel);
    }
    return configModel;
  }
  public static void main(String[] args) throws Exception {
    ConfigMOdelFactory.build();
  }
}
package model;
import java.util.HashMap;
import java.util.Map;
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 isRedirect() {
    return redirect;
  }
  public void setRedirect(boolean redirect) {
    this.redirect = redirect;
  }
}

3.修改中央控制器

以前把所有的子控制器放到map集合中，现在所有的子控制器再config。xml中。

package com.niyin.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;
import com.niyin.com.BookAction;
import com.niyin.com.Orderaction;
import model.ActionModel;
import model.ConfigMOdelFactory;
import model.ConfigModel;
import model.ForwardModel;
@WebServlet("*.action")
public class DispatherServlet extends HttpServlet {
  private ConfigModel configMOdel;
//  public Map<String, Action> actionMap=new HashMap<String, Action>();
  @Override
  public void init() throws ServletException {
//  actionMap.put("/book", new BookAction());
//  actionMap.put("/order", new Orderaction());
//  actionMap.put("/cat", new CatAction());
    try {
      configMOdel=ConfigMOdelFactory.build();
    } catch (Exception e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    }
  }
  protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  this.doPost(request, response);
  }
  protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  String uri = request.getRequestURI(); 
  uri=uri.substring(uri.lastIndexOf("/"),uri.lastIndexOf("."));
//  Action action = actionMap.get(uri);
//  要通过uri=book/再configMOdel中找
  ActionModel actionModel = configMOdel.pop(uri);
  if (actionModel==null)
    throw new RuntimeException("action 没有配置");
 String type = actionModel.getType();
    Action action;
    try {
      action = (Action) Class.forName(type).newInstance();
    } catch (Exception e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    } 
  }
}

把map集合取消，改为用模型的方式来代替map集合，如果要新增类的话只需要新增模型对象即可，不用再加入map集合中，让代码更易于维护和修改，也可以封装架包提供了可行性。

代码测试

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<p>版本1</p>
<a href="Bookservletadd">增加</a>
<a href="Bookservletupd">修改</a>
<a href="Bookservletdel">减少</a>
<a href="Bookservletlist">查询</a>
<p>版本2</p>
<a href="Bookservletadd?methodName=add">增加</a>
<a href="Bookservletupd?methodName=upd">修改</a>
<a href="Bookservletdel?methodName=del">减少</a>
<a href="Bookservletlist?methodName=list">查询</a>
<p>版本3</p>
<a href="Bookservletadd?methodName=add">增加</a>
<a href="Bookservletupd?methodName=upd">修改</a>
<a href="Bookservletdel?methodName=del">减少</a>
<a href="Bookservletlist?methodName=list">查询</a>
<p>版本4</p>
<a href="book.action?methodName=add">增加</a>
<a href="book.action?methodName=upd">修改</a>
<a href="book.action?methodName=del">减少</a>
<a href="book.action?methodName=list">查询</a>
版本4的弊端：中央控制器的action容器加载，不可以灵活配置
<p>版本五</p>
<a href="order.action?methodName=add">增加</a>
<a href="order.action?methodName=upd">修改</a>
<a href="order.action?methodName=del">减少</a>
<a href="order.action?methodName=list">查询</a>
</body>
</html>

控制台输出

3.再优化

虽然上面代码优化后可以灵活配置了，但是使用重定向和转发有问题，查询必然转发，增删改使用重定向，如果频繁刷新页面，可能会出现重复提交数据。

1.先优化Action子控制器

package com.niyin.framework;
import java.io.IOException;
import java.lang.reflect.Method;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class Action {
  protected String excute(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    String methoed = request.getParameter("methodName");
//  private
    String res="";
    try {
      Method m = this.getClass().getDeclaredMethod(methoed, HttpServletRequest.class,HttpServletResponse.class);
      m.setAccessible(true);
      res=(String) m.invoke(this, request,response);
    } catch (Exception e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    }
    return res;
  } 
}

把book里面的类型也改为String，并返回tolist，和list,通过返回值来判断它是需要重定向还是转发，并且还节约了代码。

package com.niyin.com;
import java.io.IOException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.niyin.entity.Book;
import com.niyin.framework.Action;
import com.niyin.framework.ModelDrivern;
public class BookAction extends Action implements ModelDrivern<Book> {
private Book book=new Book();
  private String list(HttpServletRequest request, HttpServletResponse response) throws Exception {
    // TODO Auto-generated method stub
    System.out.println("list");
//    response.sendRedirect("res.jsp");
    request.setAttribute("content", "你就会");
//    request.getRequestDispatcher("res.jsp").forward(request, response);
  return "list";
  }
  private String del(HttpServletRequest request, HttpServletResponse response) throws Exception {
  // TODO Auto-generated method stub
  System.out.println("del");
//  response.sendRedirect("res.jsp");
  request.setAttribute("content", "你就会");
  return "tolist";
}
private String upd(HttpServletRequest request, HttpServletResponse response) throws Exception {
  // TODO Auto-generated method stub
  System.out.println("upd");
//  response.sendRedirect("res.jsp");
  request.setAttribute("content", "你就会");
  return "tolist";
}
private String add(HttpServletRequest request, HttpServletResponse response) throws IOException {
  // TODO Auto-generated method stub
  System.out.println("add");
//  response.sendRedirect("res.jsp");
  request.setAttribute("content", "你就会");
  return "tolist";
}
@Override
public Book getModel() {
  System.out.println(book);
  return book;
}
}

优化中央控制器，通过模型对象获取·forward对象来判断该重定向还是转发。

package com.niyin.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;
import com.niyin.com.BookAction;
import com.niyin.com.Orderaction;
import model.ActionModel;
import model.ConfigMOdelFactory;
import model.ConfigModel;
import model.ForwardModel;
@WebServlet("*.action")
public class DispatherServlet extends HttpServlet {
  private ConfigModel configMOdel;
//  public Map<String, Action> actionMap=new HashMap<String, Action>();
  @Override
  public void init() throws ServletException {
//  actionMap.put("/book", new BookAction());
//  actionMap.put("/order", new Orderaction());
//  actionMap.put("/cat", new CatAction());
    try {
      configMOdel=ConfigMOdelFactory.build();
    } catch (Exception e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    }
  }
  protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  this.doPost(request, response);
  }
  protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  String uri = request.getRequestURI(); 
  uri=uri.substring(uri.lastIndexOf("/"),uri.lastIndexOf("."));
//  Action action = actionMap.get(uri);
//  要通过uri=book/再configMOdel中找
  ActionModel actionModel = configMOdel.pop(uri);
        String res= action.excute(request, response);
ForwardModel forwardModel = actionModel.pop(res);
  if (forwardModel!=null) {
    boolean redirect = forwardModel.isRedirect();
    String path = forwardModel.getPath();
  if (redirect) {
    response.sendRedirect(request.getContextPath()+path);
  }else {
    request.getRequestDispatcher(path).forward(request, response);
  }
  } 
    } catch (Exception e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    } 
  }
}

运行结果

结果是一样的说明优化成功。

4.优化传值问题

一般来说通过servlet拿到前端的值再把它传入数据库，这个过程要写很多重复代码，现在来优化一下，利用反射等等

1.先定义一个模型驱动接口

package com.niyin.framework;
/**
 * 
 * @author 匿瘾
 *
 * @param <T>
 * 模型驱动接口
 */
public interface ModelDrivern<T> {
T getModel();
}

2.让bookaction实现这个接口

package com.niyin.com;
import java.io.IOException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.niyin.entity.Book;
import com.niyin.framework.Action;
import com.niyin.framework.ModelDrivern;
public class BookAction extends Action implements ModelDrivern<Book> {
private Book book=new Book();
  private String list(HttpServletRequest request, HttpServletResponse response) throws Exception {
    // TODO Auto-generated method stub
    System.out.println("list");
//    response.sendRedirect("res.jsp");
    request.setAttribute("content", "你就会");
//    request.getRequestDispatcher("res.jsp").forward(request, response);
  return "list";
  }
  private String del(HttpServletRequest request, HttpServletResponse response) throws Exception {
  // TODO Auto-generated method stub
  System.out.println("del");
//  response.sendRedirect("res.jsp");
  request.setAttribute("content", "你就会");
  return "tolist";
}
private String upd(HttpServletRequest request, HttpServletResponse response) throws Exception {
  // TODO Auto-generated method stub
  System.out.println("upd");
//  response.sendRedirect("res.jsp");
  request.setAttribute("content", "你就会");
  return "tolist";
}
private String add(HttpServletRequest request, HttpServletResponse response) throws IOException {
  // TODO Auto-generated method stub
  System.out.println("add");
//  response.sendRedirect("res.jsp");
  request.setAttribute("content", "你就会");
  return "tolist";
}
@Override
public Book getModel() {
  System.out.println(book);
  return book;
}
}

3.优化中央控制器

在控制器内判断有没有实现接口，如果实现了就把值传进去。

package com.niyin.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;
import com.niyin.com.BookAction;
import com.niyin.com.Orderaction;
import model.ActionModel;
import model.ConfigMOdelFactory;
import model.ConfigModel;
import model.ForwardModel;
@WebServlet("*.action")
public class DispatherServlet extends HttpServlet {
  private ConfigModel configMOdel;
//  public Map<String, Action> actionMap=new HashMap<String, Action>();
  @Override
  public void init() throws ServletException {
//  actionMap.put("/book", new BookAction());
//  actionMap.put("/order", new Orderaction());
//  actionMap.put("/cat", new CatAction());
    try {
      configMOdel=ConfigMOdelFactory.build();
    } catch (Exception e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    }
  }
  protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  this.doPost(request, response);
  }
  protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  String uri = request.getRequestURI(); 
  uri=uri.substring(uri.lastIndexOf("/"),uri.lastIndexOf("."));
//  Action action = actionMap.get(uri);
//  要通过uri=book/再configMOdel中找
  ActionModel actionModel = configMOdel.pop(uri);
  if (actionModel==null)
    throw new RuntimeException("action 没有配置");
 String type = actionModel.getType();
    Action action;
    try {
      action = (Action) Class.forName(type).newInstance();
//      bookaction 有没有实现这个接口
      if (action instanceof ModelDrivern) {
        ModelDrivern md=(ModelDrivern) action;
        Object bean = md.getModel();
        Map<String, String[]> map = request.getParameterMap();
        BeanUtils.populate(bean, map);
//        把值封进去
      }
        String res= action.excute(request, response);
ForwardModel forwardModel = actionModel.pop(res);
  if (forwardModel!=null) {
    boolean redirect = forwardModel.isRedirect();
    String path = forwardModel.getPath();
  if (redirect) {
    response.sendRedirect(request.getContextPath()+path);
  }else {
    request.getRequestDispatcher(path).forward(request, response);
  }
  } 
    } catch (Exception e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    } 
  }
}

最后通过degbug查看book里面是否有值判断是否成功的，传入了值。

结果：

可以看到book里面是有值的，所以最后一个优化也成功了。

4.总结

通过建模xml和反射的方式优化代码，让代码以Mvc框架的形式出现，

MVC框架构思巧妙。让代码更为简洁。

文章标签：
前端开发
数据格式
XML
Java
数据库
关键词：
mvc进阶
匿瘾
目录
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