JAVA MVC_以MVC架構來進行Java GUI程式開發(一)_介面層邏輯和業務層邏輯的拆分




JAVA MVC架構實作

在一些現今程式應用中
很常聽到和使用到的MVC(Model-View-Controller)
最早於1978年的 特里夫·林斯高格  (Trygve Reenskaug)  所提出的軟體工程三層架構

其主張介面層邏輯要跟業務層邏輯分離
不應該混在一塊

使程式各自類可以各司其職(符合單一職責原則)
利於後續程式增多後的維護






Model : 負責儲存及維護一些來自前端使用者介面資料的流程邏輯
(使用者輸入了資料後進行捨麼計算....)

View : 舉凡使用者和前端介面互動的相關流程邏輯接歸屬於View來做控制
(捨麼時候要跳窗,當按下捨麼按鈕做....)

Controller : 介於Model和View兩者之間的溝通橋樑
主要接收View使用者於前端介面的資料後再傳遞給Model並接收來自Model回傳結果
再丟還給View進行介面渲染(更新顯示)的流程。


這樣就不會於系統維護到後期時發生
因為過去都將Model  data處理邏輯部分的Code內嵌至View而造成的
因為後續有需要用多個不同的View要來顯示某些同一資料部分
而導致出現重複黏貼Model data code 處理的區塊



開發規格與工具




新增好專案後


建置好三個java package



資源package下存著一張400*200的底圖


針對View 新增一個繼承JFrame的可視化class 及設計面板




首先將預設新增的View JFrame中進入點程式移動至main中
於此的main區塊可先暫時註解掉(留著做針對該類中的 unit test也可以)
程式運行時會自動找main進入點於哪個class的java檔案去運行


針對View 類別
起初預設的程式碼
我們進行介面端的邏輯設計規劃


Defalt View.java


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/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package com.kuanyu.view;

/**
 *
 * @author chous
 */
public class View extends javax.swing.JFrame {

    /**
     * Creates new form View
     */
    public View() {
        initComponents();
    }

    /**
     * This method is called from within the constructor to initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is always
     * regenerated by the Form Editor.
     */
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 400, Short.MAX_VALUE)
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 300, Short.MAX_VALUE)
        );

        pack();
    }// </editor-fold>                        



    // Variables declaration - do not modify                     
    // End of variables declaration                   
}

針對JFrame Form設置






在View Form上拖曳一個JPanel  (先保有後續調動的彈性不要直接在Form上設置)


JPanel的設置


設置完寬高後會發現沒有自動對齊


這時可以往上拖曳會自動做類似WinForm當中的介面屬性  Dock -> Fill

這裡會發現寬高的即時呈現跑掉
在去改為Default即可



於JPanel上設置AbsoluteLayout (會依以所想要的絕對座標位置來安排)









大致上把前端控制項位置布局完成



JLabel(for  底圖載入)


MVC當中的 Model起手式

Model package添加完後再新建Model.java

Model.java

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 * and open the template in the editor.
 */
package com.kuanyu.model;

/**
 *
 * @author chous
 */
public class Model {
    private String name;

    public String getName() {
        return name;
    }
    
    public void setName(String name) {
        this.name = name;
    }
    //toString()  overrite
    @Override
    public String toString() {
        return "Model{" + "name=" + name + '}';
    }
    
}

此段功能之單元測試




MVC 當中的View起手式


針對 View.java先完成初步的程式撰寫

UI 初始化時位置
當UI被拖曳時位置移動更新 (先點擊取得UI位置 再滑鼠拖曳按著不放移動並更新位置)
UI關閉事件

View.java

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/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package com.kuanyu.view;

import java.awt.Toolkit;

/**
 *
 * @author chous
 */
public class View extends javax.swing.JFrame {

    private int MouseX;
    private int MouseY;

    private int x , screenW;
    private int y , screenH;

    /**
     * Creates new form View Set location center
     * https://codingnote.blogspot.com/2008/04/java.html
     */
    public View() {
        initComponents();
        this.setLocationRelativeTo(null);
    }

    /**
     * This method is called from within the constructor to initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is always
     * regenerated by the Form Editor.
     */
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {

        jPanel1 = new javax.swing.JPanel();
        lblClose = new javax.swing.JLabel();
        lblName = new javax.swing.JLabel();
        txtName = new javax.swing.JTextField();
        btnEnter = new javax.swing.JButton();
        btnClear = new javax.swing.JButton();
        lblResult = new javax.swing.JLabel();
        lblBG = new javax.swing.JLabel();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        setCursor(new java.awt.Cursor(java.awt.Cursor.HAND_CURSOR));
        setUndecorated(true);
        setPreferredSize(new java.awt.Dimension(400, 200));
        setResizable(false);

        jPanel1.setMinimumSize(new java.awt.Dimension(400, 200));
        jPanel1.setPreferredSize(new java.awt.Dimension(400, 200));
        jPanel1.setLayout(new org.netbeans.lib.awtextra.AbsoluteLayout());

        lblClose.setFont(new java.awt.Font("新細明體", 1, 18)); // NOI18N
        lblClose.setForeground(new java.awt.Color(0, 0, 204));
        lblClose.setText("X");
        lblClose.addMouseListener(new java.awt.event.MouseAdapter() {
            public void mouseClicked(java.awt.event.MouseEvent evt) {
                lblCloseMouseClicked(evt);
            }
        });
        jPanel1.add(lblClose, new org.netbeans.lib.awtextra.AbsoluteConstraints(380, 0, -1, -1));

        lblName.setText("Enter your name:");
        jPanel1.add(lblName, new org.netbeans.lib.awtextra.AbsoluteConstraints(20, 40, -1, -1));
        lblName.getAccessibleContext().setAccessibleName("");

        jPanel1.add(txtName, new org.netbeans.lib.awtextra.AbsoluteConstraints(20, 70, 190, -1));

        btnEnter.setText("ENTER");
        jPanel1.add(btnEnter, new org.netbeans.lib.awtextra.AbsoluteConstraints(280, 40, -1, -1));

        btnClear.setText("CLEAR");
        jPanel1.add(btnClear, new org.netbeans.lib.awtextra.AbsoluteConstraints(280, 90, -1, -1));

        lblResult.setText("_____");
        jPanel1.add(lblResult, new org.netbeans.lib.awtextra.AbsoluteConstraints(20, 110, -1, -1));

        lblBG.setIcon(new javax.swing.ImageIcon(getClass().getResource("/com/kuanyu/resources/bg.png"))); // NOI18N
        lblBG.addMouseMotionListener(new java.awt.event.MouseMotionAdapter() {
            public void mouseDragged(java.awt.event.MouseEvent evt) {
                lblBGMouseDragged(evt);
            }
        });
        lblBG.addMouseListener(new java.awt.event.MouseAdapter() {
            public void mousePressed(java.awt.event.MouseEvent evt) {
                lblBGMousePressed(evt);
            }
        });
        jPanel1.add(lblBG, new org.netbeans.lib.awtextra.AbsoluteConstraints(0, 0, -1, -1));

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
        );

        pack();
    }// </editor-fold>                        


    
    
    private void lblBGMouseDragged(java.awt.event.MouseEvent evt) {                                   
        // TODO add your handling code here:
        int x = evt.getXOnScreen();
        int y = evt.getYOnScreen();
        this.setLocation(x - MouseX, y - MouseY);
    }                                  

    private void lblBGMousePressed(java.awt.event.MouseEvent evt) {                                   
        // TODO add your handling code here:
        MouseX = evt.getX();
        MouseY = evt.getY();
    }                                  

    private void lblCloseMouseClicked(java.awt.event.MouseEvent evt) {                                      
        // TODO add your handling code here:
        System.exit(0);
    }                                     


    // Variables declaration - do not modify                     
    private javax.swing.JButton btnClear;
    private javax.swing.JButton btnEnter;
    private javax.swing.JPanel jPanel1;
    private javax.swing.JLabel lblBG;
    private javax.swing.JLabel lblClose;
    private javax.swing.JLabel lblName;
    private javax.swing.JLabel lblResult;
    private javax.swing.JTextField txtName;
    // End of variables declaration                   

}






MVC 當中的Controller起手式

我們說 Controller是 View 以及  Model兩者之間的溝通中介
在定義完對應物件屬性後
進行Ctrl + Shift + I 可自動做缺失對應Package的 import


這裡我們要在main主程式進入點地方
去實體化我們的Controller時  傳入 model , view
因此定義我們的建構子






將原本main主程式區塊稍稍改寫成呼Controller的版本

於Controller中再去針對呼叫的View參數去做面板顯示


最後大致補上一些中介層 View和Model溝通傳輸資料
相關事件即可

Controller.java


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/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package com.kuanyu.controller;

import com.kuanyu.model.Model;
import com.kuanyu.view.View;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JOptionPane;

/**
 *
 * @author chous
 */
public class Controller implements ActionListener {

    private Model m;
    private View v;

    //Constructor
    public Controller(Model m, View v) {
        this.m = m;
        this.v = v;
        this.v.setVisible(true);

        //Set Action Commands
        this.v.getBtnEnter().setActionCommand("ENTER");
        this.v.getBtnClear().setActionCommand("CLEAR");
        //Add Action Listener
        this.v.getBtnEnter().addActionListener(this);
        this.v.getBtnClear().addActionListener(this);
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        String command = e.getActionCommand();
        switch (command) {
            case "ENTER":
                System.out.println("Enter....");
                String name = v.getTxtName().getText();
                System.out.println(name);
                if (!name.equals("")) {
                    m.setName(name);
                    //Send objects from the Model section to View section
                    v.showResult(m);
                    v.getTxtName().setText("");
                } else {
                    JOptionPane.showMessageDialog(v, "不可為空", "輸入錯誤", 0);
                }
                break;
            case "CLEAR":
                System.out.println("Clear....");
                v.getTxtName().setText("");
                v.getLblResult().setText("");
                break;
        }
    }
}


最後版的
View.java


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/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package com.kuanyu.view;

import com.kuanyu.model.Model;
import javax.swing.JButton;
import javax.swing.JLabel;
import javax.swing.JTextField;

/**
 *
 * @author chous
 */
public class View extends javax.swing.JFrame {

    private int MouseX;
    private int MouseY;

    private int x , screenW;
    private int y , screenH;

    /**
     * Creates new form View Set location center
     * https://codingnote.blogspot.com/2008/04/java.html
     */
    public View() {
        initComponents();
        this.setLocationRelativeTo(null);
    }

    /**
     * This method is called from within the constructor to initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is always
     * regenerated by the Form Editor.
     */
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {

        jPanel1 = new javax.swing.JPanel();
        lblClose = new javax.swing.JLabel();
        lblName = new javax.swing.JLabel();
        txtName = new javax.swing.JTextField();
        btnEnter = new javax.swing.JButton();
        btnClear = new javax.swing.JButton();
        lblResult = new javax.swing.JLabel();
        lblBG = new javax.swing.JLabel();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        setCursor(new java.awt.Cursor(java.awt.Cursor.HAND_CURSOR));
        setUndecorated(true);
        setPreferredSize(new java.awt.Dimension(400, 200));
        setResizable(false);

        jPanel1.setMinimumSize(new java.awt.Dimension(400, 200));
        jPanel1.setPreferredSize(new java.awt.Dimension(400, 200));
        jPanel1.setLayout(new org.netbeans.lib.awtextra.AbsoluteLayout());

        lblClose.setFont(new java.awt.Font("新細明體", 1, 18)); // NOI18N
        lblClose.setForeground(new java.awt.Color(0, 0, 204));
        lblClose.setText("X");
        lblClose.addMouseListener(new java.awt.event.MouseAdapter() {
            public void mouseClicked(java.awt.event.MouseEvent evt) {
                lblCloseMouseClicked(evt);
            }
        });
        jPanel1.add(lblClose, new org.netbeans.lib.awtextra.AbsoluteConstraints(380, 0, -1, -1));

        lblName.setText("Enter your name:");
        jPanel1.add(lblName, new org.netbeans.lib.awtextra.AbsoluteConstraints(20, 40, -1, -1));
        lblName.getAccessibleContext().setAccessibleName("");

        jPanel1.add(txtName, new org.netbeans.lib.awtextra.AbsoluteConstraints(20, 70, 190, -1));

        btnEnter.setText("ENTER");
        jPanel1.add(btnEnter, new org.netbeans.lib.awtextra.AbsoluteConstraints(280, 40, -1, -1));

        btnClear.setText("CLEAR");
        jPanel1.add(btnClear, new org.netbeans.lib.awtextra.AbsoluteConstraints(280, 90, -1, -1));

        lblResult.setText("_____");
        jPanel1.add(lblResult, new org.netbeans.lib.awtextra.AbsoluteConstraints(20, 110, -1, -1));

        lblBG.setIcon(new javax.swing.ImageIcon(getClass().getResource("/com/kuanyu/resources/bg.png"))); // NOI18N
        lblBG.addMouseMotionListener(new java.awt.event.MouseMotionAdapter() {
            public void mouseDragged(java.awt.event.MouseEvent evt) {
                lblBGMouseDragged(evt);
            }
        });
        lblBG.addMouseListener(new java.awt.event.MouseAdapter() {
            public void mousePressed(java.awt.event.MouseEvent evt) {
                lblBGMousePressed(evt);
            }
        });
        jPanel1.add(lblBG, new org.netbeans.lib.awtextra.AbsoluteConstraints(0, 0, -1, -1));

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
        );

        pack();
    }// </editor-fold>                        
    
    //Getter for Cnntroller using
    public JButton getBtnClear() {
        return btnClear;
    }

    public JButton getBtnEnter() {
        return btnEnter;
    }

    public JLabel getLblResult() {
        return lblResult;
    }

    public JTextField getTxtName() {
        return txtName;
    }
    //Getter for Cnntroller using
    
    public void showResult(Model m){
        lblResult.setText("Hi !! " + m.getName() 
                + " This is MVC test");
    }
    
    
    private void lblBGMouseDragged(java.awt.event.MouseEvent evt) {                                   
        // TODO add your handling code here:
        int x = evt.getXOnScreen();
        int y = evt.getYOnScreen();
        this.setLocation(x - MouseX, y - MouseY);
    }                                  

    private void lblBGMousePressed(java.awt.event.MouseEvent evt) {                                   
        // TODO add your handling code here:
        MouseX = evt.getX();
        MouseY = evt.getY();
    }                                  

    private void lblCloseMouseClicked(java.awt.event.MouseEvent evt) {                                      
        // TODO add your handling code here:
        System.exit(0);
    }                                     


    // Variables declaration - do not modify                     
    private javax.swing.JButton btnClear;
    private javax.swing.JButton btnEnter;
    private javax.swing.JPanel jPanel1;
    private javax.swing.JLabel lblBG;
    private javax.swing.JLabel lblClose;
    private javax.swing.JLabel lblName;
    private javax.swing.JLabel lblResult;
    private javax.swing.JTextField txtName;
    // End of variables declaration                   

}












Reference link:
https://www.javacodegeeks.com/2017/09/mvc-delivery-mechanism-domain-model.html

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