MVC 模式是如何构建用户界面的模型。
因此它定义了 3 个元素 Model、View、Controller:
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模型 模型是呈现给用户的事物的抽象。在摇摆中,您可以区分 gui 模型和数据模型。 GUI 模型抽象了 ui 组件的状态,例如 ButtonModel。数据模型抽象了用户界面呈现给用户的结构化数据,例如TableModel。
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视图 视图是一个 UI 组件,负责将数据呈现给用户。因此它负责所有与 ui 相关的问题,如布局、绘图等。 JTable。
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控制器 控制器封装了为了用户交互(鼠标移动、鼠标点击、按键等)而执行的应用程序代码。控制器可能需要输入来执行它们并产生输出。他们从模型中读取输入并更新模型作为执行的结果。他们还可能重构 ui(例如,替换 ui 组件或显示全新的视图)。但是他们一定不知道 ui 组件,因为您可以将重组封装在控制器仅调用的单独接口中。在 Swing 中,控制器通常由 ActionListener 或 Action 实现。
示例
当点击Button 时,它会调用ActionListener。 ActionListener 仅取决于其他型号。它使用一些模型作为输入,其他模型作为结果或输出。它就像方法参数和返回值。模型在更新时会通知 ui。所以控制器逻辑不需要知道 ui 组件。模型对象不知道 ui。通知由观察者模式完成。因此,模型对象只知道有人想要在模型发生变化时得到通知。
在 java swing 中有一些组件也实现了模型和控制器。例如。 javax.swing.Action。它实现了一个 ui 模型(属性:启用、小图标、名称等)并且是一个控制器,因为它扩展了 ActionListener。
详细说明、示例应用程序和源代码:https://www.link-intersystems.com/blog/2013/07/20/the-mvc-pattern-implemented-with-java-swing/。
不到 260 行的 MVC 基础知识:
import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.event.ActionEvent;
import java.util.ArrayList;
import java.util.List;
import javax.swing.AbstractAction;
import javax.swing.Action;
import javax.swing.DefaultListModel;
import javax.swing.DefaultListSelectionModel;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JList;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextField;
import javax.swing.ListSelectionModel;
import javax.swing.WindowConstants;
import javax.swing.event.ListSelectionEvent;
import javax.swing.event.ListSelectionListener;
import javax.swing.text.BadLocationException;
import javax.swing.text.Document;
import javax.swing.text.PlainDocument;
public class Main {
public static void main(String[] args) {
JFrame mainFrame = new JFrame("MVC example");
mainFrame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
mainFrame.setSize(640, 300);
mainFrame.setLocationRelativeTo(null);
PersonService personService = new PersonServiceMock();
DefaultListModel searchResultListModel = new DefaultListModel();
DefaultListSelectionModel searchResultSelectionModel = new DefaultListSelectionModel();
searchResultSelectionModel
.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
Document searchInput = new PlainDocument();
PersonDetailsAction personDetailsAction = new PersonDetailsAction(
searchResultSelectionModel, searchResultListModel);
personDetailsAction.putValue(Action.NAME, "Person Details");
Action searchPersonAction = new SearchPersonAction(searchInput,
searchResultListModel, personService);
searchPersonAction.putValue(Action.NAME, "Search");
Container contentPane = mainFrame.getContentPane();
JPanel searchInputPanel = new JPanel();
searchInputPanel.setLayout(new BorderLayout());
JTextField searchField = new JTextField(searchInput, null, 0);
searchInputPanel.add(searchField, BorderLayout.CENTER);
searchField.addActionListener(searchPersonAction);
JButton searchButton = new JButton(searchPersonAction);
searchInputPanel.add(searchButton, BorderLayout.EAST);
JList searchResultList = new JList();
searchResultList.setModel(searchResultListModel);
searchResultList.setSelectionModel(searchResultSelectionModel);
JPanel searchResultPanel = new JPanel();
searchResultPanel.setLayout(new BorderLayout());
JScrollPane scrollableSearchResult = new JScrollPane(searchResultList);
searchResultPanel.add(scrollableSearchResult, BorderLayout.CENTER);
JPanel selectionOptionsPanel = new JPanel();
JButton showPersonDetailsButton = new JButton(personDetailsAction);
selectionOptionsPanel.add(showPersonDetailsButton);
contentPane.add(searchInputPanel, BorderLayout.NORTH);
contentPane.add(searchResultPanel, BorderLayout.CENTER);
contentPane.add(selectionOptionsPanel, BorderLayout.SOUTH);
mainFrame.setVisible(true);
}
}
class PersonDetailsAction extends AbstractAction {
private static final long serialVersionUID = -8816163868526676625L;
private ListSelectionModel personSelectionModel;
private DefaultListModel personListModel;
public PersonDetailsAction(ListSelectionModel personSelectionModel,
DefaultListModel personListModel) {
boolean unsupportedSelectionMode = personSelectionModel
.getSelectionMode() != ListSelectionModel.SINGLE_SELECTION;
if (unsupportedSelectionMode) {
throw new IllegalArgumentException(
"PersonDetailAction can only handle single list selections. "
+ "Please set the list selection mode to ListSelectionModel.SINGLE_SELECTION");
}
this.personSelectionModel = personSelectionModel;
this.personListModel = personListModel;
personSelectionModel
.addListSelectionListener(new ListSelectionListener() {
public void valueChanged(ListSelectionEvent e) {
ListSelectionModel listSelectionModel = (ListSelectionModel) e
.getSource();
updateEnablement(listSelectionModel);
}
});
updateEnablement(personSelectionModel);
}
public void actionPerformed(ActionEvent e) {
int selectionIndex = personSelectionModel.getMinSelectionIndex();
PersonElementModel personElementModel = (PersonElementModel) personListModel
.get(selectionIndex);
Person person = personElementModel.getPerson();
String personDetials = createPersonDetails(person);
JOptionPane.showMessageDialog(null, personDetials);
}
private String createPersonDetails(Person person) {
return person.getId() + ": " + person.getFirstName() + " "
+ person.getLastName();
}
private void updateEnablement(ListSelectionModel listSelectionModel) {
boolean emptySelection = listSelectionModel.isSelectionEmpty();
setEnabled(!emptySelection);
}
}
class SearchPersonAction extends AbstractAction {
private static final long serialVersionUID = 4083406832930707444L;
private Document searchInput;
private DefaultListModel searchResult;
private PersonService personService;
public SearchPersonAction(Document searchInput,
DefaultListModel searchResult, PersonService personService) {
this.searchInput = searchInput;
this.searchResult = searchResult;
this.personService = personService;
}
public void actionPerformed(ActionEvent e) {
String searchString = getSearchString();
List<Person> matchedPersons = personService.searchPersons(searchString);
searchResult.clear();
for (Person person : matchedPersons) {
Object elementModel = new PersonElementModel(person);
searchResult.addElement(elementModel);
}
}
private String getSearchString() {
try {
return searchInput.getText(0, searchInput.getLength());
} catch (BadLocationException e) {
return null;
}
}
}
class PersonElementModel {
private Person person;
public PersonElementModel(Person person) {
this.person = person;
}
public Person getPerson() {
return person;
}
@Override
public String toString() {
return person.getFirstName() + ", " + person.getLastName();
}
}
interface PersonService {
List<Person> searchPersons(String searchString);
}
class Person {
private int id;
private String firstName;
private String lastName;
public Person(int id, String firstName, String lastName) {
this.id = id;
this.firstName = firstName;
this.lastName = lastName;
}
public int getId() {
return id;
}
public String getFirstName() {
return firstName;
}
public String getLastName() {
return lastName;
}
}
class PersonServiceMock implements PersonService {
private List<Person> personDB;
public PersonServiceMock() {
personDB = new ArrayList<Person>();
personDB.add(new Person(1, "Graham", "Parrish"));
personDB.add(new Person(2, "Daniel", "Hendrix"));
personDB.add(new Person(3, "Rachel", "Holman"));
personDB.add(new Person(4, "Sarah", "Todd"));
personDB.add(new Person(5, "Talon", "Wolf"));
personDB.add(new Person(6, "Josephine", "Dunn"));
personDB.add(new Person(7, "Benjamin", "Hebert"));
personDB.add(new Person(8, "Lacota", "Browning "));
personDB.add(new Person(9, "Sydney", "Ayers"));
personDB.add(new Person(10, "Dustin", "Stephens"));
personDB.add(new Person(11, "Cara", "Moss"));
personDB.add(new Person(12, "Teegan", "Dillard"));
personDB.add(new Person(13, "Dai", "Yates"));
personDB.add(new Person(14, "Nora", "Garza"));
}
public List<Person> searchPersons(String searchString) {
List<Person> matches = new ArrayList<Person>();
if (searchString == null) {
return matches;
}
for (Person person : personDB) {
if (person.getFirstName().contains(searchString)
|| person.getLastName().contains(searchString)) {
matches.add(person);
}
}
return matches;
}
}