组员向仲裁者报告，仲裁者向组员下达指示。组员之间不再相互询问和相互指示。
示例
一个GUI应用程序，它展示了一个登录对话框，用户在其中输入正确的用户名和密码后可以登录。
- 可以选择作为游客访问（Guest）或是作为用户登录（Login）
- 作为用户登录时，需要输入正确的用户名（Username）和密码（Password）
- 点击OK按钮可以登录，点击Cancel按钮可以取消登录
类图
时序图
Mediator接口
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public interface { public abstract void createColleagues(); public abstract void colleagueChanged();}
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Colleague接口
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public interface Colleague { public abstract void setMediator(Mediator mediator); public abstract void setColleagueEnabled(boolean enabled);}
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ColleagueButton类
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import java.awt.*;
public class ColleagueButton extends Button implements Colleague { private Mediator mediator;
public ColleagueButton(String caption) { super(caption); }
public void setMediator(Mediator mediator) { this.mediator = mediator; }
public void setColleagueEnabled(boolean enabled) { setEnabled(enabled); }}
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ColleagueTextField类
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import java.awt.*;import java.awt.event.TextEvent;import java.awt.event.TextListener;
public class ColleagueTextField extends TextField implements TextListener, Colleague { private Mediator mediator;
public ColleagueTextField(String text, int columns) { super(text, columns); }
public void setMediator(Mediator mediator) { this.mediator = mediator; }
public void setColleagueEnabled(boolean enabled) { setEnabled(enabled); setBackground(enabled ? Color.white : Color.lightGray); }
public void textValueChanged(TextEvent e) { mediator.colleagueChanged(); }}
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ColleagueCheckbox类
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import java.awt.*;import java.awt.event.ItemEvent;import java.awt.event.ItemListener;
public class ColleagueCheckbox extends Checkbox implements ItemListener, Colleague { private Mediator mediator;
public ColleagueCheckbox(String caption, CheckboxGroup group, boolean state) { super(caption, group, state); }
@Override public void setMediator(Mediator mediator) { this.mediator = mediator; }
@Override public void setColleagueEnabled(boolean enabled) { setEnabled(enabled); }
@Override public void itemStateChanged(ItemEvent e) { mediator.colleagueChanged(); }}
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LoginFrame类
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import java.awt.*;import java.awt.event.ActionEvent;import java.awt.event.ActionListener;
public class LoginFrame extends Frame implements ActionListener, { private ColleagueCheckbox checkGuest; private ColleagueCheckbox checkLogin; private ColleagueTextField textUser; private ColleagueTextField textPass; private ColleagueButton buttonOk; private ColleagueButton buttonCancel;
public LoginFrame(String title) { super(title); setBackground(Color.lightGray); setLayout(new GridLayout(4, 2));
createColleagues();
add(checkGuest); add(checkLogin); add(new Label("Username:")); add(textUser); add(new Label("Password:")); add(textPass); add(buttonOk); add(buttonCancel);
colleagueChanged();
pack(); show(); }
@Override public void createColleagues() { CheckboxGroup g = new CheckboxGroup(); checkGuest = new ColleagueCheckbox("Guest", g, true); checkLogin = new ColleagueCheckbox("Login", g, false); textUser = new ColleagueTextField("", 10); textPass = new ColleagueTextField("", 10); textPass.setEchoChar('*'); buttonOk = new ColleagueButton("OK"); buttonCancel = new ColleagueButton("Cancel");
checkGuest.setMediator(this); checkLogin.setMediator(this); textUser.setMediator(this); textPass.setMediator(this); buttonOk.setMediator(this); buttonCancel.setMediator(this);
checkGuest.addItemListener(checkGuest); checkLogin.addItemListener(checkLogin); textUser.addTextListener(textUser); textPass.addTextListener(textPass); buttonOk.addActionListener(this); buttonCancel.addActionListener(this); }
@Override public void colleagueChanged() { if (checkGuest.getState()) { textUser.setColleagueEnabled(false); textPass.setColleagueEnabled(false); buttonOk.setColleagueEnabled(true); } else { textUser.setColleagueEnabled(true); userpassChanged(); } }
private void userpassChanged() { if (textUser.getText().length() > 0) { textPass.setColleagueEnabled(true);
if (textPass.getText().length() > 0) buttonOk.setColleagueEnabled(true); else buttonOk.setColleagueEnabled(false); } else { textPass.setColleagueEnabled(false); buttonOk.setColleagueEnabled(false); } }
@Override public void actionPerformed(ActionEvent e) { System.out.println(e.toString()); System.exit(0); }}
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Main类
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public class Main {
public static void main(String[] args) { new LoginFrame("Mediator Sample"); }}
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运行结果
登场角色
Mediator（仲裁者、中介者）
Mediator角色负责定义与Colleague角色进行通信和做出决定的接口（API）。在示例程序中，由Mediator接口扮演此角色。
ConcreteMediator（具体的仲裁者、中介者）
ConcreteMediator角色负责实现Mediator角色的接口（API），负责实际做出决定。在示例程序中，由LoginFrame类扮演此角色。
Colleague（同事）
Colleague角色负责定义与Mediator角色进行通信的接口（API）。在示例程序中，由Colleague接口扮演此角色。
ConcreteColleague（具体的同事）
ConcreteColleague角色负责实现Colleague角色的接口（API）。在示例程序中，由ColleagueButton类、ColleagueTextField类和ColleagueCheckbox类扮演此角色。
类图
原文地址：https://www.cnblogs.com/chinatrump/p/11584628.html
时间： 2024-08-02 11:32:55