Mediator在Java Swing中的作用

Mediator在Swing中可以充当MVC中的Controller的角色，例如：

public class FrmUserManager extends JFrame {

private UserManagerMediator mediator;

private JButton addBtn = new JButton();

private JButton delBtn = new JButton();

private JComboBox userComboBox = new JComboBox();

// 下面是其他一些控件

public FrmUserManager() {

mediator = new UserManagerMediator(this);

initComponent();

}

private initComponent() {

addBtn.addActionListener(mediator.addAction());

delBtn.addActionListener(mediator.deleteAction());

userComboBox.setModel(mediator.userComboBoxModel());

// other operation

}

public JComboBox getUserComboBox() {

return userComboBox;

}

}

public class UserManagerMediator {

private FrmUserManager frmUserManager;

public UserManagerMediator(FrmUserManager frmUserManager) {

this.frmUserManager = frmUserManager;

}

public ActionListener addAction() {

return new ActionListener() {

public void actionPerformed(ActionEvent e) {

JComboBox userComboBox = frmUserManager.getUserComboBox();

DefaultComboBoxModel model = (DefaultComboBoxModel)userComboBox.getModel();

model.addElement(......);

}

};

}

public ActionListener deleteAction() {

return new ActionListener() {

public void actionPerformed(ActionEvent e) {

JComboBox userComboBox = frmUserManager.getUserComboBox();

DefaultComboBoxModel model = (DefaultComboBoxModel)userComboBox.getModel();

model.removeElement(......);

}

};

}

public DefaultComboBoxModel userComboBoxModel() {

// 比如：查询数据库得到数据

DefaultComboBoxModel model = new DefaultComboBoxModel();

// 添加数据

model.addListDataListener(new ListDataListener() {

// 实现一些方法

});

return model;

}

}

View--FrmUserManager，Controller--UserManagerMediator，Model--在控制器中调用

当View的状态改变（如：点击按钮，选择下拉框），调用Mediator中相应方法来更新Model；当Model改变（如：下拉框增加一项），会通过Mediator，更新视图。