import org.eclipse.core.runtime.Preferences.IPropertyChangeListener; //导入依赖的package包/类
@Override
public void configureClientProxy(
    final HttpClient httpClient,
    final HostConfiguration hostConfiguration,
    final HttpState httpState,
    final ConnectionInstanceData connectionInstanceData) {
    final Preferences preferences = TFSCommonUIClientPlugin.getDefault().getPluginPreferences();

    final IPropertyChangeListener preferenceChangeListener = new PreferenceChangeListener(httpClient);
    preferences.addPropertyChangeListener(preferenceChangeListener);
    httpClient.getParams().setParameter(PREFERENCE_CHANGE_LISTENER_KEY, preferenceChangeListener);

    configureProxy(httpClient);
}
 

import org.eclipse.core.runtime.Preferences.IPropertyChangeListener; //导入依赖的package包/类
/**
 * {@inheritDoc}
 * <p>
 * The object returned is reconfigured with new values when Eclipse
 * preferences change.
 */
@Override
public TFProxyServerSettings newProxyServerSettings() {
    final DefaultTFProxyServerSettings proxyServerSettings = new DefaultTFProxyServerSettings(null);

    final Preferences preferences = TFSCommonUIClientPlugin.getDefault().getPluginPreferences();

    final IPropertyChangeListener preferenceChangeListener = new PreferenceChangeListener(proxyServerSettings);
    preferences.addPropertyChangeListener(preferenceChangeListener);
    listeners.put(proxyServerSettings, preferenceChangeListener);

    configureProxySettings(proxyServerSettings);

    return proxyServerSettings;
}
 

import org.eclipse.core.runtime.Preferences.IPropertyChangeListener; //导入依赖的package包/类
public static void addListener(IPropertyChangeListener listener) {
  Preferences prefs = getPreferences();
  prefs.addPropertyChangeListener(listener);
}
 

import org.eclipse.core.runtime.Preferences.IPropertyChangeListener; //导入依赖的package包/类
public static void removeListener(IPropertyChangeListener listener) {
  Preferences prefs = getPreferences();
  prefs.removePropertyChangeListener(listener);
}
 

import org.eclipse.core.runtime.Preferences.IPropertyChangeListener; //导入依赖的package包/类
public void addListener(IPropertyChangeListener listener) {
  OldMechanicPreferences.addListener(listener);
}
 

import org.eclipse.core.runtime.Preferences.IPropertyChangeListener; //导入依赖的package包/类
public void removeListener(IPropertyChangeListener listener) {
  OldMechanicPreferences.removeListener(listener);
}
 

import org.eclipse.core.runtime.Preferences.IPropertyChangeListener; //导入依赖的package包/类
void addListener(IPropertyChangeListener listener); 

import org.eclipse.core.runtime.Preferences.IPropertyChangeListener; //导入依赖的package包/类
void removeListener(IPropertyChangeListener listener);