虽然PreferenceActivity的UI比较搓，但是由于其良好的封装性和实用性，所以在一些场景还是有一定的使用价值。所以如何能优化它的UI让它和你程序相配就十分必要了。毕竟对于程序员来说能懒点就懒点，哈哈。
首先，
public abstract class PreferenceActivity extends ListActivity implements
PreferenceManager.OnPreferenceTreeClickListener,
PreferenceFragment.OnPreferenceStartFragmentCallback
这就表明可以替换背景，可以替换Divider，Selector。
它的adapter是PreferenceGroupAdapter，见于PreferenceScreen:
public void bind(ListView listView) {
listView.setOnItemClickListener(this);
listView.setAdapter(getRootAdapter());
onAttachedToActivity();
}
这个方法在PreferenceActivity里被掉，用于加载adapter。
package android.preference;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import android.os.Handler;
import android.preference.Preference.OnPreferenceChangeInternalListener;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Adapter;
import android.widget.BaseAdapter;
import android.widget.ListView;
/**
* An adapter that returns the {@link Preference} contained in this group.
* In most cases, this adapter should be the base class for any custom
* adapters from {@link Preference#getAdapter()}.
* <p>
* This adapter obeys the
* {@link Preference}'s adapter rule (the
* {@link Adapter#getView(int, View, ViewGroup)} should be used instead of
* {@link Preference#getView(ViewGroup)} if a {@link Preference} has an
* adapter via {@link Preference#getAdapter()}).
* <p>
* This adapter also propagates data change/invalidated notifications upward.
* <p>
* This adapter does not include this {@link PreferenceGroup} in the returned
* adapter, use {@link PreferenceCategoryAdapter} instead.
*
* @see PreferenceCategoryAdapter
*/
class PreferenceGroupAdapter extends BaseAdapter implements OnPreferenceChangeInternalListener {
private static final String TAG = "PreferenceGroupAdapter";
/**
* The group that we are providing data from.
*/
private PreferenceGroup mPreferenceGroup;
/**
* Maps a position into this adapter -> {@link Preference}. These
* {@link Preference}s don't have to be direct children of this
* {@link PreferenceGroup}, they can be grand children or younger)
*/
private List<Preference> mPreferenceList;
/**
* List of unique Preference and its subclasses' names. This is used to find
* out how many types of views this adapter can return. Once the count is
* returned, this cannot be modified (since the ListView only checks the
* count once--when the adapter is being set). We will not recycle views for
* Preference subclasses seen after the count has been returned.
*/
private ArrayList<PreferenceLayout> mPreferenceLayouts;
private PreferenceLayout mTempPreferenceLayout = new PreferenceLayout();
/**
* Blocks the mPreferenceClassNames from being changed anymore.
*/
private boolean mHasReturnedViewTypeCount = false;
private volatile boolean mIsSyncing = false;
private Handler mHandler = new Handler();
private Runnable mSyncRunnable = new Runnable() {
public void run() {
syncMyPreferences();
}
};
private static class PreferenceLayout implements Comparable<PreferenceLayout> {
private int resId;
private int widgetResId;
private String name;
public int compareTo(PreferenceLayout other) {
int compareNames = name.compareTo(other.name);
if (compareNames == 0) {
if (resId == other.resId) {
if (widgetResId == other.widgetResId) {
return 0;
} else {
return widgetResId - other.widgetResId;
}
} else {
return resId - other.resId;
}
} else {
return compareNames;
}
}
}
public PreferenceGroupAdapter(PreferenceGroup preferenceGroup) {
mPreferenceGroup = preferenceGroup;
// If this group gets or loses any children, let us know
mPreferenceGroup.setOnPreferenceChangeInternalListener(this);
mPreferenceList = new ArrayList<Preference>();
mPreferenceLayouts = new ArrayList<PreferenceLayout>();
syncMyPreferences();
}
private void syncMyPreferences() {
synchronized(this) {
if (mIsSyncing) {
return;
}
mIsSyncing = true;
}
List<Preference> newPreferenceList = new ArrayList<Preference>(mPreferenceList.size());
flattenPreferenceGroup(newPreferenceList, mPreferenceGroup);
mPreferenceList = newPreferenceList;
notifyDataSetChanged();
synchronized(this) {
mIsSyncing = false;
notifyAll();
}
}
private void flattenPreferenceGroup(List<Preference> preferences, PreferenceGroup group) {
// TODO: shouldn't always?
group.sortPreferences();
final int groupSize = group.getPreferenceCount();
for (int i = 0; i < groupSize; i++) {
final Preference preference = group.getPreference(i);
preferences.add(preference);
if (!mHasReturnedViewTypeCount && !preference.hasSpecifiedLayout()) {
addPreferenceClassName(preference);
}
if (preference instanceof PreferenceGroup) {
final PreferenceGroup preferenceAsGroup = (PreferenceGroup) preference;
if (preferenceAsGroup.isOnSameScreenAsChildren()) {
flattenPreferenceGroup(preferences, preferenceAsGroup);
}
}
preference.setOnPreferenceChangeInternalListener(this);
}
}
/**
* Creates a string that includes the preference name, layout id and widget layout id.
* If a particular preference type uses 2 different resources, they will be treated as
* different view types.
*/
private PreferenceLayout createPreferenceLayout(Preference preference, PreferenceLayout in) {
PreferenceLayout pl = in != null? in : new PreferenceLayout();
pl.name = preference.getClass().getName();
pl.resId = preference.getLayoutResource();
pl.widgetResId = preference.getWidgetLayoutResource();
return pl;
}
private void addPreferenceClassName(Preference preference) {
final PreferenceLayout pl = createPreferenceLayout(preference, null);
int insertPos = Collections.binarySearch(mPreferenceLayouts, pl);
// Only insert if it doesn't exist (when it is negative).
if (insertPos < 0) {
// Convert to insert index
insertPos = insertPos * -1 - 1;
mPreferenceLayouts.add(insertPos, pl);
}
}
public int getCount() {
return mPreferenceList.size();
}
public Preference getItem(int position) {
if (position < 0 || position >= getCount()) return null;
return mPreferenceList.get(position);
}
public long getItemId(int position) {
if (position < 0 || position >= getCount()) return ListView.INVALID_ROW_ID;
return this.getItem(position).getId();
}
public View getView(int position, View convertView, ViewGroup parent) {
final Preference preference = this.getItem(position);
// Build a PreferenceLayout to compare with known ones that are cacheable.
mTempPreferenceLayout = createPreferenceLayout(preference, mTempPreferenceLayout);
// If it's not one of the cached ones, set the convertView to null so that
// the layout gets re-created by the Preference.
if (Collections.binarySearch(mPreferenceLayouts, mTempPreferenceLayout) < 0) {
convertView = null;
}
return preference.getView(convertView, parent);
}
@Override
public boolean isEnabled(int position) {
if (position < 0 || position >= getCount()) return true;
return this.getItem(position).isSelectable();
}
@Override
public boolean areAllItemsEnabled() {
// There should always be a preference group, and these groups are always
// disabled
return false;
}
public void onPreferenceChange(Preference preference) {
notifyDataSetChanged();
}
public void onPreferenceHierarchyChange(Preference preference) {
mHandler.removeCallbacks(mSyncRunnable);
mHandler.post(mSyncRunnable);
}
@Override
public boolean hasStableIds() {
return true;
}
@Override
public int getItemViewType(int position) {
if (!mHasReturnedViewTypeCount) {
mHasReturnedViewTypeCount = true;
}
final Preference preference = this.getItem(position);
if (preference.hasSpecifiedLayout()) {
return IGNORE_ITEM_VIEW_TYPE;
}
mTempPreferenceLayout = createPreferenceLayout(preference, mTempPreferenceLayout);
int viewType = Collections.binarySearch(mPreferenceLayouts, mTempPreferenceLayout);
if (viewType < 0) {
// This is a class that was seen after we returned the count, so
// don't recycle it.
return IGNORE_ITEM_VIEW_TYPE;
} else {
return viewType;
}
}
@Override
public int getViewTypeCount() {
if (!mHasReturnedViewTypeCount) {
mHasReturnedViewTypeCount = true;
}
return Math.max(1, mPreferenceLayouts.size());
}
}
它的getView里掉的是Preference的getView。Preference类似于View,是所有相关UI类的基类。以下是和UI相关的重要代码。
public View getView(View convertView, ViewGroup parent) {
if (convertView == null) {
convertView = onCreateView(parent);
}
onBindView(convertView);
return convertView;
}
protected View onCreateView(ViewGroup parent) {
final LayoutInflater layoutInflater =
(LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
final View layout = layoutInflater.inflate(mLayoutResId, parent, false);
final ViewGroup widgetFrame = (ViewGroup) layout
.findViewById(com.android.internal.R.id.widget_frame);
if (widgetFrame != null) {
if (mWidgetLayoutResId != 0) {
layoutInflater.inflate(mWidgetLayoutResId, widgetFrame);
} else {
widgetFrame.setVisibility(View.GONE);
}
}
return layout;
}
所以基本上每个Preference UI控件最多和mLayoutResId和mWidgetLayoutResId相关。
首先查找它们的布局，比如PreferenceCategory,attr为com.android.internal.R.attr.preferenceCategoryStyle，
对应主题中的style为<item name="preferenceCategoryStyle">@android:style/Preference.Category</item>。
<style name="Preference.Category"> <item name="android:layout">@android:layout/preference_category</item> <!-- The title should not dim if the category is disabled, instead only the preference children should dim. --> <item name="android:shouldDisableView">false</item> <item name="android:selectable">false</item> </style>
如下列出所有的attr： <declare-styleable name="Theme"> ...... <attr name="preferenceScreenStyle" format="reference"/> <!-- Default style for PreferenceCategory. --> <attr name="preferenceCategoryStyle" format="reference"/> <!-- Default style for Preference. --> <attr name="preferenceStyle" format="reference"/> <!-- Default style for informational Preference. --> <attr name="preferenceInformationStyle" format="reference"/> <!-- Default style for CheckBoxPreference. --> <attr name="checkBoxPreferenceStyle" format="reference"/> <!-- Default style for YesNoPreference. --> <attr name="yesNoPreferenceStyle" format="reference"/> <!-- Default style for DialogPreference. --> <attr name="dialogPreferenceStyle" format="reference"/> <!-- Default style for EditTextPreference. --> <attr name="editTextPreferenceStyle" format="reference"/> <!-- Default style for RingtonePreference. --> <attr name="ringtonePreferenceStyle" format="reference"/> <!-- The preference layout that has the child/tabbed effect. --> <attr name="preferenceLayoutChild" format="reference"/> </declare-styleable> 对应的style为: <style name="Theme"> ...... <!-- Preference styles --> <item name="preferenceScreenStyle">@android:style/Preference.PreferenceScreen</item> <item name="preferenceCategoryStyle">@android:style/Preference.Category</item> <item name="preferenceStyle">@android:style/Preference</item> <item name="preferenceInformationStyle">@android:style/Preference.Information</item> <item name="checkBoxPreferenceStyle">@android:style/Preference.CheckBoxPreference</item> <item name="yesNoPreferenceStyle">@android:style/Preference.DialogPreference.YesNoPreference</item> <item name="dialogPreferenceStyle">@android:style/Preference.DialogPreference</item> <item name="editTextPreferenceStyle">@android:style/Preference.DialogPreference.EditTextPreference</item> <item name="ringtonePreferenceStyle">@android:style/Preference.RingtonePreference</item> <item name="preferenceLayoutChild">@android:layout/preference_child</item> </style>
我没搞清楚的是这个style是在什么地方设进去的。所以如果要修改PreferenceCategory的UI，只需从系统源码中拷贝出这个布局XML，修改它的title的id:@+android:id/title为@android:id/title,同时
<PreferenceCategory
android:layout="@layout/preference_category"
android:title="你好1" >
由于PreferenceCategory是直接加载preference_category的，所以替换了默认的preference.xml，所以就算你配上android:widgetLayout也没用。
修改CheckBoxPreference的UI需要:layout->preference.xml widgetLayout->preference_widget_checkbox.xml,同时修改id。
拿到布局文件后，字体，字体大小，颜色等布局元素你想怎么弄就怎么弄了。
需要注意的是，如果你想要保存那写选中的数据，必须要对preference UI 控件设置key。因为保存XML时候必须要有key。
