PreferenceActivity UI 优化修改

 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()}. * 
 * 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()}). * 
 * This adapter also propagates data change/invalidated notifications upward. * 
 * 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         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           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             { 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               (); mPreferenceLayouts = new ArrayList                 (); syncMyPreferences(); } private void syncMyPreferences() { synchronized(this) { if (mIsSyncing) { return; } mIsSyncing = true; } List                   newPreferenceList = new ArrayList                     (mPreferenceList.size()); flattenPreferenceGroup(newPreferenceList, mPreferenceGroup); mPreferenceList = newPreferenceList; notifyDataSetChanged(); synchronized(this) { mIsSyncing = false; notifyAll(); } } private void flattenPreferenceGroup(List                       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

@android:style/Preference.Category
。

 如下列出所有的attr： 
 
   ...... 
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
  对应的style为: 

   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  

        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。