揭秘uc浏览器三

这节我们主要讨论收藏与历史记录页面的边边角角。

首先，看看他的最终的效果图了：

照例了，我们先看看他的布局文件：

 1 <!-- tab布局文件 --> 2 <TabHost xmlns:android="http://schemas.android.com/apk/res/android" 3     android:id="@android:id/tabhost" 4     android:layout_width="fill_parent" 5     android:layout_height="fill_parent"> 6     <LinearLayout 7         android:orientation="vertical" 8         android:layout_width="fill_parent" 9         android:layout_height="fill_parent"10         android:padding="5dp">11         <TabWidget12             android:id="@android:id/tabs"13             android:layout_width="fill_parent"14             android:layout_height="wrap_content" />15         <!-- 相应桢布局 -->16         <FrameLayout17             android:id="@android:id/tabcontent"18             android:layout_width="fill_parent"19             android:layout_height="fill_parent"20             android:padding="5dp" />21     </LinearLayout>22 </TabHost>

相应的布局文件说明如下：

别开这是一个布局文件其实涉及另外两个布局文件，相应布局文件是左右两边布局文件。他两个布局文件源代码又是怎么样了？一个是书签页面的布局文件，一个是历史记录的布局文件。但是布局文件共拥有一个布局文件。

相应源代码如下：

 1 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 2     android:layout_width="fill_parent" 3     android:layout_height="fill_parent"> 4     <!-- list 控件 --> 5     <ListView  6           android:id="@+id/BookmarksListActivity.List" 7         android:layout_width="fill_parent" 8         android:layout_height="fill_parent"/> 9         <!-- 文本控件 -->10   <TextView android:id="@+id/BookmarksListActivity.EmptyTextView"11         android:layout_width="fill_parent"12         android:layout_height="wrap_content"13         android:gravity="center_horizontal"14         android:layout_gravity="center_vertical"15         android:text="@string/BookmarksListActivity.Empty"/>16 17 </LinearLayout>

一个list控件加一个文本控件就ok了。

布局文件，一直都不是android工程中重头戏。java文件又是什么样子了？

我们来看看他所涉及的相应的java文件。

首先，我们看一下书签历史记录页面的java 源代码，他在这里的控制作用也只有一种抛砖引玉的作用了.

 1 /** 2  * 这是一个historyactivity 3  */ 4 public class BookmarksHistoryActivity extends TabActivity { 5  6     /** 7      * 创建的方法 8      */ 9     @Override10     protected void onCreate(Bundle savedInstanceState) {        11         super.onCreate(savedInstanceState);12         13         if (Controller.getInstance().getPreferences().getBoolean(Constants.PREFERENCES_SHOW_FULL_SCREEN, false)) {            14             getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);15         }16         17         if (Controller.getInstance().getPreferences().getBoolean(Constants.PREFERENCES_GENERAL_HIDE_TITLE_BARS, true)) {18             requestWindowFeature(Window.FEATURE_NO_TITLE);19         }20         21         setContentView(R.layout.bookmarks_history_activity);22         23         setTitle(R.string.BookmarksListActivity_Title);24         25         Resources res = getResources();26         TabHost tabHost = getTabHost();27         TabHost.TabSpec spec;28         Intent intent;29         30         // Bookmarks31         intent = new Intent().setClass(this, BookmarksListActivity.class);32         33         spec = tabHost.newTabSpec("bookmarks").setIndicator(res.getString(R.string.Main_MenuShowBookmarks),34                 res.getDrawable(R.drawable.ic_tab_bookmarks))35                 .setContent(intent);36         tabHost.addTab(spec);37         38         // History39         intent = new Intent().setClass(this, HistoryListActivity.class);40 41         spec = tabHost.newTabSpec("history").setIndicator(res.getString(R.string.Main_MenuShowHistory),42                 res.getDrawable(R.drawable.ic_tab_history))43                 .setContent(intent);44         tabHost.addTab(spec);45 46         if (PreferenceManager.getDefaultSharedPreferences(this).getBoolean(Constants.PREFERENCE_USE_WEAVE, false)) {47             // Weave bookmarks48             intent = new Intent().setClass(this, WeaveBookmarksListActivity.class);49 50             spec = tabHost.newTabSpec("weave").setIndicator(res.getString(R.string.WeaveBookmarksListActivity_Title),51                     res.getDrawable(R.drawable.ic_tab_weave))52                     .setContent(intent);53             tabHost.addTab(spec);54         }55         56         tabHost.setCurrentTab(0);57         58         tabHost.setOnTabChangedListener(new OnTabChangeListener() {            59             @Override60             public void onTabChanged(String tabId) {61                 if (tabId.equals("bookmarks")) {62                     setTitle(R.string.BookmarksListActivity_Title);63                 } else if (tabId.equals("history")) {64                     setTitle(R.string.HistoryListActivity_Title);65                 } else if (tabId.equals("weave")) {66                     setTitle(R.string.WeaveBookmarksListActivity_Title);67                 } else {68                     setTitle(R.string.ApplicationName);69                 }70             }71         });72     }73     74     /**75      * 配置文件改变的方法76      */77     @Override78     public void onConfigurationChanged(Configuration newConfig) {79         super.onConfigurationChanged(newConfig);80     }81 }

我们可以总结出来以下几个结果：

①在oncreate这个方法中，能否全频，能否有标题，这些设置的配置的参数就是存在与preference这个参数中的，可以sharedpreference这个对象保存配置参数，这也是android官方推荐的一种方式。

②一看这个布局的方式，这是一个典型tab布局，因此我们要实例化相应tabhost文件，并且为相应tabhost赋值事件，进入不同的intent，并且进入不同的界面后，赋值相应的标题。

③将相应的配置文件改变以后的，父类的配置文件也进行相应的改变。

由于要跳往不同的界面，所以就需要两个文件控制。

首先看一下BookmarksListActivity中的控制文件，相应的源代码如下：

  1 public class BookmarksListActivity extends Activity {  2               3     private static final int MENU_ADD_BOOKMARK = Menu.FIRST;  4     private static final int MENU_SORT_MODE = Menu.FIRST + 1;  5       6     private static final int MENU_OPEN_IN_TAB = Menu.FIRST + 10;      7     private static final int MENU_COPY_URL = Menu.FIRST + 11;  8     private static final int MENU_SHARE = Menu.FIRST + 12;  9     private static final int MENU_EDIT_BOOKMARK = Menu.FIRST + 13; 10     private static final int MENU_DELETE_BOOKMARK = Menu.FIRST + 14; 11      12     private static final int ACTIVITY_ADD_BOOKMARK = 0; 13     private static final int ACTIVITY_EDIT_BOOKMARK = 1; 14      15     private Cursor mCursor; 16     private BookmarksCursorAdapter mCursorAdapter; 17      18     private ListView mList; 19      20     @Override 21     public void onCreate(Bundle savedInstanceState) { 22         super.onCreate(savedInstanceState); 23         setContentView(R.layout.bookmarks_list_activity); 24          25         setTitle(R.string.BookmarksListActivity_Title); 26          27         View emptyView = findViewById(R.id.BookmarksListActivity_EmptyTextView); 28         mList = (ListView) findViewById(R.id.BookmarksListActivity_List); 29          30         mList.setEmptyView(emptyView); 31          32         mList.setOnItemClickListener(new OnItemClickListener() { 33  34             @Override 35             public void onItemClick(AdapterView<?> l, View v, int position, long id) { 36                 Intent result = new Intent(); 37                 result.putExtra(Constants.EXTRA_ID_NEW_TAB, false); 38                  39                 BookmarkItem item = BookmarksProviderWrapper.getStockBookmarkById(getContentResolver(), id); 40                 if (item != null) { 41                     result.putExtra(Constants.EXTRA_ID_URL,  item.getUrl()); 42                 } else { 43                     result.putExtra(Constants.EXTRA_ID_URL, 44                             PreferenceManager.getDefaultSharedPreferences(BookmarksListActivity.this).getString(Constants.PREFERENCES_GENERAL_HOME_PAGE, Constants.URL_ABOUT_START)); 45                 } 46                  47                 if (getParent() != null) { 48                     getParent().setResult(RESULT_OK, result); 49                 } else { 50                     setResult(RESULT_OK, result); 51                 } 52                  53                 finish(); 54             } 55         }); 56  57         registerForContextMenu(mList); 58          59         fillData(); 60     } 61      62     @Override 63     protected void onDestroy() { 64         mCursor.close(); 65         super.onDestroy(); 66     } 67  68     /** 69      * Fill the bookmark to the list UI.  70      */ 71     private void fillData() { 72         mCursor = BookmarksProviderWrapper.getStockBookmarks(getContentResolver(), 73                 PreferenceManager.getDefaultSharedPreferences(this).getInt(Constants.PREFERENCES_BOOKMARKS_SORT_MODE, 0)); 74         startManagingCursor(mCursor); 75          76         String[] from = new String[] { Browser.BookmarkColumns.TITLE, Browser.BookmarkColumns.URL}; 77         int[] to = new int[] {R.id.BookmarkRow_Title, R.id.BookmarkRow_Url}; 78          79         mCursorAdapter = new BookmarksCursorAdapter(this, 80                 R.layout.bookmark_row, 81                 mCursor, 82                 from, 83                 to, 84                 ApplicationUtils.getFaviconSizeForBookmarks(this)); 85          86         mList.setAdapter(mCursorAdapter); 87          88         setAnimation(); 89     } 90      91     /** 92      * Set the list loading animation. 93      */ 94     private void setAnimation() { 95         AnimationSet set = new AnimationSet(true); 96  97         Animation animation = new AlphaAnimation(0.0f, 1.0f); 98         animation.setDuration(100); 99         set.addAnimation(animation);100 101         animation = new TranslateAnimation(102             Animation.RELATIVE_TO_SELF, 0.0f, Animation.RELATIVE_TO_SELF, 0.0f,103             Animation.RELATIVE_TO_SELF, -1.0f, Animation.RELATIVE_TO_SELF, 0.0f104         );105         animation.setDuration(100);106         set.addAnimation(animation);107 108         LayoutAnimationController controller =109                 new LayoutAnimationController(set, 0.5f);110 111         mList.setLayoutAnimation(controller);112     }113     114     /**115      * Display the add bookmark dialog.116      */117     private void openAddBookmarkDialog() {118         Intent i = new Intent(this, EditBookmarkActivity.class);119         120         i.putExtra(Constants.EXTRA_ID_BOOKMARK_ID, (long) -1);121         i.putExtra(Constants.EXTRA_ID_BOOKMARK_TITLE, "");122         i.putExtra(Constants.EXTRA_ID_BOOKMARK_URL, "");123         124         startActivityForResult(i, ACTIVITY_ADD_BOOKMARK);125     }126     127     @Override128     public boolean onCreateOptionsMenu(Menu menu) {129         super.onCreateOptionsMenu(menu);130         131         MenuItem item;132         item = menu.add(0, MENU_ADD_BOOKMARK, 0, R.string.BookmarksListActivity_MenuAddBookmark);133         item.setIcon(R.drawable.ic_menu_add_bookmark);134         135         item = menu.add(0, MENU_SORT_MODE, 0, R.string.BookmarksListActivity_MenuSortMode);136         item.setIcon(R.drawable.ic_menu_sort);                137         138         return true;139     }140     141     @Override142     public boolean onMenuItemSelected(int featureId, MenuItem item) {143         144         switch(item.getItemId()) {145         case MENU_SORT_MODE:146             changeSortMode();147             return true;148             149         case MENU_ADD_BOOKMARK:            150             openAddBookmarkDialog();151             return true;152             153         default: return super.onMenuItemSelected(featureId, item);154         }155     }156     157     @Override158     public void onCreateContextMenu(ContextMenu menu, View v, ContextMenuInfo menuInfo) {159         super.onCreateContextMenu(menu, v, menuInfo);160         161         long id = ((AdapterContextMenuInfo) menuInfo).id;162         if (id != -1) {163             BookmarkItem item = BookmarksProviderWrapper.getStockBookmarkById(getContentResolver(), id);164             if (item != null) {165                 menu.setHeaderTitle(item.getTitle());166             }167         }168         169         menu.add(0, MENU_OPEN_IN_TAB, 0, R.string.BookmarksListActivity_MenuOpenInTab);        170         menu.add(0, MENU_COPY_URL, 0, R.string.BookmarksHistoryActivity_MenuCopyLinkUrl);171         menu.add(0, MENU_SHARE, 0, R.string.Main_MenuShareLinkUrl);172         menu.add(0, MENU_EDIT_BOOKMARK, 0, R.string.BookmarksListActivity_MenuEditBookmark);173         menu.add(0, MENU_DELETE_BOOKMARK, 0, R.string.BookmarksListActivity_MenuDeleteBookmark);174     }175     176     @Override177     public boolean onContextItemSelected(MenuItem item) {178         AdapterContextMenuInfo info = (AdapterContextMenuInfo) item.getMenuInfo();179                 180         Intent i;181         BookmarkItem bookmarkItem = BookmarksProviderWrapper.getStockBookmarkById(getContentResolver(), info.id);182         183         switch (item.getItemId()) {184         case MENU_OPEN_IN_TAB:        185             i = new Intent();186             i.putExtra(Constants.EXTRA_ID_NEW_TAB, true);187             188             if (bookmarkItem != null) {189                 i.putExtra(Constants.EXTRA_ID_URL,  bookmarkItem.getUrl());190             } else {191                 i.putExtra(Constants.EXTRA_ID_URL,192                         PreferenceManager.getDefaultSharedPreferences(BookmarksListActivity.this).getString(Constants.PREFERENCES_GENERAL_HOME_PAGE, Constants.URL_ABOUT_START));193             }194             195             if (getParent() != null) {196                 getParent().setResult(RESULT_OK, i);197             } else {198                 setResult(RESULT_OK, i);            199             }200             201             finish();202             return true;203             204         case MENU_EDIT_BOOKMARK:            205             if (bookmarkItem != null) {206                 i = new Intent(this, EditBookmarkActivity.class);207                 i.putExtra(Constants.EXTRA_ID_BOOKMARK_ID, info.id);208                 i.putExtra(Constants.EXTRA_ID_BOOKMARK_TITLE, bookmarkItem.getTitle());209                 i.putExtra(Constants.EXTRA_ID_BOOKMARK_URL, bookmarkItem.getUrl());210 211                 startActivityForResult(i, ACTIVITY_EDIT_BOOKMARK);212             }213             return true;214             215         case MENU_COPY_URL:216             if (bookmarkItem != null) {217                 ApplicationUtils.copyTextToClipboard(this,  bookmarkItem.getUrl(), getString(R.string.Commons_UrlCopyToastMessage));218             }219             return true;220             221         case MENU_SHARE:222             if (bookmarkItem != null) {223                 ApplicationUtils.sharePage(this, bookmarkItem.getTitle(), bookmarkItem.getUrl());224             }225             return true;226             227         case MENU_DELETE_BOOKMARK:228             //mDbAdapter.deleteBookmark(info.id);229             BookmarksProviderWrapper.deleteStockBookmark(getContentResolver(), info.id);230             fillData();231             return true;232         default: return super.onContextItemSelected(item);233         }234     }235     236     /**237      * Change list sort mode. Update list.238      * @param sortMode The new sort mode.239      */240     private void doChangeSortMode(int sortMode) {241         Editor editor = PreferenceManager.getDefaultSharedPreferences(this).edit();242         editor.putInt(Constants.PREFERENCES_BOOKMARKS_SORT_MODE, sortMode);243         editor.commit();244         245         fillData();246     }247     248     /**249      * Show a dialog for choosing the sort mode.250      * Perform the change if required.251      */252     private void changeSortMode() {253         254         int currentSort = PreferenceManager.getDefaultSharedPreferences(this).getInt(Constants.PREFERENCES_BOOKMARKS_SORT_MODE, 0);255         256         AlertDialog.Builder builder = new AlertDialog.Builder(this);257         builder.setInverseBackgroundForced(true);258         builder.setIcon(android.R.drawable.ic_dialog_info);259         builder.setTitle(getResources().getString(R.string.BookmarksListActivity_MenuSortMode));260         builder.setSingleChoiceItems(new String[] {getResources().getString(R.string.BookmarksListActivity_MostUsedSortMode),261                 getResources().getString(R.string.BookmarksListActivity_AlphaSortMode),262                 getResources().getString(R.string.BookmarksListActivity_RecentSortMode) },263                 currentSort,264                 new OnClickListener() {265             @Override266             public void onClick(DialogInterface dialog, int which) {267                 doChangeSortMode(which);268                 dialog.dismiss();                269             }            270         }); 271         builder.setCancelable(true);272         builder.setNegativeButton(R.string.Commons_Cancel, null);273         274         AlertDialog alert = builder.create();275         alert.show();276     }277     278     @Override279     protected void onActivityResult(int requestCode, int resultCode, Intent intent) {280         super.onActivityResult(requestCode, resultCode, intent);281         282         switch (requestCode) {283         case ACTIVITY_EDIT_BOOKMARK:284             if (resultCode == RESULT_OK) {285                 fillData();286             }287             break;288         case ACTIVITY_ADD_BOOKMARK:289             if (resultCode == RESULT_OK) {290                 fillData();291             }292             break;293             294         default:295             break;296         }297     }298 299 }

①同理在oncreate方法，实例化相应的listview，把从ContentResolver取得的网址信息，添加到相应的listview中去，并且为listview赋值与每项目的点击事件，每项的点击跳转到相应的界面上去。同时结束当前的界面。

②在方法中实现数据的填充，同时还为列表绑定上下文菜单。

③程序也是一环扣一环的，那么这个fillData方法是加载数据的方法，又是如何实现的了，把数据库存标签的数据按照一定方式（分页的方式）读取出来，并且加载到相应的列表上去。这个加载数据的过程中有一个淡入淡出动画的效果。

④你要添加这个标签对话框也是在此界面上完成这个功能的，我们用了回调结果intent来跳转到相应编辑标签的界面，编辑标签以后，在到回调结果方法中重新进行相应数据的重新初始化。

⑤这个文件大量的篇幅用于一些上下文菜单的处理，分别对相应在tab打开网页菜单，编辑标签的菜单，复制URL的菜单，分享的菜单，删除菜单的事件做一个处理。

接下来，是一个HistoryListActivity源代码控制文件的解析。源代码如下：

/** * history list activity. */public class HistoryListActivity extends ExpandableListActivity {        private static final int MENU_CLEAR_HISTORY = Menu.FIRST;        private static final int MENU_OPEN_IN_TAB = Menu.FIRST + 10;    private static final int MENU_COPY_URL = Menu.FIRST + 11;    private static final int MENU_SHARE = Menu.FIRST + 12;    private static final int MENU_DELETE_FROM_HISTORY = Menu.FIRST + 13;        private ExpandableListAdapter mAdapter;        private ProgressDialog mProgressDialog;        private OnCheckedChangeListener mBookmarkStarChangeListener;        @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);                setTitle(R.string.HistoryListActivity_Title);                registerForContextMenu(getExpandableListView());                mBookmarkStarChangeListener = new OnCheckedChangeListener() {                        @Override            public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {                                                long id = (Long) buttonView.getTag();                BookmarksProviderWrapper.toggleBookmark(getContentResolver(), id, isChecked);                                if (isChecked) {                    Toast.makeText(HistoryListActivity.this, R.string.HistoryListActivity_BookmarkAdded, Toast.LENGTH_SHORT).show();                } else {                    Toast.makeText(HistoryListActivity.this, R.string.HistoryListActivity_BookmarkRemoved, Toast.LENGTH_SHORT).show();                }            }        };                fillData();    }    /**     * Fill the history list.     */    private void fillData() {        Cursor c = BookmarksProviderWrapper.getStockHistory(getContentResolver());                mAdapter = new HistoryExpandableListAdapter(                this,                mBookmarkStarChangeListener,                c,                c.getColumnIndex(Browser.BookmarkColumns.DATE),                ApplicationUtils.getFaviconSizeForBookmarks(this));                setListAdapter(mAdapter);                if (getExpandableListAdapter().getGroupCount() > 0) {            getExpandableListView().expandGroup(0);        }    }        @Override    public void onCreateContextMenu(ContextMenu menu, View v, ContextMenuInfo menuInfo) {        super.onCreateContextMenu(menu, v, menuInfo);                ExpandableListView.ExpandableListContextMenuInfo info =            (ExpandableListView.ExpandableListContextMenuInfo) menuInfo;        int type = ExpandableListView.getPackedPositionType(info.packedPosition);        int group = ExpandableListView.getPackedPositionGroup(info.packedPosition);        int child =    ExpandableListView.getPackedPositionChild(info.packedPosition);                if (type == ExpandableListView.PACKED_POSITION_TYPE_CHILD) {                        HistoryItem item = (HistoryItem) getExpandableListAdapter().getChild(group, child);            menu.setHeaderTitle(item.getTitle());                        menu.add(0, MENU_OPEN_IN_TAB, 0, R.string.HistoryListActivity_MenuOpenInTab);            menu.add(0, MENU_COPY_URL, 0, R.string.BookmarksHistoryActivity_MenuCopyLinkUrl);            menu.add(0, MENU_SHARE, 0, R.string.Main_MenuShareLinkUrl);            menu.add(0, MENU_DELETE_FROM_HISTORY, 0, R.string.HistoryListActivity_MenuDelete);        }    }        @Override    public boolean onContextItemSelected(MenuItem menuItem) {        ExpandableListContextMenuInfo info = (ExpandableListContextMenuInfo) menuItem.getMenuInfo();                int type = ExpandableListView.getPackedPositionType(info.packedPosition);                if (type == ExpandableListView.PACKED_POSITION_TYPE_CHILD) {            int group = ExpandableListView.getPackedPositionGroup(info.packedPosition);            int child =    ExpandableListView.getPackedPositionChild(info.packedPosition);                        HistoryItem item = (HistoryItem) getExpandableListAdapter().getChild(group, child);                        switch (menuItem.getItemId()) {            case MENU_OPEN_IN_TAB:                doNavigateToUrl(item.getUrl(), true);                break;            case MENU_COPY_URL:                ApplicationUtils.copyTextToClipboard(this, item.getUrl(), getString(R.string.Commons_UrlCopyToastMessage));                break;            case MENU_SHARE:                ApplicationUtils.sharePage(this, item.getTitle(), item.getUrl());                break;            case MENU_DELETE_FROM_HISTORY:                BookmarksProviderWrapper.deleteHistoryRecord(getContentResolver(), item.getId());                fillData();                break;            default:                break;            }        }                return super.onContextItemSelected(menuItem);    }        @Override    public boolean onCreateOptionsMenu(Menu menu) {        super.onCreateOptionsMenu(menu);                MenuItem item;        item = menu.add(0, MENU_CLEAR_HISTORY, 0, R.string.Commons_ClearHistory);        item.setIcon(R.drawable.ic_menu_delete);                return true;    }        @Override    public boolean onMenuItemSelected(int featureId, MenuItem item) {                switch(item.getItemId()) {        case MENU_CLEAR_HISTORY:            clearHistory();            return true;        default: return super.onMenuItemSelected(featureId, item);        }    }        @Override    public boolean onChildClick(ExpandableListView parent, View v,    int groupPosition, int childPosition, long id) {        HistoryItem item = (HistoryItem) getExpandableListAdapter().getChild(groupPosition, childPosition);        doNavigateToUrl(item.getUrl(), false);                return super.onChildClick(parent, v, groupPosition, childPosition, id);    }        /**     * Load the given url.     * @param url The url.     * @param newTab If True, will open a new tab. If False, the current tab is used.     */    private void doNavigateToUrl(String url, boolean newTab) {        Intent result = new Intent();        result.putExtra(Constants.EXTRA_ID_NEW_TAB, newTab);        result.putExtra(Constants.EXTRA_ID_URL,  url);                if (getParent() != null) {            getParent().setResult(RESULT_OK, result);        } else {            setResult(RESULT_OK, result);        }        finish();    }    /**     * Clear history.     */    private void doClearHistory() {        mProgressDialog = ProgressDialog.show(this,                this.getResources().getString(R.string.Commons_PleaseWait),                this.getResources().getString(R.string.Commons_ClearingHistory));                new HistoryClearer();    }        /**     * Display confirmation and clear history.     */    private void clearHistory() {        ApplicationUtils.showYesNoDialog(this,                android.R.drawable.ic_dialog_alert,                R.string.Commons_ClearHistory,                R.string.Commons_NoUndoMessage,                new DialogInterface.OnClickListener() {                    @Override                    public void onClick(DialogInterface dialog, int which) {                        dialog.dismiss();                        doClearHistory();                    }                    });    }        /**     * Runnable to clear history.     */    private class HistoryClearer implements Runnable {        /**         * Constructor.         */        public HistoryClearer() {            new Thread(this).start();        }        @Override        public void run() {            BookmarksProviderWrapper.clearHistoryAndOrBookmarks(getContentResolver(), true, false);                        for (CustomWebView webView : Controller.getInstance().getWebViewList()) {                webView.clearHistory();            }                        handler.sendEmptyMessage(0);        }        private Handler handler = new Handler() {            public void handleMessage(Message msg) {                mProgressDialog.dismiss();                fillData();            }        };    }    }

观察相应的源代码了，我们可想而知其大体与标签列表界面的大体一样，上面说过方法就不做过多的赘述了，这里我们只需要阐述了为什么要HistoryClearer这个开启线程来清空历史记录。首先原因有二：

①由于打开网页是很多很多，这里面数据还是很多很多。

②正视由于数据量大，这是一个耗时操作，如果放在一个ui线程中势必会造成页面假使，极大的影响了用户体验。开启一个线程，使其在回调后，更新界面，符合提升用户体验的原则。

我们再这里可以得出来这样android开发的原则：凡是耗时操作，应该开启多线程，再相应线程回调完成后再更新界面。

这就是我对标签记录页面总结，和一点点总结。

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