Android6.0 源码修改之Setting列表配置项动态添加和静态添加

写在前面

最近客户有个需求，要求增加操作Setting列表配置项的功能，是不是一脸懵，没关系，一图胜千言，接下来就上图。诺，就是这么个意思。

 

原来的列表配置项

 

 

增加了单个配置项

 

 

增加了多个配置项
 

老铁们看懂了么，就是在原有的列表项中增加客户想要的项，来我给你们分析下，Setting是系统级APP，到时候直接打包进Room里这不用我多说吧。重点来了，如果你把这个功能写死了，那么恭喜你，准备迎接一波又一波的系统打包发更新版本吧。客户今天加个列表项，明天减个列表项啥的，不很正常么(虽然你的内心是一万只奔腾在草原)，但还是得乖乖去打升级包。

那么，今天老司机就来带你解决这一烦恼，坐稳了，要发车了。

进入正题

先说下我的思路，广播是个好东西（系统App和其它App直接交换数据或者执行命令什么的，大有用处），快拿小本本记下来，假设要增加单条配置项，广播无疑是首选项，增加和删除都很方便，如果要增加多条配置项，广播就不再适用了，当然你也可以构造复杂的数据集合，通过广播来传递解析也是可以的。

多条配置项，我们将采用xml文件配置的方式(别问我怎么想到的，看了Setting的源码你就知道了)，和系统设置一样的节点名称，方便解析和理解。

 

先献上我的分析过程图(精华都在图里了)

之前说过Hierarchy View是个好扳手，这一次我们依旧使用它来定位Setting的布局文件，搜索过程图我就不贴了，最终根据id我们定位到
settings_main_dashboard.xml 布局，长这样

通过查找布局文件的引用，接下来我们跟到了SettingsActivity中

源码位置 packages\apps\Settings\src\com\android\settings\SettingsActivity.java

 @Override
protected void onCreate(Bundle savedState) {
    super.onCreate(savedState);
...
final ComponentName cn = intent.getComponent();
final String className = cn.getClassName();
//目前显示的就是设置的主界面，mIsShowingDashboard=true
mIsShowingDashboard = className.equals(Settings.class.getName());
...
//此处加载的就是刚刚的settings_main_dashboard布局
setContentView(mIsShowingDashboard ?
  R.layout.settings_main_dashboard : R.layout.settings_main_prefs);
//settings_main_dashboard布局中的mContent需要被替换填充
mContent = (ViewGroup) findViewById(R.id.main_content);
...
    if (!mIsShowingDashboard) {
        mDisplaySearch = false;
        // UP will be shown only if it is a sub settings
        if (mIsShortcut) {
            mDisplayHomeAsUpEnabled = isSubSettings;
        } else if (isSubSettings) {
            mDisplayHomeAsUpEnabled = true;
        } else {
            mDisplayHomeAsUpEnabled = false;
        }
        setTitleFromIntent(intent);

        Bundle initialArguments = intent.getBundleExtra(EXTRA_SHOW_FRAGMENT_ARGUMENTS);
        switchToFragment(initialFragmentName, initialArguments, true, false,
                mInitialTitleResId, mInitialTitle, false);
    } else {//进入这，通过switchToFragment方法替换
        // No UP affordance if we are displaying the main Dashboard
        mDisplayHomeAsUpEnabled = false;
        // Show Search affordance
        mDisplaySearch = true;
        mInitialTitleResId = R.string.dashboard_title;
        switchToFragment(DashboardSummary.class.getName(), null, false, false,
                mInitialTitleResId, mInitialTitle, false);
    }
...
}

接下来到switchToFragment方法中

private Fragment switchToFragment(String fragmentName, Bundle args, boolean validate,
        boolean addToBackStack, int titleResId, CharSequence title, boolean withTransition) {
    if (validate && !isValidFragment(fragmentName)) {
        throw new IllegalArgumentException("Invalid fragment for this activity: "
                + fragmentName);
    }
    Fragment f = Fragment.instantiate(this, fragmentName, args);
    FragmentTransaction transaction = getFragmentManager().beginTransaction();
    //通过DashboardSummary来替换id为main_content的FrameLayout
    transaction.replace(R.id.main_content, f);
    if (withTransition) {
        TransitionManager.beginDelayedTransition(mContent);
    }
    if (addToBackStack) {
        transaction.addToBackStack(SettingsActivity.BACK_STACK_PREFS);
    }
    if (titleResId > 0) {
        transaction.setBreadCrumbTitle(titleResId);
    } else if (title != null) {
        transaction.setBreadCrumbTitle(title);
    }
    transaction.commitAllowingStateLoss();
    getFragmentManager().executePendingTransactions();
    return f;
}

到这里我们找到了Setting主界面显示的真正内容是DashboardSummary这个类，跳到这个类，让我们来一探究竟

源码位置 packages\apps\Settings\src\com\android\settings\dashboard\DashboardSummary.java

首先看到onResume()方法中

@Override
public void onResume() {
    super.onResume();
    //方法名和UI相关，应该是我们要找的
    sendRebuildUI();
    //应用删除、改变、替换广播监听，猜想应该是和设置中应用项的内层有关
    final IntentFilter filter = new IntentFilter(Intent.ACTION_PACKAGE_ADDED);
    filter.addAction(Intent.ACTION_PACKAGE_REMOVED);
    filter.addAction(Intent.ACTION_PACKAGE_CHANGED);
    filter.addAction(Intent.ACTION_PACKAGE_REPLACED);
    filter.addDataScheme("package");
    getActivity().registerReceiver(mHomePackageReceiver, filter);
   
}

sendRebuildUI()方法通过Handler发送一个MSG_REBUILD_UI消息，找到消息接收地方

private Handler mHandler = new Handler() {
    @Override
    public void handleMessage(Message msg) {
        switch (msg.what) {
            case MSG_REBUILD_UI: {
                final Context context = getActivity();
                rebuildUI(context);
            } break;
        }
    }
};

private HomePackageReceiver mHomePackageReceiver = new HomePackageReceiver();
private class HomePackageReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        rebuildUI(context);
    }
}

不难发现，最终都调用了同一个方法rebuildUI()，肯定是这货无疑了。

private void rebuildUI(Context context) {
    if (!isAdded()) {
        Log.w(LOG_TAG, "Cannot build the DashboardSummary UI yet as the Fragment is not added");
        return;
    }

    long start = System.currentTimeMillis();
    final Resources res = getResources();
    //添加之前先移除所有原来的View
    mDashboard.removeAllViews();
    //通过SettingsActivity中的getDashboardCategories方法获取所有配置项
    List categories =
            ((SettingsActivity) context).getDashboardCategories(true);

    final int count = categories.size();
    Log.i(LOG_TAG, "new categories=" + count);
    //遍历配置项列表集合，逐个添加(这块可结合上面的分析图看比较容易理解一些)
    for (int n = 0; n < count; n++) {
        
        DashboardCategory category = categories.get(n);
        //categoryView整个大类，例如无线和网络、设备
        View categoryView = mLayoutInflater.inflate(R.layout.dashboard_category, mDashboard, false);
        //大类的标题文字，无线和网络
        TextView categoryLabel = (TextView) categoryView.findViewById(R.id.category_title);
        categoryLabel.setText(category.getTitle(res));
        
        ViewGroup categoryContent =
                (ViewGroup) categoryView.findViewById(R.id.category_content);
        
        final int tilesCount = category.getTilesCount();
        //大类中添加对应的小类，例如 WLAN、蓝牙、SIM卡
        for (int i = 0; i < tilesCount; i++) {
            DashboardTile tile = category.getTile(i);

            DashboardTileView tileView = new DashboardTileView(context);
            updateTileView(context, res, tile, tileView.getImageView(),
                    tileView.getTitleTextView(), tileView.getStatusTextView());

            tileView.setTile(tile);

            categoryContent.addView(tileView);
        }

        // Add the category
        mDashboard.addView(categoryView);
    }
    long delta = System.currentTimeMillis() - start;
    Log.d(LOG_TAG, "rebuildUI took: " + delta + " ms");
}

我们再回到SettingsActivity中的getDashboardCategories方法

public List getDashboardCategories(boolean forceRefresh) {
    if (forceRefresh || mCategories.size() == 0) {
        buildDashboardCategories(mCategories);
    }
    return mCategories;
}

实际调用buildDashboardCategories()方法，再来

/**
 * Called when the activity needs its list of categories/tiles built.
 *
 * @param categories The list in which to place the tiles categories.
 */
private void buildDashboardCategories(List categories) {
    categories.clear();
    //通过解析dashboard_categories.xml文件，添加到categories中
    loadCategoriesFromResource(R.xml.dashboard_categories, categories, this);
    updateTilesList(categories);
}

dashboard_categories.xml文件内容如下

源码位置 packages\apps\Settings\res\xml\dashboard_categories.xml

    
    
    
    
   .....





    
    
    ....


...

看完这个xml文件是不是有一种恍然大明白的感觉，那就对了，这就对应了Setting的主界面，看到注释Wifi和Bluetooth等，注意观察上面的xml，dashboard-category节点为一个大类，dashboard-tile节点为里面的一个小类，对应的属性id不用多说，title即显示的标题文字，fragment对应点击时跳转的页面，icon为标题文字左边对应的图标。

回到文章开头的需求，如果只是简单的增加项或者删除项，只需在dashboard_categories.xml中增加对应的节点或者删除对应的节点，然后你就可以编译查看效果，舒舒服服的下班了。

⑧特以后你可就不舒服了，于是我灵机一动，既然系统原来是通过解析dashboard_categories.xml所有配置项，每次在onResume()中重新addView(),那么我们可以在这里做手脚(快，夸我机智)，在解析系统dashboard_categories.xml得到的List 添加我们想添加的配置项。

我们可以仿照谷歌工程师的做法，同样解析客户提供的xml来动态增加配置项。既然是解析，就得固定模板，肯定是我们需要给客户提供xml模板，他们来修改就好啦。

接下来，我们来看下系统是如何解析dashboard_categories.xml的，回到loadCategoriesFromResource()

public static void loadCategoriesFromResource(int resid, List target,
        Context context) {
    XmlResourceParser parser = null;
    try {
        parser = context.getResources().getXml(resid);
        ...

        while ((type=parser.next()) != XmlPullParser.END_DOCUMENT
                && (type != XmlPullParser.END_TAG || parser.getDepth() > outerDepth)) {
            if (type == XmlPullParser.END_TAG || type == XmlPullParser.TEXT) {
                continue;
            }

            nodeName = parser.getName();
            //大类的配置节点
            if ("dashboard-category".equals(nodeName)) {
                //大类对应的bean
                DashboardCategory category = new DashboardCategory();

                TypedArray sa = context.obtainStyledAttributes(
                        attrs, com.android.internal.R.styleable.PreferenceHeader);
                //id赋值
                category.id = sa.getResourceId(
                        com.android.internal.R.styleable.PreferenceHeader_id,
                        (int)DashboardCategory.CAT_ID_UNDEFINED);

                TypedValue tv = sa.peekValue(
                        com.android.internal.R.styleable.PreferenceHeader_title);
                if (tv != null && tv.type == TypedValue.TYPE_STRING) {
                    if (tv.resourceId != 0) {
                        category.titleRes = tv.resourceId;
                    } else {
                        //title赋值
                        category.title = tv.string;
                    }
                }
                sa.recycle();
                sa = context.obtainStyledAttributes(attrs,
                        com.android.internal.R.styleable.Preference);
                tv = sa.peekValue(
                        com.android.internal.R.styleable.Preference_key);
                if (tv != null && tv.type == TypedValue.TYPE_STRING) {
                    if (tv.resourceId != 0) {
                        category.key = context.getString(tv.resourceId);
                    } else {
                        category.key = tv.string.toString();
                    }
                }
                sa.recycle();

                final int innerDepth = parser.getDepth();
                while ((type=parser.next()) != XmlPullParser.END_DOCUMENT
                        && (type != XmlPullParser.END_TAG || parser.getDepth() > innerDepth)) {
                    if (type == XmlPullParser.END_TAG || type == XmlPullParser.TEXT) {
                        continue;
                    }

                    String innerNodeName = parser.getName();
                    //大类中对应的小类
                    if (innerNodeName.equals("dashboard-tile")) {
                        //小类对应的bean
                        DashboardTile tile = new DashboardTile();

                        sa = context.obtainStyledAttributes(
                                attrs, com.android.internal.R.styleable.PreferenceHeader);
                        tile.id = sa.getResourceId(
                                com.android.internal.R.styleable.PreferenceHeader_id,
                                (int)TILE_ID_UNDEFINED);
                        tv = sa.peekValue(
                                com.android.internal.R.styleable.PreferenceHeader_title);
                        if (tv != null && tv.type == TypedValue.TYPE_STRING) {
                            if (tv.resourceId != 0) {
                                tile.titleRes = tv.resourceId;
                            } else {
                                //小类的title
                                tile.title = tv.string;
                            }
                        }
                        tv = sa.peekValue(
                                com.android.internal.R.styleable.PreferenceHeader_summary);
                        if (tv != null && tv.type == TypedValue.TYPE_STRING) {
                            if (tv.resourceId != 0) {
                                tile.summaryRes = tv.resourceId;
                            } else {
                                tile.summary = tv.string;
                            }
                        }
                        //小类的icon
                        tile.iconRes = sa.getResourceId(
                                com.android.internal.R.styleable.PreferenceHeader_icon, 0);
                        //小类的fragment
                        tile.fragment = sa.getString(
                                com.android.internal.R.styleable.PreferenceHeader_fragment);
                        sa.recycle();

                        ...

                        // Show the SIM Cards setting if there are more than 2 SIMs installed.
                        if(tile.id != R.id.sim_settings || Utils.showSimCardTile(context)){
                            category.addTile(tile);
                          ...
                }

                target.add(category);
            } else {
                XmlUtils.skipCurrentTag(parser);
            }
        }
        ...
}

从系统的解析方法中，我提取了重要的有用的节点进而简化了解析方法，代码如下(在DashboardSummary.java中新增)

XmlPullParser xmlPullParser;
XmlPullParserFactory xmlPullParserFactory;
FileInputStream fileInputStream;
private void loadCategoriesFromXml(List categories){
    String xmlPath = Environment.getExternalStorageDirectory().getAbsolutePath()
                        +"/Android/dashboard.xml";
    File file = new File(xmlPath);
    if (file.exists() && file.canRead()){
        try {
            xmlPullParserFactory = XmlPullParserFactory.newInstance();
            xmlPullParserFactory.setNamespaceAware(true);
            xmlPullParser = xmlPullParserFactory.newPullParser();
            fileInputStream = new FileInputStream(xmlPath);
            xmlPullParser.setInput(fileInputStream, "utf-8");

            int mEventType = xmlPullParser.getEventType();
            DashboardCategory category = null;
            DashboardTile tile = null;
            while (mEventType != XmlPullParser.END_DOCUMENT){
                switch (mEventType) {
                    case XmlPullParser.START_DOCUMENT:
                        break;
                    case XmlPullParser.START_TAG:
                        String name = xmlPullParser.getName();
                        if (name.equals("dashboard-category")){
                            category = new DashboardCategory();
                            category.title = xmlPullParser.getAttributeValue(null, "title");
                        }else if (name.equals("dashboard-tile")){
                            tile = new DashboardTile();
                        }else if (name.equals("title")){
                            tile.title = xmlPullParser.nextText();
                        }else if (name.equals("action")){
                            tile.intent = new Intent(xmlPullParser.nextText());
                        }
                        break;
                    case XmlPullParser.END_TAG:
                        String nameP = xmlPullParser.getName();
                        if (nameP.equals("dashboard-tile")){
                            tile.iconRes = R.drawable.ic_settings_meituan;
                            category.addTile(tile);
                        }else if (nameP.equals("dashboard-category")){
                            categories.add(category);
                        }
                        break;
                }
                mEventType = xmlPullParser.next();
            }
        } catch (Exception e) {
            throw new RuntimeException("Error parsing categories", e);
        }finally{
            if (fileInputStream != null){
                try{
                    fileInputStream.close();
                    xmlPullParserFactory = null;
                    xmlPullParser = null;
                }catch(Exception e){

                }
            }
        }
    }else {
         Log.i(LOG_TAG, ".dashboard.xml don't exists");
    }
}

对应的xml模板如下，到时候需要将dashboard.xml文件放置在SD卡的Android目录下

 
   
     
        
      com.android.settings.SCHEDULE_POWER_ON_OFF_SETTING 
      
     
        
      android.settings.ZEN_MODE_PRIORITY_SETTINGS 
      
     
        
      android.settings.DEVICE_INFO_SETTINGS 
     
    
   
     
        
      com.android1.settings.SCHEDULE_POWER_ON_OFF_SETTING 
     
   

好了，还差最后一步，在rebuildUI方法中增加我们自己的xml解析方法调用。

private void rebuildUI(Context context) {
    ...

    mDashboard.removeAllViews();

    List categories =
            ((SettingsActivity) context).getDashboardCategories(true);
    
    /////////////////////////////////
    List myCategories = new ArrayList();
    myCategories.clear();
    loadCategoriesFromXml(myCategories);
    for (int i = 0; i < myCategories.size(); i++) {
        categories.add(i, myCategories.get(i));
    }
    ///////////////////////////

    final int count = categories.size();
    Log.i(LOG_TAG, "new categories=" + count);
    for (int n = 0; n < count; n++) {
        ...
    }
}

干的漂亮，这样就实现了文章开头的效果。

---

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