Android Settings開發之修改

原文鏈接：http://blog.csdn.net/wangjinyu501/article/details/22077803

下面是Seeings應用的截圖：

  可以看出這是很典型的使用了Fragment後的界面，設置裏面有WIFI、藍牙、顯示、存儲、應用等衆多功能。左邊的每一項，對應着右邊的一個設置界面，Fragment有四個子類：DialogFragment, ListFragment, PreferenceFragment, WebViewFragment。很明顯，Settings用的是PreferenceFragment。接着看一下Settings源碼package結構：

   主題部分的實現主要在com.android.settings下面，其他包主要是用於各自功能實現，所以重點說這個包下面的類。在AndroidManifest.xml文字中，看到程序入口是Settings類：

   打開Settings類，是繼承於PreferenceActivity：

   其他的繼承關係如下：PreferenceActivity --> ListActivity --> Activity。PreferenceActivity主要用於Settings，關於如何使用可以參考API（http://developer.android.com/reference/android/preference/PreferenceActivity.html）以及guide（http://developer.android.com/guide/topics/ui/settings.html）。和它相關聯的類有header、fragment、preference。每一個header就是左邊的一個選項條目，像藍牙、應用等，選擇之後右邊就會顯示對應的fragment（平板），然後fragment和preference聯繫在一起，組成了一個個設置項。一般在activity中設置佈局，用的是setContentView()，在PreferenceActivity中，是需要繼承onBuildHeaders(List)這個方法，

@Override
ublic void onBuildHeaders(List<Header> target) {
  loadHeadersFromResource(R.xml.preference_headers, target);

  去生成選項表，點擊選項表的一個條目，右邊顯示對應的Fragment，這就是很典型的header+fragment組合，所以如果想在Settings基礎之上添加條目的話，在這個方法裏面的xml文件中添加即可，然後對應上fragment。下面分析一下執行流程：

  首先進入onCreate(Bundle savedInstanceState)方法裏面，代碼如下：

@Override
    protected void onCreate(Bundle savedInstanceState) {
        if (getIntent().getBooleanExtra(EXTRA_CLEAR_UI_OPTIONS, false)) {
            getWindow().setUiOptions(0);
        }
        mAuthenticatorHelper = new AuthenticatorHelper();
        mAuthenticatorHelper.updateAuthDescriptions(this);
        mAuthenticatorHelper.onAccountsUpdated(this, null);
        mDevelopmentPreferences = getSharedPreferences(DevelopmentSettings.PREF_FILE,
                Context.MODE_PRIVATE);
        getMetaData();
        mInLocalHeaderSwitch = true;
        super.onCreate(savedInstanceState);
        mInLocalHeaderSwitch = false;
        if (!onIsHidingHeaders() && onIsMultiPane()) {
            highlightHeader(mTopLevelHeaderId);
            // Force the title so that it doesn't get overridden by a direct launch of
            // a specific settings screen.
            setTitle(R.string.settings_label);
        }
        // Retrieve any saved state
        if (savedInstanceState != null) {
            mCurrentHeader = savedInstanceState.getParcelable(SAVE_KEY_CURRENT_HEADER);
            mParentHeader = savedInstanceState.getParcelable(SAVE_KEY_PARENT_HEADER);
        }
        // If the current header was saved, switch to it
        if (savedInstanceState != null && mCurrentHeader != null) {
            //switchToHeaderLocal(mCurrentHeader);
            showBreadCrumbs(mCurrentHeader.title, null);
        }
        if (mParentHeader != null) {
            setParentTitle(mParentHeader.title, null, new OnClickListener() {
                public void onClick(View v) {
                    switchToParent(mParentHeader.fragment);
                }
            });
        }
        // Override up navigation for multi-pane, since we handle it in the fragment breadcrumbs
        if (onIsMultiPane()) {
            getActionBar().setDisplayHomeAsUpEnabled(false);
            getActionBar().setHomeButtonEnabled(false);
        }
    }

  第一個if用於設置window ui的對修改來說不用考慮了，意義不大，

mAuthenticatorHelper = new AuthenticatorHelper();
mAuthenticatorHelper.updateAuthDescriptions(this);
mAuthenticatorHelper.onAccountsUpdated(this, null);

  這個段代碼用於認證以及更新賬戶信息，接着往下看：

mDevelopmentPreferences = getSharedPreferences(DevelopmentSettings.PREF_FILE,Context.MODE_PRIVATE);

  用於之後保存數據，然後是getMetaData();這個方法，代碼如下：

private void getMetaData() {
        try {
            ActivityInfo ai = getPackageManager().getActivityInfo(getComponentName(),
                    PackageManager.GET_META_DATA);
            if (ai == null || ai.metaData == null) return;
            mTopLevelHeaderId = ai.metaData.getInt(META_DATA_KEY_HEADER_ID);
            mFragmentClass = ai.metaData.getString(META_DATA_KEY_FRAGMENT_CLASS);
            // Check if it has a parent specified and create a Header object
            final int parentHeaderTitleRes = ai.metaData.getInt(META_DATA_KEY_PARENT_TITLE);
            String parentFragmentClass = ai.metaData.getString(META_DATA_KEY_PARENT_FRAGMENT_CLASS);
            if (parentFragmentClass != null) {
                mParentHeader = new Header();
                mParentHeader.fragment = parentFragmentClass;
                if (parentHeaderTitleRes != 0) {
                    mParentHeader.title = getResources().getString(parentHeaderTitleRes);
                }
            }
        } catch (NameNotFoundException nnfe) {
            // No recovery
        }
    }

  這個方法用於設置mParentHeader的Fragment以及title。下面具體舉兩個例子，關於如何修改Settings。

一、添加headers

      header即是左邊的菜單，如下圖左側。它的佈局文件在res下的xml文件夾中，名字是settings_headers.xml。打開如下：

<?xml version="1.0" encoding="utf-8"?>
<!--
     Copyright (C) 2010 The Android Open Source Project

     Licensed under the Apache License, Version 2.0 (the "License");
     you may not use this file except in compliance with the License.
     You may obtain a copy of the License at

          http://www.apache.org/licenses/LICENSE-2.0

     Unless required by applicable law or agreed to in writing, software
     distributed under the License is distributed on an "AS IS" BASIS,
     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     See the License for the specific language governing permissions and
     limitations under the License.
-->

<preference-headers xmlns:android="http://schemas.android.com/apk/res/android" >

    <!-- WIRELESS and NETWORKS -->
    <header
        android:id="@+id/wireless_section"
        android:title="@string/header_category_wireless_networks" />

    <!-- Wifi -->
    <header
        android:id="@+id/wifi_settings"
        android:fragment="com.android.settings.wifi.WifiSettings"
        android:icon="@drawable/ic_settings_wireless"
        android:title="@string/wifi_settings_title" />

    <!-- Bluetooth -->
    <header
        android:id="@+id/bluetooth_settings"
        android:fragment="com.android.settings.bluetooth.BluetoothSettings"
        android:icon="@drawable/ic_settings_bluetooth2"
        android:title="@string/bluetooth_settings_title" />

    <!-- Data Usage -->
    <header
        android:id="@+id/data_usage_settings"
        android:fragment="com.android.settings.DataUsageSummary"
        android:icon="@drawable/ic_settings_data_usage"
        android:title="@string/data_usage_summary_title" />

    <!-- Operator hook -->
    <header
        android:id="@+id/operator_settings"
        android:fragment="com.android.settings.WirelessSettings" >
        <intent android:action="com.android.settings.OPERATOR_APPLICATION_SETTING" />
    </header>

    <!-- Other wireless and network controls -->
    <header
        android:id="@+id/wireless_settings"
        android:breadCrumbTitle="@string/wireless_networks_settings_title"
        android:fragment="com.android.settings.WirelessSettings"
        android:icon="@drawable/empty_icon"
        android:title="@string/radio_controls_title" />

    <!-- DEVICE -->
    <header
        android:id="@+id/device_section"
        android:title="@string/header_category_device" />

    <!-- Sound -->
    <header
        android:id="@+id/sound_settings"
        android:fragment="com.android.settings.SoundSettings"
        android:icon="@drawable/ic_settings_sound"
        android:title="@string/sound_settings" />

    <!-- Display -->
    <header
        android:id="@+id/display_settings"
        android:fragment="com.android.settings.DisplaySettings"
        android:icon="@drawable/ic_settings_display"
        android:title="@string/display_settings" />

    <!-- Storage -->
    <header
        android:id="@+id/storage_settings"
        android:fragment="com.android.settings.deviceinfo.Memory"
        android:icon="@drawable/ic_settings_storage"
        android:title="@string/storage_settings" />

    <!-- Battery -->
    <header
        android:id="@+id/battery_settings"
        android:fragment="com.android.settings.fuelgauge.PowerUsageSummary"
        android:icon="@drawable/ic_settings_battery"
        android:title="@string/power_usage_summary_title" />

    <!-- Application Settings -->
    <header
        android:id="@+id/application_settings"
        android:fragment="com.android.settings.applications.ManageApplications"
        android:icon="@drawable/ic_settings_applications"
        android:title="@string/applications_settings" />

    <!-- Manage users -->
    <header
        android:id="@+id/user_settings"
        android:fragment="com.android.settings.users.UserSettings"
        android:icon="@drawable/ic_settings_multiuser"
        android:title="@string/user_settings_title" />

    <!-- Manufacturer hook -->
    <header
        android:id="@+id/manufacturer_settings"
        android:fragment="com.android.settings.WirelessSettings" >
        <intent android:action="com.android.settings.MANUFACTURER_APPLICATION_SETTING" />
    </header>

    <!-- PERSONAL -->
    <header
        android:id="@+id/personal_section"
        android:title="@string/header_category_personal" />

    <!-- Location -->
    <header
        android:id="@+id/location_settings"
        android:fragment="com.android.settings.LocationSettings"
        android:icon="@drawable/ic_settings_location"
        android:title="@string/location_settings_title" />

    <!-- Security -->
    <header
        android:id="@+id/security_settings"
        android:fragment="com.android.settings.SecuritySettings"
        android:icon="@drawable/ic_settings_security"
        android:title="@string/security_settings_title" />

    <!-- Language -->
    <header
        android:id="@+id/language_settings"
        android:fragment="com.android.settings.inputmethod.InputMethodAndLanguageSettings"
        android:icon="@drawable/ic_settings_language"
        android:title="@string/language_settings" />

    <!-- Backup and reset -->
    <header
        android:id="@+id/privacy_settings"
        android:fragment="com.android.settings.PrivacySettings"
        android:icon="@drawable/ic_settings_backup"
        android:title="@string/privacy_settings" />
    <header
        android:id="@+id/kytusers_settings"
        android:fragment="com.android.settings.KytUsersSettings"
        android:icon="@drawable/ic_settings_backup"
        android:title="考易通賬戶" />

    <!-- ACCOUNTS section -->
    <header
        android:id="@+id/account_settings"
        android:title="@string/account_settings" />
    <header
        android:id="@+id/account_add"
        android:icon="@drawable/ic_menu_add"
        android:title="@string/add_account_label" >
        <intent android:action="android.settings.ADD_ACCOUNT_SETTINGS" />
    </header>

    <!-- SYSTEM -->
    <header
        android:id="@+id/system_section"
        android:title="@string/header_category_system" />

    <!-- Date & Time -->
    <header
        android:id="@+id/date_time_settings"
        android:fragment="com.android.settings.DateTimeSettings"
        android:icon="@drawable/ic_settings_date_time"
        android:title="@string/date_and_time_settings_title" />

    <!-- Accessibility feedback -->
    <header
        android:id="@+id/accessibility_settings"
        android:fragment="com.android.settings.AccessibilitySettings"
        android:icon="@drawable/ic_settings_accessibility"
        android:title="@string/accessibility_settings" />

    <!-- Development -->
    <header
        android:id="@+id/development_settings"
        android:fragment="com.android.settings.DevelopmentSettings"
        android:icon="@drawable/ic_settings_development"
        android:title="@string/development_settings_title" />

    <!-- About Device -->
    <header
        android:id="@+id/about_settings"
        android:fragment="com.android.settings.DeviceInfoSettings"
        android:icon="@drawable/ic_settings_about"
        android:title="@string/about_settings" />

</preference-headers>

  這些header分別對應着各自的菜單，如果想要添加還是刪除就在這裏修改即可。比如我們不想要藍牙模塊了，那就直接把下面這個header刪除即可，添加的話類似。

<!-- Bluetooth -->
  <header
      android:id="@+id/bluetooth_settings"
      android:fragment="com.android.settings.bluetooth.BluetoothSettings"
      android:icon="@drawable/ic_settings_bluetooth2"
      android:title="@string/bluetooth_settings_title" />

   如果是做添加操作的話，不要忘了創建你的PreferenceFragment，然後在header裏面添加id、fragment、icon、title等，如上面那樣。

  

二、修改顯示的應用

      先看一下應用顯示的部分：

  看一下在源碼中對應的包：

   應用顯示是一個滑動的界面，猜測是用ViewPager實現的，下面開始尋找實現。首先進入xml文件夾找到settings_headers，找到這一段代碼：

<!-- Application Settings -->
 <header
     android:id="@+id/application_settings"
     android:fragment="com.android.settings.applications.ManageApplications"
     android:icon="@drawable/ic_settings_applications"
     android:title="@string/applications_settings" />

  然後打開對應的fragment，ManageApplications。發現這個它是繼承於Fragment

  既然繼承於Fragment，那就直接定位到onCreate()方法，

@Override
   public void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);

       setHasOptionsMenu(true);

       mApplicationsState = ApplicationsState.getInstance(getActivity().getApplication());
       Intent intent = getActivity().getIntent();
       String action = intent.getAction();
       int defaultListType = LIST_TYPE_DOWNLOADED;
       String className = getArguments() != null
               ? getArguments().getString("classname") : null;
       if (className == null) {
           className = intent.getComponent().getClassName();
       }
       if (className.equals(RunningServicesActivity.class.getName())
               || className.endsWith(".RunningServices")) {
           defaultListType = LIST_TYPE_RUNNING;
       } else if (className.equals(StorageUseActivity.class.getName())
               || Intent.ACTION_MANAGE_PACKAGE_STORAGE.equals(action)
               || className.endsWith(".StorageUse")) {
           mSortOrder = SORT_ORDER_SIZE;
           defaultListType = LIST_TYPE_ALL;
       } else if (Settings.ACTION_MANAGE_ALL_APPLICATIONS_SETTINGS.equals(action)) {
           // Select the all-apps list, with the default sorting
           defaultListType = LIST_TYPE_ALL;
       }

       if (savedInstanceState != null) {
           mSortOrder = savedInstanceState.getInt(EXTRA_SORT_ORDER, mSortOrder);
           int tmp = savedInstanceState.getInt(EXTRA_DEFAULT_LIST_TYPE, -1);
           if (tmp != -1) defaultListType = tmp;
           mShowBackground = savedInstanceState.getBoolean(EXTRA_SHOW_BACKGROUND, false);
       }

       mDefaultListType = defaultListType;

       final Intent containerIntent = new Intent().setComponent(
               StorageMeasurement.DEFAULT_CONTAINER_COMPONENT);
       getActivity().bindService(containerIntent, mContainerConnection, Context.BIND_AUTO_CREATE);

       mInvalidSizeStr = getActivity().getText(R.string.invalid_size_value);
       mComputingSizeStr = getActivity().getText(R.string.computing_size);

       TabInfo tab = new TabInfo(this, mApplicationsState,
               getActivity().getString(R.string.filter_apps_third_party),
               LIST_TYPE_DOWNLOADED, this, savedInstanceState);
       mTabs.add(tab);

       if (!Environment.isExternalStorageEmulated()) {
           tab = new TabInfo(this, mApplicationsState,
                   getActivity().getString(R.string.filter_apps_onsdcard),
                   LIST_TYPE_SDCARD, this, savedInstanceState);
           mTabs.add(tab);
       }

       tab = new TabInfo(this, mApplicationsState,
               getActivity().getString(R.string.filter_apps_running),
               LIST_TYPE_RUNNING, this, savedInstanceState);
       mTabs.add(tab);

       tab = new TabInfo(this, mApplicationsState,
               getActivity().getString(R.string.filter_apps_all),
               LIST_TYPE_ALL, this, savedInstanceState);
       mTabs.add(tab);
   }

  這裏主要是初始化TabInfo的數據，之後顯示程序的時候會用到。接下來定位到onCreateView()方法，這個方法主要是初始化界面，

@Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        // initialize the inflater
        mInflater = inflater;

        View rootView = mInflater.inflate(R.layout.manage_applications_content,
                container, false);
        mContentContainer = container;
        mRootView = rootView;

        mViewPager = (ViewPager) rootView.findViewById(R.id.pager);
        MyPagerAdapter adapter = new MyPagerAdapter();
        mViewPager.setAdapter(adapter);
        mViewPager.setOnPageChangeListener(adapter);
        PagerTabStrip tabs = (PagerTabStrip) rootView.findViewById(R.id.tabs);
        tabs.setTabIndicatorColorResource(android.R.color.holo_blue_light);

        // We have to do this now because PreferenceFrameLayout looks at it
        // only when the view is added.
        if (container instanceof PreferenceFrameLayout) {
            ((PreferenceFrameLayout.LayoutParams) rootView.getLayoutParams()).removeBorders = true;
        }

        if (savedInstanceState != null && savedInstanceState.getBoolean(EXTRA_RESET_DIALOG)) {
            buildResetDialog();
        }

        if (savedInstanceState == null) {
            // First time init: make sure view pager is showing the correct tab.
            for (int i = 0; i < mTabs.size(); i++) {
                TabInfo tab = mTabs.get(i);
                if (tab.mListType == mDefaultListType) {
                    mViewPager.setCurrentItem(i);
                    break;
                }
            }
        }

        return rootView;
    }

  可以看到，正是使用了ViewPager，另外還有PagerTabStrip。先看一下最下面的：

if (savedInstanceState == null) {
          // First time init: make sure view pager is showing the correct tab.
          for (int i = 0; i < mTabs.size(); i++) {
              TabInfo tab = mTabs.get(i);
              if (tab.mListType == mDefaultListType) {
                  mViewPager.setCurrentItem(i);
                  break;
              }
          }
      }

  這段代碼的作用就是用於設置默認顯示哪個選項卡的程序，所以就是“已下載”這個界面。然後回過頭看一下上面的代碼，

MyPagerAdapter adapter = new MyPagerAdapter();
        mViewPager.setAdapter(adapter);

  這個就是熟悉的適配器了，所以顯示程序的數據在這裏面。開打這個類，

class MyPagerAdapter extends PagerAdapter
            implements ViewPager.OnPageChangeListener {
        int mCurPos = 0;

        @Override
        public int getCount() {
            return mTabs.size();
        }

        @Override
        public Object instantiateItem(ViewGroup container, int position) {
            TabInfo tab = mTabs.get(position);
            View root = tab.build(mInflater, mContentContainer, mRootView);
            container.addView(root);
            return root;
        }

        @Override
        public void destroyItem(ViewGroup container, int position, Object object) {
            container.removeView((View)object);
        }

        @Override
        public boolean isViewFromObject(View view, Object object) {
            return view == object;
        }

        @Override
        public CharSequence getPageTitle(int position) {
            return mTabs.get(position).mLabel;
        }

        @Override
        public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
        }

        @Override
        public void onPageSelected(int position) {
            mCurPos = position;
        }

        @Override
        public void onPageScrollStateChanged(int state) {
            if (state == ViewPager.SCROLL_STATE_IDLE) {
                updateCurrentTab(mCurPos);
            }
        }
    }

  可以看到，有幾個滑動的頁卡，是通過mTabs這個類來控制的，而它就是TabInfo類型。接着看一下繪製視圖的方法：

MyPagerAdapter  @Override
        public Object instantiateItem(ViewGroup container, int position) {
            TabInfo tab = mTabs.get(position);
            View root = tab.build(mInflater, mContentContainer, mRootView);
            container.addView(root);
            return root;
        }

   首先是獲取到一個tab，然後這個tab用它的build()方法去生成一個視圖，最後放到ViewPager顯示。所以問題的重點分析就是TabInfo這個類了。先說buid()方法，

public View build(LayoutInflater inflater, ViewGroup contentParent,
               View contentChild) {
           if (mRootView != null) {
               return mRootView;
           }

           mInflater = inflater;
           mRootView = inflater
                   .inflate(
                           mListType == LIST_TYPE_RUNNING ? R.layout.manage_applications_running
                                   : R.layout.manage_applications_apps, null);
           mLoadingContainer = mRootView.findViewById(R.id.loading_container);
           mLoadingContainer.setVisibility(View.VISIBLE);
           mListContainer = mRootView.findViewById(R.id.list_container);
           if (mListContainer != null) {
               // Create adapter and list view here
               View emptyView = mListContainer
                       .findViewById(com.android.internal.R.id.empty);
               ListView lv = (ListView) mListContainer
                       .findViewById(android.R.id.list);
               if (emptyView != null) {
                   lv.setEmptyView(emptyView);
               }
               lv.setOnItemClickListener(this);
               lv.setSaveEnabled(true);
               lv.setItemsCanFocus(true);
               lv.setTextFilterEnabled(true);
               mListView = lv;
               mApplications = new ApplicationsAdapter(mApplicationsState,
                       this, mFilter);
               mListView.setAdapter(mApplications);
               mListView.setRecyclerListener(mApplications);
               mColorBar = (LinearColorBar) mListContainer
                       .findViewById(R.id.storage_color_bar);
               mStorageChartLabel = (TextView) mListContainer
                       .findViewById(R.id.storageChartLabel);
               mUsedStorageText = (TextView) mListContainer
                       .findViewById(R.id.usedStorageText);
               mFreeStorageText = (TextView) mListContainer
                       .findViewById(R.id.freeStorageText);
               Utils.prepareCustomPreferencesList(contentParent, contentChild,
                       mListView, false);
               if (mFilter == FILTER_APPS_SDCARD) {
                   mStorageChartLabel.setText(mOwner.getActivity().getText(
                           R.string.sd_card_storage));
               } else {
                   mStorageChartLabel.setText(mOwner.getActivity().getText(
                           R.string.internal_storage));
               }
               applyCurrentStorage();
           }
           mRunningProcessesView = (RunningProcessesView) mRootView
                   .findViewById(R.id.running_processes);
           if (mRunningProcessesView != null) {
               mRunningProcessesView.doCreate(mSavedInstanceState);
           }

           return mRootView;
       }

  第四行是生成了一view對象，

mRootView = inflater.inflate(mListType == LIST_TYPE_RUNNING ? R.layout.manage_applications_running: R.layout.manage_applications_apps, null);

  這行代碼用來判斷加載哪個佈局文件，確實viewpager雖然動態顯示四個頁面，但是其中三個的佈局是一樣的，唯一不一樣的就是顯示正在運行的界面。

ListView lv = (ListView) mListContainer
                        .findViewById(android.R.id.list);
                if (emptyView != null) {
                    lv.setEmptyView(emptyView);
                }
                lv.setOnItemClickListener(this);
                lv.setSaveEnabled(true);
                lv.setItemsCanFocus(true);
                lv.setTextFilterEnabled(true);
                mListView = lv;
                mApplications = new ApplicationsAdapter(mApplicationsState,
                        this, mFilter);
                mListView.setAdapter(mApplications);

  這段代碼就是用於顯示app程序了，然後定位到ApplicationsAdapter這個類，在它的構造方法裏面，傳入三個參數。一個是mApplicationsState對象，以後用於對ApplicationsState類進行操作；一個是TabInfo，用來顯示不同的界面；一個是過濾器，是標識顯示哪個界面。進入這個構造方法，

public ApplicationsAdapter(ApplicationsState state, TabInfo tab,
             int filterMode) {
         mState = state;
         mSession = state.newSession(this);
         mTab = tab;
         mContext = tab.mOwner.getActivity();
         mFilterMode = filterMode;
     }

   發現沒有在這裏傳入什麼數據，然後看一下ApplicationsAdapter這個類，發現它繼承了三個接口，第一個是過濾用的，第三個是系統SDK接口用於ListView循環處理。而第二個接口正是負責處理數據的，

  它有六個回調方法：

public static interface Callbacks {
       public void onRunningStateChanged(boolean running);

       public void onPackageListChanged();

       public void onRebuildComplete(ArrayList<AppEntry> apps);

       public void onPackageIconChanged();

       public void onPackageSizeChanged(String packageName);

       public void onAllSizesComputed();
   }

  第三個回調方法onRebuildComplete(ArrayList<AppEntry> apps)正是用於返回app Entities的，但是到這裏如果我們還是按這條線是分析不下去了，找不到這個數據是從哪裏來的。所以不能按照這個思路往下走了，也就是說app程序數據不是在這裏獲取的，那會是什麼地方呢？一般情況下，我們是在onStart或者onCreat方法裏面，但是Setting裏面都沒有這樣做，那往下看一下onResume吧。果然Settings是在這個方法裏面加載數據的，

@Override
public void onResume() {
    super.onResume();
    mActivityResumed = true;
    updateCurrentTab(mViewPager.getCurrentItem());
    updateOptionsMenu();
}

  首先是調用了updateCurrentTab(mViewPager.getCurrentItem())方法，然後updateCurrentTab方法裏面又調用了TabInfo的resume方法，在TabInfo的resume方法裏面接着調用了ApplicationsAdapter 的resume方法，又在ApplicationsAdapter 的resume方法裏面調用Session的resume方法，最後又在Session的resume方法裏面調用doResumeIfNeededLocked()方法，這個方法就是從系統讀取程序信息的，代碼如下：

void doResumeIfNeededLocked() {
        if (mResumed) {
            return;
        }
        mResumed = true;
        if (mPackageIntentReceiver == null) {
            mPackageIntentReceiver = new PackageIntentReceiver();
            mPackageIntentReceiver.registerReceiver();
        }
        //這個mApplications就是所有程序數據，如果你想過濾哪些程序的信息，對這個集合進行修改即可。比如你在做定製機的時候，不想自己的程序顯示在Settings裏面，那就在這裏修改。
        mApplications = mPm.getInstalledApplications(mRetrieveFlags);
        if (mApplications == null) {
            mApplications = new ArrayList<ApplicationInfo>();
        }

        if (mInterestingConfigChanges.applyNewConfig(mContext.getResources())) {
            // If an interesting part of the configuration has changed, we
            // should completely reload the app entries.
            mEntriesMap.clear();
            mAppEntries.clear();
        } else {
            for (int i = 0; i < mAppEntries.size(); i++) {
                mAppEntries.get(i).sizeStale = true;
            }
        }

        for (int i = 0; i < mApplications.size(); i++) {
            final ApplicationInfo info = mApplications.get(i);
            // Need to trim out any applications that are disabled by
            // something different than the user.
            if (!info.enabled
                    && info.enabledSetting != PackageManager.COMPONENT_ENABLED_STATE_DISABLED_USER) {
                mApplications.remove(i);
                i--;
                continue;
            }
            final AppEntry entry = mEntriesMap.get(info.packageName);
            if (entry != null) {
                entry.info = info;
            }
        }
        mCurComputingSizePkg = null;
        if (!mBackgroundHandler.hasMessages(BackgroundHandler.MSG_LOAD_ENTRIES)) {
            mBackgroundHandler
                    .sendEmptyMessage(BackgroundHandler.MSG_LOAD_ENTRIES);
        }
    };

   至此，完成了顯示程序的剖析，其他模塊類似，只要按照流程走就行了。

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