Android Settings开发之修改

   <!-- 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" />

  
然后打开对应的fragment，ManageApplications。发现这个它是继承于Fragment

 @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);
    }

  
这里主要是初始化TabInfo的数据，之后显示程序的时候会用到。接下来定位到onCreateView()方法，这个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，另外还有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;
                }
            }
        }

  
这段代码的作用就是用于设置默认显示哪个选项卡的程序，所以就是“已下载”这个界面。然后回过头看一下上面的代码，

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

  
这个就是熟悉的适配器了，所以显示程序的数据在这里面。开打这个类，

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，有几个滑动的页卡，是通过mTabs这个类来控制的，而它就是
TabInfo类型。接着看一下绘制视图的方法：

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;
        }

  
 首先是获取到一个tab，然后这个tab用它的build()方法去生成一个视图，最后放到ViewPager显示。所以问题的重点分析就是TabInfo这个类了。先说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对象，

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

  
这行代码用来判断加载哪个布局文件，确实viewpager虽然动态显示四个页面，但是其中三个的布局是一样的，唯一不一样的就是显示正在运行的界面。

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);

  
这段代码就是用于显示app程序了，然后定位到
ApplicationsAdapter这个类，在它的构造方法里面，传入三个参数。一个是
mApplicationsState对象，以后用于对
ApplicationsState类进行操作；
一个是TabInfo，用来显示不同的界面；一个是过滤器，是标识显示哪个界面。进入这个构造方法，

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

  
 发现没有在这里传入什么数据，然后看一下ApplicationsAdapter这个类，发现它继承了三个接口，第一个是过滤用的，第三个是系统SDK接口用于ListView循环处理。而第二个接口正是负责处理数据的，

 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();    }

  
第三个回调方法onRebuildComplete(ArrayList<AppEntry> apps)正是用于返回app Entities的，但是到这里如果我们还是按这条线是分析不下去了，找不到这个数据是从哪里来的。所以不能按照这个思路往下走了，也就是说app程序数据不是在这里获取的，那会是什么地方呢？一般情况下，我们是在onStart或者onCreat方法里面，但是Setting里面都没有这样做，那往下看一下onResume吧。果然Settings是在这个方法里面加载数据的，

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

  
首先是调用了updateCurrentTab(mViewPager.getCurrentItem())方法，然后updateCurrentTab方法里面又调用了TabInfo的resume方法，在
TabInfo的resume方法里面接着调用了
ApplicationsAdapter 的
resume方法，又在
ApplicationsAdapter 的
resume方法里面调用
Session的resume方法，最后又在
Session的resume方法里面调用
doResumeIfNeededLocked()方法，这个方法就是从系统读取程序信息的，代码如下：

void doResumeIfNeededLocked() {        if (mResumed) {            return;        }        mResumed = true;        if (mPackageIntentReceiver == null) {            mPackageIntentReceiver = new PackageIntentReceiver();            mPackageIntentReceiver.registerReceiver();        }        //这个mApplications就是所有程序数据，如果你想过滤哪些程序的信息，对这个集合进行修改即可。比如你在做定制机的时候，不想自己的程序显示在Settings里面，那就在这里修改。        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，完成了显示程序的剖析，其他模块类似，只要按照流程走就行了。