android ROM设置默认Launcher(主屏幕应用)

Launcher

Launcher是android系统的桌面、是android系统的主要组件。android系统允许存在多个Launcher并设置默认主界面。

应用程序作为Home(主界面)需在Activity的intent-filter节点中添加如下内容

<category android:name="android.intent.category.HOME" />
<category android:name="android.intent.category.DEFAULT" />

当系统中存在多个Home app且没有设置默认，用户点击Home键会弹出如下图所示的界面（图一）：

用户可以选择“只有一次”或者“总是”来启动选择的APP

一般情况下android ROM中只会存在一个Home APP，系统启动后会直接启动此APP为默认，不需要用户选择。但是当ROM存在多个Home APP时，系统第一次启动就会弹出上图所示界面，让用户选择其中一个APP作为主屏幕应用，如果用户通过“ALWAYS”确认会设置选择的APP为默认的Home，用户通过“JUST ONCE”则此次以选择的APP为Home，再次按home键还是会弹出选择窗口

android ROM默认Launcher设置: 1：无效方案

网上有很多博客介绍如何设置ROM的默认Home app思路，都是在packages/apps/Provision/src/com/android/provision/DefaultActivity.java 中添加一段设置默认Home的代码，代码如下

    //网上的看到的
    private void setupDefaultLauncher() {
        // remove this activity from the package manager.
        PackageManager pm = getPackageManager();

        String examplePackageName = "******"; // package name
        String exampleActivityName = "******"; // launcher activity name

        ComponentName defaultLauncher = null;

        Intent intent = new Intent(Intent.ACTION_MAIN);
        intent.addCategory(Intent.CATEGORY_HOME);

        List<ResolveInfo> resolveInfoList =
                pm.queryIntentActivities(intent, 0);
        if (resolveInfoList != null) {
            int size = resolveInfoList.size();
            for (int j = 0; j < size; ) {
                final ResolveInfo r = resolveInfoList.get(j);
                if (!r.activityInfo.packageName.equals(examplePackageName)) {
                    resolveInfoList.remove(j);
                    size -= 1;
                } else {
                    j++;
                }
            }
            ComponentName[] set = new ComponentName[size];
            defaultLauncher = new ComponentName(examplePackageName, exampleActivityName);
            int defaultMatch = 0;
            for (int i = 0; i < size; i++) {
                final ResolveInfo resolveInfo =
                        resolveInfoList.get(i);
                Log.d(TAG, resolveInfo.toString());
                set[i] = new
                        ComponentName(resolveInfo.activityInfo.packageName, resolveInfo.activityInfo.name);
                if (defaultLauncher.getClassName().equals(resolveInfo.activityInfo.name)) {
                    defaultMatch = resolveInfo.match;
                }
            }
            Log.d(TAG, "defaultMatch =" + Integer.toHexString(defaultMatch));
            IntentFilter filter = new IntentFilter();
            filter.addAction(Intent.ACTION_MAIN);
            filter.addCategory(Intent.CATEGORY_HOME);
            filter.addCategory(Intent.CATEGORY_DEFAULT);

            pm.clearPackagePreferredActivities(defaultLauncher.getPackageName());
            pm.addPreferredActivity(filter, defaultMatch, set, defaultLauncher);
        }
    }
    //系统设置中修改默认Launcher的代码，
    private void setupDefaultLauncher2() {
    String packageName = "******"; // package name
        PackageManager mPm = getPackageManager();
        ArrayList<ResolveInfo> homeActivities = new ArrayList<ResolveInfo>();
        ComponentName currentDefaultHome  = mPm.getHomeActivities(homeActivities);
        IntentFilter mHomeFilter = new IntentFilter(Intent.ACTION_MAIN);
        mHomeFilter.addCategory(Intent.CATEGORY_HOME);
        mHomeFilter.addCategory(Intent.CATEGORY_DEFAULT);
        ComponentName[] mHomeComponentSet = new ComponentName[homeActivities.size()];
        int prefIndex = 0;
        for (int i = 0; i < homeActivities.size(); i++) {
            final ResolveInfo candidate = homeActivities.get(i);
            final ActivityInfo info = candidate.activityInfo;
            ComponentName activityName = new ComponentName(info.packageName, info.name);
            mHomeComponentSet[i] = activityName;
            if(info.packageName.equals(packageName)){
                currentDefaultHome = activityName;
            }
        }
        mPm.replacePreferredActivity(mHomeFilter, IntentFilter.MATCH_CATEGORY_EMPTY,
                mHomeComponentSet, currentDefaultHome);
    }

将以上任何一段代码添加到DefaultActivity的onCreate方法中，都无法实现修改启动后的默认Launcher，只能使设置的默认Launcher为选中状态如下图（图二）：

2：有效方案

既然使用上述设置默认主界面的做法无效，而在上述界面选择却有效，那么就从上面弹出的选择默认主界面的界面入手，通过追踪发现上述界面是一个Activity，Activity代码路径frameworks/base/core/java/com/android/internal/app/ResolverActivity.java

ResolverActivity分析

此Activity会获取系统中所有的Home app，并根据系统的设置情况显示如上界面。此类中有一个内部类ResolveListAdapter该类继承自BaseAdapter，该类是Home app选择界面的数据适配器。

ResolveListAdapter会在ResolverActivity的onCreate方法中被初始化并会传入一个ResolveInfo类型的List，ResolveListAdapter根据会传入的List<ResolveInfo>初始化一个List<DisplayResolveInfo> mList ，用户的点击事件都会在ResolveListAdapter获取数据。
用户点击”ALWAYS”的事件发生在ResolverActivity的onButtonClick 方法中，此方法会获取选中的Item的position、或者获取用户上一次启动的Home app的，mAlwaysUseOption代表用户选中的是否为历史选择（如2图中的Launcher3），并调用startSelected。

    public void onButtonClick(View v) {
        final int id = v.getId();
        startSelected(mAlwaysUseOption ?
                mListView.getCheckedItemPosition() : mAdapter.getFilteredPosition(),
                id == R.id.button_always,
                mAlwaysUseOption);
        dismiss();
    }

StartSeletced中通过ResolveListAdapter获取选择的item代表的Home app。并且finish此activity
onIntentSelected会根据传入的ResolveInfo设置默认的Home，并根据Intent跳转到相应界面，onIntentSelected的代码在这里就不列出。

    /**
     * 设置默认Home app并跳转，结束此Activity
     * @param which 用户选择的Item的position
     * @param always 是否设置为总是
     * @param filtered 是否非历史选择
     */
    void startSelected(int which, boolean always, boolean filtered) {
        if (isFinishing()) {
            return;
        }
        ResolveInfo ri = mAdapter.resolveInfoForPosition(which, filtered);
        Intent intent = mAdapter.intentForPosition(which, filtered);
        //设置默认Home，并启动
        onIntentSelected(ri, intent, always);
        finish();
    }

ResolveListAdapter的相关代码

        /**
        *
        * @param position 
        * @param filtered
        * @return 
        */
        public ResolveInfo resolveInfoForPosition(int position, boolean filtered) {
            //mList为List<DisplayResolveInfo>
            return (filtered ? getItem(position) : mList.get(position)).ri;
        }
        /**
        * 
        * @param position
        * @param filtered
        * @return 
        */
        public Intent intentForPosition(int position, boolean filtered) {
            //mList为List<DisplayResolveInfo>
            DisplayResolveInfo dri = filtered ? getItem(position) : mList.get(position);
            return intentForDisplayResolveInfo(dri);
        }

解决办法

此Activity的onCreate方法中判断是否为第一次启动，如果是则调用startSelected方法设置默认Home app。

默认Home app的从ResolveListAdapter中获取，所以在ResolveListAdapter中添加getDefaultHomePosition(String packageName)方法，用于获取默认home app在List<DisplayResolveInfo> 中的位置，代码如下：

        public int getDefaultHomePosition(String packageName){
            for (int i = 0; i < mList.size(); i++) {
                ResolveInfo info = mList.get(i).ri;
                if (DEBUG)
                Log.w(TAG,"getDefaultHomePosition " + info.activityInfo.packageName);
                if (info.activityInfo.packageName.equals(packageName)) {
                   return i;
                }
            }
            return -1;
        }

在ResolverActivity中添加设置默认app的方法setupDefaultLauncher()，代码如下：

    //用于记录默认home app是否设置过
    private static final String DEFAULT_HOME = "persist.sys.default.home";
    private void setupDefaultLauncher() {
        String first = "";
        try{
            first =  SystemProperties.get(DEFAULT_HOME);
        }catch(Exception e){
            Log.w(TAG,"exception error get DEFAULT_HOME");
        }
        //判断默认home 是否设置过，如果获取的字符串为空代表，未设置，否则return不在进行设置
        if (!TextUtils.isEmpty(first)) {
            return;
        }
        //使用包名获取所需设置的默认home app在ResolveListAdapter中的位置
        int position = mAdapter.getDefaultHomePosition("home app包名");
        //如果不存在则return
        if (position == -1) {
            if (DEBUG)
            Log.w(TAG,"not find default Home");
            return;
        }
        //设置默认home app后，则添加记录
        try{
            SystemProperties.set(DEFAULT_HOME,DEFAULT_HOME);
        }catch(Exception e){
            Log.w(TAG,"exception error set DEFAULT_HOME");
        }
        //设置默认home app，并跳转
        startSelected(position, true, true);
        //结束此activity
        dismiss();
    }

为了保证mAdapter被初始化 setupDefaultLauncher()的调用添加到ResolverActivity的onCreate函数中，代码如下：

    protected void onCreate(Bundle savedInstanceState, Intent intent,
            CharSequence title, int defaultTitleRes, Intent[] initialIntents,
            List<ResolveInfo> rList, boolean alwaysUseOption) {
        //其他初始化代码
        ............
        mIntent = new Intent(intent);
        mAdapter = new ResolveListAdapter(this, initialIntents, rList,
                mLaunchedFromUid, alwaysUseOption);
        //其它初始化代码
        ............

        if (mLaunchedFromUid < 0 || UserHandle.isIsolated(mLaunchedFromUid)) {
            // Gulp!
            finish();
            return;
        }

        int count = mAdapter.mList.size();
        //添加的代码
        setupDefaultLauncher();
        //原有逻辑
        //如果系统中home app大于1
        if (count > 1 || (count == 1 && mAdapter.getOtherProfile() != null)) {
            //初始化代码
            .........
        //如果home app等于1则设置唯一的home app为Home
        } else if (count == 1) {
            safelyStartActivity(mAdapter.intentForPosition(0, false));
            mPackageMonitor.unregister();
            mRegistered = false;
            finish();
            return;
        } else {
            setContentView(R.layout.resolver_list);

            final TextView empty = (TextView) findViewById(R.id.empty);
            empty.setVisibility(View.VISIBLE);

            mListView = (ListView) findViewById(R.id.resolver_list);
            mListView.setVisibility(View.GONE);
        }
        //其它初始化代码
        ..........
    }

通过以上方法即可实现设置默认home的功能