解析xml android Android源代码解析之（十三）(2)

好吧，这里我们大概看一下Activity的定义，这里我们重点看一下PackageInstallerActivity的定义：

<activity android:name=".PackageInstallerActivity"
                android:configChanges="orientation|keyboardHidden|screenSize"
                android:excludeFromRecents="true">
            <intent-filter>
                <action android:name="android.intent.action.VIEW" />
                <action android:name="android.intent.action.INSTALL_PACKAGE" />
                <category android:name="android.intent.category.DEFAULT" />
                <data android:scheme="file" />
                <data android:mimeType="application/vnd.android.package-archive" />
            </intent-filter>
            <intent-filter>
                <action android:name="android.intent.action.INSTALL_PACKAGE" />
                <category android:name="android.intent.category.DEFAULT" />
                <data android:scheme="file" />
                <data android:scheme="package" />
            </intent-filter>
            <intent-filter>
                <action android:name="android.content.pm.action.CONFIRM_PERMISSIONS" />
                <category android:name="android.intent.category.DEFAULT" />
            </intent-filter>
        </activity>

恩？这里不就是我们刚刚定义的启动安装Apk activity的intent filter？好吧，所以说一开始我们调用的startActivity事实上启动的就是PackageInstallerActivity。那么以下我们就看一下PackageInstellerActivity的详细实现：

@Override
    protected void onCreate(Bundle icicle) {
        super.onCreate(icicle);

        mPm = getPackageManager();
        mInstaller = mPm.getPackageInstaller();
        mUserManager = (UserManager) getSystemService(Context.USER_SERVICE);

        final Intent intent = getIntent();
        if (PackageInstaller.ACTION_CONFIRM_PERMISSIONS.equals(intent.getAction())) {
            final int sessionId = intent.getIntExtra(PackageInstaller.EXTRA_SESSION_ID, -1);
            final PackageInstaller.SessionInfo info = mInstaller.getSessionInfo(sessionId);
            if (info == null || !info.sealed || info.resolvedBaseCodePath == null) {
                Log.w(TAG, "Session " + mSessionId + " in funky state; ignoring");
                finish();
                return;
            }

            mSessionId = sessionId;
            mPackageURI = Uri.fromFile(new File(info.resolvedBaseCodePath));
            mOriginatingURI = null;
            mReferrerURI = null;
        } else {
            mSessionId = -1;
            mPackageURI = intent.getData();
            mOriginatingURI = intent.getParcelableExtra(Intent.EXTRA_ORIGINATING_URI);
            mReferrerURI = intent.getParcelableExtra(Intent.EXTRA_REFERRER);
        }

        final boolean unknownSourcesAllowedByAdmin = isUnknownSourcesAllowedByAdmin();
        final boolean unknownSourcesAllowedByUser = isUnknownSourcesEnabled();

        boolean requestFromUnknownSource = isInstallRequestFromUnknownSource(intent);
        mInstallFlowAnalytics = new InstallFlowAnalytics();
        mInstallFlowAnalytics.setContext(this);
        mInstallFlowAnalytics.setStartTimestampMillis(SystemClock.elapsedRealtime());
        mInstallFlowAnalytics.setInstallsFromUnknownSourcesPermitted(unknownSourcesAllowedByAdmin
                && unknownSourcesAllowedByUser);
        mInstallFlowAnalytics.setInstallRequestFromUnknownSource(requestFromUnknownSource);
        mInstallFlowAnalytics.setVerifyAppsEnabled(isVerifyAppsEnabled());
        mInstallFlowAnalytics.setAppVerifierInstalled(isAppVerifierInstalled());
        mInstallFlowAnalytics.setPackageUri(mPackageURI.toString());

        if (DeviceUtils.isWear(this)) {
            showDialogInner(DLG_NOT_SUPPORTED_ON_WEAR);
            mInstallFlowAnalytics.setFlowFinished(
                    InstallFlowAnalytics.RESULT_NOT_ALLOWED_ON_WEAR);
            return;
        }

        final String scheme = mPackageURI.getScheme();
        if (scheme != null && !"file".equals(scheme) && !"package".equals(scheme)) {
            Log.w(TAG, "Unsupported scheme " + scheme);
            setPmResult(PackageManager.INSTALL_FAILED_INVALID_URI);
            mInstallFlowAnalytics.setFlowFinished(
                    InstallFlowAnalytics.RESULT_FAILED_UNSUPPORTED_SCHEME);
            finish();
            return;
        }

        final PackageUtil.AppSnippet as;
        if ("package".equals(mPackageURI.getScheme())) {
            mInstallFlowAnalytics.setFileUri(false);
            try {
                mPkgInfo = mPm.getPackageInfo(mPackageURI.getSchemeSpecificPart(),
                        PackageManager.GET_PERMISSIONS | PackageManager.GET_UNINSTALLED_PACKAGES);
            } catch (NameNotFoundException e) {
            }
            if (mPkgInfo == null) {
                Log.w(TAG, "Requested package " + mPackageURI.getScheme()
                        + " not available. Discontinuing installation");
                showDialogInner(DLG_PACKAGE_ERROR);
                setPmResult(PackageManager.INSTALL_FAILED_INVALID_APK);
                mInstallFlowAnalytics.setPackageInfoObtained();
                mInstallFlowAnalytics.setFlowFinished(
                        InstallFlowAnalytics.RESULT_FAILED_PACKAGE_MISSING);
                return;
            }
            as = new PackageUtil.AppSnippet(mPm.getApplicationLabel(mPkgInfo.applicationInfo),
                    mPm.getApplicationIcon(mPkgInfo.applicationInfo));
        } else {
            mInstallFlowAnalytics.setFileUri(true);
            final File sourceFile = new File(mPackageURI.getPath());
            PackageParser.Package parsed = PackageUtil.getPackageInfo(sourceFile);

            // Check for parse errors
            if (parsed == null) {
                Log.w(TAG, "Parse error when parsing manifest. Discontinuing installation");
                showDialogInner(DLG_PACKAGE_ERROR);
                setPmResult(PackageManager.INSTALL_FAILED_INVALID_APK);
                mInstallFlowAnalytics.setPackageInfoObtained();
                mInstallFlowAnalytics.setFlowFinished(
                        InstallFlowAnalytics.RESULT_FAILED_TO_GET_PACKAGE_INFO);
                return;
            }
            mPkgInfo = PackageParser.generatePackageInfo(parsed, null,
                    PackageManager.GET_PERMISSIONS, 0, 0, null,
                    new PackageUserState());
            mPkgDigest = parsed.manifestDigest;
            as = PackageUtil.getAppSnippet(this, mPkgInfo.applicationInfo, sourceFile);
        }
        mInstallFlowAnalytics.setPackageInfoObtained();

        //set view
        setContentView(R.layout.install_start);
        mInstallConfirm = findViewById(R.id.install_confirm_panel);
        mInstallConfirm.setVisibility(View.INVISIBLE);
        PackageUtil.initSnippetForNewApp(this, as, R.id.app_snippet);

        mOriginatingUid = getOriginatingUid(intent);

        // Block the install attempt on the Unknown Sources setting if necessary.
        if (!requestFromUnknownSource) {
            initiateInstall();
            return;
        }

        // If the admin prohibits it, or we're running in a managed profile, just show error
        // and exit. Otherwise show an option to take the user to Settings to change the setting.
        final boolean isManagedProfile = mUserManager.isManagedProfile();
        if (!unknownSourcesAllowedByAdmin
                || (!unknownSourcesAllowedByUser && isManagedProfile)) {
            showDialogInner(DLG_ADMIN_RESTRICTS_UNKNOWN_SOURCES);
            mInstallFlowAnalytics.setFlowFinished(
                    InstallFlowAnalytics.RESULT_BLOCKED_BY_UNKNOWN_SOURCES_SETTING);
        } else if (!unknownSourcesAllowedByUser) {
            // Ask user to enable setting first
            showDialogInner(DLG_UNKNOWN_SOURCES);
            mInstallFlowAnalytics.setFlowFinished(
                    InstallFlowAnalytics.RESULT_BLOCKED_BY_UNKNOWN_SOURCES_SETTING);
        } else {
            initiateInstall();
        }
    }

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