android应用市场点击下载APK安装详解

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1,《android应用市场点击下载APK安装详解》

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3,《android手势分析(应用界面左往右边滑动退出应用)》

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5,《android11安装应用触发桌面图标刷新流程》

6,《Android系统多任务Recents详解》

7,《android系统导航栏视图分析》

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目录

一,背景介绍

二,安装过程

2.1 流程概述

2.2 PackageInstaller安装APK

2.3 PMS执行安装


一,背景介绍

android的APK安装流程,有四种安装方式:

1,系统应用和预制应用安装,开机时完成,没有安装界面,在PKMS的构造函数中欧冠完成安装

2,网络下载应用安装,通过应用商店来完成,调用PackageManager.installPackages(),有安装界面

3,ADB工具安装,没有安装界面,它通过启动pm脚本的形式,然后调用com.android.commands.pm.Pm类,之后调用到PMS.installStage()完成安装

4,第三方应用安装,通过SD卡里的APK文件安装,有安装界面,由packageinstaller.apk应用处理安装及卸载过程的界面.

均是通过PackageInstallObserver来监听安装是否成功。

二,安装过程

2.1 流程概述

应用安装主要流程:

1,将APK的信息通过IO流的形式写入到PackageInstaller.Session中。
2,调用PackageInstaller.Session的commit方法,将APK的信息交由PKMS处理。
3,拷贝APK
4,最后进行安装

        在应用市场点击一个未安装的apk后,发送广播打开PackageInstallerActivity,拉起com.android.packageinstaller(断点的进程)应用,弹出安装界面,这个主要是由bindUi构成,点击之后就会调用startInstall()进行安装。

/PackageInstallerActivity.java
private void bindUi() {
        mAlert.setIcon(mAppSnippet.icon);
        mAlert.setTitle(mAppSnippet.label);
        mAlert.setView(R.layout.install_content_view);
        mAlert.setButton(DialogInterface.BUTTON_POSITIVE, getString(R.string.install),
                (ignored, ignored2) -> {
                    if (mOk.isEnabled()) {
                        if (mSessionId != -1) {
                            mInstaller.setPermissionsResult(mSessionId, true);
                            finish();
                        } else {
                          //进行APK安装
                            startInstall();
                        }
                    }
                }, null);
        mAlert.setButton(DialogInterface.BUTTON_NEGATIVE, getString(R.string.cancel),
                (ignored, ignored2) -> {
                    // Cancel and finish
                    setResult(RESULT_CANCELED);
                    if (mSessionId != -1) {
                      //如果mSessionId存在,执行setPermissionsResult()完成取消安装
                        mInstaller.setPermissionsResult(mSessionId, false);
                    }
                    finish();
                }, null);
        setupAlert();

       ......
    }

//点击”安装“,跳转 InstallInstalling - 开始安装
private void startInstall() {
    // Start subactivity to actually install the application
    Intent newIntent = new Intent();
    newIntent.putExtra(PackageUtil.INTENT_ATTR_APPLICATION_INFO, mPkgInfo.applicationInfo);
    newIntent.setData(mPackageURI);
    newIntent.setClass(this, InstallInstalling.class);
    String installerPackageName = getIntent().getStringExtra( Intent.EXTRA_INSTALLER_PACKAGE_NAME);
    ...
    if (installerPackageName != null) {
        newIntent.putExtra(Intent.EXTRA_INSTALLER_PACKAGE_NAME, installerPackageName);
    }
    newIntent.addFlags(Intent.FLAG_ACTIVITY_FORWARD_RESULT);
    startActivity(newIntent);
    finish();
}

其中,R.layout.install_content_view布局视图如下:

android应用市场点击下载APK安装详解_第1张图片

        在startInstall方法组装了一个Intent,并跳转到InstallInstalling这个Activity,并关闭掉当前的PackageInstallerActivity。在InstallInstalling主要用于向包管理器发送包的信息并处理包管理的回调。

2.2 PackageInstaller安装APK

在启动InstallInstalling后,进入onCreate方法:

//InstallInstalling
protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        ApplicationInfo appInfo = getIntent()
                .getParcelableExtra(PackageUtil.INTENT_ATTR_APPLICATION_INFO);
        mPackageURI = getIntent().getData();

          ......
            setupAlert();
            requireViewById(R.id.installing).setVisibility(View.VISIBLE);

            if (savedInstanceState != null) {
                mSessionId = savedInstanceState.getInt(SESSION_ID);
                mInstallId = savedInstanceState.getInt(INSTALL_ID);

                try {
                  //.根据mInstallId向InstallEventReceiver注册一个观察者,launchFinishBasedOnResult会接收到安装事件的回调,无论安装成功或者失败都会关闭当前的Activity(InstallInstalling)。如果savedInstanceState为null,代码的逻辑也是类似的
                    InstallEventReceiver.addObserver(this, mInstallId,
                            this::launchFinishBasedOnResult);
                } catch (EventResultPersister.OutOfIdsException e) {
                    // Does not happen
                }
            } else {
                ......

                File file = new File(mPackageURI.getPath());
                try {
                    PackageParser.PackageLite pkg = PackageParser.parsePackageLite(file, 0);
                    params.setAppPackageName(pkg.packageName);
                    params.setInstallLocation(pkg.installLocation);
                    params.setSize(
                            PackageHelper.calculateInstalledSize(pkg, false, params.abiOverride));
                } catch (PackageParser.PackageParserException e) {
                    Log.e(LOG_TAG, "Cannot parse package " + file + ". Assuming defaults.");
                    Log.e(LOG_TAG,
                            "Cannot calculate installed size " + file + ". Try only apk size.");
                    params.setSize(file.length());
                } catch (IOException e) {
                    Log.e(LOG_TAG,
                            "Cannot calculate installed size " + file + ". Try only apk size.");
                    params.setSize(file.length());
                }

                try {
                  //向InstallEventReceiver注册一个观察者返回一个新的mInstallId,
                  //其中InstallEventReceiver继承自BroadcastReceiver,用于接收安装事件并回调给EventResultPersister。
                    mInstallId = InstallEventReceiver
                            .addObserver(this, EventResultPersister.GENERATE_NEW_ID,
                                    this::launchFinishBasedOnResult);
                } catch (EventResultPersister.OutOfIdsException e) {
                    launchFailure(PackageManager.INSTALL_FAILED_INTERNAL_ERROR, null);
                }

                try {
                  //PackageInstaller的createSession方法内部会通过IPackageInstaller与PackageInstallerService进行进程间通信,最终调用的是PackageInstallerService的createSession方法来创建并返回mSessionId
                    mSessionId = getPackageManager().getPackageInstaller().createSession(params);
                } catch (IOException e) {
                    launchFailure(PackageManager.INSTALL_FAILED_INTERNAL_ERROR, null);
                }
            }

            mCancelButton = mAlert.getButton(DialogInterface.BUTTON_NEGATIVE);

            mSessionCallback = new InstallSessionCallback();
        }
    }

        在onCreate中通过PackageInstaller通过创建Session并返回mSesionId,接着会在onResume中,会开启InstallingAsynTask,把包信息写入mSessionId对应的session,然后提交。

//InstallInstalling
protected void onResume() {
        super.onResume();

        // This is the first onResume in a single life of the activity
        if (mInstallingTask == null) {
            PackageInstaller installer = getPackageManager().getPackageInstaller();
          //获取sessionInfo
            PackageInstaller.SessionInfo sessionInfo = installer.getSessionInfo(mSessionId);

            if (sessionInfo != null && !sessionInfo.isActive()) {
              //创建内部类InstallingAsyncTask的对象,调用execute(),最终进入onPostExecute()
                mInstallingTask = new InstallingAsyncTask();
                mInstallingTask.execute();
            } else {
                // we will receive a broadcast when the install is finished
                mCancelButton.setEnabled(false);
                setFinishOnTouchOutside(false);
            }
        }
    }

  private final class InstallingAsyncTask extends AsyncTask {
              
    @Override
    protected PackageInstaller.Session doInBackground(Void... params) {
        
              PackageInstaller.Session session;
            try {
                session = getPackageManager().getPackageInstaller().openSession(mSessionId);
            } catch (IOException e) {
                return null;
            }

            session.setStagingProgress(0);

            try {
                File file = new File(mPackageURI.getPath());

                try (InputStream in = new FileInputStream(file)) {
                    long sizeBytes = file.length();
                  //从session中获取输出流
                    try (OutputStream out = session
                            .openWrite("PackageInstaller", 0, sizeBytes)) {
                        byte[] buffer = new byte[1024 * 1024];
                       ......
                    }
                }

                return session;
            } catch (IOException | SecurityException e) {
               ......
        }

        @Override
        protected void onPostExecute(PackageInstaller.Session session) {
            if (session != null) {
                Intent broadcastIntent = new Intent(BROADCAST_ACTION);
                broadcastIntent.setFlags(Intent.FLAG_RECEIVER_FOREGROUND);
                broadcastIntent.setPackage(getPackageName());
                broadcastIntent.putExtra(EventResultPersister.EXTRA_ID, mInstallId);

                PendingIntent pendingIntent = PendingIntent.getBroadcast(
                        InstallInstalling.this,
                        mInstallId,
                        broadcastIntent,
                        PendingIntent.FLAG_UPDATE_CURRENT);
                                //包写入session进行提交
                session.commit(pendingIntent.getIntentSender());
                mCancelButton.setEnabled(false);
                setFinishOnTouchOutside(false);
            } else {
                getPackageManager().getPackageInstaller().abandonSession(mSessionId);

                if (!isCancelled()) {
                    launchFailure(PackageManager.INSTALL_FAILED_INVALID_APK, null);
                }
            }
        }  
   }

        在InstallingAsyncTask的doInBackground()里会根据包的Uri,将APK的信息通过IO流的形式写入到PackageInstaller.Session中,最后会在onPostExecute()中调用PackageInstaller.Session的commit方法,进行安装。

        在里面会看到一个PackageInstaller,也就是APK安装器,其实在ApplicationPackageManager的getPackageInstaller中创建的:

//ApplicationPackageManager
@Override
    public PackageInstaller getPackageInstaller() {
        synchronized (mLock) {
            if (mInstaller == null) {
                try {
                    mInstaller = new PackageInstaller(mPM.getPackageInstaller(),
                            mContext.getPackageName(), getUserId());
                } catch (RemoteException e) {
                    throw e.rethrowFromSystemServer();
                }
            }
            return mInstaller;
        }
    }

        在这里会传入mPM.getPackageInstaller(),也就是IpacageInstaller的实例,其具体实现也就是PackageInstallerService, 其通过IPC的方式。它在初始化的时候会读取/data/system目录下的install_sessions文件,这个文件保存了系统未完成的Install Session。PMS则会根据文件的内容创建PackageInstallerSession对象并从插入到mSessions中。

//PackageInstallerService.java
 public PackageInstallerService(Context context, PackageManagerService pm,
            Supplier apexParserSupplier) {
        mContext = context;
        mPm = pm;
        mPermissionManager = LocalServices.getService(PermissionManagerServiceInternal.class);

        mInstallThread = new HandlerThread(TAG);
        mInstallThread.start();

        mInstallHandler = new Handler(mInstallThread.getLooper());

        mCallbacks = new Callbacks(mInstallThread.getLooper());

        mSessionsFile = new AtomicFile(
                new File(Environment.getDataSystemDirectory(), "install_sessions.xml"),
                "package-session");
   //这个文件保存了系统未完成的`Install Session`
        mSessionsDir = new File(Environment.getDataSystemDirectory(), "install_sessions");
        mSessionsDir.mkdirs();

        mApexManager = ApexManager.getInstance();
        mStagingManager = new StagingManager(this, context, apexParserSupplier);
    }

        再来看下Session,是在于mSeesionId绑定的安装会话,代表着一个在进行中的安装。Session类是对IPackageInstaller.openSession(sessionId) 获取的 PackageInstallerSession(系统服务端)的封装。

        Session的创建和打开 具体实现是在 PackageInstallerService中,主要是 初始化apk的安装信息及环境,并创建一个sessionId,将安装Session与sessionId 进行绑定.

        接着我们回到InstallingAsyncTask中,在这里调用了session.commit方法:

//PackageInstaller        
public void commit(@NonNull IntentSender statusReceiver) {
            try {
              //调用PackageInstallerSession的commit方法,进入到java框架层
                mSession.commit(statusReceiver, false);
            } catch (RemoteException e) {
                throw e.rethrowFromSystemServer();
            }
        }

//PackageInstallerSession.java
public void commit(@NonNull IntentSender statusReceiver, boolean forTransfer) {
                ......
          //如果尚未调用,则会话将被密封。此方法可能会被多次调用以更新状态接收者验证调用者权限
        if (!markAsSealed(statusReceiver, forTransfer)) {
            return;
        }
        //不同的包
        if (isMultiPackage()) {
            final SparseIntArray remainingSessions = mChildSessionIds.clone();
            final IntentSender childIntentSender =
                    new ChildStatusIntentReceiver(remainingSessions, statusReceiver)
                            .getIntentSender();
            boolean sealFailed = false;
            for (int i = mChildSessionIds.size() - 1; i >= 0; --i) {
                final int childSessionId = mChildSessionIds.keyAt(i);
                // seal all children, regardless if any of them fail; we'll throw/return
                // as appropriate once all children have been processed
                if (!mSessionProvider.getSession(childSessionId)
                        .markAsSealed(childIntentSender, forTransfer)) {
                    sealFailed = true;
                }
            }
            if (sealFailed) {
                return;
            }
        }
        dispatchStreamValidateAndCommit();
}

private void dispatchStreamValidateAndCommit() {
        mHandler.obtainMessage(MSG_STREAM_VALIDATE_AND_COMMIT).sendToTarget();
    }
mSession的类型为IPackageInstallerSession,这说明要通过IPackageInstallerSession来进行进程间的通信,最终会调用PackageInstallerSession的commit方法。
在这里发送了一个MSG_STREAM_VALIDATE_AND_COMMIT的信号,并在handler中进行处理:
public boolean handleMessage(Message msg) {
        case MSG_STREAM_VALIDATE_AND_COMMIT:
           handleStreamValidateAndCommit();
           break;
            case MSG_INSTALL:
                handleInstall(); //
                break;
        ......
}

    private void handleStreamValidateAndCommit() {
        ......
            if (unrecoverableFailure != null) {
                onSessionVerificationFailure(unrecoverableFailure);
                // fail other child sessions that did not already fail
                for (int i = nonFailingSessions.size() - 1; i >= 0; --i) {
                    PackageInstallerSession session = nonFailingSessions.get(i);
                    session.onSessionVerificationFailure(unrecoverableFailure);
                }
            }
        }

        if (!allSessionsReady) {
            return;
        }

        mHandler.obtainMessage(MSG_INSTALL).sendToTarget();
    }
在handleStreamValidateAndCommit又发送了消息MSG_INSTALL,实际上真正在执行的是在handleInstall中:
private void handleInstall() {
        ......

        // 对于 multiPackage 会话,请在锁之外读取子会话,因为在持有锁的情况下读取子会话可能会导致死锁 (b123391593)。
        List childSessions = getChildSessionsNotLocked();

        try {
            synchronized (mLock) {
                installNonStagedLocked(childSessions);
            }
        } catch (PackageManagerException e) {
            final String completeMsg = ExceptionUtils.getCompleteMessage(e);
            Slog.e(TAG, "Commit of session " + sessionId + " failed: " + completeMsg);
            destroyInternal();
            dispatchSessionFinished(e.error, completeMsg, null);
        }
    }

private void installNonStagedLocked(List childSessions)
            throws PackageManagerException {
        ......
            if (!success) {
                sendOnPackageInstalled(mContext, mRemoteStatusReceiver, sessionId,
                        isInstallerDeviceOwnerOrAffiliatedProfileOwnerLocked(), userId, null,
                        failure.error, failure.getLocalizedMessage(), null);
                return;
            }
            mPm.installStage(installingChildSessions);
        } else {
            mPm.installStage(installingSession);
        }
    }

        最后执行到了PMS的installStage方法。在上述的过程中,通过PackageInstaller维持了Session,把安装包写入到Session,真正的安装过程就要来看PMS了。

2.3 PMS执行安装

//PackageManagerService.java
void installStage(List children)
            throws PackageManagerException {
  //创建了类型未INIT_COPY的消息
        final Message msg = mHandler.obtainMessage(INIT_COPY);
  //创建InstallParams,它对应于包的安装数据
        final MultiPackageInstallParams params =
                new MultiPackageInstallParams(UserHandle.ALL, children);
        params.setTraceMethod("installStageMultiPackage")
                .setTraceCookie(System.identityHashCode(params));
        msg.obj = params;

        Trace.asyncTraceBegin(TRACE_TAG_PACKAGE_MANAGER, "installStageMultiPackage",
                System.identityHashCode(msg.obj));
        Trace.asyncTraceBegin(TRACE_TAG_PACKAGE_MANAGER, "queueInstall",
                System.identityHashCode(msg.obj));
  //将InstallParams通过消息发送出去
        mHandler.sendMessage(msg);
    }

handler对INIT_COPY的消息进行处理:

//PackageManagerService.java
void doHandleMessage(Message msg) {
            switch (msg.what) {
                case INIT_COPY: {
                    HandlerParams params = (HandlerParams) msg.obj;
                    if (params != null) {
                        if (DEBUG_INSTALL) Slog.i(TAG, "init_copy: " + params);
                        Trace.asyncTraceEnd(TRACE_TAG_PACKAGE_MANAGER, "queueInstall",
                                System.identityHashCode(params));
                        Trace.traceBegin(TRACE_TAG_PACKAGE_MANAGER, "startCopy");
                      //执行APK拷贝动作
                        params.startCopy();
                        Trace.traceEnd(TRACE_TAG_PACKAGE_MANAGER);
                    }
                    break;
                }
                ......
            }
  
  final void startCopy() {
            if (DEBUG_INSTALL) Slog.i(TAG, "startCopy " + mUser + ": " + this);
            handleStartCopy();
            handleReturnCode();
        }

        在这里调用了两个方法handleStartCopy和handleReturnCode,其实现是在InstallParams 中。
在handleStartCopy,做了以下操作:

  • 检查空间大小,如果空间不够则释放无用空间
  • 覆盖原有安装位置的文件,并根据返回结果来确定函数的返回值,并设置installFlags
  • 确定是否有任何已安装的包验证器,如有,则延迟检测。主要分三步:首先新建一个验证Intent,然后设置相关的信息,之后获取验证器列表,最后向每个验证器发送验证Intent
public void handleStartCopy() {
  ......
    //解析包 返回最小的细节:pkgName、versionCode、安装所需空间大小、获取安装位置等
    pkgLite = PackageManagerServiceUtils.getMinimalPackageInfo(mContext,
                    origin.resolvedPath, installFlags, packageAbiOverride);
  ......
    //覆盖原有安装位置的文件,并根据返回结果来确定函数的返回值,并设置installFlags。
    if (ret == PackageManager.INSTALL_SUCCEEDED) {
                int loc = pkgLite.recommendedInstallLocation;
                if (loc == PackageHelper.RECOMMEND_FAILED_INVALID_LOCATION) {
                    ret = PackageManager.INSTALL_FAILED_INVALID_INSTALL_LOCATION;
                } else if (loc == PackageHelper.RECOMMEND_FAILED_ALREADY_EXISTS) {
                    ret = PackageManager.INSTALL_FAILED_ALREADY_EXISTS;
                } else if (loc == PackageHelper.RECOMMEND_FAILED_INSUFFICIENT_STORAGE) {
                    ret = PackageManager.INSTALL_FAILED_INSUFFICIENT_STORAGE;
                } else if (loc == PackageHelper.RECOMMEND_FAILED_INVALID_APK) {
                    ret = PackageManager.INSTALL_FAILED_INVALID_APK;
                } else if (loc == PackageHelper.RECOMMEND_FAILED_INVALID_URI) {
                    ret = PackageManager.INSTALL_FAILED_INVALID_URI;
                } else if (loc == PackageHelper.RECOMMEND_MEDIA_UNAVAILABLE) {
                    ret = PackageManager.INSTALL_FAILED_MEDIA_UNAVAILABLE;
                } else {
                     .......
                }
            }
  
  //安装参数
  final InstallArgs args = createInstallArgs(this);
            mVerificationCompleted = true;
            mIntegrityVerificationCompleted = true;
            mEnableRollbackCompleted = true;
            mArgs = args;

            if (ret == PackageManager.INSTALL_SUCCEEDED) {
                final int verificationId = mPendingVerificationToken++;

                // apk完整性校验
                if (!origin.existing) {
                    PackageVerificationState verificationState =
                            new PackageVerificationState(this);
                    mPendingVerification.append(verificationId, verificationState);

                    sendIntegrityVerificationRequest(verificationId, pkgLite, verificationState);
                    ret = sendPackageVerificationRequest(
                            verificationId, pkgLite, verificationState);

                    ......
                }

}

然后来看下handleReturnCode方法:

@Override
        void handleReturnCode() {
            ......
                if (mRet == PackageManager.INSTALL_SUCCEEDED) {
                  //执行APKcopy拷贝
                    mRet = mArgs.copyApk();
                }
          //执行安装
                processPendingInstall(mArgs, mRet);
            }
        }

APK的copy过程是如何拷贝的:

//packageManagerService.java
int copyApk() {
            Trace.traceBegin(TRACE_TAG_PACKAGE_MANAGER, "copyApk");
            try {
                return doCopyApk();
            } finally {
                Trace.traceEnd(TRACE_TAG_PACKAGE_MANAGER);
            }
        }

private int doCopyApk() {
            ......

            int ret = PackageManagerServiceUtils.copyPackage(
                    origin.file.getAbsolutePath(), codeFile);
            ......
            return ret;
        }
//继续追踪下去,他会到PackagemanagerSeriveUtils的copyFile方法

//PackagemanagerSeriveUtils
private static void copyFile(String sourcePath, File targetDir, String targetName)
            throws ErrnoException, IOException {
        if (!FileUtils.isValidExtFilename(targetName)) {
            throw new IllegalArgumentException("Invalid filename: " + targetName);
        }
        Slog.d(TAG, "Copying " + sourcePath + " to " + targetName);

        final File targetFile = new File(targetDir, targetName);
        final FileDescriptor targetFd = Os.open(targetFile.getAbsolutePath(),
                O_RDWR | O_CREAT, 0644);
        Os.chmod(targetFile.getAbsolutePath(), 0644);
        FileInputStream source = null;
        try {
            source = new FileInputStream(sourcePath);
            FileUtils.copy(source.getFD(), targetFd);
        } finally {
            IoUtils.closeQuietly(source);
        }
    }

        在这里就通过文件流的操作,把Apk拷贝到/data/app的目录下了。结束完拷贝之后,就要进入真正的安装了,流程如下:

/PackageManagerService.java
private void processPendingInstall(final InstallArgs args, final int currentStatus) {
        if (args.mMultiPackageInstallParams != null) {
            args.mMultiPackageInstallParams.tryProcessInstallRequest(args, currentStatus);
        } else {
          //安装结果
            PackageInstalledInfo res = createPackageInstalledInfo(currentStatus);
          //创建一个新线程来处理安转参数来进行安装
            processInstallRequestsAsync(
                    res.returnCode == PackageManager.INSTALL_SUCCEEDED,
                    Collections.singletonList(new InstallRequest(args, res)));
        }
    }

//排队执行异步操作
private void processInstallRequestsAsync(boolean success,
            List installRequests) {
        mHandler.post(() -> {
            if (success) {
                for (InstallRequest request : installRequests) {
                  //进行检验,如果之前安装失败,则清除无用信息
                    request.args.doPreInstall(request.installResult.returnCode);
                }
                synchronized (mInstallLock) {
                  //安装的核心方法,进行解析apk安装
                    installPackagesTracedLI(installRequests);
                }
                for (InstallRequest request : installRequests) {
                  //再次检验清除无用信息
                  
                    request.args.doPostInstall(
                            request.installResult.returnCode, request.installResult.uid);
                }
            }
            for (InstallRequest request : installRequests) {
              //备份、可能的回滚、发送安装完成先关广播
                restoreAndPostInstall(request.args.user.getIdentifier(), request.installResult,
                        new PostInstallData(request.args, request.installResult, null));
            }
        });
    }

看到了核心方法installPackagesTracedLI,接着内部执行到了installPackagesLI方法:

//PackageMmanagerSerice.java 
private void installPackagesLI(List requests) {
   .......
     //分析当前任何状态,分析包并对其进行初始化验证
     prepareResult =
          preparePackageLI(request.args, request.installResult);
      
  ......
    //根据准备阶段解析包的信息上下文,进一步解析
      final ScanResult result = scanPackageTracedLI(
                            prepareResult.packageToScan, prepareResult.parseFlags,
                            prepareResult.scanFlags, System.currentTimeMillis(),
                            request.args.user, request.args.abiOverride);     
    .......
      //验证扫描后包的信息好状态,确保安装成功
      reconciledPackages = reconcilePackagesLocked(
                            reconcileRequest, mSettings.mKeySetManagerService);
          
        //提交所有的包并更新系统状态。这是安装流中唯一可以修改系统状态的地方,必须在此阶段之前确定所有可预测的错误
        commitRequest = new CommitRequest(reconciledPackages,
                            mUserManager.getUserIds());
                    commitPackagesLocked(commitRequest);
  .......
    //完成APK安装
  executePostCommitSteps(commitRequest);
 }

由上面代码可知,installPackagesLI主要做了以下事情:

  • 分析当前任何状态,分析包并对其进行初始化验证
  • 根据准备阶段解析包的信息上下文,进一步解析
  • 验证扫描后包的信息好状态,确保安装成功
  • 提交所有骚哦欧庙的包并更新系统状态
  • 完成APK安装

在 preparePackageLI() 内使用 PackageParser2.parsePackage() 解析AndroidManifest.xml,获取四大组件等信息;使用ParsingPackageUtils.getSigningDetails() 解析签名信息;重命名包最终路径 等。

完成了解析和校验准备工作后,最后一步就是对apk的安装了。这里调用了executePostCommitSteps准备app数据,并执行dex优化。

//PackageManagerService.java
private void executePostCommitSteps(CommitRequest commitRequest) {
  //进行安装
  prepareAppDataAfterInstallLIF(pkg);
   .......
   final boolean performDexopt =
                    (!instantApp || Global.getInt(mContext.getContentResolver(),
                    Global.INSTANT_APP_DEXOPT_ENABLED, 0) != 0)
                    && !pkg.isDebuggable()
                    && (!onIncremental);
  
  //为新的代码路径准备应用程序配置文件
  mArtManagerService.prepareAppProfiles(
                    pkg,
                    resolveUserIds(reconciledPkg.installArgs.user.getIdentifier()),
  
  if (performDexopt) {

             ......
               //其中分配了 dexopt 所需的库文件
               PackageSetting realPkgSetting = result.existingSettingCopied
                        ? result.request.pkgSetting : result.pkgSetting;
                if (realPkgSetting == null) {
                    realPkgSetting = reconciledPkg.pkgSetting;
                }
                
                            //执行dex优化
                mPackageDexOptimizer.performDexOpt(pkg, realPkgSetting,
                        null /* instructionSets */,
                        getOrCreateCompilerPackageStats(pkg),
                        mDexManager.getPackageUseInfoOrDefault(packageName),
                        dexoptOptions);
                Trace.traceEnd(TRACE_TAG_PACKAGE_MANAGER);
            }
}

在prepareAppDataAfterInstallLIF方法中,经过一系列的调用,最中会调用到 mInstaller.createAppData,这里也是调用Installd守护进程的入口:

public class Installer extends SystemService {
    
   @Override
    public void onStart() {
        if (mIsolated) {
            mInstalld = null;
        } else {
          //通过Binder调用到进程installd
            connect();
        }
    }

    private void connect() {
        IBinder binder = ServiceManager.getService("installd");
        ......

        if (binder != null) {
            mInstalld = IInstalld.Stub.asInterface(binder);
            try {
                invalidateMounts();
            } catch (InstallerException ignored) {
            }
        } else {
            Slog.w(TAG, "installd not found; trying again");
            BackgroundThread.getHandler().postDelayed(() -> {
                connect();
            }, DateUtils.SECOND_IN_MILLIS);
        }
    }
  
     public long createAppData(String uuid, String packageName, int userId, int flags, int appId,
            String seInfo, int targetSdkVersion) throws InstallerException {
        if (!checkBeforeRemote()) return -1;
        try {
          //进行安装操作
            return mInstalld.createAppData(uuid, packageName, userId, flags, appId, seInfo,
                    targetSdkVersion);
        } catch (Exception e) {
            throw InstallerException.from(e);
        }
    }
    }

可以看到最终调用了Installd的createAppData方法进行安装。Installer是Java层提供的Java API接口,Installd 则是在init进程启动的具有root权限的Daemon进程。

在processInstallRequestsAsync最后一步时调用了restoreAndPostInstall,在安装完成时会发送POST_INSTALL消息:

//PackageManagerService.java
private void restoreAndPostInstall(
            int userId, PackageInstalledInfo res, @Nullable PostInstallData data) {
  
  .......
    if (!doRestore) {
            
            if (DEBUG_INSTALL) Log.v(TAG, "No restore - queue post-install for " + token);

            Trace.asyncTraceBegin(TRACE_TAG_PACKAGE_MANAGER, "postInstall", token);

            Message msg = mHandler.obtainMessage(POST_INSTALL, token, 0);
            mHandler.sendMessage(msg);
        }
}

void doHandleMessage(Message msg) {
  .......
  case POST_INSTALL: {
    .......
      //处理安装结果
    handlePackagePostInstall(parentRes, grantPermissions,
                                killApp, virtualPreload, grantedPermissions,
                                whitelistedRestrictedPermissions, autoRevokePermissionsMode,
                                didRestore, args.installSource.installerPackageName, args.observer,
                                args.mDataLoaderType);
  }
}

private void handlePackagePostInstall(PackageInstalledInfo res, boolean grantPermissions,
            boolean killApp, boolean virtualPreload,
            String[] grantedPermissions, List whitelistedRestrictedPermissions,
            int autoRevokePermissionsMode,
            boolean launchedForRestore, String installerPackage,
            IPackageInstallObserver2 installObserver, int dataLoaderType) {
  
  ......
    sendPackageBroadcast(Intent.ACTION_PACKAGE_ADDED, packageName,
                        extras, 0 /*flags*/,
                        null /*targetPackage*/, null /*finishedReceiver*/,
                        updateUserIds, instantUserIds, newBroadcastWhitelist);
}

最后发送了ACTION_PACKAGE_ADDED广播,launcher接收到这个广播之后就会在桌面上添加应用图标了。

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