PackageManagerService之应用卸载

应用卸载从这里作为入口吧，这个类位于

com.android.settings进程中，com.android.settings.SubSettings

应用卸载入口

package com.android.settings;

import android.util.Log;

/**
 * Stub class for showing sub-settings; we can't use the main Settings class
 * since for our app it is a special singleTask class.
 */
public class SubSettings extends SettingsActivity {

    @Override
    public boolean onNavigateUp() {
        finish();
        return true;
    }

    @Override
    protected boolean isValidFragment(String fragmentName) {
        Log.d("SubSettings", "Launching fragment " + fragmentName);
        return true;
    }
}

啥都没有，真正的实现在

com.android.settings.applications.appinfo.AppButtonsPreferenceController中的UninstallAndDisableButtonListener内部类中

private class UninstallAndDisableButtonListener implements View.OnClickListener {

        @Override
        public void onClick(View v) {
            final String packageName = mAppEntry.info.packageName;
            // Uninstall
           ....
           ....
           ....
           ....
           // 一堆判断，判断用户类型，需要卸载的app类型
            } else if ((mAppEntry.info.flags & ApplicationInfo.FLAG_INSTALLED) == 0) {
                uninstallPkg(packageName, true, false);
            } else {
               // 一般三方应用都在到这里
                uninstallPkg(packageName, false, false);
            }
        }
    }

// 最终还是用过隐试匹配到com.android.packageinstaller进程中的com.android.packageinstaller.UninstallerActivity
void uninstallPkg(String packageName, boolean allUsers, boolean andDisable) {
        stopListeningToPackageRemove();
        // 应用包名
        Uri packageUri = Uri.parse("package:" + packageName);
        Intent uninstallIntent = new Intent("android.intent.action.UNINSTALL_PACKAGE", packageUri);
        uninstallIntent.putExtra("android.intent.extra.UNINSTALL_ALL_USERS", allUsers);

        mMetricsFeatureProvider.action(
                mActivity, SettingsEnums.ACTION_SETTINGS_UNINSTALL_APP);
        mFragment.startActivityForResult(uninstallIntent, mRequestUninstall);
        mDisableAfterUninstall = andDisable;
    }

最终唤起一个卸载对话框

卸载对话框

UninstallerUninstalling

点击确定就会从UninstallerActivity跳转到UninstallerUninstalling中，是不是比较熟悉，就是安装的逆向操作

// 首先还是注册监听,这次对应的文件就是uninstall_results.xml
mUninstallId = UninstallEventReceiver.addObserver(this,
                        EventResultPersister.GENERATE_NEW_ID, this);

// 这里是一个IPC的过程，注意这里如果需要调试的话，不是packageinstaller进程中的PackageInstaller类
// 这里同样包装了一个延迟意图，删除后PMS的回调
// 而是直接在PackageInstallerService中uninstall方法，卸载的时候没有用PackageInstaller做桥接
// ActivityThread->PackageManagerService->PackageInstallerService->uninstall方法
ActivityThread.getPackageManager().getPackageInstaller().uninstall(
                            new VersionedPackage(mAppInfo.packageName,
                                    PackageManager.VERSION_CODE_HIGHEST),
                            getPackageName(), flags, pendingIntent.getIntentSender(),
                            user.getIdentifier());

PackageManagerService

通过上面的代码会调用到PackageManagerService中的deletePackageVersioned方法

// mHandler的类型还是PackageHandler
mHandler.post(() -> {
            int returnCode;
            // 获取所卸载应用的PackageSetting信息，就是安装时候全量解析出来的信息
            final PackageSetting ps = mSettings.mPackages.get(internalPackageName);
            boolean doDeletePackage = true;
            if (ps != null) {
                final boolean targetIsInstantApp =
                        ps.getInstantApp(UserHandle.getUserId(callingUid));
                doDeletePackage = !targetIsInstantApp
                        || canViewInstantApps;
            }
            if (doDeletePackage) {
                if (!deleteAllUsers) {
                    // 卸载第三方应用一般都会走到这里
                    returnCode = deletePackageX(internalPackageName, versionCode,
                            userId, deleteFlags);
                } 
                ....
                ....
                ....
            try {
               // 这里会将之前包装的延迟意图发出，回调给UninstallerUninstalling中注册的回调
                observer.onPackageDeleted(packageName, returnCode, null);
            } catch (RemoteException e) {
                Log.i(TAG, "Observer no longer exists.");
            } //end catch
        });

PMS中的mPackages中保存了所有应用的信息

mPackages

deletePackageX中的代码比较多，主要执行了下面逻辑

1. 移除mPackages和mSettings中保存的应用信息
2. 清理应用在/data/app/包名的所有文件
3. 杀掉应用进程
4. mSettings中的部分信息回写package.xml
5. 通知packageinstaller卸载成功

package.xml是PMS用来记录应用部分信息的文件，PMS中经常出现，以某个应用举例看看他记录的内容

其实就是包名，签名，abi，版本号，权限等信息；

packages.xml在PMS启动的时候会进行读取（系统启动，WatchDog杀死PMS后重启等）