APK安装使用意图在Android上时启用降级4.2+ [英] Enable downgrade when installing apk using intent on Android 4.2+
问题描述
可以安装APK时使用的意图在Android 4.2+启用降级？我发现，这是可能的，通过shell命令安装应用程序时（使用-d） ADB安装-r -d＆LT;链接APK＆GT; ，所以我希望它是在某种程度上可能也可以通过意向。我一直在寻找某种标志或东西，但我didin't找到任何有用的。
这是我的意图打开包装安装：
意向意图=新的意图（Intent.ACTION_VIEW）;
乌里applicatonFileUri = Uri.fromFile（applicationFile）;
intent.setDataAndType（applicatonFileUri，PACKAGE_TYPE）;
startActivity（意向）;
这是不可能的非平台（第三方）的应用程序：你必须让安装的请求的直接<一个href="https://developer.android.com/reference/android/content/pm/PackageManager.html">PackageManager.
PackageManager有非公开的API，<一个href="https://android.googlesource.com/platform/frameworks/base/+/master/core/java/android/content/pm/PackageManager.java">installPackage() （行2584截至记者发稿）：
/ **
* @隐藏
*
*安装包。因为这可能需要一小会儿，结果会
*调回给定的观察者。安装会失败，如果调用上下文
*缺少{@link android.Manifest.permission＃INSTALL_PACKAGES}许可，如果
已安装*在包文件清单命名的包，或者如果没有空间
*可在设备上。
*
*参数packageURI包文件的位置来安装。这可以是一个文件：或
*'的内容：URI。
* @参数观测得到通知的观察员回调，包安装
* 完成。 {@link IPackageInstallObserver＃packageInstalled（字符串，INT）}会
*调用时出现这种情况。观察者可以为空，表明没有回调的需要。
*参数标志 - 可能值：{@link #INSTALL_FORWARD_LOCK}，
* {@link #INSTALL_REPLACE_EXISTING}，{@link #INSTALL_ALLOW_TEST}。
* @参数installerPackageName可选软件包正在执行的应用程序的名称
* 安装。这标识从市场包装来了。
* /
公共抽象无效installPackage（
乌里packageURI，IPackageInstallObserver观测，INT标志，
字符串installerPackageName）;
，其中可能的标志之一是 INSTALL_ALLOW_DOWNGRADE ：
/ **
*为{@link #installPackage}标志参数，以表明它是好的
*安装更新到一个应用程序中新安装的应用程序，具有较低的
*版本code比当前已安装的应用程序。
*
* @隐藏
* /
公共静态最终诠释INSTALL_ALLOW_DOWNGRADE = 0x00000080;
所有这些API是隐藏的，而不是针对第三方应用程序进行访问。现在，你可以尝试反映，但我pretty的积极的平台，将限制对它们的访问反正。
Is possible to enable downgrade when installing apk using intent on Android 4.2+? I found out that it is possible, when installing app via command shell (using -d) adb install -r -d <link to apk>, so I hope it is somehow possible also via Intent. I was looking for some flag or something, but I didin't find anything helpful.
This is my intent to open package installer:
Intent intent = new Intent(Intent.ACTION_VIEW);
Uri applicatonFileUri = Uri.fromFile(applicationFile);
intent.setDataAndType(applicatonFileUri, PACKAGE_TYPE);
startActivity(intent);
That's not possible for non-platform (3rd-party) apps: you have to make the installation request directly to PackageManager.
PackageManager has non-public API, installPackage() (line 2584 as of this writing):
/**
* @hide
*
* Install a package. Since this may take a little while, the result will
* be posted back to the given observer. An installation will fail if the calling context
* lacks the {@link android.Manifest.permission#INSTALL_PACKAGES} permission, if the
* package named in the package file's manifest is already installed, or if there's no space
* available on the device.
*
* @param packageURI The location of the package file to install. This can be a 'file:' or a
* 'content:' URI.
* @param observer An observer callback to get notified when the package installation is
* complete. {@link IPackageInstallObserver#packageInstalled(String, int)} will be
* called when that happens. observer may be null to indicate that no callback is desired.
* @param flags - possible values: {@link #INSTALL_FORWARD_LOCK},
* {@link #INSTALL_REPLACE_EXISTING}, {@link #INSTALL_ALLOW_TEST}.
* @param installerPackageName Optional package name of the application that is performing the
* installation. This identifies which market the package came from.
*/
public abstract void installPackage(
Uri packageURI, IPackageInstallObserver observer, int flags,
String installerPackageName);
where one of the possible flags is INSTALL_ALLOW_DOWNGRADE:
/**
* Flag parameter for {@link #installPackage} to indicate that it is okay
* to install an update to an app where the newly installed app has a lower
* version code than the currently installed app.
*
* @hide
*/
public static final int INSTALL_ALLOW_DOWNGRADE = 0x00000080;
All these APIs are hidden and not accessible for 3rd-party apps. Now, you may try reflection, but I am pretty positive that platform will restrict access to them anyway.
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