在
Android 4.2上使用intent安装apk时可以启用降级吗？我发现有可能,当通过命令shell安装app时(使用-d)adb install -r -d< link to apk>,所以我希望它也可以通过Intent以某种方式实现.我正在寻找一些旗帜或东西,但我没有找到任何有用的东西.
这是我打开包安装程序的意图：
Intent intent = new Intent(Intent.ACTION_VIEW); Uri applicatonFileUri = Uri.fromFile(applicationFile); intent.setDataAndType(applicatonFileUri,PACKAGE_TYPE); startActivity(intent);
解决方法
对于非平台(第三方)应用程序而言,这是不可能的：您必须直接向
PackageManager发出安装请求.
PackageManager具有非公共API,installPackage()(撰写本文时第2584行)：
/**
* @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);
其中一个可能的标志是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;
所有这些API都是隐藏的,第三方应用无法访问.现在,您可以尝试反思,但我非常肯定平台会限制对它们的访问.
