安装 apk，居然意外收获

个人比较喜欢命令行操作，特别是在 android开发的时候，方便！

在终端敲入命令，会出现关于adb工具的使用帮助。

adb -help

安装 apk，一般都是使用命令：

adb install **

在 adb -help 可以看到如下帮助：

adb install [-l] [-r] [-s] <file> - push this package file to the device and install it
                                 ('-l' means forward-lock the app)
                                 ('-r' means reinstall the app, keeping its data)
                                 ('-s' means install on SD card instead of internal storage)

如果你的手机或者模拟器已经安装了某个 apk，如 my.apk，那么你没有卸载 my.apk 的话，（命令行操作）再次安装该 apk 的话，会包如下错误：

Failure [INSTALL_FAILED_ALREADY_EXISTS]

-r 参数表示重新安装 apk，所以加上这个参数就不会有上述错误。

-s 参数表示安装 apk 到 SDcard，好了。郁闷的时刻到来！-l 参数什么意思？

自己做了很多测试，也不是很明白。最后在 sdk api上找到答案。感谢：sdk-path/docs/guide/appendix/market-filters.html

看下面这张截图，也许回得到点启发。大致意思是在发布 apk 到 android market上时，可以设置相关标志位来保护你的 app。

那么，再从 PackageManager.java 源码中寻找一些蛛丝马迹、、、、、、

该类是一个抽象类，声明如下：

/**
 * Class for retrieving various kinds of information related to the application
 * packages that are currently installed on the device.
 *
 * You can find this class through {@link Context#getPackageManager}.
 */
public abstract class PackageManager 

PackageManager 主要是用于获得安装在设备上应用的各种信息。看一个常量和一个方法，定义如下：

    /**
     * Flag parameter for {@link #installPackage(android.net.Uri, IPackageInstallObserver, int)} to
     * indicate that this package should be installed as forward locked, i.e. only the app itself
     * should have access to its code and non-resource assets.
     * @hide
     */
    public static final int INSTALL_FORWARD_LOCK = 0x00000001;

    /**
     * @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);

可以看出，INSTALL_FORWARD_LOCK 常量主要是用来保护自己的 app，installPackage方法的参数 int flags 可以是INSTALL_FORWARD_LOCK。

注意：在 android1.5 源码中，INSTALL_FORWARD_LOCK 常量是ORWARD_LOCK_PACKAGE。

好了，目前为止，-l 参数是用来保护自己的 app，即forward-locked（正向锁定）！平时安装测试 app，该参数没什么作用！