mirror of https://github.com/python/cpython
137 lines
4.9 KiB
Markdown
137 lines
4.9 KiB
Markdown
# Python for Android
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These instructions are only needed if you're planning to compile Python for
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Android yourself. Most users should *not* need to do this. Instead, use one of
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the tools listed in `Doc/using/android.rst`, which will provide a much easier
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experience.
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## Prerequisites
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First, make sure you have all the usual tools and libraries needed to build
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Python for your development machine.
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Second, you'll need an Android SDK. If you already have the SDK installed,
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export the `ANDROID_HOME` environment variable to point at its location.
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Otherwise, here's how to install it:
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* Download the "Command line tools" from <https://developer.android.com/studio>.
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* Create a directory `android-sdk/cmdline-tools`, and unzip the command line
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tools package into it.
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* Rename `android-sdk/cmdline-tools/cmdline-tools` to
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`android-sdk/cmdline-tools/latest`.
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* `export ANDROID_HOME=/path/to/android-sdk`
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The `android.py` script also requires the following commands to be on the `PATH`:
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* `curl`
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* `java` (or set the `JAVA_HOME` environment variable)
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* `tar`
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* `unzip`
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## Building
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Python can be built for Android on any POSIX platform supported by the Android
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development tools, which currently means Linux or macOS. This involves doing a
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cross-build where you use a "build" Python (for your development machine) to
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help produce a "host" Python for Android.
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The easiest way to do a build is to use the `android.py` script. You can either
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have it perform the entire build process from start to finish in one step, or
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you can do it in discrete steps that mirror running `configure` and `make` for
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each of the two builds of Python you end up producing.
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The discrete steps for building via `android.py` are:
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```sh
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./android.py configure-build
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./android.py make-build
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./android.py configure-host HOST
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./android.py make-host HOST
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```
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`HOST` identifies which architecture to build. To see the possible values, run
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`./android.py configure-host --help`.
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To do all steps in a single command, run:
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```sh
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./android.py build HOST
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```
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In the end you should have a build Python in `cross-build/build`, and an Android
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build in `cross-build/HOST`.
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You can use `--` as a separator for any of the `configure`-related commands –
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including `build` itself – to pass arguments to the underlying `configure`
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call. For example, if you want a pydebug build that also caches the results from
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`configure`, you can do:
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```sh
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./android.py build HOST -- -C --with-pydebug
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```
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## Testing
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The test suite can be run on Linux, macOS, or Windows:
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* On Linux, the emulator needs access to the KVM virtualization interface, and
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a DISPLAY environment variable pointing at an X server.
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* On Windows, you won't be able to do the build on the same machine, so you'll
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have to copy the `cross-build/HOST` directory from somewhere else.
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The test suite can usually be run on a device with 2 GB of RAM, but this is
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borderline, so you may need to increase it to 4 GB. As of Android
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Studio Koala, 2 GB is the default for all emulators, although the user interface
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may indicate otherwise. Locate the emulator's directory under `~/.android/avd`,
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and find `hw.ramSize` in both config.ini and hardware-qemu.ini. Either set these
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manually to the same value, or use the Android Studio Device Manager, which will
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update both files.
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Before running the test suite, follow the instructions in the previous section
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to build the architecture you want to test. Then run the test script in one of
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the following modes:
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* In `--connected` mode, it runs on a device or emulator you have already
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connected to the build machine. List the available devices with
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`$ANDROID_HOME/platform-tools/adb devices -l`, then pass a device ID to the
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script like this:
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```sh
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./android.py test --connected emulator-5554
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```
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* In `--managed` mode, it uses a temporary headless emulator defined in the
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`managedDevices` section of testbed/app/build.gradle.kts. This mode is slower,
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but more reproducible.
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We currently define two devices: `minVersion` and `maxVersion`, corresponding
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to our minimum and maximum supported Android versions. For example:
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```sh
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./android.py test --managed maxVersion
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```
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By default, the only messages the script will show are Python's own stdout and
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stderr. Add the `-v` option to also show Gradle output, and non-Python logcat
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messages.
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Any other arguments on the `android.py test` command line will be passed through
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to `python -m test` – use `--` to separate them from android.py's own options.
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See the [Python Developer's
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Guide](https://devguide.python.org/testing/run-write-tests/) for common options
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– most of them will work on Android, except for those that involve subprocesses,
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such as `-j`.
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Every time you run `android.py test`, changes in pure-Python files in the
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repository's `Lib` directory will be picked up immediately. Changes in C files,
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and architecture-specific files such as sysconfigdata, will not take effect
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until you re-run `android.py make-host` or `build`.
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## Using in your own app
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See `Doc/using/android.rst`.
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