为 Android 添加 OpenSSL 支持

The Qt installation package comes with OpenSSL support but the OpenSSL libraries are not part of the package due to legal restrictions in some countries. If your application depends on OpenSSL, consider packaging the SSL libraries with your Application Package (APK) as the target device may or may not have them.

可以使用 QSslSocket::supportsSsl () static function to check for SSL support on the target device. First include the header:

#include <QSslSocket>

Then use the following line to check if SSL is supported:

qDebug() << "Device supports OpenSSL: " << QSslSocket::supportsSsl();

Check Qt Creator's Application Output section or the Android logcat for the result.

构建用于 Android 的 OpenSSL

A convenient Github repository with prebuilt and a build script can be used without the need for manual step-by-step build. For more information, see OpenSSL for Android . If you download the repository, you can then skip to Using OpenSSL Libraries with Qt for Android .

The following instructions guide you to build the OpenSSL libraries manually:

下载 OpenSSL 1.1.x sources.
Extract the sources to a folder and navigate to that folder using the CLI.

注意： If your development platform is Windows, you need msys with perl v5.14 or later to build OpenSSL.

Add the Android LLVM toolchain (NDK r20b or r21) to your path:

export PATH="<android_ndk_path>/toolchains/llvm/prebuilt/<host>/bin":$PATH

Configure the OpenSSL sources to build for Android using the following command:
```
./Configure shared android-<arch> -D__ANDROID_API__=21
							
```
Where <arch> can take a value of: arm , arm64 , x86 , x86_64 .

注意： You must consider enabling or disabling the SSL features based on the legal restrictions in the region where your application is available. For more information about the configurable features, see OpenSSL Configure Options .
To build libcrypto and libssl shared libraries that are not versioned, but with an _1_1 suffix, run:
```
make -j$(nproc) SHLIB_VERSION_NUMBER= SHLIB_EXT=_1_1.so build_libs
							
```
Without a suffix, Android 5 (API 21) will load the system libraries libcrypto.so and libssl.so , which are OpenSSL 1.0, rather than your libraries.

If you want to use a different suffix, you must change SHLIB_EXT in the previous command, and set the ANDROID_OPENSSL_SUFFIX environment variable before you access the Qt Network API.
```
make -j$(nproc) SHLIB_VERSION_NUMBER= SHLIB_EXT=<custom_suffix>.so build_libs
							
```
Then set the environment variable in your main.ccp file:
```
qputenv("ANDROID_OPENSSL_SUFFIX", "<custom_suffix>");
							
```
注意： Android does not load versioned libraries.

Using OpenSSL Libraries with Qt for Android

Depending on the method you obtained the OpenSSL libraries, you can use one of the following step to include those libraries in your project:

Using the project files:
Using the convenience OpenSSL for Android repository, you can directly add the include projects into your own project, by adding the following to your .pro 文件：
```
android: include(<path/to/android_openssl/openssl.pri)
							
```
Or if using CMake, add the following to your CMakeLists.txt :
```
if (ANDROID)
    include(<path/to/android_openssl/CMakeLists.txt)
endif()
							
```
Alternatively, you can either use the Qt for Android variable ANDROID_EXTRA_LIBS to add extra libraries, mainly libcrypto and libssl . For QMake use:
```
ANDROID_EXTRA_LIBS += \
    <path_to_libs_dir>/libcrypto_1_1.so \
    <path_to_libs_dir>/libssl_1_1.so
							
```
For CMake:
```
set(ANDROID_EXTRA_LIBS
    <path_to_libs_dir>/ibcrypto_1_1.so
    <path_to_libs_dir>/libssl_1_1.so
CACHE INTERNAL "")
							
```
注意： When targeting multiple architectures, include OpenSSL libraries for all the targeted architectures.
Using Qt Creator, it is possible to add extra libraries. For more information, see Qt Creator: Adding Libraries to Projects .