libwebsockets依赖libuv,libz,mbedtls，所以构建脚本需要提前构建以上几个库，下面介绍使用NDK的独立工具链（standalone toolchain）来编译步骤。独立工具链的参考链接为：https://developer.android.com/ndk/guides/standalone_toolchain
#!/bin/bash
# Build libwebsockets library for Android
# path to NDK
export NDK=
export ANDROID_NDK=${NDK}
export TOOLCHAIN=${NDK}/toolchain
export CORSS_SYSROOT=${NDK}/sysroot
export SYSROOT=${NDK}/platforms/android-22/arch-arm
set -e
# for zlib-1.2.8, libuv, mbedtls-2.11.0, libwebsockets-3.0
# create a local android toolchain
API=${3:-24}
$NDK/build/tools/make-standalone-toolchain.sh \
--toolchain=arm-linux-androideabi-4.9 \
--arch=arm \
--install-dir=`pwd`/android-toolchain-arm \
--platform=android-$API \
--stl=libc++ \
--force \
--verbose
# setup environment to use the gcc/ld from the android toolchain
export INSTALL_PATH=/media/luckfish/share_ext/libwebsockets_android/android-toolchain-arm
export TOOLCHAIN_PATH=`pwd`/android-toolchain-arm
export TOOL=arm-linux-androideabi
export NDK_TOOLCHAIN_BASENAME=${TOOLCHAIN_PATH}/bin/${TOOL}
export PATH=`pwd`/android-toolchain-arm/bin:$PATH
export CC=$NDK_TOOLCHAIN_BASENAME-gcc
export CXX=$NDK_TOOLCHAIN_BASENAME-g++
export LINK=${CXX}
export LD=$NDK_TOOLCHAIN_BASENAME-ld
export AR=$NDK_TOOLCHAIN_BASENAME-ar
export RANLIB=$NDK_TOOLCHAIN_BASENAME-ranlib
export STRIP=$NDK_TOOLCHAIN_BASENAME-strip
export PLATFORM=android
export CFLAGS="D__ANDROID_API__=$API"
# configure and build libuv
[ ! -f ./android-toolchain-arm/lib/libuv.so ] && {
cd libuv
echo "=============================================>> build libuv"
PATH=$TOOLCHAIN_PATH:$PATH make clean
PATH=$TOOLCHAIN_PATH:$PATH make
PATH=$TOOLCHAIN_PATH:$PATH make install
echo "<<============================================= build libuv"
cd ..
}
# configure and build zlib
[ ! -f ./android-toolchain-arm/lib/libz.a ] && {
cd zlib-1.2.8
echo "=============================================>> build libz"
PATH=$TOOLCHAIN_PATH:$PATH make clean
PATH=$TOOLCHAIN_PATH:$PATH make
PATH=$TOOLCHAIN_PATH:$PATH make install
echo "<<============================================= build libz"
cd ..
}
# configure and build mbedtls
[ ! -f ./android-toolchain-arm/lib/libmbedtls.so ] && {
echo "=============================================>> build mbedtls"
PREFIX=$TOOLCHAIN_PATH
cd mbedtls-2.11.0
[ ! -d build ] && mkdir build
cd build
export CFLAGS="$CFLAGS -fomit-frame-pointer"
PATH=$TOOLCHAIN_PATH:$PATH cmake .. -DCMAKE_TOOLCHAIN_FILE=`pwd`/../cross-arm-android-gnueabi.cmake \
-DCMAKE_INSTALL_PREFIX:PATH=${INSTALL_PATH} \
-DCMAKE_BUILD_TYPE=RELEASE -DUSE_SHARED_MBEDTLS_LIBRARY=On
PATH=$TOOLCHAIN_PATH:$PATH make clean
PATH=$TOOLCHAIN_PATH:$PATH make SHARED=1
PATH=$TOOLCHAIN_PATH:$PATH make install
echo "<<============================================= build mbedtls"
cd ../..
}
# configure and build libwebsockets
[ ! -f ./android-toolchain-arm/lib/libwebsockets.a ] && {
cd libwebsockets
[ ! -d build ] && mkdir build
cd build
echo "=============================================>> build libwebsockets"
PATH=$TOOLCHAIN_PATH:$PATH cmake .. -DCMAKE_TOOLCHAIN_FILE=`pwd`/../cross-arm-android-gnueabi.cmake \
-DCMAKE_INSTALL_PREFIX:PATH=${INSTALL_PATH} \
-DLWS_WITH_LWSWS=1 \
-DLWS_WITH_MBEDTLS=1 \
-DLWS_WITHOUT_TESTAPPS=1 \
-DLWS_MBEDTLS_LIBRARIES="${INSTALL_PATH}/lib/libmbedcrypto.a;${INSTALL_PATH}/lib/libmbedtls.a;${INSTALL_PATH}/lib/libmbedx509.a" \
-DLWS_MBEDTLS_INCLUDE_DIRS=${INSTALL_PATH}/include \
-DLWS_LIBUV_LIBRARIES=${INSTALL_PATH}/lib/libuv.so \
-DLWS_LIBUV_INCLUDE_DIRS=${INSTALL_PATH}/include \
-DLWS_ZLIB_LIBRARIES=${INSTALL_PATH}/lib/libz.so \
-DLWS_ZLIB_INCLUDE_DIRS=${INSTALL_PATH}/include
PATH=$TOOLCHAIN_PATH:$PATH make
PATH=$TOOLCHAIN_PATH:$PATH make install
echo "<<============================================= build libwebsockets"
cd ../..
}
后记：
如果单独编译mbedtls库，可以使用命令：
1）cmake .. -DCMAKE_TOOLCHAIN_FILE=`pwd`/../cross-arm-android-gnueabi.cmake -DCMAKE_BUILD_TYPE=RELEASE -DUSE_SHARED_MBEDTLS_LIBRARY=On
2）删除build目录下的CMakeCache.txt
3）cmake -DUSE_SHARED_MBEDTLS_LIBRARY=On ..
4）make
得到动态库，其中cross-arm-android-gnueabi.cmake 指定了编译工具，
cross-arm-android-gnueabi.cmake文件如下：
#
# CMake Toolchain file for crosscompiling on ARM.
#
# This can be used when running cmake in the following way:
# cd build/
# cmake .. -DCMAKE_TOOLCHAIN_FILE=../cross-arm-linux-gnueabihf.cmake
#
set(CROSS_PATH /media/xxx/share_ext/libwebsockets_android/android-toolchain-arm)
# Target operating system name.
set(CMAKE_SYSTEM_NAME Android)
# Target build dynamic libs.
set(BUILD_SHARED_LIBS ON)
# Name of C compiler.
set(CMAKE_C_COMPILER "${CROSS_PATH}/bin/arm-linux-androideabi-gcc")
set(CMAKE_CXX_COMPILER "${CROSS_PATH}/bin/arm-linux-androideabi-g++")
# Where to look for the target environment. (More paths can be added here)
set(CMAKE_FIND_ROOT_PATH "${CROSS_PATH}")
# Adjust the default behavior of the FIND_XXX() commands:
# search programs in the host environment only.
set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
# Search headers and libraries in the target environment only.
set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)