一、总体概览
C库：libcurl 3.7
目标平台：android
编译平台：ubuntu 12
编译工具：ndk r7 or later
二、已知方法
1. 官网上给了两种方法，第一种方法是使用android源代码来一块编译，原文如下：
Method using the static makefile:
see the build notes in the packages/Android/Android.mk file.
Android.mk如下：
# Google Android makefile for curl and libcurl
#
# This file can be used when building curl using the full Android source
# release or the NDK. Most users do not want or need to do this; please
# instead read the Android section in docs/INSTALL for alternate
# methods.
#
# Place the curl source (including this makefile) into external/curl/ in the
# Android source tree. Then build them with 'make curl' or just 'make libcurl'
# from the Android root. Tested with Android versions 1.5, 2.1-2.3
#
# Note: you must first create a curl_config.h file by running configure in the
# Android environment. The only way I've found to do this is tricky. Perform a
# normal Android build with libcurl in the source tree, providing the target
# "showcommands" to make. The build will eventually fail (because curl_config.h
# doesn't exist yet), but the compiler commands used to build curl will be
# shown. Now, from the external/curl/ directory, run curl's normal configure
# command with flags that match what Android itself uses. This will mean
# putting the compiler directory into the PATH, putting the -I, -isystem and
# -D options into CPPFLAGS, putting the -W, -m, -f, -O and -nostdlib options
# into CFLAGS, and putting the -Wl, -L and -l options into LIBS, along with the
# path to the files libgcc.a, crtbegin_dynamic.o, and ccrtend_android.o.
# Remember that the paths must be absolute since you will not be running
# configure from the same directory as the Android make. The normal
# cross-compiler options must also be set. Note that the -c, -o, -MD and
# similar flags must not be set.
#
# To see all the LIBS options, you'll need to do the "showcommands" trick on an
# executable that's already buildable and watch what flags Android uses to link
# it (dhcpcd is a good choice to watch). You'll also want to add -L options to
# LIBS that point to the out/.../obj/lib/ and out/.../obj/system/lib/
# directories so that additional libraries can be found and used by curl.
#
# The end result will be a configure command that looks something like this
# (the environment variable A is set to the Android root path which makes the
# command shorter):
#
# A=`realpath ../..` &&
# PATH="$A/prebuilt/linux-x86/toolchain/arm-eabi-X/bin:$PATH"
# ./configure --host=arm-linux CC=arm-eabi-gcc
# CPPFLAGS="-I $A/system/core/include ..."
# CFLAGS="-nostdlib -fno-exceptions -Wno-multichar ..."
# LIBS="$A/prebuilt/linux-x86/toolchain/arm-eabi-X/lib/gcc/arm-eabi/X
# /interwork/libgcc.a ..."
#
# Finally, copy the file COPYING to NOTICE so that the curl license gets put
# into the right place (but see the note about this below).
3. 第二中方法使用 android ndk的脚本自己定制一套工具链，方便配置变量
Method using a configure cross-compile (tested with Android NDK r7c, r8):
prepare the toolchain of the Android NDK for standalone use; this can be done by invoking the script:
./build/tools/make-standalone-toolchain.sh
which creates a usual cross-compile toolchain. Lets assume that you put this toolchain below /opt then invoke configure with something like:
export PATH=/opt/arm-linux-androideabi-4.4.3/bin:$PATH
./configure --host=arm-linux-androideabi [more configure options]
make
三、自己方法
第一种方法需要用到android源代码，很不方便；第二种需要配置很多configure参数才能保证make成功。我的方法是结合了以上两种方法，用./configure得到curl_config.h等文件，然后使用ndk-build来编译Android.mk，而不是直接用make.
1. 搭建NDK环境：
1.1 下载NDK
官网下载页：http://developer.android.com/tools/sdk/ndk/index.html下载下来后，解压缩
注：下载符合你操作系统位数的ndk；还有就是下载ndk32的，因为android的64位支持没多久，大部分还都是32位的；版本越新越好，新版本会修复很多编译器bug，支持更多的语言特性。
1.2 配置NDK环境参数
打开 ~/.bashrc文件:
export NDK_HOME=~/Android /android-ndk-r8
export PATH=$PATH:$NDK_HOME
export PATH=$PATH:$NDK_HOME/toolchains/arm-linux-androideabi-4.6/prebuilt/linux/bin
测试一下
ndk-build –v
注1：修改环境变量的方法有三种，但是以上这种关机后不会失效：
比如要把/etc/apache/bin目录添加到PATH中
- #PATH=$PATH:/etc/apache/bin
使用这种方法,每当登出PATH就会恢复
2. #vi /etc/profile
在适当位置添加PATH=$PATH:/etc/apache/bin
这种方法最好,除非你强制手动修改PATH的值,否则将不会被改变
3. #vi ~/.bash_profile
修改PATH行,把/etc/apache/bin添加进去
这种方法是针对用户起作用的
注2：ndk-build使用有两种方法
- cd ~/android-ndk-r9/samples/hello-jni/jni
ndk-build
2. $NDK_HOME/ndk-build -C ~/android-ndk-r9/samples/hello-jni/jni
用 -C 指出工程目录路径
2. 配置和编译libcurl
2.1 下载源代码http://curl.haxx.se/download.html，解压
2.2 命令行进入curl目录后,执行
./configure –host=arm-linux-androideabi
注：记住host一定是工具链前缀
2.3 把package/android/Android.mk修改一下，去掉后边的可执行文件相关的语句，我们只要生成静态库就行了。然后把package/android改为package/jni
注：文件结构必须是jni/Android.mk，否则ndk-build找不到。
2.4 命令行进入package，执行ndk-build,大功告成。