在使用 CMake 的 C++ android 应用程序中使用 libcurl

Question

也许这个论坛已经有一些关于这个问题的答案，但是我已经尝试了很多解决方案，但我仍然没有解决这个问题。

我必须使用 C++ 制作一个 Android 应用程序，它使用 libcurl。

无论我做什么，我都无法运行我的程序，因为它找不到库。

在我的 .cpp 中，我使用这一行：

#include <curl/curl.h>

这是我的 CMakeLists.txt

# Sets the minimum version of CMake required to build the native
# library. You should either keep the default value or only pass a
# value of 3.4.0 or lower.

cmake_minimum_required(VERSION 3.4.1)

# Creates and names a library, sets it as either STATIC
# or SHARED, and provides the relative paths to its source code.
# You can define multiple libraries, and CMake builds it for you.
# Gradle automatically packages shared libraries with your APK.

add_library( # Sets the name of the library.
             native-lib

             # Sets the library as a shared library.
             SHARED

             # Provides a relative path to your source file(s).
             # Associated headers in the same location as their source
             # file are automatically included.
             src/main/cpp/native-lib.cpp )

# Searches for a specified prebuilt library and stores the path as a
# variable. Because system libraries are included in the search path by
# default, you only need to specify the name of the public NDK library
# you want to add. CMake verifies that the library exists before
# completing its build.

find_library( # Sets the name of the path variable.
              log-lib
              -lcurl

              # Specifies the name of the NDK library that
              # you want CMake to locate.
              log
              -lcurl )

# Specifies libraries CMake should link to your target library. You
# can link multiple libraries, such as libraries you define in the
# build script, prebuilt third-party libraries, or system libraries.




INCLUDE_DIRECTORIES($/usr/include/)

target_link_libraries( # Specifies the target library.
                       native-lib
                       -lcurl

                       # Links the target library to the log library
                       # included in the NDK.
                       ${log-lib} )

我使用了命令：

sudo aptitude install libcurl4-gnutls-dev

和

sudo aptitude install libcurl-dev

Answer 1

您应该使用内置功能来集成 libcurl：

[...]

find_package(CURL REQUIRED)
include_directories(${CURL_INCLUDE_DIRS})
add_library(native-lib SHARED src/main/cpp/native-lib.cpp) 
target_link_libraries(native-lib ${CURL_LIBRARIES})

您似乎正在为 Android 进行交叉编译，以下内容将使您为 Ubuntu 安装的 curl 库可用于编译（在上述内容之前添加它）。

set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY BOTH)
set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE BOTH)
set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE BOTH)

但是在链接步骤中可能会出现问题，因为您为 Ubuntu 安装了该库，而您要编译它的程序是用于 Android 的。 如果这不起作用，请尝试在您的交叉编译工具集中使用 curl 库（但我对此了解不多，无法告诉您如何操作）。

Answer 2

我认为您需要指示 cmake 查找 libcurl 依赖项。
请阅读How_To_Find_Libraries。
看看find_package和FindCURL module

作为快速入门，将以下内容添加到您的 CMakeLists.txt：

find_package(CURL REQUIRED)  
include_directories(${CURL_INCLUDE_DIRS})  
add_library(native-lib SHARED  ... )
target_link_libraries(native-lib ${CURL_LIBRARIES})

（更好的是：使用 target_include_directories() 而不是 include_directories()）。