Android项目的CMakeLists.txt代码如下，so文件放在项目的$Project/app/src/main/jniLibs/$arch下，
$arch替换为arm64-v8a armv7a等

cmake_minimum_required(VERSION 3.4.1)
set(ARCH arch-arm64)
set(libs_DIR /Users/musictom/libs/android/${ARCH}/usr/lib)
set(libs_include_DIR /Users/musictom/libs/android/${ARCH}/usr/include)

add_library(ghttp-lib SHARED IMPORTED)
set_target_properties(ghttp-lib PROPERTIES IMPORTED_LOCATION
             ${libs_DIR}/libghttp.so)

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).
             src/main/cpp/native-lib.cpp )

target_link_libraries( # Specifies the target library.
                       native-lib my-lib ghttp-lib pocofoundation-lib poconet-lib pocoutil-lib

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

app.gradle如下：

apply plugin: 'com.android.application'

android {
    compileSdkVersion 25
    buildToolsVersion "25.0.2"
    defaultConfig {
        applicationId "com.example.musictom.andcpp"
        minSdkVersion 21
        targetSdkVersion 25
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
        externalNativeBuild {
            cmake {
                cppFlags "-std=c++11 -frtti -fexceptions -I/Users/musictom/libs/android/arch-arm64/usr/include/"
            }
        }
        ndk {
            // Specifies the ABI configurations of your native
            // libraries Gradle should build and package with your APK.
            //'x86', 'x86_64',
abiFilters 'arm64-v8a'
        }
        // 设置so文件路径 so文件如果不在jniLibs目录下，需要在这里指定目录
        //sourceSets {
        //    main {
        //        jniLibs.srcDirs = ['src/main/jni/arm64-v8a']
        //    }
        //}
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
    externalNativeBuild {
        cmake {
            path "CMakeLists.txt"
        }
    }
}

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
        exclude group: 'com.android.support', module: 'support-annotations'
    })
    compile 'com.android.support.constraint:constraint-layout:1.0.0-alpha7'
    testCompile 'junit:junit:4.12'
}

native-lib.cpp代码如下：

#include <jni.h>
#include <string>

#include <ghttp/ghttp.h>

#include <Poco/Net/HTTPClientSession.h>
#include <Poco/Net/HttpRequest.h>
#include <Poco/Net/HttpResponse.h>
#include <Poco/StreamCopier.h>
#include <Poco/Net/HTMLForm.h>
#include <Poco/Net/NetException.h>
#include <Poco/BinaryReader.h>
#include <Poco/URI.h>
#include <string>

std::string get_ghttp() {
    /* This is the http request object */
    ghttp_request *request = NULL;
    /* Allocate a new empty request object */
    request = ghttp_request_new();
    /* Set the URI for the request object */
    ghttp_set_uri(request, "http://www.fuhan.org/wechat/verify");
    /* Close the connection after you are done. */
    ghttp_set_header(request, http_hdr_Connection, "close");
    /* Prepare the connection */
    ghttp_prepare(request);
    /* Process the request */
    ghttp_process(request);
    /* Write out the body. Note that the body of the request may not be null terminated so we have to be careful of the length. */
    //fwrite(ghttp_get_body(request), ghttp_get_body_len(request), 1, stdout);
    char* buf = ghttp_get_body(request);
    std::string s = buf;
    /* Destroy the request. This closes any file descriptors that may be open and will free any memory associated with the request. */
    ghttp_request_destroy(request);
    return s;
}

extern std::string aa();
extern "C"
JNIEXPORT jstring JNICALL
Java_com_example_musictom_andcpp_MainActivity_stringFromJNI(
        JNIEnv* env,
        jobject /* this */) {
    std::string hello = "Hello from C++";
    hello = aa();
    std::string result;
    std::string responseText;

    if (false) {

        try {
            Poco::URI url("http://www.fuhan.org");
            Poco::Net::HTTPClientSession session(url.getHost(), url.getPort());
            //Poco::Net::HTTPClientSession s("www.cnblogs.com");

            //Poco::Net::HTTPRequest request(Poco::Net::HTTPRequest::HTTP_GET, "/auroratony/archive/2012/06/06/2537516.html");
            Poco::Net::HTTPRequest request(Poco::Net::HTTPRequest::HTTP_GET, "/wechat/verify",
                                           Poco::Net::HTTPRequest::HTTP_1_1);
            //request.set("/wechat/verify", "");

            //Poco::Net::HTMLForm form;
            //form.add("entry1", "value1");
            //form.prepareSubmit(request);
            session.sendRequest(request);
            Poco::Net::HTTPResponse response;

            std::istream &rs = session.receiveResponse(response);

            //Poco::StreamCopier copier;
            //copier.copyToString(rs, responseText);
std::istreambuf_iterator<char> eos;
            std::string s(std::istreambuf_iterator<char>(rs), eos);
            responseText = s;
        }
        catch (Poco::Net::NetException &ex) {
            result = ex.displayText();
            responseText = "error:" + result;
        }
    }
    else {
        responseText = get_ghttp();
    }

    return env->NewStringUTF(responseText.c_str());
}