Question

TL; DR我试图通过JNI向Java发送std::function并在执行异步方法后将其用作Callable（请参阅SBCallable下）。有没有办法做到这一点？

我试图通过JNI从C ++发起一个http请求，获取响应并将其发送回C ++。

我的Java NetworkManager课程：

RequestQueue queue; //initialised in the constructor

private class SBCallable<V> implements Callable<V>{
        private String response;
        private int responseCode;
    public SBCallable(/**function from c++ to call?**/) {

    }
    public setResponseCode(int responseCode)
    {
         this.responseCode = responseCode;
    }
    public setResponse(String response)
    {
         this.response = response;
    }
    public V call() throws Exception {
        /**call my c++ function(response_code, response);**/
        return null;
    }
}

public void get(final String url,
                final HashMap<String, String> mHeaders,
                final SBCallable<Void> callback)
{
    queue.add(new StringRequest(
            Request.Method.GET,
            url,
            new Response.Listener<String>() {
                @Override
                public void onResponse(String response) {
                    try {
                        callback.setResponseCode(200); /**for test purposes**/
                        callback.setResponse(response);
                        callback.call();
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
            },
            new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {

                }
            })
    {
        @Override
        public HashMap<String, String> getHeaders() throws AuthFailureError 
        {
            return mHeaders;
        }
    });
}

我的C ++网络界面：

void get(const std::string &url,
         const std::vector<std::pair<std::string, std::string>> &headers,
         std::function<void(int, std::vector<char>)> response_fn)

JNI桥接代码：

// OnCreate, the app is saving a pointer to JVM.
void getHTTP(const std::string &url,
             const const std::vector<std::pair<std::string, std::string>> &headers,
             std::function<void(int, std::vector<char>)> response_fn_t /**callback function, with response code and content**/)
{
    JavaVM* jvm = app.getJVM();
    JNIEnv *env;
    jvm->GetEnv((void**)&env,JNI_VERSION_1_6);
    jobject headersMap = vectorStringPairToJavaHashMap(env, headers); // transforms from vector<pair<string, string>> to HashMap<String,String>
    jstring url = env->NewStringUTF(url.c_str());
    jclass clazz = env->FindClass("NetworkManager");
    jobject object = env->NewObject(clazz, env->GetMethodID(clazz, "<init>", "()V"));
    /**HOW DO I WRAP response_fn_t for Java to be able to call it? **/
    env->CallObjectMethod(object, env->GetMethodID(clazz, "get", "(Ljava/lang/String;Ljava/lang/Object;Ljava/lang/Object;)V"), url, headersMap, /**wrapped function here**/);
}

Java Callable中的Wrap C ++函数

0 个答案: