【RISC-V 生态软件系列】HaaS UI进阶教学之HaaSUI系统框架扩展JSAPI之异步操作及调度

名词解释





JSAPI注册&实现


1. 注册：

void register_download_jsapi()
{
    ariver::iot::ExtensionProxyBase* proxy = getJSApiExtensionProxy();
    proxy->REGISTER_JSAPI(&BrightnessApiExtension::download, Download, download);
}

2. 实现：

string downloadFile(string url)
{
    string content;

    // implement download & store to content

    return content;
}

void DownloadApiExtension::download(const std::string& callbackId,
                                    const std::string& params)
{
    ariver::iot::ExtensionProxyBase* proxy =
            ariver::iot::getJSApiExtensionProxy();

    std::string error;
    JQuick::Json jsonParams;
    JQuick::Json::object failJson;
    JQuick::Json::object jsonCallback;
    APIStatus status = API_Success;

    JQuick::Json::object data;
    JQuick::Json::object::iterator dataIter;

    JQuick::Json result;
    std::string url;

    jsonParams = JQuick::Json::parse(params, error);
    if (!error.empty()) {
        failJson["errorMessage"] =
                JQuick::Json(std::string("params must be json format!"));
        goto Fail;
    }

    url = jsonParams["url"].string_value();
    if (url.empty()) {
        failJson["errorMessage"] = JQuick::Json(std::string("parameter error"));
        goto Fail;
    }

    jsonCallback["result"] = downloadFile(url);

    result = JQuick::Json(jsonCallback);
    proxy->postCallback(callbackId, status, result.dump());

    return;

Fail:
    jsonCallback["result"] = failJson;
    result = JQuick::Json(jsonCallback);
    status = API_Failed;

    proxy->postCallback(callbackId, status, result.dump());
}
3. 子线程实现JSAPI




class downloadArgs {
public:
    downloadArgs(string url, string callbackId) :
            mUrl(url),
            mCallbackId(callbackId) {}

    string mUrl;
    string mCallbackId;
};

string downloadFile(string url)
{
    string content;

    // implement download & store to content
    printf("complete download url: %sn", url.c_str());

    content = "url: " + url + " has be downloaded";

    return content;
}

void* downloadTask(void* arg)
{
    downloadArgs* args = (downloadArgs*)arg;
    ariver::iot::ExtensionProxyBase* proxy =
            ariver::iot::getJSApiExtensionProxy();

    JQuick::Json::object jsonCallback;
    JQuick::Json result;

    APIStatus status = API_Success;

    jsonCallback["result"] = downloadFile(args->mUrl);

    result = JQuick::Json(jsonCallback);
    proxy->postCallback(args->mCallbackId, status, result.dump());

    printf("has postCallbackn");

    delete args;
    return nullptr;
}

void DownloadApiExtension::download(const std::string& callbackId,
                                    const std::string& params)
{
    printf("enter downloadn");

    ariver::iot::ExtensionProxyBase* proxy =
            ariver::iot::getJSApiExtensionProxy();

    std::string error;
    JQuick::Json jsonParams;
    JQuick::Json::object failJson;
    JQuick::Json::object jsonCallback;
    APIStatus status = API_Success;

    JQuick::Json::object data;
    JQuick::Json::object::iterator dataIter;

    JQuick::Json result;
    std::string url;
    downloadArgs* args;

    jsonParams = JQuick::Json::parse(params, error);
    if (!error.empty()) {
        failJson["errorMessage"] =
                JQuick::Json(std::string("params must be json format!"));
        goto Fail;
    }

    url = jsonParams["url"].string_value();
    if (url.empty()) {
        failJson["errorMessage"] = JQuick::Json(std::string("parameter error"));
        goto Fail;
    }

    args = new downloadArgs(url, callbackId);
    jquick_thread_create("download", &downloadTask, args);

    return;

Fail:
    jsonCallback["result"] = failJson;
    result = JQuick::Json(jsonCallback);
    status = API_Failed;

    proxy->postCallback(callbackId, status, result.dump());
}

JSAPI调度



{
  $falcon.jsapi.Download.download({url:"http://aiot.aliyun.com/mini_app/list.json"},
                                  (result) => {
    console.log(">>>result: ", result)
  });

  console.log("run here");
}







小结

• 在我们实现jsapi时，如果有耗时操作，那么一定要在子线程中执行，执行完后调用postCallback通知js层，注意，postCallback必须调用，否则会出现内存泄漏；
• 不管是js中调用jsapi还是native代码中调用postCallback，都是异步执行；
  
  

文章转载自：平头哥芯片开放社区 作者：sucool