Question

我正在学习android并尝试开发一个项目。出于项目目的，我想使用远程数据初始化数组。虽然我不知道，是否可能！

假设这是一个数组

String values[] = {"a","b","c","d","e"};

此阵列已初始化但我想初始化它以使用来自远程服务器的一些数据。远程服务器数据是JSON编码的。

有可能吗？

如果可能，我该怎么办？

如果不可能，那该怎么办？

Answer 1

您可以改用ArrayList，

// initialize ArrayList of Strings
ArrayList<String> myArray = new ArrayList<>();

// add data to your Array list
myArray.add(yourDatahere);

您可以根据需要为myArray添加尽可能多的数据，因为ArrayList尺寸是动态的。

添加更多数据，

myArray.add(yourDatahere);
myArray.add(yourDatahere);
myArray.add(yourDatahere);
myArray.add(yourDatahere);
myArray.add(yourDatahere);

从ArrayList打印数据

for (ArrayList<String> data : myArray){
        System.out.println(data);
}

使用myArray.get(position)

从您想要的位置检索数据

Answer 2

你可以这样做 -

将你的json转换为字符串然后 -

jsonString.replace("},{", " ,");
String values[] = jsonString.split(" ");

它将删除内部＆＃34;}，{＆＃34;你将获得最终的字符串，如{＆＃34; a＆＃34;，＆＃34; b＆＃34;，＆＃34; c＆＃34;} 只是玩这个。

Answer 3

是的，这是可能的。您需要做的就是提供代码以便从服务器获取数据。这是一个使用POST的例子：

private String sendRequest(String targetUrl) {

    //Here, you define how method you'll use. In this case, I'm using POST
    HttpPost method = new HttpPost(targetUrl);
    HttpParams httpParameters = new BasicHttpParams();

    //If you need, place here your TIMEOUT. 
    HttpConnectionParams.setConnectionTimeout(httpParameters,
            <TIME TO OUT IN MILLIS>);
    HttpConnectionParams.setSoTimeout(httpParameters, <TIME TO OUT IN MILLIS>);

    //Define here your client in order to make requests to your servers
    HttpClient client = new DefaultHttpClient(httpParameters);

    //If you're using POST method, may be you need to add parameters in your request where it'll be used by your server in order to return a response to you.
    List<NameValuePair> postParams = new ArrayList<NameValuePair>();
    postParams.add(new BasicNameValuePair("<PARAMETER'S NAME>", "<PARAMETER'S VALUES>"));
    //You may add multiple parameters here

    //Here starts your request
    try {
        //Define your entity
        UrlEncodedFormEntity entity = new UrlEncodedFormEntity(postParams);
        entity.setContentEncoding(HTTP.UTF_8);
        method.setEntity(entity);
    } catch (UnsupportedEncodingException e) {
        //In case of any error
        Log.e("REQUEST_ERROR", "Something was wrong: " + e);
    }

    try {
        //The string wich will receive your result
        String result;
        //Send your request
        HttpResponse response = client.execute(method);         
        StatusLine statusLine = response.getStatusLine();
        if (statusLine.getStatusCode() == HttpStatus.SC_OK) {
            BasicManagedEntity entity = (BasicManagedEntity) response.getEntity();
            //Get the result
            result = EntityUtils.toString(entity);

        //Return your result in order to be processed
        return result;

    } catch(ConnectTimeoutException cte) {
        return null;
    } catch (UnknownHostException e) {
        return null;
    } catch (Exception e) {
        return null;
    }
}

在此之后，通过写：

来调用此函数

String result = sendRequest(<URL HERE>);

现在您已经能够处理您的JSON数据了。通过知道您的响应是String类型但是采用JSON格式，您需要添加此代码以从String中获取JSON类型：

JSONObject obj = new JSONObject();
obj = new JSONObject(result);

我不知道你的JSON是如何形成的，但我认为你在JSON中将它作为一个数组得到了，对吧？

在这种情况下，您可以执行以下操作：

String[] array;
JSONArray jArray = obj.getJSONArray("<KEY_TO_LETTERS_ARRAY>");
int size = jArray.length();
if (size > 0) {
   array = new String[size];
   for(int i = 0; i < jArray.length(); i++) {
      array[i] = new String(jArray.getString(i));
   }
}

同样重要的是，在使用数组之前，请确定它是否为null，因为在最后一段代码中，只有当JSON数组的大小大于0时才初始化数组

if(array != null) {
  //It's ok
} else {
  //Something wrong
}

现在，您的数组已初始化。

享受它。

Answer 4

public String readJSONFeed(String URL)throws JSONException {
    StringBuilder stringBuilder = new StringBuilder();
    HttpClient httpClient = new DefaultHttpClient();
    HttpPost httpPost = new HttpPost(URL);
    httpPost.setHeader("Content-Type",
            "application/json");
    JSONObject params=new JSONObject();
    params.put("latitude", 43.6014049);
    params.put("longitude",1.4478449);
    try {
        httpPost.setEntity(new StringEntity(params.toString()));
        HttpResponse response = httpClient.execute(httpPost);
        StatusLine statusLine = response.getStatusLine();
        int statusCode = statusLine.getStatusCode();
        if (statusCode == 200) {
            HttpEntity entity = response.getEntity();
            InputStream inputStream = entity.getContent();
            BufferedReader reader = new BufferedReader(
                    new InputStreamReader(inputStream));
            String line;
            while ((line = reader.readLine()) != null) {
                stringBuilder.append(line);
            }
            inputStream.close();
        } else {
            Log.d("JSON", "Failed to download file");
        }
    } catch (Exception e) {
        Log.d("readJSONFeed", e.getLocalizedMessage());
    }
    return stringBuilder.toString();
}

private class ReadJSONFeedTask extends AsyncTask<String, Void, String> {
    String url=.......................;
    protected  void onPreExecute(){
        super.onPreExecute();

    }
    protected String doInBackground(String... urls) {
        try {
            return readJSONFeed(url);
        }catch (JSONException jsonException){
            return null;
        }
    }

    protected void onPostExecute(String result) {
        try {
            JSONObject jsonObject = new JSONObject(result);
            // code to parse the jsonObject and assign it to your array
        }catch (Exception e) {
            Log.d("ReadWeatherJSONFeedTask", e.getLocalizedMessage());
        }

    }
}

这是我编写的示例代码，使用Post方法从Web服务获取一些数据。根据您的json结构，您可以添加一些代码来解析来自JSONObject的正确数据。当然，您可以使用GET方法获取数据并使用其他一些参数。我希望这对您有所帮助。顺便说一下，我使用AsyncTask类来下载异步数据。

通过远程数据初始化数组

4 个答案: