通过 Android Studio NoClassDefFoundError 的 HTTP 请求

Question

我正在 Android Studio 上构建一个应用程序，我必须在其中通过 JSON 对象使货币汇率与外部源保持同步。我已关注 this tutorial，这是该论坛上另一个答案给我的。消息来源似乎可靠。但是，我不断收到 NoClassDefError。我在我的代码中放置了一个标记为 //Exception 的标志，以向您显示异常发生的位置。请注意，我已将 httpclient-4.3-beta1.jar 添加为库，因此我认为这不是依赖性问题。我找到了关于同一问题的主题，但他们只提供解释而没有答案。这是我的代码。任何帮助将非常感激！谢谢。

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;

import org.apache.http.HttpEntity;
import org.apache.http.ParseException;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;
import org.json.JSONException;
import org.json.JSONObject;

public class LiveResponseDemo{

    // essential URL structure is built using constants
    public static final String ACCESS_KEY = "YOUR_ACCESS_KEY";
    public static final String BASE_URL = "https://apilayer.net/api/";
    public static final String ENDPOINT = "live";

    // this object is used for executing requests to the (REST) API
    //Exception
    static CloseableHttpClient httpClient = HttpClients.createDefault(); 


    public static void sendLiveRequest(){

        // The following line initializes the HttpGet Object with the URL in order to send a request
        HttpGet get = new HttpGet(BASE_URL + ENDPOINT + "?access_key=" + ACCESS_KEY);

        try {
            CloseableHttpResponse response =  httpClient.execute(get);
            HttpEntity entity = response.getEntity();

            // the following line converts the JSON Response to an equivalent Java Object
            JSONObject exchangeRates = new JSONObject(EntityUtils.toString(entity));

            System.out.println("Live Currency Exchange Rates");

            // Parsed JSON Objects are accessed according to the JSON resonse's hierarchy, output strings are built
            Date timeStampDate = new Date((long)(exchangeRates.getLong("timestamp")*1000));
            DateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss a");
            String formattedDate = dateFormat.format(timeStampDate);
            System.out.println("1 " + exchangeRates.getString("base") + " in GBP : " + exchangeRates.getJSONObject("rates").getDouble("GBP") + " (as of " + formattedDate + ")");
            System.out.println("\n");
            response.close();

        } catch (ClientProtocolException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (ParseException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (JSONException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}

Answer 1

这不是他问题的正确答案，而是对他有效的解决方案。

HttpClient 不再是 Android SDK 的一部分，并且已标记为已弃用。
使用带有 httpclient impl 的库 jar。在类路径中两次调用 httpclient 框架，这很难。

我建议的解决方案是保持标准并遵循 google 的建议。如 API 文档中所述：http://developer.android.com/reference/org/apache/http/client/HttpClient.html

我们应该使用 URLConnection 来替代 apache httpclient。如此处所述： http://developer.android.com/reference/java/net/URLConnection.html

通过 Android Studio NoClassDefFoundError 的 HTTP 请求

HTTP request via Android Studio NoClassDefFoundError

android

httprequest

noclassdeffounderror