Android/OkHttp - client.newCall(request).execute() 总是返回异常

Question

我必须制作一个android应用程序项目。起初，我尝试使用 HttpURLConnection 但它不起作用。所以在和 friend 讨论之后，我尝试使用OkHttp。我一直对“responses = client.newCall(request).execute();”有一个异常(exception)。经过长时间的搜索，我只是尝试了这段代码，这是“https://github.com/square/okhttp/wiki/Recipes”的教程
而且.....它也不起作用!
我的问题是，到底发生了什么？我目前正在 Android Studio 1.5.1 下开发 4.0.3 应用程序。我还添加了以下两个依赖项:

// DEPENDENCIES
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

// Class Http
public static String run(String url) throws IOException {
    try {
        OkHttpClient client = new OkHttpClient();
        RequestBody formBody = new FormEncodingBuilder()
                .add("login", "Mr. X")
                .add("password", "********")
                .build();
        Request request = new Request.Builder()
                .url(url)
                .post(formBody)
                .build();
        Response responses = null;

        try {
            Log.d("DEBUGG ", "----------------------------------");
            responses = client.newCall(request).execute();
            Log.d("DEBUGG ", "----------------------------------");
            return (responses.body().string());
        } catch (IOException e) {
            e.printStackTrace();
        }
        String jsonData = responses.body().string();
        JSONObject Jobject = new JSONObject(jsonData);
        JSONArray Jarray = Jobject.getJSONArray("employees");

        for (int i = 0; i < Jarray.length(); i++) {
            JSONObject object = Jarray.getJSONObject(i);
        }
    } catch (JSONException e) {

    }
    return null;
}

// MainActivity
private TextView textView;
private Button button;

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    textView = (TextView)findViewById(R.id.textViewJSon);
    button = (Button)findViewById(R.id.Hit);

    textView.setText("Hello !");

    button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            try {
                textView.setText(Http.run("https://epitech-api.herokuapp.com/login"));
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    });

}

Answer 1

{答案}
我终于尝试使用像 Selvin 所说的多线程编程并且效果很好所以解决方案是打开另一个线程

public static int responseCode = 0;
public static String responseString = "";

public static Thread login = new Thread(new Runnable() {
    private OkHttpClient client = new OkHttpClient();
    private String url = "https://epitech-api.herokuapp.com/login";
    private User user = User.getUser();

    public void run() {
        try {
            // Build the request
            RequestBody formBody = new FormEncodingBuilder()
                .add("login", user._login)
                .add("password", user._password)
                .build();
            Request request = new Request.Builder()
                .url(url)
                .post(formBody)
                .build();
            Response responses = null;

            // Reset the response code
            responseCode = 0;

            // Make the request
            responses = client.newCall(request).execute();

            if ((responseCode = responses.code()) == 200) {
                // Get response
                String jsonData = responses.body().string();

                // Transform reponse to JSon Object
                JSONObject json = new JSONObject(jsonData);

                // Use the JSon Object
                user._token = json.getString("token");
            }

        } catch (IOException e) {
            responseString = e.toString();
        } catch (JSONException e) {
            responseString = e.toString();
      }
   }
});