POST JSON 到服务器并接收响应

Posted 2023-04-19

【中文标题】POST JSON 到服务器并接收响应

【英文标题】：POST JSON to Server and Receive Response

【发布时间】：2020-03-25 09:13:11

【问题描述】：

我有一个名为FindMeARestaurantDAO 的类，它包含的方法可以在我的Activity 中使用AsyncTask 内部类对服务器进行网络调用。我的POST request Method 有问题，如下：

@Override
    public String findMeARestaurant(List<CheckboxDTO> filters) 
        String inputLine;
        String errors;
        String result;
        try
        
            // For each CheckboxDTO, get the Id and add it to JSONArray
            JSONArray checkboxJSONArray = new JSONArray();
            for (CheckboxDTO checkbox : filters)
            
                try
                
                    // Create JSONObject
                    JSONObject object = new JSONObject();
                    // Build the object
                    object.put("id", checkbox.getId());
                    // Add object to JSONArray
                    checkboxJSONArray.put(object);
                
                catch (Exception e)
                
                    e.printStackTrace();
                

            

            // Put JSONArray into wrapping JSONObject
            JSONObject serverObject = new JSONObject();
            try
            
                // Create wrapping JSONObject
                serverObject.put("filtersIds", checkboxJSONArray);
            
            catch (Exception e)
            
                e.printStackTrace();
            

            // Create URL object to hold URL
            URL findMeARestaurantURL = new URL(findMeARestaurantsURL);
            // Create connection to server
            HttpURLConnection connection = (HttpURLConnection) findMeARestaurantURL.openConnection();

            // Set request method and timeouts
            connection.setRequestMethod(FIND_RESTAURANT_REQUEST_METHOD);
            connection.setRequestProperty("Content-Type", "application/json; utf-8");
            connection.setRequestProperty("Accept", "application/json");
            connection.setChunkedStreamingMode(0);
            connection.setDoOutput(true);
            connection.setReadTimeout(READ_TIMEOUT);
            connection.setConnectTimeout(CONNECTION_TIMEOUT);

            // Connect to server
            connection.connect();

            // Create Writer
            Writer writer = new BufferedWriter(new OutputStreamWriter(connection.getOutputStream()));
            writer.write(String.valueOf(serverObject));

            // Close Writer
            writer.close();


            // Create InputStreamReader to read response from server
            InputStreamReader streamReader = new InputStreamReader(connection.getInputStream(), "utf-8");

            // Create BufferedReader to read through InputStream
            BufferedReader reader = new BufferedReader(streamReader);
            // Create StringBuilder to hold our result
            StringBuilder stringBuilder = new StringBuilder();

            // Check if the line read is null
            while ((inputLine = reader.readLine()) != null)
                stringBuilder.append(inputLine);
            

            // Close out InputStream and BufferedReader
            reader.close();
            streamReader.close();

            // Set result to stringBuilder
            result = stringBuilder.toString();
            connection.disconnect();
        
        catch (IOException e)
        
            e.printStackTrace();
            return null;
        

        return result;
    

该方法是 POST，当我运行我的应用程序时，它似乎将JSON serverObject 发送到服务器，但它在InputStreamReader 上失败并返回FileNotFoundException。服务器是由该项目的合作伙伴设置的，并表示 API 的这一部分应该可以工作。我错过了 POST 请求的内容吗？我需要做一些不同的事情来读取服务器的响应吗？任何帮助将不胜感激。

【问题讨论】：

我强烈建议使用 Volley 来进行 API 操作。简单且易于实施。 - developer.android.com/training/volley

@Reaz Murshed，我很欣赏这个建议。我将研究实现它来处理网络请求。我实际上想通了为什么这行不通；我试图发布错误类型的数据。原来我必须在 URL 的末尾发送数据才能接收响应。现在一切正常

很高兴知道你让它工作了。请将您的解决方案也作为答案发布。

【参考方案1】：

这个问题的解决方案是我如何通过POST 请求将数据发送到服务器。在建立连接之前，我必须通过将过滤器的 ID 添加到我的 URL 来将它们发送到服务器。我修改后的方法遍历每个CheckboxDTO 并捕获Id，然后将其添加到数组中，然后将其添加到URL：

@Override
    public String findMeARestaurant(List<CheckboxDTO> filters) 
        String inputLine;
        String result;
        try
        

            // For each CheckboxDTO, get the Id and add it to String Array
            int checkboxArray[] = new int[filters.size()];
            int i = 0;
            for (CheckboxDTO checkbox : filters)
            
                try
                
                    int id = checkbox.getId();
                    checkboxArray[i] = id;
                    i++;
                
                catch (Exception e)
                
                    e.printStackTrace();
                

            

            // Add filters to end of URL for POST Request
            findMeARestaurantsURL += "?filterIds=";
            for (i = 0; i < checkboxArray.length; i++)
            
                if (i+1 != checkboxArray.length)
                
                    findMeARestaurantsURL += checkboxArray[i] + ",";
                
                else
                
                    findMeARestaurantsURL += checkboxArray[i];
                
            
            // Create URL object to hold URL
            URL findMeARestaurantURL = new URL(findMeARestaurantsURL);
            // Create connection to server
            HttpURLConnection connection = (HttpURLConnection) findMeARestaurantURL.openConnection();

            // Set request method and timeouts
            connection.setRequestMethod(FIND_RESTAURANT_REQUEST_METHOD);
            connection.setRequestProperty("Content-Type", "application/json; utf-8");
            connection.setRequestProperty("Accept", "application/json");
            connection.setChunkedStreamingMode(0);
            connection.setDoOutput(true);
            connection.setReadTimeout(READ_TIMEOUT);
            connection.setConnectTimeout(CONNECTION_TIMEOUT);

            // Connect to server
            connection.connect();

            // Create InputStreamReader to read response from server
            InputStreamReader streamReader = new InputStreamReader(connection.getInputStream(), "utf-8");

            // Create BufferedReader to read through InputStream
            BufferedReader reader = new BufferedReader(streamReader);
            // Create StringBuilder to hold our result
            StringBuilder stringBuilder = new StringBuilder();

            // Check if the line read is null
            while ((inputLine = reader.readLine()) != null)
                stringBuilder.append(inputLine);
            

            // Close out InputStream and BufferedReader
            reader.close();
            streamReader.close();

            // Set result to stringBuilder
            result = stringBuilder.toString();
            connection.disconnect();
        
        catch (IOException e)
        
            e.printStackTrace();
            return null;
        

        return result;
    

服务器使用Spring框架，据我的伙伴说，没有使用JSONObject。