JAVA中带有JSON字符串的HTTP POST请求

Posted 2023-03-31

【中文标题】JAVA中带有JSON字符串的HTTP POST请求

【英文标题】：HTTP POST request with JSON String in JAVA

【发布时间】：2013-12-23 09:17:10

【问题描述】：

我必须使用我已经生成的 JSON 字符串发出 http Post 请求。 我尝试了两种不同的方法：

1.HttpURLConnection
2.HttpClient

但是我从他们两个那里得到了相同的“不想要的”结果。 到目前为止，我使用 HttpURLConnection 的代码是：

public static void SaveWorkflow() throws IOException 
    URL url = null;
    url = new URL(myURLgoeshere);
    HttpURLConnection urlConn = null;
    urlConn = (HttpURLConnection) url.openConnection();
    urlConn.setDoInput (true);
    urlConn.setDoOutput (true);
    urlConn.setRequestMethod("POST");
    urlConn.setRequestProperty("Content-Type", "application/json");
    urlConn.connect();

    DataOutputStream output = null;
    DataInputStream input = null;
    output = new DataOutputStream(urlConn.getOutputStream());

                /*Construct the POST data.*/
    String content = generatedJSONString;

    /* Send the request data.*/
    output.writeBytes(content);
    output.flush();
    output.close();

    /* Get response data.*/
    String response = null;
    input = new DataInputStream (urlConn.getInputStream());
    while (null != ((response = input.readLine()))) 
        System.out.println(response);
        input.close ();
    

到目前为止，我使用 HttpClient 的代码是：

public static void SaveWorkflow() 
    try 

        HttpClient httpClient = new DefaultHttpClient();
        HttpPost postRequest = new HttpPost(myUrlgoeshere);
        StringEntity input = new StringEntity(generatedJSONString);
        input.setContentType("application/json;charset=UTF-8");
        postRequest.setEntity(input);
        input.setContentEncoding(new BasicHeader(HTTP.CONTENT_TYPE,"application/json;charset=UTF-8"));
        postRequest.setHeader("Accept", "application/json");
        postRequest.setEntity(input); 

        HttpResponse response = httpClient.execute(postRequest);

        BufferedReader br = new BufferedReader(
                        new InputStreamReader((response.getEntity().getContent())));

        String output;

        while ((output = br.readLine()) != null) 
            System.out.println(output);
        

        httpClient.getConnectionManager().shutdown();

     catch (MalformedURLException e) 

        e.printStackTrace();

     catch (IOException e) 

        e.printStackTrace();

    

生成JsonString的地方是这样的：

"description":"prova_Process","modelgroup":"","modified":"false"

我得到的回应是：

"response":false,"message":"Error in saving the model. A JSONObject text must begin with '' at 1 [character 2 line 1]","ids":[]

有什么想法吗？

【问题讨论】：

您是否尝试过仅将字符串转换为对象（解析 JSON）而中间没有 HTTP 传输步骤？

尝试使用 generatedJSONString.trim()

看起来你想使用一个 RESTful web 服务；您可能希望通过应用 JAX-RS API 让您的生活变得非常轻松。

事实上，我首先将 json 生成为一个对象，然后将其转换为字符串 ...

【参考方案1】：

终于找到了解决问题的办法……

public static void SaveWorkFlow() throws IOException
    
        CloseableHttpClient httpClient = HttpClients.createDefault();
        HttpPost post = new HttpPost(myURLgoesHERE);
        List<NameValuePair> params = new ArrayList<>();
        params.add(new BasicNameValuePair("task", "savemodel"));
        params.add(new BasicNameValuePair("code", generatedJSONString));
        CloseableHttpResponse response = null;
        Scanner in = null;
        try
        
            post.setEntity(new UrlEncodedFormEntity(params));
            response = httpClient.execute(post);
            // System.out.println(response.getStatusLine());
            HttpEntity entity = response.getEntity();
            in = new Scanner(entity.getContent());
            while (in.hasNext())
            
                System.out.println(in.next());

            
            EntityUtils.consume(entity);
         finally
        
            in.close();
            response.close();
        
    

【讨论】：

你能列出这个所需的罐子吗

你去 ---> 编译组：'org.apache.httpcomponents'，名称：'httpclient-android'，版本：'4.3.5.1' |但它已被弃用，所以尝试找到其他东西：-\

【参考方案2】：

另一种实现方式如下所示：

public static void makePostJsonRequest(String jsonString)

    HttpClient httpClient = new DefaultHttpClient();
    try 
        HttpPost postRequest = new HttpPost("Ur_URL");
        postRequest.setHeader("Content-type", "application/json");
        StringEntity entity = new StringEntity(jsonString);

        postRequest.setEntity(entity);

        long startTime = System.currentTimeMillis();
        HttpResponse response = httpClient.execute(postRequest);
        long elapsedTime = System.currentTimeMillis() - startTime;
        //System.out.println("Time taken : "+elapsedTime+"ms");

        InputStream is = response.getEntity().getContent();
        Reader reader = new InputStreamReader(is);
        BufferedReader bufferedReader = new BufferedReader(reader);
        StringBuilder builder = new StringBuilder();
        while (true) 
            try 
                String line = bufferedReader.readLine();
                if (line != null) 
                    builder.append(line);
                 else 
                    break;
                
             catch (Exception e) 
                e.printStackTrace();
            
        
        //System.out.println(builder.toString());
        //System.out.println("****************");
     catch (Exception ex) 
        ex.printStackTrace();