在Java中使用JSON的HTTP POST

Question

我想在Java中使用JSON进行简单的HTTP POST.

我们说URL是 www.site.com

并且它采用{"name":"myname","age":"20"}标记'details'为例如的值.

我将如何创建POST的语法？

我似乎也无法在JSON Javadocs中找到POST方法.

Answer 1

这是你需要做的:

1. 获取Apache HttpClient,这将使您能够提出所需的请求
2. 用它创建一个HttpPost请求并添加标题"application/x-www-form-urlencoded"
3. 创建一个StringEntity,您将JSON传递给它
4. 执行通话

代码大致看起来像(你仍然需要调试它并让它工作)

//Deprecated
//HttpClient httpClient = new DefaultHttpClient(); 

HttpClient httpClient = HttpClientBuilder.create().build(); //Use this instead 

try {

    HttpPost request = new HttpPost("http://yoururl");
    StringEntity params =new StringEntity("details={\"name\":\"myname\",\"age\":\"20\"} ");
    request.addHeader("content-type", "application/x-www-form-urlencoded");
    request.setEntity(params);
    HttpResponse response = httpClient.execute(request);

    //handle response here...

}catch (Exception ex) {

    //handle exception here

} finally {
    //Deprecated
    //httpClient.getConnectionManager().shutdown(); 
}

Answer 2

您可以使用Gson库将您的Java类转换为JSON对象.

按照上面的示例为要发送的变量创建一个pojo类

{"name":"myname","age":"20"}

变

class pojo1
{
   String name;
   String age;
   //generate setter and getters
}

一旦你在pojo1类中设置变量,你可以使用以下代码发送它

String       postUrl       = "www.site.com";// put in your url
Gson         gson          = new Gson();
HttpClient   httpClient    = HttpClientBuilder.create().build();
HttpPost     post          = new HttpPost(postUrl);
StringEntity postingString = new StringEntity(gson.toJson(pojo1));//gson.tojson() converts your pojo to json
post.setEntity(postingString);
post.setHeader("Content-type", "application/json");
HttpResponse  response = httpClient.execute(post);

这些是进口

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.HttpClientBuilder;

而对于GSON

import com.google.gson.Gson;

Answer 3

@momo对Apache HttpClient 4.3.1或更高版本的回答.我正在使用JSON-Java构建我的JSON对象:

JSONObject json = new JSONObject();
json.put("someKey", "someValue");    

CloseableHttpClient httpClient = HttpClientBuilder.create().build();

try {
    HttpPost request = new HttpPost("http://yoururl");
    StringEntity params = new StringEntity(json.toString());
    request.addHeader("content-type", "application/json");
    request.setEntity(params);
    httpClient.execute(request);
// handle response here...
} catch (Exception ex) {
    // handle exception here
} finally {
    httpClient.close();
}

Answer 4

使用HttpURLConnection可能最简单.

http://www.xyzws.com/Javafaq/how-to-use-httpurlconnection-post-data-to-web-server/139

您将使用JSONObject或其他任何内容构建您的JSON,但不能处理网络; 你需要序列化它,然后将它传递给HttpURLConnection进行POST.

Answer 5

试试这段代码:

HttpClient httpClient = new DefaultHttpClient();

try {
    HttpPost request = new HttpPost("http://yoururl");
    StringEntity params =new StringEntity("details={\"name\":\"myname\",\"age\":\"20\"} ");
    request.addHeader("content-type", "application/json");
    request.addHeader("Accept","application/json");
    request.setEntity(params);
    HttpResponse response = httpClient.execute(request);

    // handle response here...
}catch (Exception ex) {
    // handle exception here
} finally {
    httpClient.getConnectionManager().shutdown();
}

Answer 6

protected void sendJson(final String play, final String prop) {
     Thread t = new Thread() {
     public void run() {
        Looper.prepare(); //For Preparing Message Pool for the childThread
        HttpClient client = new DefaultHttpClient();
        HttpConnectionParams.setConnectionTimeout(client.getParams(), 1000); //Timeout Limit
        HttpResponse response;
        JSONObject json = new JSONObject();

            try {
                HttpPost post = new HttpPost("http://192.168.0.44:80");
                json.put("play", play);
                json.put("Properties", prop);
                StringEntity se = new StringEntity(json.toString());
                se.setContentType(new BasicHeader(HTTP.CONTENT_TYPE, "application/json"));
                post.setEntity(se);
                response = client.execute(post);

                /*Checking response */
                if (response != null) {
                    InputStream in = response.getEntity().getContent(); //Get the data in the entity
                }

            } catch (Exception e) {
                e.printStackTrace();
                showMessage("Error", "Cannot Estabilish Connection");
            }

            Looper.loop(); //Loop in the message queue
        }
    };
    t.start();
}

Answer 7

我发现这个问题正在寻找有关如何从Java客户端向Google端点发送帖子请求的解决方案.以上答案,很可能是正确的,但在Google端点的情况下无效.

Google端点解决方案.

1. 请求正文必须只包含JSON字符串,而不是name = value对.

2. 内容类型标题必须设置为"application/json".

   post("http://localhost:8888/_ah/api/langapi/v1/createLanguage",
                      "{\"language\":\"russian\", \"description\":\"dsfsdfsdfsdfsd\"}");
   
   
   
   public static void post(String url, String param ) throws Exception{
     String charset = "UTF-8"; 
     URLConnection connection = new URL(url).openConnection();
     connection.setDoOutput(true); // Triggers POST.
     connection.setRequestProperty("Accept-Charset", charset);
     connection.setRequestProperty("Content-Type", "application/json;charset=" + charset);
   
     try (OutputStream output = connection.getOutputStream()) {
       output.write(param.getBytes(charset));
     }
   
     InputStream response = connection.getInputStream();
   }
   

   确定也可以使用HttpClient来完成.

Answer 8

您可以将以下代码用于Apache HTTP：

String payload = "{\"name\": \"myname\", \"age\": \"20\"}";
post.setEntity(new StringEntity(payload, ContentType.APPLICATION_JSON));

response = client.execute(request);

另外，您可以创建一个json对象，并像这样将字段放入对象

HttpPost post = new HttpPost(URL);
JSONObject payload = new JSONObject();
payload.put("name", "myName");
payload.put("age", "20");
post.setEntity(new StringEntity(payload.toString(), ContentType.APPLICATION_JSON));

Answer 9

对于 Java 11，您可以使用新的HTTP 客户端：

HttpClient client = HttpClient.newHttpClient();
HttpRequest request = HttpRequest.newBuilder()
    .uri(URI.create("http://localhost/api"))
    .header("Content-Type", "application/json")
    .POST(ofInputStream(() -> getClass().getResourceAsStream(
        "/some-data.json")))
    .build();

client.sendAsync(request, BodyHandlers.ofString())
    .thenApply(HttpResponse::body)
    .thenAccept(System.out::println)
    .join();

您可以使用来自InputStream、String、 的发布者File。可以使用 Jackson将 JSON 转换为 aString或IS。