Performing HTTP POST operation in JAVA

Question

Consider the following scenario:

A person wants to make a simple HTTP POST using JSON in Java.

Let's say the URL is www.site.com

and it takes in the value {"name":"myname","age":"20"} labeled as 'details' for example.

How would he go about creating the syntax for the POST?

Also please point me to POST method in the JSON Javadocs.

Answer 1

I would suggest the following two ways:

1. One is through the below mentioned code

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();
}

2. Also you can make use of Gson library to convert your java classes to JSON objects.

Create a pojo class for variables you want to send as per above Example

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

becomes

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

once you set the variables in pojo1 class you can send that using the following code

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);

and these are the imports

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;

and for GSON

import com.google.gson.Gson;

Answer 2

I'm using JSON-Java to build my JSON object:

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();
}