使用java如何實現以下請求curl -X POST -H 'Content-Type: application/json' -H 'Accept: application/json' -d '{ "grant_type": "client_credentials", "client_id": "YXA6i-Ak8Ol4Eei2l11ZjV-EAg", "client_secret": "YXA6VunqiNxoB7IwXHInk1cGiXOOJfc", "ttl": "1024000" }' 'http://a1.easemob.com/easemob-demo/testapp/token'

使用Java可以通过HttpURLConnection或者OkHttp库发送POST请求实现以下命令：
curl -X POST -H 'Content-Type: application/json' -H 'Accept: application/json' -d '{ "grant_type": "client_credentials", "client_id": "YXA6i-Ak8Ol4Eei2l11ZjV-EAg","client_secret": "YXA6VunqiNxoB7IwXHInk1cGiXOOJfc","ttl": "1024000" }' 'http://a1.easemob.com/easemob-demo/testapp/token'

示例代码：

使用HttpURLConnection发送POST请求：

import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;

public class HttpPost {

    public static void main(String[] args) throws Exception{

        String url = "http://a1.easemob.com/easemob-demo/testapp/token";
        URL obj = new URL(url);
        HttpURLConnection con = (HttpURLConnection) obj.openConnection();

        //添加请求头
        con.setRequestMethod("POST");
        con.setRequestProperty("Content-Type", "application/json");
        con.setRequestProperty("Accept", "application/json");

        //发送POST请求
        con.setDoOutput(true);
        DataOutputStream wr = new DataOutputStream(con.getOutputStream());
        wr.writeBytes("{ \"grant_type\": \"client_credentials\", \"client_id\": \"YXA6i-Ak8Ol4Eei2l11ZjV-EAg\",\"client_secret\": \"YXA6VunqiNxoB7IwXHInk1cGiXOOJfc\",\"ttl\": \"1024000\" }");
        wr.flush();
        wr.close();

        //读取响应
        int responseCode = con.getResponseCode();
        BufferedReader in = new BufferedReader(new InputStreamReader(con.getInputStream()));
        String inputLine;
        StringBuffer response = new StringBuffer();
        while ((inputLine = in.readLine()) != null) {
            response.append(inputLine);
        }
        in.close();

        //打印响应结果
        System.out.println(response.toString());

    }

}

使用OkHttp库发送POST请求：

import okhttp3.*;

import java.io.IOException;

public class OkHttpPost {

    public static void main(String[] args) throws Exception{

        String url = "http://a1.easemob.com/easemob-demo/testapp/token";
        String json = "{ \"grant_type\": \"client_credentials\", \"client_id\": \"YXA6i-Ak8Ol4Eei2l11ZjV-EAg\",\"client_secret\": \"YXA6VunqiNxoB7IwXHInk1cGiXOOJfc\",\"ttl\": \"1024000\" }";

        OkHttpClient client = new OkHttpClient();

        MediaType mediaType = MediaType.parse("application/json");
        RequestBody body = RequestBody.create(mediaType, json);
        Request request = new Request.Builder()
                .url(url)
                .post(body)
                .addHeader("Content-Type", "application/json")
                .addHeader("Accept", "application/json")
                .build();

        //发送POST请求
        Response response = client.newCall(request).execute();
        System.out.println(response.body().string());

    }

}