您可以使用以下方法向URL发送HTTP-POST请求并接收响应。我总是用这个:

try {
    AsyncHttpClient client = new AsyncHttpClient();
    // Http Request Params Object
    RequestParams params = new RequestParams();
    String u = "B2mGaME";
    String au = "gamewrapperB2M";
    // String mob = "880xxxxxxxxxx";
    params.put("usr", u.toString());
    params.put("aut", au.toString());
    params.put("uph", MobileNo.toString());
    //  params.put("uph", mob.toString());
    client.post("http://196.6.13.01:88/ws/game_wrapper_reg_check.php", params, new AsyncHttpResponseHandler() {
        @Override
        public void onSuccess(String response) {
            playStatus = response;
            //////Get your Response/////
            Log.i(getClass().getSimpleName(), "Response SP Status. " + playStatus);
        }
        @Override
        public void onFailure(Throwable throwable) {
            super.onFailure(throwable);
        }
    });
} catch (Exception e) {
    e.printStackTrace();
}

你还需要在libs文件夹中添加风箱Jar文件

android-async-http-1.3.1.jar

最后，我编辑了你的build.gradle:

dependencies {
    compile files('libs/<android-async-http-1.3.1.jar>')
}

在最后一个重建你的项目。

注(2020年10月):以下答案中使用的AsyncTask已在Android API级别30中弃用。有关更新的示例，请参考官方文档或本博客文章

更新(2017年6月)答案，适用于Android 6.0+。感谢@Rohit Suthar， @Tamis Bolvari和@sudhiskr的评论。

    public class CallAPI extends AsyncTask<String, String, String> {
    
        public CallAPI(){
            //set context variables if required
        }
    
        @Override
        protected void onPreExecute() {
            super.onPreExecute();
        }
    
         @Override
         protected String doInBackground(String... params) {
            String urlString = params[0]; // URL to call
            String data = params[1]; //data to post
            OutputStream out = null;

            try {
                URL url = new URL(urlString);
                HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
                out = new BufferedOutputStream(urlConnection.getOutputStream());

                BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(out, "UTF-8"));
                writer.write(data);
                writer.flush();
                writer.close();
                out.close();

                urlConnection.connect();
            } catch (Exception e) {
                System.out.println(e.getMessage());
            }
        }
    }

引用:

https://developer.android.com/reference/java/net/HttpURLConnection.html 如何使用NameValuePair使用POST添加参数到HttpURLConnection

原答案(2010年5月)

注意:此解决方案已过时。它只能在5.1版本以下的安卓设备上运行。Android 6.0及以上版本不包括本回答中使用的Apache http客户端。

来自Apache Commons的Http Client是可行的。它已经包含在android中。下面是一个简单的例子，说明如何使用它来执行HTTP Post。

public void postData() {
    // Create a new HttpClient and Post Header
    HttpClient httpclient = new DefaultHttpClient();
    HttpPost httppost = new HttpPost("http://www.yoursite.com/script.php");

    try {
        // Add your data
        List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(2);
        nameValuePairs.add(new BasicNameValuePair("id", "12345"));
        nameValuePairs.add(new BasicNameValuePair("stringdata", "Hi"));
        httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));

        // Execute HTTP Post Request
        HttpResponse response = httpclient.execute(httppost);
        
    } catch (ClientProtocolException e) {
        // TODO Auto-generated catch block
    } catch (IOException e) {
        // TODO Auto-generated catch block
    }
} 

最好使用Apache Commons HttpClient，它已经包含在android中了。 看一看 Android开发人员:Apache HTTP客户端包摘要 一般API信息。

下面的方法适用于最新的Android库和使用okhttp。

    OkHttpClient client = new OkHttpClient();
    RequestBody formBody = new FormBody.Builder()
            .add("key1", "value1")
            .add("key2", "value2")  //optional
            .add("key3", "value3")  //optional
            .add("key4", "value4")  //optional
            .build();


    Request request = new Request.Builder()
    .url("http://.....")   //URL
    .post(formBody)
    .build();


    client.newCall(request).enqueue(new Callback() {
        @Override
        public void onFailure(@NonNull Call call, @NonNull IOException e) {
            e.getStackTrace();
        }

        @Override
       public void onResponse(@NonNull Call call, @NonNull Response response) throws IOException {
            if(response.isSuccessful()){
                ResponseBody responseBody = response.body();
                Log.e("TAG_", responseBody.string());
       }
    }

对我来说，接下来的工作是:

 private sendData() {
     JSONObject jsonObject = new JSONObject();
     jsonObject.accumulate("key1", value1);
     jsonObject.accumulate("key2", value2);

     boolean success = sendPost(SERVER_URL + "/v1/auth", jsonObject);
 }

 private boolean sendPost(String url, JSONObject parameters) {
        boolean requestResult = false;
        InputStream inputStream = null;
        String result = "";
        try {

            HttpClient httpclient = new DefaultHttpClient();
            HttpPost httpPost = new HttpPost(url);

            String json = "";

            json = parameters.toString();

            StringEntity se = new StringEntity(json);
            httpPost.setEntity(se);

            httpPost.setHeader("Accept", "application/json");
            httpPost.setHeader("Content-type", "application/json");

            HttpResponse httpResponse = httpclient.execute(httpPost);

            inputStream = httpResponse.getEntity().getContent();

            if (inputStream != null) {
                result = convertInputStreamToString(inputStream);
                requestResult = true;
            } else {
                result = "Did not work!";
                requestResult = false;
            }
            System.out.println(result);
        } catch (Exception e) {
            Log.d("InputStream", e.getLocalizedMessage());
            requestResult = false;
        }
        return requestResult;
    }

这是一个如何在不使用外部Apache库的情况下POST多部分数据的例子:

byte[] buffer = getBuffer();

if(buffer.length > 0) {
   String lineEnd = "\r\n"; 
   String twoHyphens = "--"; 
   String boundary =  "RQdzAAihJq7Xp1kjraqf"; 

   ByteArrayOutputStream baos = new ByteArrayOutputStream();
   DataOutputStream dos = new DataOutputStream(baos);

   // Send parameter #1
   dos.writeBytes(twoHyphens + boundary + lineEnd); 
   dos.writeBytes("Content-Disposition: form-data; name=\"param1\"" + lineEnd);
   dos.writeBytes("Content-Type: text/plain; charset=US-ASCII" + lineEnd);
   dos.writeBytes("Content-Transfer-Encoding: 8bit" + lineEnd);
   dos.writeBytes(lineEnd);
   dos.writeBytes(myStringData + lineEnd);

   // Send parameter #2
   //dos.writeBytes(twoHyphens + boundary + lineEnd); 
   //dos.writeBytes("Content-Disposition: form-data; name=\"param2\"" + lineEnd + lineEnd);
   //dos.writeBytes("foo2" + lineEnd);

   // Send a binary file
   dos.writeBytes(twoHyphens + boundary + lineEnd); 
   dos.writeBytes("Content-Disposition: form-data; name=\"param3\";filename=\"test_file.dat\"" + lineEnd); 
   dos.writeBytes("Content-Type: application/octet-stream" + lineEnd);
   dos.writeBytes("Content-Transfer-Encoding: binary" + lineEnd);
   dos.writeBytes(lineEnd); 
   dos.write(buffer);
   dos.writeBytes(lineEnd); 
   dos.writeBytes(twoHyphens + boundary + twoHyphens + lineEnd); 
   dos.flush(); 
   dos.close();

   ByteArrayInputStream content = new ByteArrayInputStream(baos.toByteArray());
   BasicHttpEntity entity = new BasicHttpEntity();
   entity.setContent(content);

   HttpPost httpPost = new HttpPost(myURL);
   httpPost.addHeader("Connection", "Keep-Alive");
   httpPost.addHeader("Content-Type", "multipart/form-data; boundary="+boundary);

   //MultipartEntity entity = new MultipartEntity();
   //entity.addPart("param3", new ByteArrayBody(buffer, "test_file.dat"));
   //entity.addPart("param1", new StringBody(myStringData));

   httpPost.setEntity(entity);

   /*
   String httpData = "";
   ByteArrayOutputStream baos1 = new ByteArrayOutputStream();
   entity.writeTo(baos1);
   httpData = baos1.toString("UTF-8");
   */

   /*
   Header[] hdrs = httpPost.getAllHeaders();
   for(Header hdr: hdrs) {
     httpData += hdr.getName() + " | " + hdr.getValue() + " |_| ";
   }
   */

   //Log.e(TAG, "httpPost data: " + httpData);
   response = httpClient.execute(httpPost);
}