安卓如何post一个json并接收返回的json信息

可以使用Android中的HttpClient或者Volley库来实现POST请求并接收返回的JSON信息。

1. 使用HttpClient

HttpClient已经过时，但是仍然可以使用。以下是一个示例代码：

try {
    HttpClient httpClient = new DefaultHttpClient();
    HttpPost httpPost = new HttpPost(url);

    // 设置请求头
    httpPost.setHeader("Content-Type", "application/json");
    httpPost.setHeader("Accept", "application/json");

    // 构造JSON数据
    JSONObject jsonObject = new JSONObject();
    jsonObject.put("key1", "value1");
    jsonObject.put("key2", "value2");
    StringEntity stringEntity = new StringEntity(jsonObject.toString());

    // 设置请求体
    httpPost.setEntity(stringEntity);

    // 发送请求
    HttpResponse httpResponse = httpClient.execute(httpPost);

    // 获取返回的JSON信息
    BufferedReader reader = new BufferedReader(new InputStreamReader(httpResponse.getEntity().getContent()));
    StringBuffer stringBuffer = new StringBuffer();
    String line = "";
    while ((line = reader.readLine()) != null) {
        stringBuffer.append(line);
    }

    // 处理返回的JSON信息
    String response = stringBuffer.toString();
    JSONObject responseJson = new JSONObject(response);
} catch (Exception e) {
    e.printStackTrace();
}

2. 使用Volley

Volley是一个网络请求库，可以更轻松地发送网络请求。以下是一个示例代码：

try {
    RequestQueue requestQueue = Volley.newRequestQueue(context);
    String url = "http://example.com/api";
    JSONObject jsonBody = new JSONObject();
    jsonBody.put("key1", "value1");
    jsonBody.put("key2", "value2");
    final String requestBody = jsonBody.toString();

    JsonObjectRequest jsonObjectRequest = new JsonObjectRequest(Request.Method.POST, url, null, new Response.Listener<JSONObject>() {
        @Override
        public void onResponse(JSONObject response) {
            // 处理返回的JSON信息
        }
    }, new Response.ErrorListener() {
        @Override
        public void onErrorResponse(VolleyError error) {
            error.printStackTrace();
        }
    }) {
        @Override
        public String getBodyContentType() {
            return "application/json; charset=utf-8";
        }

        @Override
        public byte[] getBody() {
            try {
                return requestBody == null ? null : requestBody.getBytes("utf-8");
            } catch (UnsupportedEncodingException e) {
                e.printStackTrace();
                return null;
            }
        }
    };

    requestQueue.add(jsonObjectRequest);
} catch (JSONException e) {
    e.printStackTrace();
}

以上代码仅供参考，具体实现可能需要根据具体情况进行调整。