安卓如何post请求发送一个json

可以使用HttpURLConnection或者OkHttp库来发送POST请求，并且将JSON作为请求体发送。

下面是用HttpURLConnection发送POST请求并发送JSON的代码示例：

try {
    // 创建URL对象
    URL url = new URL("http://example.com/api/users");

    // 创建HttpURLConnection对象
    HttpURLConnection conn = (HttpURLConnection) url.openConnection();
    conn.setRequestMethod("POST");
    conn.setRequestProperty("Content-Type", "application/json");
    conn.setDoOutput(true);

    // 创建JSON对象
    JSONObject jsonObject = new JSONObject();
    jsonObject.put("name", "John Doe");
    jsonObject.put("age", 30);

    // 将JSON转换为字符串
    String jsonInputString = jsonObject.toString();

    // 将JSON字符串写入请求体
    OutputStream os = conn.getOutputStream();
    byte[] input = jsonInputString.getBytes("utf-8");
    os.write(input, 0, input.length);

    // 发送请求
    int responseCode = conn.getResponseCode();
    if (responseCode == HttpURLConnection.HTTP_OK) {
        // 读取响应
        BufferedReader in = new BufferedReader(new InputStreamReader(conn.getInputStream()));
        String inputLine;
        StringBuffer response = new StringBuffer();
        while ((inputLine = in.readLine()) != null) {
            response.append(inputLine);
        }
        in.close();
        System.out.println(response.toString());
    } else {
        System.out.println("POST request failed: " + responseCode);
    }
} catch (Exception e) {
    System.out.println("Exception: " + e.getMessage());
}

如果使用OkHttp库，可以使用以下代码：

try {
    // 创建OkHttpClient对象
    OkHttpClient client = new OkHttpClient();

    // 创建JSON对象
    JSONObject jsonObject = new JSONObject();
    jsonObject.put("name", "John Doe");
    jsonObject.put("age", 30);

    // 创建RequestBody对象
    RequestBody body = RequestBody.create(jsonObject.toString(), MediaType.parse("application/json"));

    // 创建Request对象
    Request request = new Request.Builder()
            .url("http://example.com/api/users")
            .post(body)
            .build();

    // 发送请求
    Response response = client.newCall(request).execute();

    if (response.isSuccessful()) {
        // 读取响应
        String responseBody = response.body().string();
        System.out.println(responseBody);
    } else {
        System.out.println("POST request failed: " + response.code());
    }
} catch (Exception e) {
    System.out.println("Exception: " + e.getMessage());
}