Java Android JSON api存在PUT操作问题

我有一个在asp.NETMVC4中制作的web api，它公开了数据库的CRUD操作，我正在制作一个android应用程序来尝试和操作这些数据

我面临的问题是json解析器中的更新操作，该操作由http PUT请求（/api/products/id）公开

这是我使用的解析器，我从一个示例中获得，我修改了POST部分，因此它确实放了：

public class JSONParser {

static InputStream is = null;
static JSONObject jObj = null;
static JSONArray jArr = null;
static String json = "";

// constructor
public JSONParser() {

}

// function get json from url
    // by making HTTP POST or GET method
    public JSONObject makeHttpRequest(String url, String method,
            List<NameValuePair> params) {

        // Making HTTP request
        try {

            // check for request method
            if (method == "PUT") {
                DefaultHttpClient httpClient = new DefaultHttpClient();
                HttpPut httpPut = new HttpPut(url);
                httpPut.setEntity(new UrlEncodedFormEntity(params));

                HttpResponse httpResponse = httpClient.execute(httpPut);
                HttpEntity httpEntity = httpResponse.getEntity();
                is = httpEntity.getContent();
            }
            if(method == "POST"){
                // request method is POST
                // defaultHttpClient
                DefaultHttpClient httpClient = new DefaultHttpClient();
                HttpPost httpPost = new HttpPost(url);
                httpPost.setEntity(new UrlEncodedFormEntity(params));

                HttpResponse httpResponse = httpClient.execute(httpPost);
                HttpEntity httpEntity = httpResponse.getEntity();
                is = httpEntity.getContent();

            }else if(method == "GET"){
                // request method is GET
                DefaultHttpClient httpClient = new DefaultHttpClient();
                String paramString = URLEncodedUtils.format(params, "utf-8");
                url += "?" + paramString;
                HttpGet httpGet = new HttpGet(url);

                HttpResponse httpResponse = httpClient.execute(httpGet);
                HttpEntity httpEntity = httpResponse.getEntity();
                is = httpEntity.getContent();
            }           

        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

        try {
            BufferedReader reader = new BufferedReader(new InputStreamReader(
                    is, "iso-8859-1"), 8);
            StringBuilder sb = new StringBuilder();
            String line = null;
            while ((line = reader.readLine()) != null) {
                sb.append(line + "\n");
            }
            is.close();
            json = sb.toString();
        } catch (Exception e) {
            Log.e("Buffer Error", "Error converting result " + e.toString());
        }

        // try parse the string to a JSON object
        try {
            jObj = new JSONObject(json);
        } catch (JSONException e) {
            Log.e("JSON Parser", "Error parsing data " + e.toString());
        }

        // return JSON String
        return jObj;

    }
}

我做错了什么？

三件事（其中两件更重要）

首先（重要），在处理响应正文之前，您需要确定您的请求是否成功。鉴于代码的结构，我建议在检索方法的开头声明一个状态代码变量，并在每次执行后设置它：

HttpResponse httpResponse = httpClient.execute(httpPut);
status = httpResponse.getStatusLine().getStatusCode();

第二个（重要），在调用响应实体上的任何方法之前，需要检查响应实体是否为非空。总的来说，使用

EntityUtils

类来处理您的响应会更好

httpEntity = httpResponse.getEntity(); // Declare httpentity outside your try/catch
is = httpEntity.getContent();          // Remove this line entirely

然后，该实体将按如下方式进行处理：

try {
    if(status == HttpStatus.SC_OK) {
        json = httpentity != null ?
            EntityUtils.toString(httpentity, "iso-8859-1") : null;
    } else {
        Log.e("Server responded with error status " + status);
    }
} catch (Exception e) {
    Log.e("Buffer Error", "Error converting result " + e.toString());
}

---

最后（非常重要），您应该删除解析器类中的所有静态变量，并将它们改为方法的局部变量。

似乎不是我面临的问题，操作确实成功了，是响应返回了问题

try {
    if(status == HttpStatus.SC_OK) {
        json = httpentity != null ?
            EntityUtils.toString(httpentity, "iso-8859-1") : null;
    } else {
        Log.e("Server responded with error status " + status);
    }
} catch (Exception e) {
    Log.e("Buffer Error", "Error converting result " + e.toString());
}