android - 列表有什么用或数组列表

Question

我想知道什么是List<NameValuePair>或ArrayList<NameValuePair>在android中的用途？特别是当我们使用网络服务时AsyncTask<...>

Answer 1

NameValuePair 是一个特殊的<Key, Value>对，用于表示 http 请求中的参数，即www.example.com?key=value.

NameValuePair 是一个接口，定义在 apache http 客户端中，在 java 中广泛用于处理 http 操作。AList<NameValuePair>只是对的列表<key, value>，将用作 http post 请求中的参数。

HttpPost request = new HttpPost();
List<NameValuePair> params = new ArrayList<NameValuePair>();
params.add(new BasicNameValuePair("key", "value"));
request.setEntity(new UrlEncodedFormEntity(params));

httpClient.execute(request);

Answer 2

一些对你有用的东西。

List是一个接口，ArrayList是接口的一个实现List。

List:List是集合框架中的一个接口。几个类ArrayList，LinkedList实现这个接口。List是一个有序集合，所以对象的位置很重要。

ArrayList: AnArrayList是一个可以在运行时增长的类。您可以将 java 对象存储在 an 中ArrayList，还可以在运行时添加新对象。

ArrayList当您不必经常从中添加或删除对象时，您将使用它。因为当你删除一个对象时，所有其他的对象都需要重新定位在 中ArrayList，如果你有这种情况，请尝试使用LinkedList。

您可以从这里了解更多信息。

Answer 3

List<NameValuePair>或ArrayList<NameValuePair>用于将值从 android 应用程序发送到服务器。

@Override
    protected Header[] doInBackground(String... params) {
        try {
            DefaultHttpClient httpClient = new DefaultHttpClient();
            HttpPost httpPost = new HttpPost(params[1]);

            ArrayList<NameValuePair> nameValuePair = new ArrayList<NameValuePair>();
            nameValuePair.add(new BasicNameValuePair("ssn", params[0]));
            httpPost.setEntity(new UrlEncodedFormEntity(nameValuePair,
                    "UTF-8"));
            HttpResponse httpResponse = httpClient.execute(httpPost);
            HttpEntity httpEntity = httpResponse.getEntity();
            response = EntityUtils.toString(httpEntity);
            allHeaders = httpResponse.getAllHeaders();

        } catch (Exception ex) {

            ex.printStackTrace();

        }
        return allHeaders;
    }

在上面的代码中，我ssn使用ArrayList<NameValuePair>.

Answer 4

使用此代码将数据从 android 应用程序上传到服务器端..

  // image file *********************************
 // here send all the sqlite database datas to local sever via HttpPost("url"); 

ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();

nameValuePairs.add(new BasicNameValuePair("job_id","001"));
nameValuePairs.add(new BasicNameValuePair("picture_path",picturejson.toString()));
        nameValuePairs.add(new BasicNameValuePair("date_time",datetime_str));
        nameValuePairs.add(new BasicNameValuePair("location",gpslocation_str));
        try{

        HttpClient httpclient = new DefaultHttpClient();
        HttpPost httppost = new HttpPost("http://Sample/iphone/getinput");
        httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
        httpclient.execute(httppost);
        HttpResponse response = httpclient.execute(httppost);
        //HttpEntity entity = response.getEntity();
        //is = entity.getContent();
        //HttpResponse response = httpClient.execute(postRequest);
         BufferedReader reader = new BufferedReader(new InputStreamReader(
             response.getEntity().getContent(), "UTF-8"));
                        String sResponse;
                        StringBuilder s = new StringBuilder();

                        while ((sResponse = reader.readLine()) != null) {
                            s = s.append(sResponse);
                        }
                    System.out.println("Response: ");
                    Log.v("hari", "Response : ");
        }catch(Exception e){
        //Log.e("log_tag", "Error in http connection "+e.toString());

        }

Answer 5

protected String  doInBackground(String... params)
        {
            try
            {
                List<NameValuePair> param = new ArrayList<NameValuePair>();
            param.add(new BasicNameValuePair("username", edName));
            param.add(new BasicNameValuePair("email", edEmail));
            param.add(new BasicNameValuePair("password",  edPassword));
            param.add(new BasicNameValuePair("mobile", edMobile));


            DefaultHttpClient httpClient = new DefaultHttpClient();
            HttpPost httpPost = new HttpPost(params[0]);
            httpPost.setEntity(new UrlEncodedFormEntity(param));

            HttpResponse httpResponse = httpClient.execute(httpPost);

            HttpEntity httpEntity = httpResponse.getEntity();
            InputStream is = httpEntity.getContent();

            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");
            }

            String  json = sb.toString();
            JSONObject jObj = new JSONObject(json);
            msg= jObj.getString("message");
        }
        catch(Exception e)
        {

            Log.e("error", "Network problem");
        }
        return msg;

    }
}