Question

太过困惑！使用BufferReader，InputStream和StringBuffer的唯一目的是什么？为什么要使用它们以及我们应该以什么样的序列/模式对它们进行编码。我最近遇到了一大堆代码，同时了解如何在android中使用HTTP发送和接收HttpUrlConnection请求。我试图搜索所有这些条款，但我没有得到我需要的东西。在这种情况下，如何按顺序或模式使用它们？将这三种组合使用的任何简单例子都会很棒。还有什么应该是外行人的所有这3个？感谢

InputStream用于一次一个字节地从Web服务器（或url）读取基于字节的数据。
BufferReader它用于从输入流中一次性读取数据

StringBuffer用于创建字符串的可修改字符序列，其中所有访问都是同步的。这个类大部分已被StringBuilder取代，因为这种同步很少有用。此类主要用于与公开它的旧API进行交互。 [不明白这意味着什么，因为我的官方语言不是英语]

//These two need to be declared outside the try/catch
//so that they can be closed in the finally block.
HttpURLConnection urlConnection = null;
BufferedReader reader = null;
//Will contain the raw JSON response as a string.
String forecastJsonStr = null;
try {
//Construct the URL for the OpenWeatherMap query
//Possible parameters are avaiable at OWM's forecast API page, at
//http://openweathermap.org/API#forecast
    URL url = new URL("http://api.openweathermap.org/data/2.5/forecast/daily?q=94043&mode=json&units=metric&cnt=7");
    //Create the request to OpenWeatherMap, and open the connection
    urlConnection = (HttpURLConnection) url.openConnection();
    urlConnection.setRequestMethod("GET"); 
    urlConnection.connect();
    //Read the input stream into a String
    InputStream inputStream = urlConnection.getInputStream();
    StringBuffer buffer = new StringBuffer();
    if (inputStream == null) {
    //Nothing to do.
        forecastJsonStr = null;
    }
    reader = new BufferedReader(new InputStreamReader(inputStream));
    String line;
    while ((line = reader.readLine()) != null) {
    //Since it's JSON, adding a newline isn't necessary (it won't affect parsing)
    //But it does make debugging a *lot* easier if you print out the completed
    //buffer for debugging.
    buffer.append(line + "\n");
    }
    if (buffer.length() == 0) {
    //Stream was empty. No point in parsing.
        forecastJsonStr = null;
    }
    forecastJsonStr = buffer.toString();
    } catch (IOException e) {
        Log.e("PlaceholderFragment", "Error ", e);
    //If the code didn't successfully get the weather data, there's no point in attemping
    //to parse it.
        forecastJsonStr = null;
    } finally{
        if (urlConnection != null) {
            urlConnection.disconnect();
        }
        if (reader != null) {
        try {
            reader.close();
            } catch (final IOException e) {
                Log.e("PlaceholderFragment", "Error closing stream", e);
              }
          }
      }

BufferedReader到InputStream vs StringBuffer

0 个答案: