从http服务器检索xml流 - android问题

Question

在我的应用程序中，我必须从服务器获取一些作业的列表。在服务器上，我有一个方法，例如 fetchAssignments(int ,String)，它采用两个值作为其参数。

1. 期间（今天、当前月份或本周） - 整数
2. 用户 ID - 字符串

此函数以 XML 流的形式返回作业列表。我知道如何连接到 http 服务器。但我不知道如何在服务器上调用该方法并将这些参数传递给它。谁能建议我更好的方法......？

Answer 1

您可以使用 HTTP GET 请求从服务器请求 XML 作为 InputStream，并将参数作为请求参数传递：

http://some.server/webapp?period=1&userid=user1

使用类似下面的方法，您可以从服务器获取流：

/**
 * Returns an InputStream to read from the given HTTP url.
 * @param url
 * @return InputStream
 * @throws IOException
 */
public InputStream get(final String url) throws IOException {
    HttpClient httpClient = new DefaultHttpClient();
    HttpParams httpParams = httpClient.getParams();
    HttpConnectionParams.setConnectionTimeout(httpParams, TIMEOUT);
    HttpConnectionParams.setSoTimeout(httpParams, TIMEOUT);
    HttpGet httpget = new HttpGet(url);
    HttpResponse httpResponse = httpClient.execute(httpget);
    StatusLine statusLine = httpResponse.getStatusLine();
    if(! statusLine.getReasonPhrase().equals("OK")) {
        throw new IOException(String.format("Request failed with %s", statusLine));
    }
    HttpEntity entity = httpResponse.getEntity();
    return entity.getContent();
}

然后您可以使用“Simple” (http://simple.sourceforge.net/) XML 库，用于将 XML 解析为类似 JAXB 的实体：

/**
 * Reads the XML from the given InputStream using "Simple" and returns a list of assignments.
 * @param InputStream
 * @return List<Assignment>
 */
public List<Assignment> readSimple(final InputStream inputStream) throws Exception {

    Serializer serializer = new Persister();

    return serializer.read(AssignmentList.class, inputStream).getAssignments();     
}

我正在这样做，只是使用 REST 服务，所以我不使用请求参数。

Answer 2

根据语言，您可以通过 URL HTTP 请求或使用 POST 传递参数。在类的构造函数中（假设它是一个网页？.php？.aspx？）检索这些值并将它们传递给上面提到的方法？

try{        
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost("http://www.yoursite.com/getfeed.php");
InputSource inStream = new InputSource();

try {
// Add data
List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(2);
nameValuePairs.add(new BasicNameValuePair("period", period));
nameValuePairs.add(new BasicNameValuePair("userid", user_id));
httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));

 // Execute HTTP Post Request
HttpResponse response = httpclient.execute(httppost);
HttpEntity r_entity = response.getEntity();
String xmlString = EntityUtils.toString(r_entity);

xmlString = xmlString.trim();
InputStream in = new ByteArrayInputStream(xmlString.getBytes("UTF-8"));

if(xmlString.length() != 0){
inStream.setByteStream(in);
PARSE_FLAG = true;
}
else
{
PARSE_FLAG = false;
}

} catch (ClientProtocolException e) {
// TODO Auto-generated catch block
} catch (IOException e) {
// TODO Auto-generated catch block
}