Question

我找到了一个我想玩的API，因为我有空。我想询问是否要使用API开发Android应用程序，API是基于HTTP协议的（RESTful），如何使用 HTTPClient 对象进行操作？

我有一般要求信息。

HEAD /authenticate/ HTTP/1.1
Host: my.api.com
Date: Thu, 17 Jul 2008 14:52:54 GMT
X-SE-Client: some-value
X-SE-Accept: xml
X-SE-Auth: 90a6d325e982f764f86a7e248edf6a660d4ee833

上述反应将取决于成功。

HTTP/1.1 200 OK
Date: Thu, 17 Jul 2008 14:52:55 GMT
Server: MyApi
Content-Length: 795
Connection: close
Content-Type: text/xml

我知道如何使用HTTPClient发送HTTP请求，但它是否会在请求中添加额外的标头和其他不必要的内容？如何查看HTTPClient对象发出的请求？我想简单地请求传递文本，如 telnet 。

Answer 1

你应该可以在Android中使用HttpClient来做你需要的事情。我刚刚完成了Android与ASP.NET MVC 3站点集成的第一部分，我必须说 - 它非常轻松。我使用Json作为我的数据交换格式。

通过在构建请求后设置调试点，您可以准确查看标头的外观。下面是一些示例代码（请记住它只是示例代码 - 而不是完整的实现）。

此类由与UI线程不同的线程调用：

public class RemoteDBAdapter {


    public String register(String email, String password) throws Exception
    {
        RestClient c = new RestClient("http://myurl/Account/Register");
        c.AddHeader("Accept", "application/json");
        c.AddHeader("Content-type", "application/json");
        c.AddParam("Email", email);
        c.AddParam("Password", password);

        c.Execute(RequestMethod.POST);

        JSONObject key = new JSONObject(c.getResponse());

        return key.getString("status");


    }

}

使用此类构建您的请求并执行它：

public class RestClient {

    public enum RequestMethod {
        GET,
        POST
    }

    private ArrayList <NameValuePair> params;
    private ArrayList <NameValuePair> headers;

    private String url;

    private int responseCode;
    private String message;

    private String response;

    public String getResponse() {
        return response;
    }

    public String getErrorMessage() {
        return message;
    }

    public int getResponseCode() {
        return responseCode;
    }

    public RestClient(String url)
    {
        this.url = url;
        params = new ArrayList<NameValuePair>();
        headers = new ArrayList<NameValuePair>();
    }

    public void AddParam(String name, String value)
    {
        params.add(new BasicNameValuePair(name, value));
    }

    public void AddHeader(String name, String value)
    {
        headers.add(new BasicNameValuePair(name, value));
    }

    public void Execute(RequestMethod method) throws Exception
    {
        switch(method) {
            case GET:
            {
                //add parameters
                String combinedParams = "";
                if(!params.isEmpty()){
                    combinedParams += "?";
                    for(NameValuePair p : params)
                    {
                        String paramString = p.getName() + "=" + URLEncoder.encode(p.getValue(),"UTF-8");
                        if(combinedParams.length() > 1)
                        {
                            combinedParams  +=  "&" + paramString;
                        }
                        else
                        {
                            combinedParams += paramString;
                        }
                    }
                }

                HttpGet request = new HttpGet(url + combinedParams);

                //add headers
                for(NameValuePair h : headers)
                {
                    request.addHeader(h.getName(), h.getValue());
                }

                executeRequest(request, url);
                break;
            }
            case POST:
            {
                HttpPost request = new HttpPost(url);

                //add headers
                for(NameValuePair h : headers)
                {
                    request.addHeader(h.getName(), h.getValue());
                }
                JSONObject jo = new JSONObject();


                if(!params.isEmpty()){
                    for (int i = 0; i < params.size();i++)
                    {
                        jo.put(params.get(i).getName(),params.get(i).getValue());


                    }
                    StringEntity se = new StringEntity(jo.toString());
                    se.setContentType("text/xml"); 
                    se.setContentEncoding( new BasicHeader(HTTP.CONTENT_TYPE, "application/json")); 

                    request.setEntity(se);
                    //request.setEntity(new UrlEncodedFormEntity(params, HTTP.UTF_8));
                }

                executeRequest(request, url);
                break;
            }
        }
    }

    private void executeRequest(HttpUriRequest request, String url)
    {
        //HttpClient client = new DefaultHttpClient();
        HttpClient client = HttpClientFactory.getThreadSafeClient();

        HttpResponse httpResponse;

        try {
            httpResponse = client.execute(request);
            responseCode = httpResponse.getStatusLine().getStatusCode();
            message = httpResponse.getStatusLine().getReasonPhrase();

            HttpEntity entity = httpResponse.getEntity();

            if (entity != null) {

                InputStream instream = entity.getContent();
                response = convertStreamToString(instream);

                // Closing the input stream will trigger connection release
                instream.close();
            }

        } catch (ClientProtocolException e)  {
            client.getConnectionManager().shutdown();
            e.printStackTrace();
        } catch (IOException e) {
            client.getConnectionManager().shutdown();
            e.printStackTrace();
        }
    }

    private static String convertStreamToString(InputStream is) {

        BufferedReader reader = new BufferedReader(new InputStreamReader(is));
        StringBuilder sb = new StringBuilder();

        String line = null;
        try {
            while ((line = reader.readLine()) != null) {
                sb.append(line + "\n");
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                is.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return sb.toString();
    }
}

编辑：

哦，你和HttpClientFactory：

// Should be thread safe
public class HttpClientFactory {

            private static DefaultHttpClient client;

            public synchronized static DefaultHttpClient getThreadSafeClient() {
                    if (client != null)
                            return client;
                    client = new DefaultHttpClient();
                    ClientConnectionManager mgr = client.getConnectionManager();
                    HttpParams params = client.getParams();
                    client = new DefaultHttpClient(new ThreadSafeClientConnManager(params,
                                    mgr.getSchemeRegistry()), params);
                return client;

            }
    }

Answer 2

REST使用的格式与旧的SOAP方法相比要严格得多。

如果你想传递一个字符串或类似的东西，我建议在REST中使用JSON。 REST with XML用于更复杂的结构，如嵌套的XML有效负载等等。 JSON也可能会快得多。 Android中也内置了对JSON的支持。

使用Java For Android的HTTP API请求

2 个答案: