如何将AsyncTask转换为Retrofit以从Android中的WCF Web服务获取数据

Question

我有一个WCF Web服务，它以JSON格式返回SQL Server数据库数据，现在我正在使用AsyncTask通过以下代码在Android中获取此数据：

public class FetchInfo extends AsyncTask {

private String year = "94";
private String month = "1";
private String requested_column = "";
private String kodemelli = "";

public FetchInfo(String year, String month,String requested_column, String kodemelli) {
    this.year = year;
    this.month = month;
    this.requested_column = requested_column;
    this.kodemelli = kodemelli;
}
@Override
protected String doInBackground(Object[] params) {
    try {
        System.out.println("guru");
        DefaultHttpClient httpClient=new DefaultHttpClient();

        //Connect to the server
        HttpGet httpGet=new HttpGet("http://SERVERIP:8005/Service1.svc/checkLogin1?year="+year+"&month="+month+"&requested_column="+requested_column+"&kode_melli="+kodemelli);
        //Get the response

        String result = "";
        HttpResponse httpResponse = httpClient.execute(httpGet);
        HttpEntity httpEntity = httpResponse.getEntity();
        InputStream stream=httpEntity.getContent();
        result = convertStreamToString(stream);
        //Convert the stream to readable format
        if (result.contains("\"error\"") || result.contains("\"server error\"")){
            Main.result = "0";
            MainFish.result = "0";
        }else {
            Main.result = result;
            MainFish.result = result;
        }

    } catch (Exception e) {
        Main.result = "error";
        MainFish.result = "error";
    }

    return "";
}
public 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();
}
}

这样，当请求大于例如10个请求时，响应时间就很长。 从本主题开始， 如何加快使用JSON从服务器获取数据的速度？ 我意识到我应该使用Retrofit而不是AsyncTask来使程序正常工作。

现在我的问题是如何将AsyncTask类转换为Retrofit？

谢谢。

Answer 1

好的，所以首先您将不会在改造中使用异步任务。 翻新将处理异步部分。 首先，您需要定义一个rest适配器。

这是一个默认的Rest适配器，其中包含您的参数。

public class ApiClient {

private static ApiInterface sApiInterface;

public static ApiInterface getApiClient(Context context) {

//build the rest adapter
if (sApiInterface == null) {
    final RestAdapter restAdapter = new RestAdapter.Builder()
            .setEndpoint("http://SERVERIP:8005")
            .build();
    sApiInterface = restAdapter.create(ApiInterface.class);
}
return sApiInterface;
}


public interface ApiInterface {
// /Service1.svc/checkLogin1?year="+year+"&month="+month+"&requested_column="+requested_column+"&kode_melli="+kodemelli
@GET("/Service1.svc/checkLogin1")
void getYourObject(
    @Query("year") String year,       
    @Query("month") String month,    
    @Query("requested_column") String requested_column,
    @Query("kode_melli") String kodemelli,
    RetrofitCallback<YourObjectModel> callback);

}

有了rest适配器之后，您需要一个模型来放入数据。使用jsonschema2pojo将有效的JSON转换为POJO模型。 这是我的json响应之一及其模型的示例。

{
"id": "37",
"title": "",
"short_name": "",
"short_description": "",
"full_description": "",
"url": "http:\/\/\/shows\/programname",
"Image": {
    "url": "https:\/\/s3.amazonaws.com\/image\/original\/b2mWDPX.jpg",
    "url_sm": "https:\/\/s3.amazonaws.com\/image\/small\/b2mWDPX.jpg",
},
"image": "b2mWDPX.jpg",
"hosts": [{
    "id": "651",
    "display_name": "",
    "username": "",
    "Image": {
        "url": "https:\/\/s3.amazonaws.com\/image\/original\/selfie.jpg",
        "url_sm": "https:\/\/s3.amazonaws.com\/image\/small\/selfie.jpg",
    }
}],
"airtimes": [{
    "start": "11:00:00",
    "end": "13:30:00",
    "weekday": "6"
}],
"categories": [{
    "id": "84",
    "title": "Bluegrass",
    "short_name": "bluegrass"
}],
"meta": []
}

我得到这个模型。 还有其他一些。

public class Program {
@Expose
private doublea.models.Airtime Airtime;
@Expose
private String id;
@Expose
private String title;
@SerializedName("short_name")
@Expose
private String shortName;
@SerializedName("full_description")
@Expose
private String fullDescription;
@SerializedName("short_description")
@Expose
private String shortDescription;
@Expose
private doublea.models.Image Image;
@SerializedName("image")
@Expose
private String imageName;
@Expose
private List<Host> hosts = new ArrayList<Host>();
@Expose
private List<Category> categories = new ArrayList<Category>();
@Expose
private List<Airtime> airtimes = new ArrayList<Airtime>();

/** Getters and Setters */

public Program() {
}

然后确保您处理故障案例。

public class RetrofitCallback<S> implements Callback<S> {
private static final String TAG = RetrofitCallback.class.getSimpleName();


@Override
public void success(S s, Response response) {

}

@Override
public void failure(RetrofitError error) {
    Log.e(TAG, "Failed to make http request for: " + error.getUrl());
    Response errorResponse = error.getResponse();
    if (errorResponse != null) {
        Log.e(TAG, errorResponse.getReason());
        if (errorResponse.getStatus() == 500) {
            Log.e(TAG, "Handle Server Errors Here");
        }
    }
}
}

最后进行api调用。

private void executeProgramApiCall(String year, String month, String requested_column, String kodemelli) {
ApiClient.getApiClient(this).getProgram(year, month, requested_column, kodemelli, new RetrofitCallback<Program>() {

    @Override
    public void success(YourObjectModel program, Response response) {
        super.success(YourObjectModel , response);
        //TODO: Do something here with your ObjectMadel
    }
});
}

我强烈建议您查看改造文档，以防您需要特殊的东西，例如标头或请求拦截器。 快乐的编码。