问题描述
我会尽量保持这个简单.
I'll keep this one as simple as I can.
我的控制层中有一个方法，该方法使用扩展 AsyncTask 的类 CallServiceTask.当调用 new CallServiceTask().execute(parameters)
如何检索从 doInBackground 返回的数据?我发现的所有教程都使用直接从它们的 Activity 扩展 AsyncTask 的类.
我的问题比那要复杂一点.
我想要的只是获取 doInBackground 返回的 Object[] 并将其设置为我的 RestClient 类的私有数据成员.
I have a method in my control layer that uses a class CallServiceTask that extends AsyncTask. When calling new CallServiceTask().execute(parameters)
How do I retrieve the data returned from doInBackground? All the tutorials I've found use the class that extends AsyncTask directly from their Activity.
My problem is a little bit more complex than that.
All I want is to take the Object[] returned by doInBackground and set it to the private data members of my RestClient class.
CallServiceTask 看起来像这样:
private class CallServiceTask extends AsyncTask<Object, Void, Object[]>
{
protected Object[] doInBackground(Object... params)
{
HttpUriRequest req = (HttpUriRequest) params[0];
String url = (String) params[1];
return executeRequest(req, url);
}
}
我的 RestClient 类如下所示:
And my RestClient class looks like this:
public class RestClient
{
private ArrayList <NameValuePair> params;
private ArrayList <NameValuePair> headers;
private JSONObject jsonData;
private Object[] rtnData;
private String url;
private boolean connError;
public int getResponseCode() {
return responseCode;
}
/**
*
* @return the result of whether the login was successful by looking at the response parameter of the JSON object.
*/
public Boolean DidLoginSucceed()
{
// Will Crash on socket error
return ((JSONObject) rtnData[0]).optBoolean("response");
}
public String GetToken()
{
return jsonData.optString("token");
}
public RestClient(String url)
{
this.url = url;
params = new ArrayList<NameValuePair>();
headers = new ArrayList<NameValuePair>();
rtnData = new Object[]{ new JSONObject() , Boolean.TRUE };
}
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));
}
/**
* This method will execute, call the service and instantiate the JSON Object through executeRequest().
*
* @param method an enum defining which method you wish to execute.
* @throws Exception
*/
public void ExecuteCall(RequestMethod method) throws Exception
{
Object[] parameters = new Object[]{ new HttpGet() , new String("") };
switch(method) {
case GET:
{
//add parameters
String combinedParams = "";
if(!params.isEmpty()){
combinedParams += "?";
for(NameValuePair p : params)
{
String paramString = p.getName() + "=" + URLEncoder.encode(p.getValue());
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());
}
parameters[0] = request;
parameters[1] = url;
new CallServiceTask().execute(parameters);
jsonData = ((JSONObject) rtnData[0]).optJSONObject("data");
connError = (Boolean) rtnData[1];
break;
}
case POST:
{
HttpPost request = new HttpPost(url);
//add headers
for(NameValuePair h : headers)
{
request.addHeader(h.getName(), h.getValue());
}
if(!params.isEmpty()){
request.setEntity(new UrlEncodedFormEntity(params, HTTP.UTF_8));
}
new CallServiceTask().execute(request, url);
break;
}
}
}
private Object[] executeRequest(HttpUriRequest request, String url)
{
HttpClient client = new DefaultHttpClient();
client = getNewHttpClient();
HttpResponse httpResponse;
try {
httpResponse = client.execute(request);
HttpEntity entity = httpResponse.getEntity();
if (entity != null) {
InputStream instream = entity.getContent();
String response = convertStreamToString(instream);
try {
rtnData[0] = new JSONObject(response);
rtnData[1] = false;
} catch (JSONException e1) {
rtnData[1] = true;
e1.printStackTrace();
}
// 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();
}
return rtnData;
}
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 + "
");
}
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
is.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return sb.toString();
}
/**
* Custom HTTP Client accepting all SSL Certified Web Services.
*
* @return n HttpClient object.
*/
public HttpClient getNewHttpClient() {
try {
KeyStore trustStore = KeyStore.getInstance(KeyStore.getDefaultType());
trustStore.load(null, null);
SSLSocketFactory sf = new MySSLSocketFactory(trustStore);
sf.setHostnameVerifier(SSLSocketFactory.ALLOW_ALL_HOSTNAME_VERIFIER);
HttpParams params = new BasicHttpParams();
HttpProtocolParams.setVersion(params, HttpVersion.HTTP_1_1);
HttpProtocolParams.setContentCharset(params, HTTP.UTF_8);
SchemeRegistry registry = new SchemeRegistry();
registry.register(new Scheme("http", PlainSocketFactory.getSocketFactory(), 80));
registry.register(new Scheme("https", sf, 443));
ClientConnectionManager ccm = new ThreadSafeClientConnManager(params, registry);
return new DefaultHttpClient(ccm, params);
} catch (Exception e) {
return new DefaultHttpClient();
}
}
推荐答案
执行此操作的唯一方法是使用回调.你可以这样做:
The only way to do this is using a CallBack. You can do something like this:
new CallServiceTask(this).execute(request, url);
然后在您的 CallServiceTask 添加一个本地类变量并在您的 onPostExecute 中从该类调用一个方法:
Then in your CallServiceTask add a local class variable and call a method from that class in your onPostExecute:
private class CallServiceTask extends AsyncTask<Object, Void, Object[]>
{
RestClient caller;
CallServiceTask(RestClient caller) {
this.caller = caller;
}
protected Object[] doInBackground(Object... params)
{
HttpUriRequest req = (HttpUriRequest) params[0];
String url = (String) params[1];
return executeRequest(req, url);
}
protected onPostExecute(Object result) {
caller.onBackgroundTaskCompleted(result);
}
}
然后在 RestClient 类的 onBackgroundTaskCompleted() 方法中随意使用对象.
Then simply use the Object as you like in the onBackgroundTaskCompleted() method in your RestClient class.
更优雅和可扩展的解决方案是使用接口.有关示例实现，请参阅 this 库.我刚刚开始，但它有一个你想要的例子.
A more elegant and extendible solution would be to use interfaces. For an example implementation see this library. I've just started it but it has an example of what you want.
这篇关于如何从 AsyncTasks doInBackground() 检索数据?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！