您好我正在尝试检查用户名是否可用但必须通过异步任务进行检查。尝试了一些方法，但无法做到这一点。所以，我带来了这个：
异步任务在普通类中，因此将调用新实例，调用异步任务（checkusername），然后等待异步任务完成（在postexecute上，它将更新公共变量，＆＃39; resultOut＆＃ 39）。在活动时，为了防止锁定，在退出之前循环到1000或resultOut。
我一直在＆＃39; resultOut＆＃39;假的。这是代码：
urlConnection url = new urlConnection();
if(url.isConnected(view.getContext())) {
Toast.makeText(getApplicationContext(), "connected ", Toast.LENGTH_LONG).show();
boolean result=false;
url.checkUserName(user_name);
int i = 0;
while (!result && i!=1000){
i++;
result=url.resultOut;
}
这是urlconnection类（已编辑）
private void connectUrl(String action, String user_name, String pwd) {
String urlParam = null;
strAction=action;
switch (action){
case "update":
urlParam = "/test.php?action=update&user_id=7&lat="+latitude+"&lon="+longitude;
break;
case "locate":
urlParam = "/test.php?action=locate&user_id=7";
break;
case "insert":
urlParam = "/test.php?action=insert&user_name="+user_name+"&pwd="+pwd;
break;
case "check":
urlParam = "/test.php?action=check&user_name="+user_name;
}
//Toast.makeText(, "Connecting to site: " + WB_URL + urlParam, Toast.LENGTH_LONG).show();
new DownloadWebpageTask().execute(WB_URL + urlParam);
}
private class DownloadWebpageTask extends AsyncTask<String, Void, String> {
@Override
protected String doInBackground(String... urls) {
// params comes from the execute() call: params[0] is the url.
try {
return downloadUrl(urls[0]);
} catch (IOException e) {
return "Unable to retrieve web page. URL may be invalid.";
}
}
// onPostExecute displays the results of the AsyncTask.
@Override
protected void onPostExecute(String result) {
result=result.trim();
switch (strAction){
case "update":
int i = Integer.parseInt(result);
if (i > 0) {
//Toast.makeText(getApplicationContext(), "Update successful", Toast.LENGTH_LONG).show();
}else{
//Toast.makeText(getApplicationContext(), "Update failed", Toast.LENGTH_LONG).show();
}
break;
case "locate":
String[] s = result.split(",");
case "insert":
break;
case "check":
int x = Integer.parseInt(result);
resultOut=true;
//Toast.makeText(getApplicationContext(), "Check Result: "+x, Toast.LENGTH_LONG).show();
if (x==0){
//cannot locate name so, name usable
isUserNameUsed=false;
}else{
isUserNameUsed=true;
}
}
//showLocation(null);
}
}
private String downloadUrl(String myurl) throws IOException {
InputStream is = null;
// Only display the first 500 characters of the retrieved
// web page content.
int len = 500;
try {
URL url = new URL(myurl);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setReadTimeout(10000 /* milliseconds */);
conn.setConnectTimeout(15000 /* milliseconds */);
conn.setRequestMethod("GET");
conn.setDoInput(true);
// Starts the query
conn.connect();
int response = conn.getResponseCode();
Log.d(DEBUG_TAG, "The response is: " + response);
is = conn.getInputStream();
// Convert the InputStream into a string
String contentAsString = readIt(is, len);
return contentAsString;
// Makes sure that the InputStream is closed after the app is
// finished using it.
} finally {
if (is != null) {
is.close();
}
}
}
public String readIt(InputStream stream, int len) throws IOException, UnsupportedEncodingException {
Reader reader = null;
reader = new InputStreamReader(stream, "UTF-8");
char[] buffer = new char[len];
reader.read(buffer);
return new String(buffer);
}
}
帮助表示感谢，提前谢谢。理查德
答案 0 :(得分：0)
你的实用程序asyncTask类，你必须在你的片段或活动中实现它。 apiKey用于检查你呼叫的api的响应。
public class UtilityAsyncRequest extends AsyncTask<String, Integer, String> {
private final OnAsyncRequestComplete caller;
private String requestType = "";
private String strJsonData = "";
private int apiKey = 0;
/**
* @param caller callback interface for request
* @param requestType GET POST
* @param jsonStringData payload with request type POST
* @param apiKey apiKey
*/
public UtilityAsyncRequest(OnAsyncRequestComplete caller, String requestType,
String jsonStringData, int apiKey) {
this.caller = caller;
this.apiKey = apiKey;
if (requestType.equalsIgnoreCase("Get")) {
this.requestType = "Get";
} else if (jsonStringData != null && requestType.equalsIgnoreCase("Post")) {
this.requestType = "Post";
this.strJsonData = jsonStringData;
}
}
public String doInBackground(String... urls) {
// callApi url pointing to entry point of API
String address = urls[0];
String response = "";
if (requestType.equalsIgnoreCase("Post")) {
response = Connection.postAPIResponse(address, strJsonData);
} else if (requestType.equalsIgnoreCase("Get")) {
response = Connection.getAPIResponse(address);
}
return response;
}
public void onPreExecute() {
if(caller!=null)
caller.onPreExecute(apiKey);
}
public void onPostExecute(String response) {
if (caller != null)
caller.onPostExecute(response, apiKey);
}
protected void onCancelled(String response) {
if(caller!=null)
caller.onCancelled(apiKey);
}
// Interface to be implemented by calling activity
public interface OnAsyncRequestComplete {
void onPreExecute(int api);
void onPostExecute(String response, int api);
void onCancelled(int api);
}
}
现在要进行异步请求，您可以在活动中执行此操作。通过实现接口。
public class MainActivity extends Activity implements UtilityAsyncRequest.OnAsyncRequestComplete{
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//first Api Call
UtilityAsyncRequest utilityAsyncRequest=new UtilityAsyncRequest(this,"GET",null,1);
utilityAsyncRequest.execute("https://www.google.co.in/?gws_rd=ssl");
//Second Api Call
utilityAsyncRequest=new UtilityAsyncRequest(this,"GET",null,2);
utilityAsyncRequest.execute("https://www.google.co.in/?gws_rd=ssl");
}
@Override
public void onPreExecute(int api) {
switch (api){
case 1:
//first api call pre show Loading dialog else whatever you want
break;
case 2:
//second api call pre
break;
}
}
@Override
public void onPostExecute(String response, int api) {
switch (api){
case 1:
//first api call response
break;
case 2:
//second api call response
break;
}
}
@Override
public void onCancelled(int api) {
}
}
用于处理接收和发布数据。
public class Connection {
// Private constructor prevents instantiation from other classes
private Connection() {
}
public static String postAPIResponse(String url, String data) {
HttpURLConnection con = null;
InputStream inputStream;
StringBuffer responses = null;
try {
URL urlObject = new URL(url);
con = (HttpURLConnection) (urlObject.openConnection());
con.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
con.setRequestMethod("POST");
con.setRequestProperty("Content-Type", "application/json; charset=UTF-8");
con.setRequestProperty("Content-Length", Integer.toString(data.getBytes().length));
con.setRequestProperty("Content-Language", "en-US");
if (Cookie.getCookie() != null)
con.addRequestProperty("Cookie", Cookie.getCookie());
con.setUseCaches(false);
con.setDoInput(true);
con.setDoOutput(true);
//Send request
DataOutputStream wr = new DataOutputStream(con.getOutputStream());
wr.writeBytes(data);
wr.flush();
wr.close();
//Get Response
if (con.getResponseCode() == 200) {
if (Cookie.getCookie() == null)
Cookie.setCookie(con.getHeaderField("Set-Cookie"));
InputStream is = con.getInputStream();
BufferedReader rd = new BufferedReader(new InputStreamReader(is));
String line;
responses = new StringBuffer();
while ((line = rd.readLine()) != null) {
responses.append(line);
}
rd.close();
} else {
inputStream = new BufferedInputStream(con.getErrorStream());
return convertInputStreamToString(inputStream);
}
} catch (Exception e) {
e.printStackTrace();
} finally {
assert con != null;
con.disconnect();
}
return responses != null ? responses.toString() : "";
}
public static String getAPIResponse(String urlName) {
String response = null;
HttpURLConnection con = null;
InputStream inputStream;
try {
URL url = new URL(urlName);
con = (HttpURLConnection) (url.openConnection());
con.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
if (Cookie.getCookie() != null)
con.addRequestProperty("Cookie", Cookie.getCookie());
int statusCode = con.getResponseCode();
if (statusCode == 200) {
inputStream = new BufferedInputStream(con.getInputStream());
response = convertInputStreamToString(inputStream);
if (Cookie.getCookie() == null)
Cookie.setCookie(con.getHeaderField("Set-Cookie"));
} else {
inputStream = new BufferedInputStream(con.getErrorStream());
response = convertInputStreamToString(inputStream);
}
} catch (Exception e) {
e.printStackTrace();
} finally {
assert con != null;
con.disconnect();
}
return response != null ? response : "";
}
static public String convertInputStreamToString(InputStream inputStream) throws IOException {
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
String line;
String result = "";
while ((line = bufferedReader.readLine()) != null) {
result += line;
}
/* Close Stream */
inputStream.close();
return result;
}
}
并处理cookie模型类。
public class Cookie {
private static String Cookie;
//private static final com.core.Cookie singleton = new Cookie( );
/* A private Constructor prevents any other
* class from instantiating.
*/
private Cookie() {
}
/* Other methods protected by singleton */
public static String getCookie() {
return Cookie;
}
public static void setCookie(String cookie) {
Cookie = cookie;
}
}