我的移动设备突然无法连接到本地服务器。异步任务没有执行，我只是无法弄清楚原因。慢慢地，我变得非常绝望，因为在我看来，我没有改变任何事情导致这一点。 例如，这是一个无效的后台任务
public class Login extends AsyncTask<String, Void, String>{
private String loginUrl = "http://...";
private int loginSuccess = 0;
public String getToken(String fromJson) throws JSONException {
JSONObject json = new JSONObject(fromJson);
if(json.has("api_authtoken")) {
loginSuccess = 1;
String appToken = json.getString("api_authtoken");
return appToken;
}
else {
return json.toString();
}
}
public String doInBackground(String... arg0) {
// so that they can be closed in the finally block.
HttpURLConnection urlConnection = null;
BufferedReader reader = null;
String authToken;
try {
// get logged in to get the api_authtoken
String email = (String) arg0[0];
String password = (String) arg0[1];
URL url = new URL(loginUrl);
// Create the request and open the connection
urlConnection = (HttpURLConnection) url.openConnection();
urlConnection.setRequestMethod("POST");
urlConnection.setRequestProperty("Content-Type", "application/json");
urlConnection.setRequestProperty("Accept", "application/json");
//put values of edittexts into json-Object
JSONObject data = new JSONObject();
try {
data.put("email", email);
data.put("password", password);
} catch(JSONException e) {
Log.e("EXCEPTION", "unexpected JSON exception", e);
e.printStackTrace();
}
urlConnection.connect();
OutputStreamWriter wr = new OutputStreamWriter(urlConnection.getOutputStream());
wr.write(data.toString());
wr.flush();
reader = new BufferedReader(new InputStreamReader(urlConnection.getInputStream()));
StringBuilder sb = new StringBuilder();
String line = null;
//read server response
while((line = reader.readLine()) != null) {
sb.append(line);
}
//receive server "answer"
try {
return getToken(sb.toString());
}catch(JSONException e) {
Log.e("LOG", "unexpected JSON exception", e);
e.printStackTrace();
} finally{
if (urlConnection != null) {
urlConnection.disconnect();
}
if (reader != null) {
try {
reader.close();
} catch (final IOException e) {
Log.e("MainActivity", "Error closing stream", e);
}
}
}
//return sb.toString();
return null;
}
catch(IOException e) {
Log.e("LoginTask", "Error ", e);
// If the code didn't successfully get the data, there's no point in attempting
// to parse it.
//forecastJsonStr = null;
return null;
}
}
public void onPostExecute(String result) {
super.onPostExecute(result);
//Log.v("RESULT", result);
if(result == null) {
CharSequence text = "no internet connection";
int duration = Toast.LENGTH_LONG;
Toast toast = Toast.makeText(MainActivity.this, text, duration);
toast.setGravity(Gravity.CENTER_VERTICAL, 0, 0);
toast.show();
}
if(loginSuccess == 0) {
// if the request wasn't successful
// give user a message via toast
CharSequence text = "wrong password or user. please try again";
int duration = Toast.LENGTH_LONG;
Toast toast = Toast.makeText(MainActivity.this, text, duration);
toast.setGravity(Gravity.CENTER_VERTICAL, 0, 0);
toast.show();
}
else {
// save token in shared preferences
SharedPreferences tokenPref = getSharedPreferences(getString(R.string.preference_token), Context.MODE_PRIVATE);
SharedPreferences.Editor editorToken = tokenPref.edit();
editorToken.putString(getString(R.string.saved_auth_token), result);
editorToken.commit();
//save login status = 1 in shared preferences
SharedPreferences loginPref = getSharedPreferences(getString(R.string.preference_logged_in), Context.MODE_PRIVATE);
SharedPreferences.Editor editorLogin = loginPref.edit();
editorLogin.putString(getString(R.string.saved_login), "1");
editorLogin.commit();
Intent mapsIntent = new Intent(getApplicationContext(), MapsActivity.class);
startActivity(mapsIntent);
}
}
}
答案 0 :(得分：0)
HttpClient。你必须使用URLConnection或降级到sdk 22 (compile 'com.android.support:appcompat-v7:22.2.0')
如果您需要sdk 23，请将其添加到您的gradle：
android {
useLibrary 'org.apache.http.legacy'
}
答案 1 :(得分：0)
你应该考虑使用HTTP库，在互联网上有很多它们，有些非常容易使用，优化和无错误。
例如，Volley（由Google制作，我非常喜欢这个），okHttp或Picasso（用于图片）。
你应该看看this。
答案 2 :(得分：0)
如果你想发送（输出），例如POST或PUT请求你需要使用它： -
urlConnection.setDoOutput(true);
在您的代码中： -
public class Login extends AsyncTask<String, Void, String>{
private String loginUrl = "http://...";
private int loginSuccess = 0;
public String getToken(String fromJson) throws JSONException {
JSONObject json = new JSONObject(fromJson);
if(json.has("api_authtoken")) {
loginSuccess = 1;
String appToken = json.getString("api_authtoken");
return appToken;
}
else {
return json.toString();
}
}
public String doInBackground(String... arg0) {
// so that they can be closed in the finally block.
HttpURLConnection urlConnection = null;
BufferedReader reader = null;
String authToken;
try {
// get logged in to get the api_authtoken
String email = (String) arg0[0];
String password = (String) arg0[1];
URL url = new URL(loginUrl);
// Create the request and open the connection
urlConnection = (HttpURLConnection) url.openConnection();
urlConnection.setRequestMethod("POST");
urlConnection.setRequestProperty("Content-Type", "application/json");
urlConnection.setRequestProperty("Accept", "application/json");
urlConnection.setDoOutput(true); // HERE
//put values of edittexts into json-Object
JSONObject data = new JSONObject();
try {
data.put("email", email);
data.put("password", password);
} catch(JSONException e) {
Log.e("EXCEPTION", "unexpected JSON exception", e);
e.printStackTrace();
}
OutputStreamWriter wr = new OutputStreamWriter(urlConnection.getOutputStream());
wr.write(data.toString());
wr.flush();
urlConnection.connect();
reader = new BufferedReader(new InputStreamReader(urlConnection.getInputStream()));
StringBuilder sb = new StringBuilder();
String line = null;
//read server response
while((line = reader.readLine()) != null) {
sb.append(line);
}
//receive server "answer"
try {
return getToken(sb.toString());
}catch(JSONException e) {
Log.e("LOG", "unexpected JSON exception", e);
e.printStackTrace();
} finally{
if (urlConnection != null) {
urlConnection.disconnect();
}
if (reader != null) {
try {
reader.close();
} catch (final IOException e) {
Log.e("MainActivity", "Error closing stream", e);
}
}
}
//return sb.toString();
return null;
}
catch(IOException e) {
Log.e("LoginTask", "Error ", e);
// If the code didn't successfully get the data, there's no point in attempting
// to parse it.
//forecastJsonStr = null;
return null;
}
}
public void onPostExecute(String result) {
super.onPostExecute(result);
//Log.v("RESULT", result);
if(result == null) {
CharSequence text = "no internet connection";
int duration = Toast.LENGTH_LONG;
Toast toast = Toast.makeText(MainActivity.this, text, duration);
toast.setGravity(Gravity.CENTER_VERTICAL, 0, 0);
toast.show();
}
if(loginSuccess == 0) {
// if the request wasn't successful
// give user a message via toast
CharSequence text = "wrong password or user. please try again";
int duration = Toast.LENGTH_LONG;
Toast toast = Toast.makeText(MainActivity.this, text, duration);
toast.setGravity(Gravity.CENTER_VERTICAL, 0, 0);
toast.show();
}
else {
// save token in shared preferences
SharedPreferences tokenPref = getSharedPreferences(getString(R.string.preference_token), Context.MODE_PRIVATE);
SharedPreferences.Editor editorToken = tokenPref.edit();
editorToken.putString(getString(R.string.saved_auth_token), result);
editorToken.commit();
//save login status = 1 in shared preferences
SharedPreferences loginPref = getSharedPreferences(getString(R.string.preference_logged_in), Context.MODE_PRIVATE);
SharedPreferences.Editor editorLogin = loginPref.edit();
editorLogin.putString(getString(R.string.saved_login), "1");
editorLogin.commit();
Intent mapsIntent = new Intent(getApplicationContext(), MapsActivity.class);
startActivity(mapsIntent);
}
}
}