我尝试通过选项卡通过backgroundtask连接到数据库，但它不喜欢它。你们可以看看问题是什么，因为我在另一个项目中使用相同的代码并且运行良好..
public class Tab2Activity extends Activity
{
SharedPreferences preferences;
String driver;
String task;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.tab2);
preferences = getSharedPreferences("MYPREFS", Context.MODE_PRIVATE);
TextView name = (TextView) findViewById (R.id.textView1);
// dummy data to send
task="login";
driver="2";
// create and call background activity
BackgroundTask backgroundTask = new BackgroundTask(Tab2Activity.this);
backgroundTask.execute(task,driver);
//get data back from sharedpreference
String mName = preferences.getString("myData","ERROR getting name");
//display data
name.setText(mName);
}
@Override
public boolean onCreateOptionsMenu(Menu menu)
{
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.tab2, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
这是backGroundTask代码
public class BackgroundTask extends AsyncTask<String,Void,String>
{
SharedPreferences preferences;
SharedPreferences.Editor editor;
SharedPreferences.Editor pig;
Context context;
BackgroundTask(Context ctx)
{
this.context = ctx;
}
@Override
protected String doInBackground(String... params)
{
preferences = context.getSharedPreferences("MYPREFS", Context.MODE_PRIVATE);
editor = preferences.edit();
editor.putString("flag","0");
editor.commit();
String urlLogin = "http://Domain.com/GetJobs.php";
String task = params[0];
String driver_id_app = params[1];
try {
URL url = new URL(urlLogin);
HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
httpURLConnection.setRequestMethod("POST");
httpURLConnection.setDoOutput(true);
httpURLConnection.setDoInput(true);
//send the driver number to the database
OutputStream outputStream = httpURLConnection.getOutputStream();
OutputStreamWriter outputStreamWriter = new OutputStreamWriter(outputStream,"UTF-8");
BufferedWriter bufferedWriter = new BufferedWriter(outputStreamWriter);
String myData = URLEncoder.encode("driver_id","UTF-8")+"="+URLEncoder.encode(driver_id_app,"UTF-8");
//+"&"+URLEncoder.encode("identifier_loginPassword","UTF-8")+"="+URLEncoder.encode(loginPassword,"UTF-8");
bufferedWriter.write(myData);
bufferedWriter.flush();
bufferedWriter.close();
outputStream.close();
//get response from the database
InputStream inputStream = httpURLConnection.getInputStream();
InputStreamReader inputStreamReader = new InputStreamReader(inputStream,"UTF-8");
BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
String dataResponse = "";
String inputLine = "";
while((inputLine = bufferedReader.readLine()) != null){
dataResponse += inputLine;
}
bufferedReader.close();
inputStream.close();
httpURLConnection.disconnect();
//System.out.println("!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!");
///System.out.println(dataResponse);
editor.putString("flag","login");
editor.commit();
pig = preferences.edit();
pig.putString("myData",dataResponse);
pig.commit();
return dataResponse;
}
catch (MalformedURLException e)
{
e.printStackTrace();
}
catch (IOException e)
{
e.printStackTrace();
}
return null;
}
@Override
protected void onPreExecute() {
super.onPreExecute();
}
@Override
protected void onProgressUpdate(Void... values)
{
super.onProgressUpdate(values);
}
public void display(String title, String message){
AlertDialog.Builder builder = new AlertDialog.Builder(context);
builder.setCancelable(true);
builder.setTitle(title);
builder.setMessage(message);
builder.show();
}
}
这些是错误日志
01-21 23:28:26.074: E/AndroidRuntime(27426): FATAL EXCEPTION: AsyncTask #3
01-21 23:28:26.074: E/AndroidRuntime(27426): Process: com.example.tabdemo, PID: 27426
01-21 23:28:26.074: E/AndroidRuntime(27426): java.lang.RuntimeException: An error occurred while executing doInBackground()
01-21 23:28:26.074: E/AndroidRuntime(27426): at android.os.AsyncTask$3.done(AsyncTask.java:309)
01-21 23:28:26.074: E/AndroidRuntime(27426): at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:354)
01-21 23:28:26.074: E/AndroidRuntime(27426): at java.util.concurrent.FutureTask.setException(FutureTask.java:223)
01-21 23:28:26.074: E/AndroidRuntime(27426): at java.util.concurrent.FutureTask.run(FutureTask.java:242)
01-21 23:28:26.074: E/AndroidRuntime(27426): at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:234)
01-21 23:28:26.074: E/AndroidRuntime(27426): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1113)
01-21 23:28:26.074: E/AndroidRuntime(27426): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588)
01-21 23:28:26.074: E/AndroidRuntime(27426): at java.lang.Thread.run(Thread.java:818)
01-21 23:28:26.074: E/AndroidRuntime(27426): Caused by: java.lang.SecurityException: Permission denied (missing INTERNET permission?)
01-21 23:28:26.074: E/AndroidRuntime(27426): at java.net.InetAddress.lookupHostByName(InetAddress.java:464)
01-21 23:28:26.074: E/AndroidRuntime(27426): at java.net.InetAddress.getAllByNameImpl(InetAddress.java:252)
01-21 23:28:26.074: E/AndroidRuntime(27426): at java.net.InetAddress.getAllByName(InetAddress.java:215)
01-21 23:28:26.074: E/AndroidRuntime(27426): at com.android.okhttp.internal.Network$1.resolveInetAddresses(Network.java:29)
01-21 23:28:26.074: E/AndroidRuntime(27426): at com.android.okhttp.internal.http.RouteSelector.resetNextInetSocketAddress(RouteSelector.java:220)
01-21 23:28:26.074: E/AndroidRuntime(27426): at com.android.okhttp.internal.http.RouteSelector.nextProxy(RouteSelector.java:176)
01-21 23:28:26.074: E/AndroidRuntime(27426): at com.android.okhttp.internal.http.RouteSelector.next(RouteSelector.java:108)
01-21 23:28:26.074: E/AndroidRuntime(27426): at com.android.okhttp.internal.http.HttpEngine.createNextConnection(HttpEngine.java:482)
01-21 23:28:26.074: E/AndroidRuntime(27426): at com.android.okhttp.internal.http.HttpEngine.nextConnection(HttpEngine.java:465)
01-21 23:28:26.074: E/AndroidRuntime(27426): at com.android.okhttp.internal.http.HttpEngine.connect(HttpEngine.java:447)
01-21 23:28:26.074: E/AndroidRuntime(27426): at com.android.okhttp.internal.http.HttpEngine.sendRequest(HttpEngine.java:353)
01-21 23:28:26.074: E/AndroidRuntime(27426): at com.android.okhttp.internal.huc.HttpURLConnectionImpl.execute(HttpURLConnectionImpl.java:476)
01-21 23:28:26.074: E/AndroidRuntime(27426): at com.android.okhttp.internal.huc.HttpURLConnectionImpl.connect(HttpURLConnectionImpl.java:118)
01-21 23:28:26.074: E/AndroidRuntime(27426): at com.android.okhttp.internal.huc.HttpURLConnectionImpl.getOutputStream(HttpURLConnectionImpl.java:249)
01-21 23:28:26.074: E/AndroidRuntime(27426): at com.example.tabdemo.BackgroundTask.doInBackground(BackgroundTask.java:63)
01-21 23:28:26.074: E/AndroidRuntime(27426): at com.example.tabdemo.BackgroundTask.doInBackground(BackgroundTask.java:1)
01-21 23:28:26.074: E/AndroidRuntime(27426): at android.os.AsyncTask$2.call(AsyncTask.java:295)
01-21 23:28:26.074: E/AndroidRuntime(27426): at java.util.concurrent.FutureTask.run(FutureTask.java:237)
01-21 23:28:26.074: E/AndroidRuntime(27426): ... 4 more
01-21 23:28:26.074: E/AndroidRuntime(27426): Caused by: android.system.GaiException: android_getaddrinfo failed: EAI_NODATA (No address associated with hostname)
01-21 23:28:26.074: E/AndroidRuntime(27426): at libcore.io.Posix.android_getaddrinfo(Native Method)
01-21 23:28:26.074: E/AndroidRuntime(27426): at libcore.io.ForwardingOs.android_getaddrinfo(ForwardingOs.java:55)
01-21 23:28:26.074: E/AndroidRuntime(27426): at java.net.InetAddress.lookupHostByName(InetAddress.java:451)
01-21 23:28:26.074: E/AndroidRuntime(27426): ... 21 more
01-21 23:28:26.074: E/AndroidRuntime(27426): Caused by: android.system.ErrnoException: android_getaddrinfo failed: EACCES (Permission denied)
01-21 23:28:26.074: E/AndroidRuntime(27426): ... 24 more
真的希望你们能提出一些建议......
答案 0 :(得分：0)
我可以清楚地看到您错过了互联网连接权限。
async private void btnCourse1_Click(object sender, RoutedEventArgs e)
{
string[] names = new string[3] { "COP3488C,", "UWP1,", "This course is mobile app development." };
await WorkerAsync(names);
}
async private void btnCourse2_Click(object sender, RoutedEventArgs e)
{
string[] names = new string[3] { "DOP3488B,", "UWC1,", "This course is Cloud Computing." };
await WorkerAsync(names);
}
async private void btnCourse3_Click(object sender, RoutedEventArgs e)
{
string[] names = new string[3] { "BOP3589,", "UWP2,", "This course Computer Programming Java 1." };
await WorkerAsync(names);
}
private async Task WorkerAsync(string[] names)
{
string VarOutput = "";
for (int i = 0; i < names.Length; i++)
{
VarOutput = VarOutput + names[i] + " ";
}
txtBoxCourse.Text = VarOutput;
var dialog = new MessageDialog(VarOutput);
await dialog.ShowAsync();
}
您需要在清单中添加此项以启用互联网连接：
Caused by: java.lang.SecurityException: Permission denied (missing INTERNET permission?)