在我的 android 应用程序中，我想从 async-task 启动活动类。这是一个登录 pahe 类。else它部分给出错误onPostExecute(String result)（在新活动中开始时）。错误：Android - android.os.NetworkOnMainThreadException我使用了几种方法来解决这个问题，但我无法解决这个问题。请有人帮我
public class Login extends Activity {
private Button btnLogin;
private EditText txtusername;
private EditText txtPassword;
public String username;
public String password;
public boolean doLogin = false;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
setContentView(R.layout.login);
btnLogin = (Button) findViewById(R.id.btnLogin);
txtusername = (EditText) findViewById(R.id.txtuserName);
txtPassword = (EditText) findViewById(R.id.txtPassword);
btnLogin.setOnClickListener(new OnClickListener() {
public void onClick(View arg0) {
username = txtusername.getText().toString();
password = txtPassword.getText().toString();
if (username.equals("") || password.equals("")) {
AlertDialog alert = new AlertDialog.Builder(Login.this)
.create();
alert.setMessage("Username or Password can not be Empty");
alert.setButton("OK",
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog,
int which) {
}
});
alert.setIcon(R.drawable.loginlogo);
alert.show();
}
else {
HttpAsync httpasync = new HttpAsync();
httpasync.execute(new String[] { "http://www.diskonbanget.com/bni/login/login.php" });
}
}
});
}
private class HttpAsync extends AsyncTask<String, Void, String> {
@Override
protected String doInBackground(String... params) {
String str = null;
try {
// Create a new HttpClient and Post Header
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost(
"http://www.diskonbanget.com/bni/login/login.php");
List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(
2);
nameValuePairs
.add(new BasicNameValuePair("username", username));
nameValuePairs
.add(new BasicNameValuePair("password", password));
httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
// Execute HTTP Post Request
HttpResponse response = httpclient.execute(httppost);
str = inputStreamToString(response.getEntity().getContent())
.toString();
} catch (Exception e) {
return str;
}
return str;
}
@Override
protected void onPostExecute(String result) {
String str = result;
if (str.toString().equalsIgnoreCase("false")) {
AlertDialog alert = new AlertDialog.Builder(Login.this)
.create();
alert.setMessage("Please enter valid username & Password");
alert.setButton("OK", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
}
});
alert.setIcon(R.drawable.loginlogo);
alert.show();
}
else if (str.toString().equalsIgnoreCase("null")) {
AlertDialog alert = new AlertDialog.Builder(Login.this)
.create();
alert.setMessage("Can not Connect to the server.please make sure your internet is Switch on ");
alert.setButton("OK", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
}
});
alert.setIcon(R.drawable.loginlogo);
alert.show();
}
else {
Intent intent = new Intent(Login.this, MainMenu.class);
intent.putExtra("photo", str);
intent.putExtra("username", username);
startActivity(intent);
}
}
}
private StringBuilder inputStreamToString(InputStream is) {
String line = "";
StringBuilder total = new StringBuilder();
// Wrap a BufferedReader around the InputStream
BufferedReader rd = new BufferedReader(new InputStreamReader(is));
// Read response until the end
try {
while ((line = rd.readLine()) != null) {
total.append(line);
}
return total;
} catch (Exception e) {
return null;
}
}
这是我的 LogCat
10-11 18:37:52.540: E/AndroidRuntime(2858): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.bni.www/com.bni.www.MainMenu}: android.os.NetworkOnMainThreadException
10-11 19:00:45.498: E/AndroidRuntime(2925): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1026)
10-11 19:00:45.498: E/AndroidRuntime(2925): at android.os.Handler.dispatchMessage(Handler.java:99)
10-11 19:00:45.498: E/AndroidRuntime(2925): at android.os.Looper.loop(Looper.java:132)
10-11 19:00:45.498: E/AndroidRuntime(2925): at java.lang.reflect.Method.invokeNative(Native Method)
10-11 19:00:45.498: E/AndroidRuntime(2925): at java.lang.reflect.Method.invoke(Method.java:491)
10-11 19:00:45.498: E/AndroidRuntime(2925): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:841)
10-11 19:00:45.498: E/AndroidRuntime(2925): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:599)
10-11 19:00:45.498: E/AndroidRuntime(2925): at dalvik.system.NativeStart.main(Native Method)
10-11 19:00:45.498: E/AndroidRuntime(2925): Caused by: android.os.NetworkOnMainThreadException
10-11 19:00:45.498: E/AndroidRuntime(2925): at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1077)
10-11 19:00:45.498: E/AndroidRuntime(2925): at java.net.InetAddress.lookupHostByName(InetAddress.java:477)
10-11 19:00:45.498: E/AndroidRuntime(2925): at java.net.InetAddress.getAllByNameImpl(InetAddress.java:277)
10-11 19:00:45.498: E/AndroidRuntime(2925): at java.net.InetAddress.getAllByName(InetAddress.java:249)
10-11 19:00:45.498: E/AndroidRuntime(2925): at org.apache.harmony.luni.internal.net.www.protocol.http.HttpConnection.<init>(HttpConnection.java:69)
10-11 19:00:45.498: E/AndroidRuntime(2925): at org.apache.harmony.luni.internal.net.www.protocol.http.HttpConnection.<init>(HttpConnection.java:48)
10-11 19:00:45.498: E/AndroidRuntime(2925): at org.apache.harmony.luni.internal.net.www.protocol.http.HttpConnection$Address.connect(HttpConnection.java:304)
10-11 19:00:45.498: E/AndroidRuntime(2925): at org.apache.harmony.luni.internal.net.www.protocol.http.HttpConnectionPool.get(HttpConnectionPool.java:89)
10-11 19:00:45.498: E/AndroidRuntime(2925): at org.apache.harmony.luni.internal.net.www.protocol.http.HttpURLConnectionImpl.getHttpConnection(HttpURLConnectionImpl.java:292)
10-11 19:00:45.498: E/AndroidRuntime(2925): at org.apache.harmony.luni.internal.net.www.protocol.http.HttpURLConnectionImpl.makeConnection(HttpURLConnectionImpl.java:274)
10-11 19:00:45.498: E/AndroidRuntime(2925): at org.apache.harmony.luni.internal.net.www.protocol.http.HttpURLConnectionImpl.connect(HttpURLConnectionImpl.java:217)
10-11 19:00:45.498: E/AndroidRuntime(2925): at java.net.URLConnection.getContent(URLConnection.java:197)
10-11 19:00:45.498: E/AndroidRuntime(2925): at java.net.URL.getContent(URL.java:613)
10-11 19:00:45.498: E/AndroidRuntime(2925): at com.bni.www.MainMenu.onCreate(MainMenu.java:48)
10-11 19:00:45.498: E/AndroidRuntime(2925): at android.app.Activity.performCreate(Activity.java:4411)
10-11 19:00:45.498: E/AndroidRuntime(2925): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1048)
10-11 19:00:45.498: E/AndroidRuntime(2925): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1781)
10-11 19:00:45.498: E/AndroidRuntime(2925): ... 11 more
10-11 19:01:22.538: I/Process(2925): Sending signal. PID: 2925 SIG: 9
10-11 19:12:24.357: D/dalvikvm(2998): GC_FOR_ALLOC freed 43K, 3% free 6404K/6595K, paused 111ms
10-11 19:12:24.377: I/dalvikvm-heap(2998): Grow heap (frag case) to 7.295MB for 1031504-byte allocation
10-11 19:12:24.489: D/dalvikvm(2998): GC_FOR_ALLOC freed <1K, 3% free 7411K/7623K, paused 86ms