我在 android 3.1 上运行，并且在我的登录 java 类中实现了异步。但是，在我实现它之后，我得到了严格模式异常。为什么会出现这种错误？
登录.java
public class LoginActivity extends Activity {
Button btnLogin;
Button btnLinkToRegister;
EditText inputNric;
EditText inputPassword;
TextView loginErrorMsg;
// Progress Dialog
private ProgressDialog pDialog;
// JSON Response node names
//success is the column name of the database - KEY_SUCCESS is we create the name
private static String KEY_SUCCESS = "success";
private static String KEY_ERROR = "error";
private static String KEY_ERROR_MSG = "error_msg";
private static String KEY_NAME = "name";
private static String KEY_NRIC = "nric";
private static String KEY_CREATED_AT = "created_at";
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.login);
//StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
// StrictMode.setThreadPolicy(policy);
// Importing all assets like buttons, text fields
inputNric = (EditText) findViewById(R.id.loginNric);
inputPassword = (EditText) findViewById(R.id.loginPassword);
btnLogin = (Button) findViewById(R.id.buttonLogin);
btnLinkToRegister = (Button) findViewById(R.id.btnLinkToRegisterScreen);
loginErrorMsg = (TextView) findViewById(R.id.login_error);
// login button click event
btnLogin.setOnClickListener(new View.OnClickListener() {
public void onClick(View arg0) {
// starting background task to update case
new LoginUser().execute();
}
});
/*// Link to Register Screen
btnLinkToRegister.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
Intent i = new Intent(getApplicationContext(),
RegisterActivity.class);
startActivity(i);
finish();
}
});*/
}
/**
* Background Async Task to Login User
* */
class LoginUser extends AsyncTask<String, String, String> {
/**
* Before starting background thread Show Progress Dialog
* */
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(LoginActivity.this);
pDialog.setMessage("Logging In ...");
pDialog.setIndeterminate(false);
pDialog.setCancelable(true);
pDialog.show();
}
/**
* Logging in
* */
protected String doInBackground(String... params) {
// updating UI from Background Thread
runOnUiThread(new Runnable() {
public void run() {
String nric = inputNric.getText().toString();
String password = inputPassword.getText().toString();
UserFunctions userFunction = new UserFunctions();
Log.d("Button", "Login");
JSONObject json = userFunction.loginUser(nric, password);
// check for login response
try {
if (json.getString(KEY_SUCCESS) != null) {
loginErrorMsg.setText("");
String res = json.getString(KEY_SUCCESS);
if(Integer.parseInt(res) == 1){
// user successfully logged in
// Store user details in SQLite Database
DatabaseHandler db = new DatabaseHandler(getApplicationContext());
JSONObject json_user = json.getJSONObject("user");
// Clear all previous data in database
userFunction.logoutUser(getApplicationContext());
db.addUser(json_user.getString(KEY_NAME), json_user.getString(KEY_NRIC), json_user.getString(KEY_CREATED_AT));
// Launch home Screen
Intent home = new Intent(getApplicationContext(), AllTabActivity.class);
// Close all views before launching home
home.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(home);
// Close Login Screen
finish();
}else{
// Error in login
loginErrorMsg.setText("Incorrect username/password");
}
}
} catch (JSONException e) {
e.printStackTrace();
}
}
});
return null;
}
/**
* After completing background task Dismiss the progress dialog
* **/
protected void onPostExecute(String file_url) {
// dismiss the dialog once case deleted
pDialog.dismiss();
}
}
}
Logcat 错误：
08-14 17:46:37.766: E/AndroidRuntime(1208): android.os.NetworkOnMainThreadException
08-14 17:46:37.766: E/AndroidRuntime(1208): at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1077)
08-14 17:46:37.766: E/AndroidRuntime(1208): at java.net.InetAddress.lookupHostByName(InetAddress.java:477)
08-14 17:46:37.766: E/AndroidRuntime(1208): at java.net.InetAddress.getAllByNameImpl(InetAddress.java:277)
08-14 17:46:37.766: E/AndroidRuntime(1208): at java.net.InetAddress.getAllByName(InetAddress.java:249)
08-14 17:46:37.766: E/AndroidRuntime(1208): at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:136)
08-14 17:46:37.766: E/AndroidRuntime(1208): at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164)
08-14 17:46:37.766: E/AndroidRuntime(1208): at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119)
08-14 17:46:37.766: E/AndroidRuntime(1208): at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:360)
08-14 17:46:37.766: E/AndroidRuntime(1208): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555)
08-14 17:46:37.766: E/AndroidRuntime(1208): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)
08-14 17:46:37.766: E/AndroidRuntime(1208): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465)
08-14 17:46:37.766: E/AndroidRuntime(1208): at com.pivestigator.JSONParser.makeHttpRequest(JSONParser.java:51)
08-14 17:46:37.766: E/AndroidRuntime(1208): at com.pivestigator.login.library.UserFunctions.loginUser(UserFunctions.java:40)
08-14 17:46:37.766: E/AndroidRuntime(1208): at com.pivestigator.login.LoginActivity$LoginUser$1.run(LoginActivity.java:112)
08-14 17:46:37.766: E/AndroidRuntime(1208): at android.os.Handler.handleCallback(Handler.java:587)
08-14 17:46:37.766: E/AndroidRuntime(1208): at android.os.Handler.dispatchMessage(Handler.java:92)
08-14 17:46:37.766: E/AndroidRuntime(1208): at android.os.Looper.loop(Looper.java:132)
08-14 17:46:37.766: E/AndroidRuntime(1208): at android.app.ActivityThread.main(ActivityThread.java:4025)
08-14 17:46:37.766: E/AndroidRuntime(1208): at java.lang.reflect.Method.invokeNative(Native Method)
08-14 17:46:37.766: E/AndroidRuntime(1208): at java.lang.reflect.Method.invoke(Method.java:491)
08-14 17:46:37.766: E/AndroidRuntime(1208): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:841)
08-14 17:46:37.766: E/AndroidRuntime(1208): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:599)
08-14 17:46:37.766: E/AndroidRuntime(1208): at dalvik.system.NativeStart.main(Native Method)