我目前正在开发一个应用程序，我正在尝试使用login / registatration实现一个用户系统。我一直在阅读几个教程，以了解该做什么。现在我开始怀疑我的eclipse环境是否有问题，因为在尝试了2或3个教程（并下载源代码进行测试）后，我不断遇到相同的错误。
而不是发布所有代码（有很多）...这是项目教程的链接 http://www.learn2crack.com/2013/08/develop-android-login-registration-with-php-mysql.html
I also tried this tutorial and had the same errors.
以下是我遇到的错误。有人可以就我应该尝试的内容提出一些想法。我在我的域IE http://mydomain.com/apifolder/, and tested this locally http://192.168.0.6/apifolder/上传了代码。如果我需要发布任何其他内容，请告诉我。
03-06 08:15:23.120: E/ViewRootImpl(32166): sendUserActionEvent() mView == null
03-06 08:15:23.405: E/JSON(32166): Table 'usertest.users' doesn't exist
03-06 08:15:23.405: E/JSON Parser(32166): Error parsing data org.json.JSONException: Value Table of type java.lang.String cannot be converted to JSONObject
03-06 08:15:23.405: D/AndroidRuntime(32166): Shutting down VM
03-06 08:15:23.405: W/dalvikvm(32166): threadid=1: thread exiting with uncaught exception (group=0x4195e700)
03-06 08:15:23.410: E/AndroidRuntime(32166): FATAL EXCEPTION: main
03-06 08:15:23.410: E/AndroidRuntime(32166): java.lang.NullPointerException
03-06 08:15:23.410: E/AndroidRuntime(32166): at com.learn2crack.Login$ProcessLogin.onPostExecute(Login.java:212)
03-06 08:15:23.410: E/AndroidRuntime(32166): at com.learn2crack.Login$ProcessLogin.onPostExecute(Login.java:1)
03-06 08:15:23.410: E/AndroidRuntime(32166): at android.os.AsyncTask.finish(AsyncTask.java:631)
03-06 08:15:23.410: E/AndroidRuntime(32166): at android.os.AsyncTask.access$600(AsyncTask.java:177)
03-06 08:15:23.410: E/AndroidRuntime(32166): at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:644)
03-06 08:15:23.410: E/AndroidRuntime(32166): at android.os.Handler.dispatchMessage(Handler.java:99)
03-06 08:15:23.410: E/AndroidRuntime(32166): at android.os.Looper.loop(Looper.java:137)
03-06 08:15:23.410: E/AndroidRuntime(32166): at android.app.ActivityThread.main(ActivityThread.java:5455)
03-06 08:15:23.410: E/AndroidRuntime(32166): at java.lang.reflect.Method.invokeNative(Native Method)
03-06 08:15:23.410: E/AndroidRuntime(32166): at java.lang.reflect.Method.invoke(Method.java:525)
03-06 08:15:23.410: E/AndroidRuntime(32166): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1209)
03-06 08:15:23.410: E/AndroidRuntime(32166): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1025)
03-06 08:15:23.410: E/AndroidRuntime(32166): at dalvik.system.NativeStart.main(Native Method)
package com.learn2crack;
/**
* Author :Raj Amal
* Email :raj.amalw@learn2crack.com
* Website:www.learn2crack.com
**/
import android.app.Activity;
import android.app.ProgressDialog;
import android.content.Context;
import android.content.Intent;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
import com.learn2crack.library.DatabaseHandler;
import com.learn2crack.library.UserFunctions;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.IOException;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
public class Register extends Activity {
/**
* JSON Response node names.
**/
private static String KEY_SUCCESS = "success";
private static String KEY_UID = "uid";
private static String KEY_FIRSTNAME = "fname";
private static String KEY_LASTNAME = "lname";
private static String KEY_USERNAME = "uname";
private static String KEY_EMAIL = "email";
private static String KEY_CREATED_AT = "created_at";
private static String KEY_ERROR = "error";
/**
* Defining layout items.
**/
EditText inputFirstName;
EditText inputLastName;
EditText inputUsername;
EditText inputEmail;
EditText inputPassword;
Button btnRegister;
TextView registerErrorMsg;
/**
* Called when the activity is first created.
*/
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.register);
/**
* Defining all layout items
**/
inputFirstName = (EditText) findViewById(R.id.fname);
inputLastName = (EditText) findViewById(R.id.lname);
inputUsername = (EditText) findViewById(R.id.uname);
inputEmail = (EditText) findViewById(R.id.email);
inputPassword = (EditText) findViewById(R.id.pword);
btnRegister = (Button) findViewById(R.id.register);
registerErrorMsg = (TextView) findViewById(R.id.register_error);
/**
* Button which Switches back to the login screen on clicked
**/
Button login = (Button) findViewById(R.id.bktologin);
login.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
Intent myIntent = new Intent(view.getContext(), Login.class);
startActivityForResult(myIntent, 0);
finish();
}
});
/**
* Register Button click event.
* A Toast is set to alert when the fields are empty.
* Another toast is set to alert Username must be 5 characters.
**/
btnRegister.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if ( ( !inputUsername.getText().toString().equals("")) && ( !inputPassword.getText().toString().equals("")) && ( !inputFirstName.getText().toString().equals("")) && ( !inputLastName.getText().toString().equals("")) && ( !inputEmail.getText().toString().equals("")) )
{
if ( inputUsername.getText().toString().length() > 4 ){
NetAsync(view);
}
else
{
Toast.makeText(getApplicationContext(),
"Username should be minimum 5 characters", Toast.LENGTH_SHORT).show();
}
}
else
{
Toast.makeText(getApplicationContext(),
"One or more fields are empty", Toast.LENGTH_SHORT).show();
}
}
});
}
/**
* Async Task to check whether internet connection is working
**/
private class NetCheck extends AsyncTask<String,String,Boolean>
{
private ProgressDialog nDialog;
@Override
protected void onPreExecute(){
super.onPreExecute();
nDialog = new ProgressDialog(Register.this);
nDialog.setMessage("Loading..");
nDialog.setTitle("Checking Network");
nDialog.setIndeterminate(false);
nDialog.setCancelable(true);
nDialog.show();
}
@Override
protected Boolean doInBackground(String... args){
/**
* Gets current device state and checks for working internet connection by trying Google.
**/
ConnectivityManager cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo netInfo = cm.getActiveNetworkInfo();
if (netInfo != null && netInfo.isConnected()) {
try {
URL url = new URL("http://www.google.com");
HttpURLConnection urlc = (HttpURLConnection) url.openConnection();
urlc.setConnectTimeout(3000);
urlc.connect();
if (urlc.getResponseCode() == 200) {
return true;
}
} catch (MalformedURLException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
return false;
}
@Override
protected void onPostExecute(Boolean th){
if(th == true){
nDialog.dismiss();
new ProcessRegister().execute();
}
else{
nDialog.dismiss();
registerErrorMsg.setText("Error in Network Connection");
}
}
}
private class ProcessRegister extends AsyncTask<String, String, JSONObject> {
/**
* Defining Process dialog
**/
private ProgressDialog pDialog;
String email,password,fname,lname,uname;
@Override
protected void onPreExecute() {
super.onPreExecute();
inputUsername = (EditText) findViewById(R.id.uname);
inputPassword = (EditText) findViewById(R.id.pword);
fname = inputFirstName.getText().toString();
lname = inputLastName.getText().toString();
email = inputEmail.getText().toString();
uname= inputUsername.getText().toString();
password = inputPassword.getText().toString();
pDialog = new ProgressDialog(Register.this);
pDialog.setTitle("Contacting Servers");
pDialog.setMessage("Registering ...");
pDialog.setIndeterminate(false);
pDialog.setCancelable(true);
pDialog.show();
}
@Override
protected JSONObject doInBackground(String... args) {
UserFunctions userFunction = new UserFunctions();
JSONObject json = userFunction.registerUser(fname, lname, email, uname, password);
return json;
}
@Override
protected void onPostExecute(JSONObject json) {
/**
* Checks for success message.
**/
try {
if (json.getString(KEY_SUCCESS) != null) {
registerErrorMsg.setText("");
String res = json.getString(KEY_SUCCESS);
String red = json.getString(KEY_ERROR);
if(Integer.parseInt(res) == 1){
pDialog.setTitle("Getting Data");
pDialog.setMessage("Loading Info");
registerErrorMsg.setText("Successfully Registered");
DatabaseHandler db = new DatabaseHandler(getApplicationContext());
JSONObject json_user = json.getJSONObject("user");
/**
* Removes all the previous data in the SQlite database
**/
UserFunctions logout = new UserFunctions();
logout.logoutUser(getApplicationContext());
db.addUser(json_user.getString(KEY_FIRSTNAME),json_user.getString(KEY_LASTNAME),json_user.getString(KEY_EMAIL),json_user.getString(KEY_USERNAME),json_user.getString(KEY_UID),json_user.getString(KEY_CREATED_AT));
/**
* Stores registered data in SQlite Database
* Launch Registered screen
**/
Intent registered = new Intent(getApplicationContext(), Registered.class);
/**
* Close all views before launching Registered screen
**/
registered.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
pDialog.dismiss();
startActivity(registered);
finish();
}
else if (Integer.parseInt(red) ==2){
pDialog.dismiss();
registerErrorMsg.setText("User already exists");
}
else if (Integer.parseInt(red) ==3){
pDialog.dismiss();
registerErrorMsg.setText("Invalid Email id");
}
}
else{
pDialog.dismiss();
registerErrorMsg.setText("Error occured in registration");
}
} catch (JSONException e) {
e.printStackTrace();
}
}}
public void NetAsync(View view){
new NetCheck().execute();
}}
package com.learn2crack;
/**
* Author :Raj Amal
* Email :raj.amalw@learn2crack.com
* Website:www.learn2crack.com
**/
import android.app.ProgressDialog;
import android.content.Context;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.AsyncTask;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
import com.learn2crack.library.DatabaseHandler;
import com.learn2crack.library.UserFunctions;
import java.io.IOException;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
public class Login extends Activity {
Button btnLogin;
Button Btnregister;
Button passreset;
EditText inputEmail;
EditText inputPassword;
private TextView loginErrorMsg;
/**
* Called when the activity is first created.
*/
private static String KEY_SUCCESS = "success";
private static String KEY_UID = "uid";
private static String KEY_USERNAME = "uname";
private static String KEY_FIRSTNAME = "fname";
private static String KEY_LASTNAME = "lname";
private static String KEY_EMAIL = "email";
private static String KEY_CREATED_AT = "created_at";
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
inputEmail = (EditText) findViewById(R.id.email);
inputPassword = (EditText) findViewById(R.id.pword);
Btnregister = (Button) findViewById(R.id.registerbtn);
btnLogin = (Button) findViewById(R.id.login);
passreset = (Button)findViewById(R.id.passres);
loginErrorMsg = (TextView) findViewById(R.id.loginErrorMsg);
passreset.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
Intent myIntent = new Intent(view.getContext(), PasswordReset.class);
startActivityForResult(myIntent, 0);
finish();
}});
Btnregister.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
Intent myIntent = new Intent(view.getContext(), Register.class);
startActivityForResult(myIntent, 0);
finish();
}});
/**
* Login button click event
* A Toast is set to alert when the Email and Password field is empty
**/
btnLogin.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
if ( ( !inputEmail.getText().toString().equals("")) && ( !inputPassword.getText().toString().equals("")) )
{
NetAsync(view);
}
else if ( ( !inputEmail.getText().toString().equals("")) )
{
Toast.makeText(getApplicationContext(),
"Password field empty", Toast.LENGTH_SHORT).show();
}
else if ( ( !inputPassword.getText().toString().equals("")) )
{
Toast.makeText(getApplicationContext(),
"Email field empty", Toast.LENGTH_SHORT).show();
}
else
{
Toast.makeText(getApplicationContext(),
"Email and Password field are empty", Toast.LENGTH_SHORT).show();
}
}
});
}
/**
* Async Task to check whether internet connection is working.
**/
private class NetCheck extends AsyncTask<String,String,Boolean>
{
private ProgressDialog nDialog;
@Override
protected void onPreExecute(){
super.onPreExecute();
nDialog = new ProgressDialog(Login.this);
nDialog.setTitle("Checking Network");
nDialog.setMessage("Loading..");
nDialog.setIndeterminate(false);
nDialog.setCancelable(true);
nDialog.show();
}
/**
* Gets current device state and checks for working internet connection by trying Google.
**/
@Override
protected Boolean doInBackground(String... args){
ConnectivityManager cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo netInfo = cm.getActiveNetworkInfo();
if (netInfo != null && netInfo.isConnected()) {
try {
URL url = new URL("http://www.google.com");
HttpURLConnection urlc = (HttpURLConnection) url.openConnection();
urlc.setConnectTimeout(3000);
urlc.connect();
if (urlc.getResponseCode() == 200) {
return true;
}
} catch (MalformedURLException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
return false;
}
@Override
protected void onPostExecute(Boolean th){
if(th == true){
nDialog.dismiss();
new ProcessLogin().execute();
}
else{
nDialog.dismiss();
loginErrorMsg.setText("Error in Network Connection");
}
}
}
/**
* Async Task to get and send data to My Sql database through JSON respone.
**/
private class ProcessLogin extends AsyncTask<String, String, JSONObject> {
private ProgressDialog pDialog;
String email,password;
@Override
protected void onPreExecute() {
super.onPreExecute();
inputEmail = (EditText) findViewById(R.id.email);
inputPassword = (EditText) findViewById(R.id.pword);
email = inputEmail.getText().toString();
password = inputPassword.getText().toString();
pDialog = new ProgressDialog(Login.this);
pDialog.setTitle("Contacting Servers");
pDialog.setMessage("Logging in ...");
pDialog.setIndeterminate(false);
pDialog.setCancelable(true);
pDialog.show();
}
@Override
protected JSONObject doInBackground(String... args) {
UserFunctions userFunction = new UserFunctions();
JSONObject json = userFunction.loginUser(email, password);
return json;
}
@Override
protected void onPostExecute(JSONObject json) {
try {
if (json.getString(KEY_SUCCESS) != null) {
String res = json.getString(KEY_SUCCESS);
if(Integer.parseInt(res) == 1){
pDialog.setMessage("Loading User Space");
pDialog.setTitle("Getting Data");
DatabaseHandler db = new DatabaseHandler(getApplicationContext());
JSONObject json_user = json.getJSONObject("user");
/**
* Clear all previous data in SQlite database.
**/
UserFunctions logout = new UserFunctions();
logout.logoutUser(getApplicationContext());
db.addUser(json_user.getString(KEY_FIRSTNAME),json_user.getString(KEY_LASTNAME),json_user.getString(KEY_EMAIL),json_user.getString(KEY_USERNAME),json_user.getString(KEY_UID),json_user.getString(KEY_CREATED_AT));
/**
*If JSON array details are stored in SQlite it launches the User Panel.
**/
Intent upanel = new Intent(getApplicationContext(), Main.class);
upanel.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
pDialog.dismiss();
startActivity(upanel);
/**
* Close Login Screen
**/
finish();
}else{
pDialog.dismiss();
loginErrorMsg.setText("Incorrect username/password");
}
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}
public void NetAsync(View view){
new NetCheck().execute();
}
}
问题显然都与连接失败有关。我弄清楚错误的位置，特别是数据库没有正确设置，它正在工作。有没有办法在不创建空异常的情况下捕获它？如果由于某种原因数据库不可用，我希望应用程序不会崩溃。