所以我的第一部分登录正在工作。它没有问题。现在，当我尝试使用相同的应用程序进行注册时，它就停止了工作。我在这里迷路了，我是安卓开发的新手，所以我真的不明白给出的错误。
主活动.java
public class MainActivity extends AppCompatActivity {
EditText UsernameEt, PasswordEt;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
UsernameEt = (EditText) findViewById(R.id.etUserName);
PasswordEt = (EditText) findViewById(R.id.etPassword);
}
public void OnLogin(View view){
String username = UsernameEt.getText().toString();
String password = PasswordEt.getText().toString();
String type = "login";
BackgroundWorker backgroundWorker = new BackgroundWorker(this);
backgroundWorker.setOnTaskFinishedListener(new BackgroundWorker.OnTaskFinishedListener() {
@Override
public void onTaskFinished(String result) {
// Now you have the result of your login here.
// Result should be "admin", "user", or "failed"
// You can now create an intent and open the page
// to your next activity.
switch (result) {
case "admin":
// Create your intent.
Intent adminIntent = new Intent(MainActivity.this, AdminPageActivity.class);
// Start the admin page activity.
startActivity(adminIntent);
break;
case "user":
// Create your intent.
Intent userIntent = new Intent(MainActivity.this, UserPageActivity.class);
// Start the user page activity.
startActivity(userIntent);
break;
default:
// Login failed.
Intent failIntent = new Intent(MainActivity.this, MainActivity.class);
startActivity(failIntent);
break;
}
}
});
backgroundWorker.execute(type, username, password);
}
public void openRegistration(View view){
startActivity(new Intent(this, Registration.class));
}
}
注册.java
public class Registration extends AppCompatActivity {
EditText NameEt, RoleEt, UsernameEt, PasswordEt;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_registration);
NameEt = (EditText) findViewById(R.id.etName);
UsernameEt = (EditText) findViewById(R.id.etUserName);
PasswordEt = (EditText) findViewById(R.id.etPassword);
RoleEt = (EditText) findViewById(R.id.etRole);
}
public void OnRegister(View view) {
String str_name = NameEt.getText().toString();
String str_username = UsernameEt.getText().toString();
String str_password = PasswordEt.getText().toString();
String str_role = RoleEt.getText().toString();
String type = "register";
BackgroundWorker backgroundWorker = new BackgroundWorker(this);
backgroundWorker.execute(type, str_name, str_username, str_password, str_role);
}
}
背景工作者.java
public class BackgroundWorker extends AsyncTask<String,Void,String> {
Context context;
AlertDialog alertDialog;
BackgroundWorker (Context ctx) {
context = ctx;
}
@Override
protected String doInBackground(String... params) {
String type = params[0];
String login_url = "http://ipaddress/folder/login.php";
String register_url = "http://ipaddress/folder/register.php";
if(type.equals("login")) {
try {
String user_name = params[1];
String password = params[2];
URL url = new URL(login_url);
HttpURLConnection httpURLConnection = (HttpURLConnection)url.openConnection();
httpURLConnection.setRequestMethod("POST");
httpURLConnection.setDoOutput(true);
httpURLConnection.setDoInput(true);
OutputStream outputStream = httpURLConnection.getOutputStream();
BufferedWriter bufferedWriter = new BufferedWriter(new OutputStreamWriter(outputStream, "UTF-8"));
String post_data = URLEncoder.encode("user_name","UTF-8")+"="+URLEncoder.encode(user_name,"UTF-8") +"&" + URLEncoder.encode("password","UTF-8") + "=" + URLEncoder.encode(password,"UTF-8");
bufferedWriter.write(post_data);
bufferedWriter.flush();
bufferedWriter.close();
outputStream.close();
InputStream inputStream = httpURLConnection.getInputStream();
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream,"iso-8859-1"));
String result="";
String line="";
while((line = bufferedReader.readLine())!= null) {
result += line;
}
bufferedReader.close();
inputStream.close();
httpURLConnection.disconnect();
return result;
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
} else if(type.equals("register")) {
try {
String name = params[1];
String username = params[2];
String password = params[3];
String role = params[4];
URL url = new URL(register_url);
HttpURLConnection httpURLConnection = (HttpURLConnection)url.openConnection();
httpURLConnection.setRequestMethod("POST");
httpURLConnection.setDoOutput(true);
httpURLConnection.setDoInput(true);
OutputStream outputStream = httpURLConnection.getOutputStream();
BufferedWriter bufferedWriter = new BufferedWriter(new OutputStreamWriter(outputStream, "UTF-8"));
String post_data = URLEncoder.encode("name", "UTF-8") + "=" + URLEncoder.encode(name,"UTF-8") + "&" + URLEncoder.encode("username", "UTF-8")+"="+URLEncoder.encode(username,"UTF-8") + "&" + URLEncoder.encode("password", "UTF-8") + "=" + URLEncoder.encode(password,"UTF-8") + "&" + URLEncoder.encode("role","UTF-8") + "=" + URLEncoder.encode(role,"UTF-8");
bufferedWriter.write(post_data);
bufferedWriter.flush();
bufferedWriter.close();
outputStream.close();
InputStream inputStream = httpURLConnection.getInputStream();
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream,"iso-8859-1"));
String result="";
String line="";
while((line = bufferedReader.readLine())!= null) {
result += line;
}
bufferedReader.close();
inputStream.close();
httpURLConnection.disconnect();
return result;
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
return null;
}
public interface OnTaskFinishedListener {
void onTaskFinished(String result);
}
// Member property to reference listener.
private OnTaskFinishedListener mOnTaskFinishedListener;
// Setter for listener.
public void setOnTaskFinishedListener(OnTaskFinishedListener listener) {
mOnTaskFinishedListener = listener;
}
@Override
protected void onPreExecute() {
alertDialog = new AlertDialog.Builder(context).create();
alertDialog.setTitle("Login Status");
}
@Override
protected void onPostExecute(String result) {
alertDialog.setMessage(result);
alertDialog.show();
switch (result) {
case "failed":
// Login failed.
break;
case "user": // Login successful, result (role) is "user"
result = "user";
break;
case "admin": // Login successful, result (role) is "admin"
result = "admin";
break;
}
if (mOnTaskFinishedListener != null) {
mOnTaskFinishedListener.onTaskFinished(result);
}
}
@Override
protected void onProgressUpdate(Void... values) {
super.onProgressUpdate(values);
}
}
我刚刚添加了另一个if else用于在backgroundworker.java上注册。
注册.php
<?php
require "conn.php";
$name = $_POST["name"];
$username = $_POST["username"];
$password = $_POST["password"];
$role = $_POST["role"];
$mysql_qry = "insert into employee_data (name, username, password, role) values ('$name', '$username', '$password', '$role')";
if($conn->query($mysql_qry) === TRUE){
echo "success";
}
else {
echo "fail".$mysql_qry."<br>".$conn->error;
}
$conn->close();
?>
我被困在这里，请帮忙。
错误日志
Process: com.example.user.mysqldemo, PID: 1325
java.lang.IllegalStateException: Could not execute method for android:onClick
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:275)
at android.view.View.performClick(View.java:4438)
at android.view.View$PerformClick.run(View.java:18422)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5001)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:270)
at android.view.View.performClick(View.java:4438)
at android.view.View$PerformClick.run(View.java:18422)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5001)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.example.user.mysqldemo.Registration.OnRegister(Registration.java:28)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:270)
at android.view.View.performClick(View.java:4438)
at android.view.View$PerformClick.run(View.java:18422)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5001)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
at dalvik.system.NativeStart.main(Native Method)
6.Activity_registration.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:orientation="vertical"
android:layout_height="match_parent"
android:layout_width="match_parent"
android:padding="10dp">
<TextView
android:layout_width="wrap_content"
android:text="Name"
android:layout_height="wrap_content" />
<EditText
android:id="@+id/etName"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginBottom="10dp"/>
<TextView
android:layout_width="wrap_content"
android:text="Username"
android:layout_height="wrap_content" />
<EditText
android:id="@+id/etUsername"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginBottom="10dp"/>
<TextView
android:layout_width="wrap_content"
android:text="Password"
android:layout_height="wrap_content" />
<EditText
android:id="@+id/etPassword"
android:layout_width="match_parent"
android:inputType="textPassword"
android:layout_height="wrap_content"
android:layout_marginBottom="10dp"/>
<TextView
android:layout_width="wrap_content"
android:text="Role"
android:layout_height="wrap_content" />
<EditText
android:id="@+id/etRole"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginBottom="10dp"/>
<Button
android:id="@+id/bRegister"
android:text="Register"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:onClick="OnRegister"/>
当您添加 android:onClick 属性时，您还必须进行widget clickable。将 xml 更新为
<Button
android:id="@+id/bRegister"
android:text="Register"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:clickable="true"
android:onClick="OnRegister"/>
希望这有帮助。
更新这行UsernameEt = (EditText) findViewById(R.id.etUserName);是罪魁祸首，因为register_activity xml不包含 ID etUserName 。它指向其他一些 xml，而不是此 xml 包含此 id etUsername