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안드로이드 프로젝트에 약간의 문제가 있습니다. MySQL 데이터베이스의 데이터로 목록을 채우고 싶지만 안드로이드가 연결되지 않았습니다.안드로이드를 통한 MySQL 연결 오류
MySQLConnector:
private static Connection con = null;
private static String dbHost = "85.214.101.213"; // changed the ip :)
private static String dbPort = "3306"; // Port -- Standard: 3306
private static String dbName = "ticketsystem"; // Datenbankname
private static String dbUser = "admin"; // Datenbankuser
private static String dbPass = "root"; // Datenbankpasswort
public static void conect() {
try {
Class.forName("com.mysql.jdbc.Driver"); // Datenbanktreiber für JDBC
System.out.println("jdbc:mysql://" + dbHost + ":" + dbPort + "/" + dbName + "?" + "user="
+ dbUser + "&" + "password=" + dbPass);
con = DriverManager.getConnection("jdbc:mysql://" + dbHost + ":" + dbPort + "/" + dbName + "?" + "user="
+ dbUser + "&" + "password=" + dbPass);
} catch (ClassNotFoundException e) {
System.out.println("Treiber nicht gefunden");
} catch (SQLException e) {
System.out.println(e);
System.out.println("Verbindung nicht moglich");
System.out.println("SQLException: " + e.getMessage());
System.out.println("SQLState: " + e.getSQLState());
System.out.println("VendorError: " + e.getErrorCode());
}
}
SQLManager:
public SQLManager() {
MySQLConnection.conect();
Log.e("test", "nach conect");
con = MySQLConnection.getCon();
}
public String[] getFreeEvents() {
ArrayList<String> mList = new ArrayList();
try
{
PreparedStatement ps = con.prepareStatement(" SELECT `EventID`,`Name`,`Zeit`,`Ort` FROM `event` WHERE `freeTickets` >= ?");
ps.setInt(1, 0);
ResultSet rs = ps.executeQuery();
while (rs.next())
{
int EventID = rs.getInt("EventID");
String Name = rs.getString("Name");
String Zeit = rs.getString("Zeit");
String Ort = rs.getString("Ort");
String info = Name +"," + Zeit + ","+Ort ;
mList.add(info);
System.out.println(info);
}
}
catch (SQLException e)
{
e.printStackTrace();
}
String[] array = mList.toArray(new String[0]);
return array;
}
And the Class form the Android activity:
Button b;
ListView list;
EditText vor;
TextView nach;
SQLManager man = new SQLManager();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_new_ticket);
setContentView(R.layout.activity_main);
b = findViewById(R.id.button);
b.setOnClickListener(this);
list = findViewById(R.id.list);
list.setAdapter(new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_1, man.getFreeEvents())); //here is the SQL request...
vor = findViewById(R.id.editText);
nach = findViewById(R.id.editText2);
}
내 probem 안드로이드는 connction를 열 수 없습니다 것입니다 :
여기 내 코드입니다.
I/System.out: `com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Could not create connection to database server.´
I/System.out: Verbindung nicht moglich
I/System.out: SQLException: Could not create connection to database server.
I/System.out: SQLState: 08001
I/System.out: VendorError: 0
E/test: nach conect
D/AndroidRuntime: Shutting down VM
E/AndroidRuntime: FATAL EXCEPTION: main
Process: ml.gottfried.myapp, PID: 10440
java.lang.RuntimeException: Unable to start activity ComponentInfo{ml.gottfried.myapp/ml.gottfried.myapp.NewTicket}: java.lang.NullPointerException: Attempt to invoke interface method 'java.sql.PreparedStatement java.sql.Connection.prepareStatement(java.lang.String)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2665)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2726)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1477)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6119)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
Caused by: java.lang.NullPointerException: Attempt to invoke interface method 'java.sql.PreparedStatement java.sql.Connection.prepareStatement(java.lang.String)' on a null object reference
at ml.gottfried.myapp.SQLManager.getFreeEvents(SQLManager.java:82)
at ml.gottfried.myapp.NewTicket.onCreate(NewTicket.java:43)
at android.app.Activity.performCreate(Activity.java:6679)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2618)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2726)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1477)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6119)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
난 당신이 나에게
감사합니다 :)
을 도울 수 있기를 바랍니다 : 그래서 적어도 나는이 오류가 발생했습니다<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
: 나는 안드로이드 매니페스트에서 권한 요청을 추가 한
추신 : 어떤 질문을하면 물어보십시오 :)
데이터베이스에 연결되어 있지 않은 것이 분명합니다. 따라서이 연결로 작업을 시작할 때 NPE를 얻습니다. 장치가 동일한 네트워크에 있는지 주먹으로 확인합니다. –
괜찮습니다 ... 이제 정상적인 java에서 MySQLConnector 및 SQLManager를 테스트했습니다. 여기 잘 작동 ... 내 문제는 내가 왜 내가 내 데이터베이스에 연결을 못해 ... 편집 : 내 데이터베이스는 외부 서버에 있습니다. –
전체 설치/환경을 제공 할 수 있습니까? –