We Keep Coding

Is the MySQL procedure in this Minecraft plugin correct?

To get an idea of what the basic structure looks like, I downloaded a money system including MySQL from Spigot and looked at the code.
public static boolean playerExists(String uuid) {
try {
ResultSet rs = Simplecoinsystem.mysql.query("SELECT * FROM CoinData WHERE UUID= '" + uuid + "'");
if (rs.next())
return (rs.getString("UUID") != null);
return false;
} catch (SQLException e) {
e.printStackTrace();
return false;
}
}
public static void createPlayer(String uuid) {
if (!playerExists(uuid))
Simplecoinsystem.mysql.update("INSERT INTO CoinData (UUID, COINS) VALUES ('" + uuid +
"', '" + Simplecoinsystem.getInstance().getConfig().getInt("startcoins") + "');");
}
public static Integer getCoins(String uuid) {
Integer i = Integer.valueOf(0);
if (playerExists(uuid)) {
try {
ResultSet rs = Simplecoinsystem.mysql.query("SELECT * FROM CoinData WHERE UUID= '" + uuid + "'");
if (rs.next())
Integer.valueOf(rs.getInt("COINS"));
i = Integer.valueOf(rs.getInt("COINS"));
} catch (SQLException e) {
e.printStackTrace();
}
} else {
createPlayer(uuid);
}
return i;
}
public static void setCoins(String uuid, Integer coins) {
if (playerExists(uuid)) {
Simplecoinsystem.mysql.update("UPDATE CoinData SET COINS= '" + coins + "' WHERE UUID= '" + uuid + "';");
} else {
createPlayer(uuid);
}
}
Am I correct that it is actually impractical to create a new entry with the uuid of the non-existent player after each query of the coins if the player does not exist?
Wouldn't this make it possible to flood the database with thousands of unnecessary entries by issuing, for example, a "/money (player)" command as an evil player/admin?
Couldn't I just ask when entering the server if the uuid is already stored and if not, just enter it? This way there would only be entries from players who have already been on the server before. Whether this needs great server performance, I'm not sure.
This is my first own MySQL class.
public class MySQL {
private String host, database, user, password;
private int port;
private Connection con;
public MySQL(String host, int port, String database, String user, String password) {
this.host = host;
this.port = port;
this.database = database;
this.user = user;
this.password = password;
connect();
}
public void connect() {
try {
con = DriverManager.getConnection("jdbc:mysql://" + host + ":" + port + "/" + database + "?autoReconnect=true", user, password);
System.out.println("&cDie MySQL Verbindung wurde erfolgreich aufgebaut!");
} catch (SQLException e) {
e.printStackTrace();
}
}
public void disconnect() {
try {
if(this.con != null) {
this.con.close();
System.out.println("§cDie MySQL Verbindung wurde erfolgreich beendet!");
}
} catch (Exception e) {
e.printStackTrace();
}
}
public void update(String query) {
try {
Statement st = con.createStatement();
st.executeUpdate(query);
st.close();
} catch (Exception e) {
e.printStackTrace();
connect();
}
}
public ResultSet qry(String query) {
ResultSet rs = null;
try {
Statement st = con.createStatement();
rs = st.executeQuery(query);
} catch (Exception e) {
e.printStackTrace();
connect();
}
return rs;
}
public Connection getConnection() {
return this.con;
}
}
Except for this part, both MySQL classes are built relatively the same.
This is the part that is in the MySQL class of the Spigot plugin.

Your code have multiple issues.
When the connection will be closed, next time you will have an error. In your Mysql class, I suggest you to do:
public Connection getConnection() {
if(con == null || con.isClosed())
connect();
return con;
}
Then, use it in all method like getConnection().prepareStatement().
You can be attacked with SQL Injection. To fix this, try to do something like:
PreparedStatement st = con.prepareStatement("SELECT * FROM CoinData WHERE UUID = ?");
st.setString(1, uuid.toString()); // Yes it start at 1 !!
st.executeUpdate();
With this, even with all values, you can't be attacked with injections.
You will have an error while getting coins:
if (rs.next()) // go to good line
Integer.valueOf(rs.getInt("COINS")); // useless convertion
i = Integer.valueOf(rs.getInt("COINS")); // error if no line.
You can just do:
if(rs.next())
i = rs.getInt("COINS");
If the column "UUID" is unique, you will not have duplicated lines.
Finally, about performance, it's better to do it one time: at login, instead of all time. You can also create an object stored in an hashmap to easier access to it, without using SQL, like that:
public static HashMap<UUID, Integer> coinsByPlayer = new HashMap<>();
OR:
public static HashMap<UUID, MyObject> coinsByPlayer = new HashMap<>();
public class MyObject {
private int coins = 0;
public MyObject(UUID uuid) {
// make SQL request to get data
}
public int getCoins() {
return coins;
}
public void setCoins(int next){
coins = next;
// here make "UPDATE" sql query
}
}

What do you say? Is it ok with the try/catch function? #Elikill58
public Connection getConnection() {
try {
if(con == null || con.isClosed()) {
connect();
}
} catch (SQLException e) {
e.printStackTrace();
}
return con;
}
edit:
public Connection getConnection_one() throws SQLException {
if(con == null || con.isClosed()) {
connect();
return con;
} else {
return con;
}
}

Discord bot unusually repeats

So I'm trying to create a discord bot that has simple access to a database for printing out values, my code currently will print the values to the discord server but it repeats them 5 times.
Bot functionality class:
private MySQLAccess sql = new MySQLAccess();
public static void main(String[] args) throws Exception {
JDABuilder ark = new JDABuilder(AccountType.BOT);
ark.setToken("insert_discord_token_here");
ark.addEventListener(new MessageListener());
ark.buildAsync();
}
#Override
public void onMessageReceived(MessageReceivedEvent e) {
if (e.getAuthor().isBot()) return;
Message msg = e.getMessage();
String str = msg.getContentRaw();
//Ping pong
if (str.equalsIgnoreCase("!ping")) {
e.getChannel().sendMessage("Pong!").queue();
}
//Bal check
if (str.contains("!bal")) {
String user = str.substring(5);
System.out.println(user);
try {
sql.readDataBase(e.getChannel(), user);
} catch (Exception e1) {
}
}
}
Database Access Class:
private Connection connect = null;
private Statement statement = null;
private ResultSet resultSet = null;
private final String user = "pass";
private final String pass = "user";
public void readDataBase(MessageChannel msg, String username) throws Exception {
//Retrieve data and search for username
try {
Class.forName("com.mysql.cj.jdbc.Driver");
connect = DriverManager.getConnection("jdbc:mysql://localhost/serverusers?allowPublicKeyRetrieval=true&useSSL=false", user, pass);
statement = connect.createStatement();
resultSet = statement
.executeQuery("select * from serverusers.userinfo where user=\"" + username + "\"");
writeResultSet(resultSet, msg);
} catch (Exception e) {
throw e;
} finally {
close();
}
}
private void writeResultSet(ResultSet resultSet, MessageChannel msg) throws SQLException {
// Check resultSet and print its contents
if (resultSet.next()) {
String user = resultSet.getString(2);
Double website = resultSet.getDouble(3);
msg.sendMessage("User: " + user).queue();
msg.sendMessage("Bank Amount: " + website).queue();
}
}
private void close() {
try {
if (resultSet != null) {
resultSet.close();
}
if (statement != null) {
statement.close();
}
if (resultSet != null) {
resultSet.close();
}
if (connect != null) {
connect.close();
}
} catch (Exception e) {
}
}
When the program is run it finds the correct data that I'm looking for and the search function is fine, but for some odd reason the program will spit the same username and balance out 5 times.
Screenshot of Discord Bot

The common mistake here is that you run the program multiple times, each instance then responds accordingly with the same thing. You can check if that is the case by opening the task manager and looking for java processes. This often occurs with developers using the Eclipse IDE because of the console hiding other processes behind a drop-down menu on the console.

MYSQL JDBC java.sql.SQLException: Operation not allowed after ResultSet closed

I have a program that queries a database using different jdbc drivers. This error is specific to the MySQL driver.
Here's the basic rundown.
I have another query runner class that uses a postgresql jdbc driver that works just fine. Note the line conn.close(); this works fine on my postgresql query runner, but for this SQL runner it comes up with the error.
I have removed the line conn.close(); and this code works fine, but over time it accumulates sleeping connections in the database. How can I fix this?
New Relic is a third party application that I am feeding data to, if you dont know what it is, don't worry it's not very relevant to this error.
MAIN CLASS
public class JavaPlugin {
public static void main(String[] args) {
try {
Runner runner = new Runner();
runner.add(new MonitorAgentFactory());
runner.setupAndRun(); // never returns
}
catch (ConfigurationException e) {
System.err.println("ERROR: " + e.getMessage());
System.exit(-1);
}
catch (Exception e) {
System.err.println("ERROR: " + e.getMessage());
System.exit(-1);
}
}
}
MYSQL QUERY RUNNER CLASS
import com.newrelic.metrics.publish.util.Logger;
import java.sql.DriverManager;
import java.sql.Connection;
import java.sql.SQLException;
import java.sql.ResultSet;
import java.sql.Statement;
public class MySQLQueryRunner {
private static final Logger logger = Logger.getLogger(MySQLQueryRunner.class);
private String connectionStr;
private String username;
private String password;
public MySQLQueryRunner(String host, long port, String database, String username, String password) {
this.connectionStr = "jdbc:mysql://" + host + ":" + port + "/" + database + "?useSSL=false";
this.username = username;
this.password = password;
}
private void logError(String message) {
logger.error(new Object[]{message});
}
private void logDebugger(String message) {
logger.debug(new Object[]{message});
}
private Connection establishConnection() {
try {
Class.forName("com.mysql.jdbc.Driver");
} catch (ClassNotFoundException e) {
logError("MySQL Driver could not be found");
e.printStackTrace();
return null;
}
Connection connection = null;
try {
connection = DriverManager.getConnection(connectionStr, username, password);
logDebugger("Connection established: " + connectionStr + " using " + username);
} catch (SQLException e) {
logError("Connection Failed! Check output console");
e.printStackTrace();
return null;
}
return connection;
}
public ResultSet run(String query) {
Connection conn = establishConnection();
if (conn == null) {
logError("Connection could not be established");
return null;
}
try {
Statement stmt = conn.createStatement();
ResultSet rs = stmt.executeQuery(query);
conn.close();
return rs;
} catch (SQLException e) {
logError("Failed to collect data from database");
e.printStackTrace();
return null;
}
}
}
AGENT CLASS
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Map;
import com.newrelic.metrics.publish.Agent;
public class LocalAgent extends Agent {
private MySQLQueryRunner queryRunner;
private String name;
private Map<String, Object> thresholds;
private int intervalDuration;
private int intervalCount;
public LocalAgent(String name, String host, long port, String database, String username, String password, Map<String, Object> thresholds, int intervalDuration) {
super("com.mbt.local", "1.0.0");
this.name = name;
this.queryRunner = new MySQLQueryRunner(host, port, database, username, password);
// this.eventPusher = new NewRelicEvent();
this.thresholds = thresholds;
this.intervalDuration = intervalDuration;
this.intervalCount = 0;
}
/**
* Description of query
*/
private void eventTestOne() {
String query = "select count(1) as jerky from information_schema.tables;";
ResultSet rs = queryRunner.run(query);
try {
while (rs.next()) {
NewRelicEvent event = new NewRelicEvent("localTestOne");
event.add("jerky", rs.getInt("jerky"));
event.push();
}
} catch (SQLException e) {
e.printStackTrace();
}
}
/**
* blah
*/
private void eventTestTwo() {
String query = "SELECT maxlen FROM information_schema.CHARACTER_SETS;";
ResultSet rs = queryRunner.run(query);
try {
while (rs.next()) {
NewRelicEvent event = new NewRelicEvent("localTestTwo");
event.add("beef", rs.getString("maxlen"));
event.push();
}
} catch (SQLException e) {
e.printStackTrace();
}
}
#Override
public void pollCycle() {
if (this.intervalCount % this.intervalDuration == 0) {
eventTestOne();
eventTestTwo();
this.intervalCount = 0;
}
// Always incrementing intervalCount, keeping track of poll cycles that have passed
this.intervalCount++;
}
#Override
public String getAgentName() {
return this.name;
}
}

The problem is that you are trying to access the ResultSet after the connection is closed.
You should open and close the connection in the method that is calling run() this way the connection will be open when you access and loop through the Resultset and close it in the finally block of the calling method.
Even better would be if you can just loop through the ResultSet in the run() method and add the data to an object and return the object, this way you can close it in the finally block of the run() method.

Opening and closing database

I'm working on an application that records do my MySql database on my server. Every time I want to use the database, get the existing connection, if not, I think for the first time. When I do an insert or select, works very well, but followed that consultation, when it ends, I can never regain the connection and do not return to consultations.
My class of Database
public class Database {
/**
* Gets just one instance of the class
* Connects on construct
* #returns connection
*/
private Connection _conn = null;
private long timer;
//singleton code
private static Database DatabaseObject;
private Database() {}
public static Database connect() {
if (DatabaseObject == null)
DatabaseObject = new Database();
return DatabaseObject._connect();
}
public Object clone() throws CloneNotSupportedException {
throw new CloneNotSupportedException();
}
//end singleton code
/**
* Connects with the defined parameters on Config
* Prevents re-connection if object was already connected
* #throws SQLException
*/
private Database _connect() {
try {
if (this._conn == null || !this._conn.isValid(0)) {
try {
Class.forName("com.mysql.jdbc.Driver");
Properties connProps = new Properties();
connProps.put("user", Config.Config.DB_USER);
connProps.put("password", Config.Config.DB_PASS);
this._conn = DriverManager.
getConnection("jdbc:" + Config.Config.DB_DBMS + "://" + Config.Config.DB_HOST + ":"
+ Config.Config.DB_PORT + "/" + Config.Config.DB_NAME, Config.Config.DB_USER, Config.Config.DB_PASS);
timer = System.currentTimeMillis();
} catch (ClassNotFoundException e) {
System.out.println("Where is your MySQL JDBC Driver?");
e.printStackTrace();
} catch (Exception e) {
System.out.println("Could not connect to DB");
e.printStackTrace();
}
} else {
try {
long tmp = System.currentTimeMillis() - timer;
if (tmp > 1200000) { //3600000 one hour ; 1200000 twenty minutes
System.out.println("Forcing reconnection ("+tmp+" milliseconds passed since last connection)");
this.close();
this._connect();
}
} catch (Exception e) {
e.printStackTrace();
System.out.println("Forcing reconnection");
this._conn = null;
this._connect();
}
}
} catch (Exception e) {
e.printStackTrace();
}
return this;
}
/**
* Closes connections
* This has to be invoked when database connection is no longer needed
* #throws SQLException
*/
public void close() throws SQLException {
if (this._conn != null) {
this._conn.close();
this._conn = null;
}
}
/**
* Getter for connection
* #return
*/
public Connection get() {
return this._conn;
}
}
The following function I make a query:
private Statement sment = null;
private PreparedStatement psment = null;
private ResultSet rset = null;
public boolean existsByNameAndUserId(String md5, int userId, int eventId) {
Connection conn = Database.connect().get();
try {
psment = conn.prepareStatement("SELECT * FROM files "
+ "WHERE user_id = ? AND md5 = ? AND evento_id = ?");
psment.setInt(1, userId);
psment.setString(2, md5);
psment.setInt(3, eventId);
rset = psment.executeQuery();
if (rset.next()) {
return true;
}
} catch (Exception e) {
e.printStackTrace();
}
return false;
}
private void close() {
try { if (rset != null) rset.close(); } catch (Exception e) {System.out.println(e.getMessage());};
try { if (psment != null) psment.close(); } catch (Exception e) {System.out.println(e.getMessage());};
try { if (sment != null) sment.close(); } catch (Exception e) {System.out.println(e.getMessage());};
}
And in the next, I call the above function to find out whether or not a record with these characteristics, if not, I do an insert.
String SQL_INSERT = "INSERT INTO files (evento_id, user_id, path, thumb, preview, width, height, md5, numero_corredor, created, modified) "
+ "VALUES (?,?,?,?,?,?,?,?,?,NOW(),NOW())";
public void save(List<components.File.Schema> files) throws SQLException {
try (
Connection conn = Database.connect().get();
PreparedStatement statement = conn.prepareStatement(SQL_INSERT);
) {
int i = 0;
for (components.File.Schema file : files) {
if(!existsByNameAndUserId(file.getMd5(), file.getUserId(), file.getEventId())){
statement.setInt(1, file.getEventId());
statement.setInt(2, file.getUserId());
statement.setString(3, file.getPath());
statement.setString(4, file.getPreview());
statement.setString(5, file.getThumb());
statement.setInt(6, file.getWidth());
statement.setInt(7, file.getHeight());
statement.setString(8, file.getMd5());
statement.setString(9, null);
statement.addBatch();
i++;
if (i % 1000 == 0 || i == files.size()) {
statement.executeBatch(); // Execute every 1000 items.
}
}
}
}
}

Your issue is due to the fact that you put Connection conn = Database.connect().get() in a try-with-resources statement which is what you are supposed to do but it closes your connection and when you call it again as the method _connect() doesn't have a valid test, it doesn't create a new connection. The valid test is this._conn == null || !this._conn.isValid(0), indeed in your original test you call this._conn.isValid(0) which will returns false in our context since the connection is closed so it won't create a new connection which is not what we want here.
Response Update: The second part of the problem is the fact that in the save method you call existsByNameAndUserId which closes the current connection, you should only close the statement and let the method save close the connection.

Cannot connect to Oracle DB from Java - ORA-12560: TNS:protocol adapter error

This is my first Java application I am creating (using Eclipse IDE) and the second Oracle based app (I'm a .NET/MSSQL guy for years). The first Oracle app I wrote in .NET did not have any issues, and I'm trying to connect to the same server.
I have installed:
'Java 2 Platform, Enterprise Edition 1.4 SDK'
'Java DB `10.5.3.0'
-'Java(TM) 6 Update 21
'Java(TM) SE Development Kit 6 update 21
'Oracle IRM Client' (11g)
Oracle 11g Release 2 JDBC Drivers (ojdbc6.jar)
My code is very simple. Here it is:
OracleDataSource ods = new OracleDataSource();
ods.setURL("jdbc:oracle:oci:#");
ods.setUser("username");
ods.setPassword("password");
ods.setServerName("servername");
ods.setPortNumber(1549);
ods.setServiceName("foo.myservice.com");
Connection conn = ods.getConnection();
I get below exception:
Exception in thread "main" java.sql.SQLException: ORA-12560: TNS:protocol adapter error
at oracle.jdbc.driver.T2CConnection.checkError(T2CConnection.java:737)
at oracle.jdbc.driver.T2CConnection.logon(T2CConnection.java:401)
at oracle.jdbc.driver.PhysicalConnection.<init>(PhysicalConnection.java:531)
at oracle.jdbc.driver.T2CConnection.<init>(T2CConnection.java:148)
at oracle.jdbc.driver.T2CDriverExtension.getConnection(T2CDriverExtension.java:53)
at oracle.jdbc.driver.OracleDriver.connect(OracleDriver.java:503)
at oracle.jdbc.pool.OracleDataSource.getPhysicalConnection(OracleDataSource.java:280)
at oracle.jdbc.pool.OracleDataSource.getConnection(OracleDataSource.java:207)
at oracle.jdbc.pool.OracleDataSource.getConnection(OracleDataSource.java:157)
at Select.GetScalar(Select.java:47)
at Job.Run(Job.java:20)
at Main.main(Main.java:19)
I have google'd the hack out of this.. I've tried adding a 'TNS entry to the tnsnames.ora file'. I've tried adding '##NAMES.DIRECTORY_PATH = (TNSNAMES, EZCONNECT)' to the sqlnet.ora file. I've tried various other things but nothing is working.
Has anyone experienced this before and has any clue on how to get this to work?? Am I using the wrong version? Server is remote (I don't have Oracle server installed locally, just client). Maybe I have wrong version of Java SDK or the wrong version of the JDBC .jar file?? I just need to connect to Oracle and run a single simple query! Thanks much for any help.

Try using the type IV JDBC driver instead of OCI if you can. The thin url looks like this:
jdbc:oracle:thin:#host[:port]/service
I'd try code that looked more like this (fill in your defaults for the driver, URL, username, and password):
package persistence;
import java.sql.*;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class DatabaseUtils
{
private static final String DEFAULT_DRIVER = "";
private static final String DEFAULT_URL = "";
private static final String DEFAULT_USERNAME = "";
private static final String DEFAULT_PASSWORD = "";
public static void main(String[] args)
{
String driver = ((args.length > 0) ? args[0] : DEFAULT_DRIVER);
String url = ((args.length > 1) ? args[1] : DEFAULT_URL);
String username = ((args.length > 2) ? args[2] : DEFAULT_USERNAME);
String password = ((args.length > 3) ? args[3] : DEFAULT_PASSWORD);
Connection connection = null;
try
{
connection = createConnection(driver, url, username, password);
DatabaseMetaData meta = connection.getMetaData();
System.out.println(meta.getDatabaseProductName());
System.out.println(meta.getDatabaseProductVersion());
}
catch (Exception e)
{
e.printStackTrace();
}
finally
{
close(connection);
}
}
public static Connection createConnection(String driver, String url, String username, String password) throws ClassNotFoundException, SQLException
{
Class.forName(driver);
if ((username == null) || (password == null) || (username.trim().length() == 0) || (password.trim().length() == 0))
{
return DriverManager.getConnection(url);
}
else
{
return DriverManager.getConnection(url, username, password);
}
}
public static void close(Connection connection)
{
try
{
if (connection != null)
{
connection.close();
}
}
catch (SQLException e)
{
e.printStackTrace();
}
}
public static void close(Statement st)
{
try
{
if (st != null)
{
st.close();
}
}
catch (SQLException e)
{
e.printStackTrace();
}
}
public static void close(ResultSet rs)
{
try
{
if (rs != null)
{
rs.close();
}
}
catch (SQLException e)
{
e.printStackTrace();
}
}
public static void rollback(Connection connection)
{
try
{
if (connection != null)
{
connection.rollback();
}
}
catch (SQLException e)
{
e.printStackTrace();
}
}
public static List<Map<String, Object>> map(ResultSet rs) throws SQLException
{
List<Map<String, Object>> results = new ArrayList<Map<String, Object>>();
try
{
if (rs != null)
{
ResultSetMetaData meta = rs.getMetaData();
int numColumns = meta.getColumnCount();
while (rs.next())
{
Map<String, Object> row = new HashMap<String, Object>();
for (int i = 1; i <= numColumns; ++i)
{
String name = meta.getColumnName(i);
Object value = rs.getObject(i);
row.put(name, value);
}
results.add(row);
}
}
}
finally
{
close(rs);
}
return results;
}
}

If you want something simple, you should try using the THIN client instead of OCI client.
Don't forget to include the right jar (ojdbc5.jar for Java 5, ojdbc6.jar for Java 6).

Is the ServiceName you specified the service name of the Oracle instance you're trying to connect to? You're sure the port is correct?