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私のJavaプロジェクトで私はutf8からutf8mb4に切り替えました。私はデータベースを削除し、utf8mb4で新しいデータベースを作成しました。 は、私はまた、mysqlの - 設定変更：https://mathiasbynens.be/notes/mysql-utf8mb4 からの入力とのmy.iniを変更次のようになります。私はオーバー確認JDBCの置換：SQLNonTransientConnectionException
[client]
default-character-set = utf8mb4
[mysql]
default-character-set = utf8mb4
[mysqld]
character-set-server = utf8mb4
collation-server = utf8mb4_unicode_ci
：
SHOW VARIABLES WHERE Variable_name LIKE 'character\_set\_%' OR Variable_name LIKE 'collation%';
character_set_filesystem, binary
character_set_client, utf8
character_set_connection, utf8
character_set_results, utf8
character_set_system, utf8
collation_connection, utf8_general_ci
character_set_database, utf8mb4
character_set_server, utf8mb4
collation_database, utf8mb4_unicode_ci
collation_server, utf8mb4_unicode_ci
私が追加しようとした - のmysqlのdidnをが、今すぐ始めました - 削除しました：
character_set_client=utf8mb4
character_set_connection=utf8mb4
character_set_results=utf8mb4
私はデータベースを再起動しました。
次に、新しいドライバをプロジェクトにロードし、古いものを最新のものに置き換えました。 （ - > now：mysql-connector-java-6.0.5-bin） 私はjavaコードを（ドライバのエラーが私に言ったので）変更しました： Class.forName（ "com.mysql.cj.jdbc。ドライバ"）;
は、その後私が変更されました：String databaseUrl = "jdbc:mysql://localhost:3306/myDB?useSSL=false&autoReconnect=true&characterEncoding=utf8mb4";
(because: SQLException: java.sql.SQLException: Unsupported character encoding 'utf8mb4'
Exception in thread "JavaFX Application Thread" java.lang.ExceptionInInitializerError)
に：
SQLException: java.sql.SQLNonTransientConnectionException: Could not create connection to database server. Attempted reconnect 3 times. Giving up.
Exception in thread "JavaFX Application Thread" java.lang.ExceptionInInitializerError
at auxiliary.InputCreater.saveFile(InputCreater.java:100)
at auxiliary.InputCreater.searchnewfiles(InputCreater.java:54)
at gui.EingabefensterController$3.handle(EingabefensterController.java:70)
at gui.EingabefensterController$3.handle(EingabefensterController.java:1)
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:49)
at javafx.event.Event.fireEvent(Event.java:198)
at javafx.scene.control.MenuItem.fire(MenuItem.java:462)
at com.sun.javafx.scene.control.skin.ContextMenuContent$MenuItemContainer.doSelect(ContextMenuContent.java:1405)
at com.sun.javafx.scene.control.skin.ContextMenuContent$MenuItemContainer.lambda$createChildren$343(ContextMenuContent.java:1358)
at com.sun.javafx.event.CompositeEventHandler$NormalEventHandlerRecord.handleBubblingEvent(CompositeEventHandler.java:218)
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:80)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54)
at javafx.event.Event.fireEvent(Event.java:198)
at javafx.scene.Scene$MouseHandler.process(Scene.java:3757)
at javafx.scene.Scene$MouseHandler.access$1500(Scene.java:3485)
at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1762)
at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2494)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:380)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:294)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$354(GlassViewEventHandler.java:416)
at com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:389)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:415)
at com.sun.glass.ui.View.handleMouseEvent(View.java:555)
at com.sun.glass.ui.View.notifyMouse(View.java:937)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.lambda$null$148(WinApplication.java:191)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.NullPointerException
at java.util.concurrent.ArrayBlockingQueue.checkNotNull(ArrayBlockingQueue.java:150)
at java.util.concurrent.ArrayBlockingQueue.offer(ArrayBlockingQueue.java:325)
at java.util.AbstractQueue.add(AbstractQueue.java:95)
at java.util.concurrent.ArrayBlockingQueue.add(ArrayBlockingQueue.java:312)
at mysql.ConnectionPoolManager.initializeConnectionPool(ConnectionPoolManager.java:49)
at mysql.ConnectionPoolManager.initialize(ConnectionPoolManager.java:43)
at mysql.ConnectionPoolManager.<init>(ConnectionPoolManager.java:28)
at mysql.CrawlerUpdate.<clinit>(CrawlerUpdate.java:18)
... 46 more
なぜ接続がない：
String databaseUrl = "jdbc:mysql://localhost:3306/myDB?useSSL=false&autoReconnect=true";
それがスロー新しいアプローチでは？これらすべての変更を行う前に、すべてうまく機能しました。
このプロパティは、MySQLキャラクタセットではなく、使用するJavaキャラクタセットを示します。また、ExceptionInInitializerErrorsのスタックトレース全体を投稿してください。通常、問題の原因が含まれています。 –