Question

我刚刚开始学习数据库中的新手。我有MySQL Server 8.0。，Workbench 8.0，Java连接器5.1.31，Java 1.8本身。为新手如何开始遵循多个指南。

所以有这种情况。我在localhost上有数据库，并通过workbench和windows提示符成功连接到它。但是我在java中执行代码之后：

        Driver sqlDriver = new FabricMySQLDriver();
        DriverManager.registerDriver(sqlDriver);
        Connection sqlConnection = DriverManager.getConnection("jdbc:mysql://localhost:3306/?user=root", "root", "root");

我得到例外com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Could not create connection to database server.

为什么会发生？我试图重新安装MySQL，清理操作系统变量，到处寻找并找不到解决方案。很高兴在这里找到它。

UPD：

com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Could not create connection to database server. Attempted reconnect 3 times. Giving up.
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
    at com.mysql.jdbc.Util.handleNewInstance(Util.java:408)
    at com.mysql.jdbc.Util.getInstance(Util.java:383)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1023)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:997)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:983)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:928)
    at com.mysql.jdbc.ConnectionImpl.connectWithRetries(ConnectionImpl.java:2407)
    at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2328)
    at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:832)
    at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:46)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
    at com.mysql.jdbc.Util.handleNewInstance(Util.java:408)
    at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:417)
    at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:344)
    at java.sql.DriverManager.getConnection(DriverManager.java:664)
    at java.sql.DriverManager.getConnection(DriverManager.java:247)
    at com.company.Main.main(Main.java:11)
Caused by: java.lang.NullPointerException
    at com.mysql.jdbc.ConnectionImpl.getServerCharacterEncoding(ConnectionImpl.java:3309)
    at com.mysql.jdbc.MysqlIO.sendConnectionAttributes(MysqlIO.java:1985)
    at com.mysql.jdbc.MysqlIO.proceedHandshakeWithPluggableAuthentication(MysqlIO.java:1911)
    at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1288)
    at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2508)
    at com.mysql.jdbc.ConnectionImpl.connectWithRetries(ConnectionImpl.java:2346)
    ... 13 more

Answer 1

问题是旧版MySQL Connector / J与MySQL 8的兼容性。您需要升级到MySQL Connector / J 5.1.46或 - 更好 - 8.0.11。

Answer 2

就我而言，我使用maven依赖来使用JDBC连接器。我只是改变了依赖的版本。这对我有用

    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>5.1.46</version>
    </dependency>

Answer 3

请确保您已将jar（mysql-connector.jar）包含在类路径中。请参考以下链接： Could not create connection to database server - Eclipse MySQL error

com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException：无法创建与数据库服务器的连接

3 个答案: