通过 jdbc 连接 mysql 的异常 [英] Exception in connection with mysql through jdbc
问题描述
当我尝试通过 jdbc 与 mysql 连接时出现异常.已经问过这种类型的问题,但我没有得到解决我的问题的方法,这是我的代码...
I got exception when i have tried to connect with mysql through jdbc.This type of question is already asked but i didn't get solution for my problem, here is my code...
public static void main(String[] args) {
String url="jdbc:mysql://localhost:3306/student?
autoReconnect=true&useSSL=false";
String user="root";
String pass="system";
try {
Class.forName("com.mysql.jdbc.Driver");
System.out.println("Now connecting to databse...
");
Connection con=DriverManager.getConnection(url,user,pass);
System.out.println("Connected !!!
");
con.close();
System.out.println("connection close !!!
");
} catch (ClassNotFoundException | SQLException e) {System.out.println(e);
e.printStackTrace();
}
}
}
这些是我得到的例外...
these are exception which i got...
run:
Now connecting to databse...
com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Could not create connection to database server. Attempted reconnect 3 times. Giving up.
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:404)
at com.mysql.jdbc.Util.getInstance(Util.java:387)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:917)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:896)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:885)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:860)
at com.mysql.jdbc.ConnectionImpl.connectWithRetries(ConnectionImpl.java:2165)
at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2090)
at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:795)
at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:44)
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:404)
at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:400)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:327)
at java.sql.DriverManager.getConnection(DriverManager.java:664)
at java.sql.DriverManager.getConnection(DriverManager.java:247)
at dbms_basic.Dbms_Basic.main(Dbms_Basic.java:28)
Caused by: java.lang.NullPointerException
at com.mysql.jdbc.ConnectionImpl.getServerCharset(ConnectionImpl.java:3005)
at com.mysql.jdbc.MysqlIO.sendConnectionAttributes(MysqlIO.java:1916)
at com.mysql.jdbc.MysqlIO.proceedHandshakeWithPluggableAuthentication(MysqlIO.java:1845)
at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1215)
at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2255)
at com.mysql.jdbc.ConnectionImpl.connectWithRetries(ConnectionImpl.java:2106)
... 13 more
BUILD SUCCESSFUL (total time: 4 seconds)
有人帮我解决这个错误..
someone help me solve this error..
推荐答案
当您尝试在 Mysql 8 或更高版本的数据库上使用 Mysql 5 JDBC 驱动程序时,会发生此错误.您可以使用以下 JAR 文件
This error happens when you try to use a Mysql 5 JDBC driver on a Mysql 8 or higher DB. You can use the following JAR file
mysql-connector-java 8.0.11
或者使用这个Maven依赖
Or use this Maven dependency
<!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.11</version>
</dependency>
如果您需要在同一个应用程序中同时连接到 MySQL 5 和 MySQL 8,您将需要隔离类加载器,如下所示可能会起作用
If you need to have connection both to MySQL 5 and MySQL 8 in the same app you will need to isolate classloaders, something like the following may work
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