为什么可以'；我是否将java连接到MySql（连接错误）？_Java_Mysql

为什么可以'；我是否将java连接到MySql（连接错误）？

java mysql

为什么可以'；我是否将java连接到MySql（连接错误）？,java,mysql,Java,Mysql,我试图连接MySql和Java，但我从这段代码中得到了这个错误代码：错误： Exception in thread "main" com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure The last packet sent successfully to the server was 0 milliseconds ago. The driver has not

我试图连接MySql和Java，但我从这段代码中得到了这个错误

代码：

错误：

Exception in thread "main" com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
    at com.mysql.cj.jdbc.exceptions.SQLError.createCommunicationsException(SQLError.java:174)
    at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:64)
    at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:836)
    at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:456)
    at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:246)
    at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:198)
    at java.sql/java.sql.DriverManager.getConnection(DriverManager.java:677)
    at java.sql/java.sql.DriverManager.getConnection(DriverManager.java:228)
    at ConnessioneMySql.main(ConnessioneMySql.java:11)
Caused by: com.mysql.cj.exceptions.CJCommunicationsException: Communications link failure

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
    at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
    at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.base/java.lang.reflect.Constructor.newInstanceWithCaller(Constructor.java:500)
    at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:481)
    at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:61)
    at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:105)
    at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:151)
    at com.mysql.cj.exceptions.ExceptionFactory.createCommunicationsException(ExceptionFactory.java:167)
    at com.mysql.cj.protocol.a.NativeSocketConnection.connect(NativeSocketConnection.java:89)
    at com.mysql.cj.NativeSession.connect(NativeSession.java:144)
    at com.mysql.cj.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:956)
    at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:826)
    ... 6 more
Caused by: java.net.ConnectException: Connection refused: connect
    at java.base/sun.nio.ch.Net.connect0(Native Method)
    at java.base/sun.nio.ch.Net.connect(Net.java:503)
    at java.base/sun.nio.ch.Net.connect(Net.java:492)
    at java.base/sun.nio.ch.NioSocketImpl.connect(NioSocketImpl.java:588)
    at java.base/java.net.SocksSocketImpl.connect(SocksSocketImpl.java:333)
    at java.base/java.net.Socket.connect(Socket.java:648)
    at com.mysql.cj.protocol.StandardSocketFactory.connect(StandardSocketFactory.java:155)
    at com.mysql.cj.protocol.a.NativeSocketConnection.connect(NativeSocketConnection.java:63)
    ... 9 more

Process finished with exit code 1

线程“main”com.mysql.cj.jdbc.exceptions.CommunicationsException中的异常：通信链路故障成功发送到服务器的最后一个数据包是0毫秒前的。驱动程序尚未从服务器收到任何数据包。位于com.mysql.cj.jdbc.exceptions.SQLError.createCommunicationsException（SQLError.java:174）位于com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException（SQLExceptionsMapping.java:64）位于com.mysql.cj.jdbc.ConnectionImpl.createNewIO（ConnectionImpl.java:836）位于com.mysql.cj.jdbc.ConnectionImpl.（ConnectionImpl.java:456）位于com.mysql.cj.jdbc.ConnectionImpl.getInstance（ConnectionImpl.java:246）位于com.mysql.cj.jdbc.NonRegisteringDriver.connect（NonRegisteringDriver.java:198）位于java.sql/java.sql.DriverManager.getConnection（DriverManager.java:677）位于java.sql/java.sql.DriverManager.getConnection（DriverManager.java:228）位于ConnessioneMySql.main（ConnessioneMySql.java:11）原因：com.mysql.cj.exceptions.CJCommunicationsException:通信链路故障成功发送到服务器的最后一个数据包是0毫秒前的。驱动程序尚未从服务器收到任何数据包。位于java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0（本机方法）位于java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance（NativeConstructorAccessorImpl.java:62）位于java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance（DelegatingConstructorAccessorImpl.java:45）位于java.base/java.lang.reflect.Constructor.newInstanceWithCaller（Constructor.java:500）位于java.base/java.lang.reflect.Constructor.newInstance（Constructor.java:481）在com.mysql.cj.exceptions.ExceptionFactory.createException（ExceptionFactory.java:61）上在com.mysql.cj.exceptions.ExceptionFactory.createException（ExceptionFactory.java:105）上在com.mysql.cj.exceptions.ExceptionFactory.createException上（ExceptionFactory.java:151）位于com.mysql.cj.exceptions.ExceptionFactory.createCommunicationsException（ExceptionFactory.java:167）位于com.mysql.cj.protocol.a.NativeSocketConnection.connect（NativeSocketConnection.java:89）位于com.mysql.cj.NativeSession.connect（NativeSession.java:144）位于com.mysql.cj.jdbc.ConnectionImpl.connectOneTryOnly（ConnectionImpl.java:956）位于com.mysql.cj.jdbc.ConnectionImpl.createNewIO（ConnectionImpl.java:826） ... 还有6个原因：java.net.ConnectException:连接被拒绝：连接位于java.base/sun.nio.ch.Net.connect0（本机方法）位于java.base/sun.nio.ch.Net.connect（Net.java:503）位于java.base/sun.nio.ch.Net.connect（Net.java:492）位于java.base/sun.nio.ch.NioSocketImpl.connect（NioSocketImpl.java:588）位于java.base/java.net.socksocketimpl.connect（socksocketimpl.java:333）位于java.base/java.net.Socket.connect（Socket.java:648）位于com.mysql.cj.protocol.StandardSocketFactory.connect（StandardSocketFactory.java:155）位于com.mysql.cj.protocol.a.NativeSocketConnection.connect（NativeSocketConnection.java:63） ... 9更多进程已完成，退出代码为1 我实际上并没有使用localhost，但我只是用“localhost”替换了真正的地址

MySql正在运行

MySql版本：8.0.21

mysql连接器java版本：8.0.22

也许是防火墙的问题或者其他什么

确保您有一个名为“TelegramBot”的数据库

2.确保MySql服务正在运行。您可以通过在任务管理器中选中“服务”来完成此操作

修改代码：替换此项：

cn=DriverManager.getConnection（“jdbc:mysql://localhost:3306/TelegramBot“，”根“，”密码“）

为此：

String url=“jdbc:mysql://localhost:3306/TelegramBot?useUnicode=true&useJDBCCompliantTimeZoneShift=true&useLegacyDatetimeCode=false&serverTimezone=UTC";

最后我发现这是防火墙的问题，我在vps中解决了它

Exception in thread "main" com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
    at com.mysql.cj.jdbc.exceptions.SQLError.createCommunicationsException(SQLError.java:174)
    at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:64)
    at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:836)
    at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:456)
    at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:246)
    at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:198)
    at java.sql/java.sql.DriverManager.getConnection(DriverManager.java:677)
    at java.sql/java.sql.DriverManager.getConnection(DriverManager.java:228)
    at ConnessioneMySql.main(ConnessioneMySql.java:11)
Caused by: com.mysql.cj.exceptions.CJCommunicationsException: Communications link failure

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
    at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
    at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.base/java.lang.reflect.Constructor.newInstanceWithCaller(Constructor.java:500)
    at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:481)
    at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:61)
    at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:105)
    at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:151)
    at com.mysql.cj.exceptions.ExceptionFactory.createCommunicationsException(ExceptionFactory.java:167)
    at com.mysql.cj.protocol.a.NativeSocketConnection.connect(NativeSocketConnection.java:89)
    at com.mysql.cj.NativeSession.connect(NativeSession.java:144)
    at com.mysql.cj.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:956)
    at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:826)
    ... 6 more
Caused by: java.net.ConnectException: Connection refused: connect
    at java.base/sun.nio.ch.Net.connect0(Native Method)
    at java.base/sun.nio.ch.Net.connect(Net.java:503)
    at java.base/sun.nio.ch.Net.connect(Net.java:492)
    at java.base/sun.nio.ch.NioSocketImpl.connect(NioSocketImpl.java:588)
    at java.base/java.net.SocksSocketImpl.connect(SocksSocketImpl.java:333)
    at java.base/java.net.Socket.connect(Socket.java:648)
    at com.mysql.cj.protocol.StandardSocketFactory.connect(StandardSocketFactory.java:155)
    at com.mysql.cj.protocol.a.NativeSocketConnection.connect(NativeSocketConnection.java:63)
    ... 9 more

Process finished with exit code 1

    cn = DriverManager.getConnection(url, "root", "password");