写帖子是为了让更多的程序员减少再调试bug中的时间，也希望大家能一起把自己遇到的错误及解决方法写出来。我是一个刚开始学java的大二学生，用的是《java开发实战经典》。在写p646的程序中一直报错。特贴出来

先把代码发出来

public class ConnectionDemo02 {

//定义MySql的数据库驱动程序

public static final String DBDRIVER="com.mysql.jdbc.Driver";   //错误，应改为com.mysql.cj.jdbc.Driver

//定义MySql数据库的链接地址

public static final String DBURL="jdbc:mysql://localhost:3306/mldn";

//错误，应该改为：jdbc:mysql://localhost:3306/mldn?useSSL=false&serverTimezone=GMT";//定义MySql数据库的连接用户名

public static final String DBUSER="root";

//定义MySql数据库的连接密码

public static final String DBPASS="12315";

public static void main(String[] args)

{

Connection conn=null;

try

{

Class.forName(DBDRIVER);

}catch(ClassNotFoundException e)

{

e.printStackTrace();

}

try

{

conn=DriverManager.getConnection(DBURL, DBUSER, DBPASS);

}catch(SQLException e)

{

e.printStackTrace();

}

System.out.println(conn);

try

{

conn.close();

}catch(SQLException e)

{

e.printStackTrace();

}

}

报错是

Loading class `com.mysql.jdbc.Driver'. This is deprecated. The new driver class is `com.mysql.cj.jdbc.Driver'. The driver is automatically registered via the SPI and manual loading of the driver class is generally unnecessary.

Sat May 05 09:24:57 GMT+08:00 2018 WARN: Establishing SSL connection without server's identity verification is not recommended. According to MySQL 5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by default if explicit option isn't set. For compliance with existing applications not using SSL the verifyServerCertificate property is set to 'false'. You need either to explicitly disable SSL by setting useSSL=false, or set useSSL=true and provide truststore for server certificate verification.

java.sql.SQLException: The server time zone value '???ú±ê×??±??' is unrecognized or represents more than one time zone. You must configure either the server or JDBC driver (via the serverTimezone configuration property) to use a more specifc time zone value if you want to utilize time zone support.

at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:127)

at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:95)

at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:87)

at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:61)

at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:71)

at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:76)

at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:862)

at com.mysql.cj.jdbc.ConnectionImpl.(ConnectionImpl.java:444)

at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:230)

at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:226)

at java.sql.DriverManager.getConnection(DriverManager.java:664)

at java.sql.DriverManager.getConnection(DriverManager.java:247)

at 连接数据库.ConnectionDemo02.main(ConnectionDemo02.java:28)

Caused by: com.mysql.cj.exceptions.InvalidConnectionAttributeException: The server time zone value '???ú±ê×??±??' is unrecognized or represents more than one time zone. You must configure either the server or JDBC driver (via the serverTimezone configuration property) to use a more specifc time zone value if you want to utilize time zone support.

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.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:59)

at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:83)

at com.mysql.cj.util.TimeUtil.getCanonicalTimezone(TimeUtil.java:128)

at com.mysql.cj.protocol.a.NativeProtocol.configureTimezone(NativeProtocol.java:2201)

at com.mysql.cj.protocol.a.NativeProtocol.initServerSession(NativeProtocol.java:2225)

at com.mysql.cj.jdbc.ConnectionImpl.initializePropsFromServer(ConnectionImpl.java:1391)

at com.mysql.cj.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:993)

at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:852)

... 6 more

null

Exception in thread "main" java.lang.NullPointerException

at 连接数据库.ConnectionDemo02.main(ConnectionDemo02.java:36)改正方法在原码有