运行 jdbc 程序时线程“主”java.sql.SQLException 异常？

Question

I have recently started learning JDBC and write a program to create table in a MySQL database, but bad luck I am getting some error or may be exceptions which I am unable to figure it out on my own. I am just a beginner so please help me to get if of this rid.

Below is the program I have written:

package first;
import java.sql.*;
public class Firstclass {

    public static void main(String[] args) throws Exception 
    {
        // TODO Auto-generated method stub
        String driver="com.mysql.jdbc.Driver";
        String JDBC_URL=" jdbc:mysql://localhost:3306/demodatabase";
        String user_name="root";
        String password="toor";
        String sqlquery="create table employee(eno number,ename varchar2(10),esal number(10,2),addr varchar2(10))";
        Class.forName(driver);
        Connection con=DriverManager.getConnection(JDBC_URL,user_name,password);
        Statement st=con.createStatement();
        st.executeUpdate(sqlquery);
        System.out.println("Table created Successfully");
        con.close();
    }

}

I am working on Eclipse IDE. And i have oracle java 14.0.1 installed.

Below is the error/Exceptions I get:

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.
Exception in thread "main" java.sql.SQLException: No suitable driver found for  jdbc:mysql://localhost:3306/demodatabase
    at java.sql/java.sql.DriverManager.getConnection(DriverManager.java:702)
    at java.sql/java.sql.DriverManager.getConnection(DriverManager.java:228)
    at first.Firstclass.main(Firstclass.java:14)

Answer 1

The driver class name was changed to com.mysql.cj.jdbc.Driver in the version that you are using. Since you are trying this out with pure java without maven or gradle you will have to provide all the dependent jars that you are using for this to work yourself. Check the following:

• For your version of the connector mysql-connector-java-8.0.20.jar to work, the java version needs to be java8.
• Verify that Protocol Buffers and Simple Logging Facade API are on the classpath if you are building from source.

You may also need to install the following third-party libraries on your system for Connector/J 8.0 to work: Protocol Buffers (required for using X DevAPI)\ Simple Logging Facade API (required for using the logging capabilities provided by the default implementation of org.slf4j.Logger.Slf4JLogger by Connector/J). These and other third-party libraries are required for building Connector/J from source (see the section for more information on the required libraries).

Also, in the MySql docs they suggest we call newInstance() like this (the documentation doesn't have proper explanation for this):

public class LoadDriver {
    public static void main(String[] args) {
        try {
            // The newInstance() call is a work around for some
            // broken Java implementations

            Class.forName("com.mysql.cj.jdbc.Driver").newInstance();
        } catch (Exception ex) {
            // handle the error
        }
    }
}

Official doc link

Also, since java 6 we need not provide the Class.forName() to load the driver because of the java SPI (Service Provider Interface) mechanism which should automatically detect the appropriate driver. It will still work perfectly even if you provide it like the old way.

The DriverManager methods getConnection and getDrivers have been enhanced to support the Java Standard Edition Service Provider mechanism.

Java official link .