使用的MySQL 8.0版本 ，首先匯入JAR包 右鍵new一個libs的packdge ，把下載好的mysql-connector-java-8.0.13.jar貼上到libs包中，右鍵Build Path選擇的Add buildpath 就會在下面生成referenced libs ，同理刪除jar包右鍵Build Path,選擇Configure Build path選擇romove即可。

第一種錯誤:com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Could not create connection to database server.

然後還需修改第二個地方：
將com.mysql.jdbc.Driver改為com.mysql.cj.jdbc.Driver即可

第二種錯誤：java.sql.SQLException: The server time zone value ‘Öйú±ê׼ʱ¼ä’ is unrecognized or represents more than one time

提示系統時區出現錯誤，可以在mysql中執行命令：
set global time_zone=’+8:00’
或者在url 中新增 serverTimezone=UTC
如果只是第一個引數，應寫成
url = “jdbc:mysql://localhost:3306/qlgydx?serverTimezone=GMT”

package jdbc;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.Statement;

public class DjbcDemo1 {

    
 
public static void main(String[] args) throws Exception {
        // TODO Auto-generated method stub
        //1.匯入驅動jar包
        //2.註冊驅動
        Class.forName("com.mysql.cj.jdbc.Driver");
        System.out.println("資料庫驅動載入成功!");
        //3.獲取資料庫的連線物件
        Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/db3?serverTimezone=GMT", "root", "123456");
        System.out.println("資料庫連線成功!");
        //4.定義sql語句
        String sql ="update stu set balance =1000 where id =1";
        //5.獲取執行sql的物件 Statement
        Statement stmt = conn.createStatement();
        //6.執行sql
        int count = stmt.executeUpdate(sql);
        //7.處理結果
        System.out.println(count);
        //8.釋放資源
        stmt.close();
        conn.close();
    }

}
下面還出現了一堆紅字 我還以為是又報錯了呢 = = 

資料庫驅動載入成功!
資料庫連線成功!
1
Fri Jul 24 16:17:54 CST 2020 WARN: Caught while disconnecting...

EXCEPTION STACK TRACE:



** BEGIN NESTED EXCEPTION ** 

javax.net.ssl.SSLException
MESSAGE: closing inbound before receiving peer's close_notify

STACKTRACE:

javax.net.ssl.SSLException: closing inbound before receiving peer's close_notify
    at java.base/sun.security.ssl.Alert.createSSLException(Alert.java:133)
    at java.base/sun.security.ssl.Alert.createSSLException(Alert.java:117)
    at java.base/sun.security.ssl.TransportContext.fatal(TransportContext.java:311)
    at java.base/sun.security.ssl.TransportContext.fatal(TransportContext.java:267)
    at java.base/sun.security.ssl.TransportContext.fatal(TransportContext.java:258)
    at java.base/sun.security.ssl.SSLSocketImpl.shutdownInput(SSLSocketImpl.java:801)
    at java.base/sun.security.ssl.SSLSocketImpl.shutdownInput(SSLSocketImpl.java:780)
    at com.mysql.cj.protocol.a.NativeProtocol.quit(NativeProtocol.java:1312)
    at com.mysql.cj.NativeSession.quit(NativeSession.java:182)
    at com.mysql.cj.jdbc.ConnectionImpl.realClose(ConnectionImpl.java:1750)
    at com.mysql.cj.jdbc.ConnectionImpl.close(ConnectionImpl.java:720)
    at jdbc.DjbcDemo1.main(DjbcDemo1.java:28)


** END NESTED EXCEPTION **