Caused by: java.lang.ClassNotFoundException: Could not load requested class : com.mysql.jdbc.Driver
作者:mmseoamin日期:2023-12-25

一、报错问题

Caused by: java.lang.ClassNotFoundException: Could not load requested class : com.mysql.jdbc.Driver

Caused by: java.lang.ClassNotFoundException: Could not load requested class : com.mysql.jdbc.Driver,在这里插入图片描述,第1张

二、问题背景

新建Java项目,并添加 Hibernate 框架支持,启动测试(运行默认的Main类中的main()方法),出现报错。

Main.java

import org.hibernate.HibernateException;
import org.hibernate.Metamodel;
import org.hibernate.query.Query;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
import javax.persistence.metamodel.EntityType;
import java.util.Map;
public class Main {
    private static final SessionFactory ourSessionFactory;
    static {
        try {
            Configuration configuration = new Configuration();
            configuration.configure();
            ourSessionFactory = configuration.buildSessionFactory();
        } catch (Throwable ex) {
            throw new ExceptionInInitializerError(ex);
        }
    }
    public static Session getSession() throws HibernateException {
        return ourSessionFactory.openSession();
    }
    public static void main(final String[] args) throws Exception {
        final Session session = getSession();
        try {
            System.out.println("querying all the managed entities...");
            final Metamodel metamodel = session.getSessionFactory().getMetamodel();
            for (EntityType entityType : metamodel.getEntities()) {
                final String entityName = entityType.getName();
                final Query query = session.createQuery("from " + entityName);
                System.out.println("executing: " + query.getQueryString());
                for (Object o : query.list()) {
                    System.out.println("  " + o);
                }
            }
        } finally {
            session.close();
        }
    }
}

项目结构如下图所示

Caused by: java.lang.ClassNotFoundException: Could not load requested class : com.mysql.jdbc.Driver,在这里插入图片描述,第2张

三、原因分析

缺少mysql对应版本的驱动包。

四、解决方案

步骤1:去官网下载对应版本的驱动,然后解压得到jar包(本文以下载5.1.47版本为例)

官网下载对应版本的驱动(jar包)地址:https://downloads.mysql.com/archives/c-j/

Caused by: java.lang.ClassNotFoundException: Could not load requested class : com.mysql.jdbc.Driver,在这里插入图片描述,第3张

下载后的文件:mysql-connector-java-5.1.47.zip

Caused by: java.lang.ClassNotFoundException: Could not load requested class : com.mysql.jdbc.Driver,在这里插入图片描述,第4张

解压文件,得到jar包:mysql-connector-java-5.1.47.jar

Caused by: java.lang.ClassNotFoundException: Could not load requested class : com.mysql.jdbc.Driver,在这里插入图片描述,第5张

步骤2:将 jar 包导入项目

Caused by: java.lang.ClassNotFoundException: Could not load requested class : com.mysql.jdbc.Driver,在这里插入图片描述,第6张

Caused by: java.lang.ClassNotFoundException: Could not load requested class : com.mysql.jdbc.Driver,在这里插入图片描述,第7张

选择 mysql-connector-java-5.1.47.jar,如下图所示。

Caused by: java.lang.ClassNotFoundException: Could not load requested class : com.mysql.jdbc.Driver,在这里插入图片描述,第8张

添加 mysql-connector-java-5.1.47.jar 之后,如下图所示。然后点击“OK”按钮即可。

Caused by: java.lang.ClassNotFoundException: Could not load requested class : com.mysql.jdbc.Driver,在这里插入图片描述,第9张