一、報(bào)錯(cuò)問(wèn)題
Caused by: java.lang.ClassNotFoundException: Could not load requested class : com.mysql.jdbc.Driver
二、問(wèn)題背景
新建Java項(xiàng)目,并添加 Hibernate 框架支持,啟動(dòng)測(cè)試(運(yùn)行默認(rèn)的Main類中的main()方法),出現(xiàn)報(bào)錯(cuò)。
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();
}
}
}
項(xiàng)目結(jié)構(gòu)如下圖所示:
三、原因分析
缺少mysql對(duì)應(yīng)版本的驅(qū)動(dòng)包。
四、解決方案
步驟1:去官網(wǎng)下載對(duì)應(yīng)版本的驅(qū)動(dòng),然后解壓得到j(luò)ar包(本文以下載5.1.47版本為例)
官網(wǎng)下載對(duì)應(yīng)版本的驅(qū)動(dòng)(jar包)地址:https://downloads.mysql.com/archives/c-j/
下載后的文件:mysql-connector-java-5.1.47.zip
解壓文件,得到j(luò)ar包:mysql-connector-java-5.1.47.jar
步驟2:將 jar 包導(dǎo)入項(xiàng)目
選擇 mysql-connector-java-5.1.47.jar,如下圖所示。文章來(lái)源:http://www.zghlxwxcb.cn/news/detail-784092.html
添加 mysql-connector-java-5.1.47.jar 之后,如下圖所示。然后點(diǎn)擊“OK”按鈕即可。文章來(lái)源地址http://www.zghlxwxcb.cn/news/detail-784092.html
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