出于测试目的,我编写了非常小的代码,它反复抛出与jdbc驱动程序相关的异常。
package sally;
import org.hibernate.Session;
import org.hibernate.Transaction;
public class MainClass {
public static void main(String args[]){
try{
Session session=HibernateUtil.getSession();
Transaction tx=session.beginTransaction();
Employee ee=new Employee("abx","asd",2000);
session.save(ee);
tx.commit();
}catch(Exception e){
e.printStackTrace();
}
}
}
这是我用于映射的ben / pojo类
package sally;
public class Employee {
private int id;
private String firstName;
private String lastName;
private int salary;
public Employee() {}
public Employee(String fname, String lname, int salary) {
this.firstName = fname;
this.lastName = lname;
this.salary = salary;
}
public int getId() {
return id;
}
public void setId( int id ) {
this.id = id;
}
public String getFirstName() {
return firstName;
}
public void setFirstName( String first_name ) {
this.firstName = first_name;
}
public String getLastName() {
return lastName;
}
public void setLastName( String last_name ) {
this.lastName = last_name;
}
public int getSalary() {
return salary;
}
public void setSalary( int salary ) {
this.salary = salary;
}
}
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD//EN"
"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
<class name="sally.Employee" table="EMPLOYEE">
<meta attribute="class-description">
This class contains the employee detail.
</meta>
<id name="id" type="int" column="id">
<generator class="native"/>
</id>
<property name="firstName" column="first_name" type="string"/>
<property name="lastName" column="last_name" type="string"/>
<property name="salary" column="salary" type="int"/>
</class>
</hibernate-mapping>
这是pojo类的cfg文件:
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="hibernate.connection.url">jdbc:mysql://localhost:3306/test</property>
<property name="hibernate.connection.password"></property>
<property name="hibernate.connection.username">root</property>
<property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
<property name="show_sql">true</property>
<mapping class="sally.Employee"></mapping>
</session-factory>
但每次我运行代码时都会抛出exxception:
log4j:WARN No appenders could be found for logger (org.hibernate.cfg.Environment).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.
org.hibernate.exception.JDBCConnectionException: Cannot open connection
at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:74)
at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:43)
at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:29)
at org.hibernate.jdbc.ConnectionManager.openConnection(ConnectionManager.java:420)
at org.hibernate.jdbc.ConnectionManager.getConnection(ConnectionManager.java:144)
at org.hibernate.jdbc.JDBCContext.connection(JDBCContext.java:119)
at org.hibernate.transaction.JDBCTransaction.begin(JDBCTransaction.java:57)
at org.hibernate.impl.SessionImpl.beginTransaction(SessionImpl.java:1326)
at sally.MainClass.main(MainClass.java:12)
Caused by: java.sql.SQLException: No suitable driver found for jdbc:mysql://localhost:3306/test
at java.sql.DriverManager.getConnection(DriverManager.java:596)
at java.sql.DriverManager.getConnection(DriverManager.java:187)
at org.hibernate.connection.DriverManagerConnectionProvider.getConnection(DriverManagerConnectionProvider.java:110)
at org.hibernate.jdbc.ConnectionManager.openConnection(ConnectionManager.java:417)
... 5 more
任何人都可以在这里说错了吗?
这是db列表:first_name last_name salary。
答案 0 :(得分:1)
您需要将mysql JDBC驱动程序JAR放在类路径
上答案 1 :(得分:0)
“ org.hibernate.exception.JDBCConnectionException:无法打开连接”发生在您尚未启动xampp和MySql时。
答案 2 :(得分:0)
驱动程序类的名称必须以及服务器时区进行更新(对我来说这很疯狂,但必须这样做
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<property name="hibernate.connection.driver_class">com.mysql.cj.jdbc.Driver</property>
<property name="hibernate.connection.url">jdbc:mysql://127.0.0.1:3306/hibernate?serverTimezone=UTC</property>
<property name="hibernate.connection.username">root</property>
<property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
</session-factory>
</hibernate-configuration>