持久性提供者未發現異常

Question

嘿，我得到一個持久性提供未發現異常爲我的persistence.xml代碼

<?xml version="1.0" encoding="UTF-8"?> 
<persistence version="2.0" 
xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd"> 
<persistence-unit name="GWTSales" 
    transaction-type="RESOURCE_LOCAL"> 
    <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider> 
    <class>com.jeroennouws.sales.beans.Branch</class> 
    <class>com.jeroennouws.sales.beans.Customer</class> 
    <class>com.jeroennouws.sales.beans.Employee</class> 
    <class>com.jeroennouws.sales.beans.Product</class> 
    <class>com.jeroennouws.sales.beans.Purchase</class> 
    <class>com.jeroennouws.sales.beans.PurchaseDetail</class> 
    <class>com.jeroennouws.sales.beans.PurchaseDetailPK</class> 
    <class>com.jeroennouws.sales.beans.Sale</class> 
    <class>com.jeroennouws.sales.beans.SalesDesk</class> 
    <class>com.jeroennouws.sales.beans.SalesDetail</class> 
    <class>com.jeroennouws.sales.beans.SalesDetailPK</class> 
    <class>com.jeroennouws.sales.beans.Stock</class> 
    <class>com.jeroennouws.sales.beans.Supplier</class> 
    <class>com.jeroennouws.sales.beans.User</class> 
    <properties> 
     <property name="eclipselink.jdbc.password" value="" /> 
     <property name="eclipselink.jdbc.user" value="root" /> 
     <property name="eclipselink.jdbc.driver" value="com.mysql.jdbc.Driver" /> 
     <property name="eclipselink.jdbc.url" value="jdbc:mysql://localhost:3306/sales" /> 
     <property name="eclipselink.logging.level" value="INFO" /> 
    </properties> 
</persistence-unit> 
</persistence> 

和產生這種異常的代碼是

public BranchJpaController() { 
    emf = Persistence.createEntityManagerFactory("GWTSales"); 
} 

我已經嘗試過所有不同類型的東西了，eclipselink jar文件位於我的WEB-INF/lib文件夾中，我的persistence.xml文件位於我的src/META-INF文件夾中。 這是否與eclipse插件中的GWT Jetty服務器有關或者我錯過了什麼？

Answer 1

檢查MySQL JDBC驅動程序是否在您的WEB-INF/lib文件夾中。

我希望它有幫助。