我正在从事这个Java项目,但我是一名C#开发人员,对环境完全陌生,因此,如果这里有任何真正的基本错误,我深表歉意,我完全同意!
基本上,当在Eclipse中运行时,我的JPA连接工作正常,但只要我编译到。jar我有一个java。lang.NullPointerException。
这是我的代码:
public List<DecUpdate> getDecUpdates() {
EntityManagerFactory conn = null;
EntityManager db = null;
try {
// Connect:
conn = Persistence.createEntityManagerFactory("DatabaseName");
db = conn.createEntityManager();
// Get entities:
String queryString = "select d from DecUpdate d "
+ "where d.Requested >= :from "
+ "and d.Completed is null "
+ "and d.Requested = "
+ "(select max(d1.Requested) from DecUpdate d1 "
+ "where d.Requested >= :from "
+ "and d1.Completed is null "
+ "and d1.GroupId = d.GroupId "
+ "and d1.ServiceId = d.ServiceId) "
+ "and not exists "
+ "(select d2 from DecUpdate d2 "
+ "where d.Requested >= :from "
+ "and d2.Requested > d.Requested "
+ "and d2.GroupId = d.GroupId "
+ "and d2.ServiceId = d.ServiceId) ";
Query query = db.createQuery(queryString);
query.setParameter("from", new Timestamp(new DateTime().minusHours(3).getMillis()));
List<DecUpdate> resultList = query.getResultList();
return resultList;
}
catch (Exception e) {
throw e;
}
finally { // Close context and connection:
db.close();
conn.close();
}
}
这就是我的坚持。xml:
<?xml version="1.0" encoding="UTF-8"?>
<persistence xmlns="http://java.sun.com/xml/ns/persistence" version="2.0">
<persistence-unit name="DatabaseName" transaction-type="RESOURCE_LOCAL">
<exclude-unlisted-classes>false</exclude-unlisted-classes>
<properties>
<property name="javax.persistence.jdbc.driver" value="com.microsoft.sqlserver.jdbc.SQLServerDriver"></property>
<property name="javax.persistence.jdbc.url" value="jdbc:sqlserver://1.1.1.1:1111;DatabaseName=DatabaseName"></property>
<property name="javax.persistence.jdbc.user" value="foo"></property>
<property name="javax.persistence.jdbc.password" value="bar"></property>
<!-- EclipseLink should create the database schema automatically -->
<property name="eclipselink.ddl-generation" value="create-tables" />
<property name="eclipselink.ddl-generation.output-mode" value="database" />
</properties>
</persistence-unit>
</persistence>
我已经尽可能多地阅读了这个主题,但我不明白为什么它在开发环境中工作,但在编译时却不工作。我怀疑我缺乏一些我正在阅读的所有教程所假定的基本知识,但我自自学以来就没有这些知识。
有人愿意指出我的新手错误吗?
编辑:
多亏了@Thomasewin的一些调查,我发现了一个更有用的错误:
org.eclipse.persistence.exceptions.PersistenceUnitLoadingException:
Exception Description: An exception was thrown while trying to load persistence unit at url: rsrc:../
Internal Exception: Exception [EclipseLink-30004] (Eclipse Persistence Services - 2.7.0.v20170811-d680af5): org.eclipse.persistence.exceptions.PersistenceUnitLoadingException
Exception Description: An exception was thrown while processing persistence.xml from URL: rsrc:../
Internal Exception: java.net.MalformedURLException
at...
在我看来,这就像我引用了我的持久性。xml不正确还是什么?它位于src/META-INF文件夹中,是否需要在编译期间将其移动、包含或引用?
