oracle 获取 JPA 中的命名查询字符串
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Get the named query string within JPA
提问by Prashanth
I am trying to externalize all named queries for JPA in an orm.xml file. I would like to get the named query string in my Java program for some manipulation purposes but JPA doesnt seem to expose any method that returns the named query as a string. All I can do is createNamedQuerywith the name of the named query.
我正在尝试在 orm.xml 文件中外部化 JPA 的所有命名查询。我想在我的 Java 程序中获取命名查询字符串以用于某些操作目的，但 JPA 似乎没有公开任何将命名查询作为字符串返回的方法。我所能做的就是createNamedQuery使用命名查询的名称。
Is there any other way around this problem to get the named query string like Hibernate exposes ? Similar to getSession().getNamedQuery("namedQueryName");in JPA?
有没有其他方法可以解决这个问题来获取像 Hibernate 公开这样的命名查询字符串？类似于getSession().getNamedQuery("namedQueryName");在 JPA 中？
Thanks, Sonu.
谢谢，索努。
回答by axtavt
If you actually need, you can always access provider-specific classes via JPA (with unwrap()in JPA 2.0, or with downcasting in previous versions):
如果您确实需要，您始终可以通过 JPA 访问特定unwrap()于提供程序的类（在 JPA 2.0 中，或在以前的版本中向下转换）：
String s = em.createNamedQuery("...")
.unwrap(org.hibernate.Query.class)
.getQueryString();
回答by alessandro
oh well you can use introspection to get named queries annotations like:
哦，您可以使用自省来获取命名查询注释，例如：
String getNamedQueryCode(Class<? extends Object> clazz, String namedQueryKey) {
NamedQueries namedQueriesAnnotation = clazz.getAnnotation(NamedQueries.class);
NamedQuery[] namedQueryAnnotations = namedQueriesAnnotation.value();
String code = null;
for (NamedQuery namedQuery : namedQueryAnnotations) {
if (namedQuery.name().equals(namedQueryKey)) {
code = namedQuery.query();
break;
}
}
if (code == null) {
if (clazz.getSuperclass().getAnnotation(MappedSuperclass.class) != null) {
code = getNamedQueryCode(clazz.getSuperclass(), namedQueryKey);
}
}
//if not found
return code;
}
