通过在某个包中添加所有类来在 Hibernate 中添加带注释的类。 JAVA

Question

有没有办法循环（例如通过 for）所有包含在某个包中的类？ 我必须在AnnotationConfiguration 上addAnnotatedClass(Class c)。 这样做：

    AnnotationConfiguration annotationConfiguration.addAnnotatedClass(AdditionalInformation.class);
    annotationConfiguration.addAnnotatedClass(AdditionalInformationGroup.class);
    annotationConfiguration.addAnnotatedClass(Address.class);
    annotationConfiguration.addAnnotatedClass(BankAccount.class);
    annotationConfiguration.addAnnotatedClass(City.class);
    //et cetera

我所有的表格都在 Tables.Informations 包中。

Answer 1

以下代码遍历指定包中的所有类，并列出带有“@Entity”注释的类。这些类中的每一个都会添加到您的 Hibernate 工厂配置中，而无需明确列出它们。

public static void main(String[] args) throws URISyntaxException, IOException, ClassNotFoundException {
    try {
        Configuration configuration = new Configuration().configure();
        for (Class cls : getEntityClassesFromPackage("com.example.hib.entities")) {
            configuration.addAnnotatedClass(cls);
        }
        sessionFactory = configuration.buildSessionFactory();
    } catch (Throwable ex) {
        System.err.println("Failed to create sessionFactory object." + ex);
        throw new ExceptionInInitializerError(ex);
    }
}

public static List<Class<?>> getEntityClassesFromPackage(String packageName) throws ClassNotFoundException, IOException, URISyntaxException {
    List<String> classNames = getClassNamesFromPackage(packageName);
    List<Class<?>> classes = new ArrayList<Class<?>>();
    for (String className : classNames) {
        Class<?> cls = Class.forName(packageName + "." + className);
        Annotation[] annotations = cls.getAnnotations();

        for (Annotation annotation : annotations) {
            System.out.println(cls.getCanonicalName() + ": " + annotation.toString());
            if (annotation instanceof javax.persistence.Entity) {
                classes.add(cls);
            }
        }
    }

    return classes;
}

public static ArrayList<String> getClassNamesFromPackage(String packageName) throws IOException, URISyntaxException, ClassNotFoundException {
    ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
    ArrayList<String> names = new ArrayList<String>();

    packageName = packageName.replace(".", "/");
    URL packageURL = classLoader.getResource(packageName);

    URI uri = new URI(packageURL.toString());
    File folder = new File(uri.getPath());
    File[] files = folder.listFiles();
    for (File file: files) {
        String name = file.getName();
        name = name.substring(0, name.lastIndexOf('.'));  // remove ".class"
        names.add(name);
    }

    return names;
}

有用的参考：https://stackoverflow.com/a/7461653/7255

Answer 2

有一个很好的开源包，叫做“org.reflections”。你可以在这里找到它：https://github.com/ronmamo/reflections

使用该包，您可以扫描以下实体：

Reflections reflections = new Reflections("Tables.Informations");
Set<Class<?>> importantClasses = reflections.getTypesAnnotatedWith(Entity.class);
for (Class<?> clazz : importantClasses) {
    configuration.addAnnotatedClass(clazz);
}

Answer 3

如 cmets 中所述，使用 AnnotationConfiguration API 无法实现在包中加载所有类的功能。以下是您可以使用所述 API 执行的一些操作（请注意，“addPackage”方法仅读取包元数据，例如在 package-info.java 类中找到的元数据，它不会加载包中的所有类）：

http://docs.jboss.org/hibernate/annotations/3.5/reference/en/html/ch01.html

sessionFactory = new AnnotationConfiguration()
                    .addPackage("test.animals") //the fully qualified package name
                    .addAnnotatedClass(Flight.class)
                    .addAnnotatedClass(Sky.class)
                    .addAnnotatedClass(Person.class)
                    .addAnnotatedClass(Dog.class)
                    .addResource("test/animals/orm.xml")
                    .configure()
                    .buildSessionFactory();

Answer 4

您可以使用 LocalSessionFactoryBuilder 来构建会话工厂，使您能够指定 scanPackages 属性。

SessionFactory sessionFactory = new LocalSessionFactoryBuilder(hikariDataSource())
        .scanPackages("com.animals.entities")
        .addProperties(properties)
        .buildSessionFactory();